Seismic Hazard Assessment of Eastern Salt Range, Pakistan Submitted by Ahsan Ul Haq Under the Supervision of Prof. Dr. Muhammad

Home , Jalalpur Sharif, Palaeochoerus, Wagh

Seismic Hazard Assessment of Eastern Salt Range, Pakistan

Submitted by

Ahsan Ul Haq

Under the supervision of

Prof. Dr. Muhammad Nawaz Chaudhry

Prof. Dr.Jean-Pierre BURG

Thesis submitted for the Partial Fulfillment of the

requirement for the degree of

Doctor of Philosophy

College of Earth & Environmental Sciences

University of the Punjab, Lahore

(2015)

Dedication

I dedicate this thesis to my beloved mother who gave me

affection and encouragement in every sphere of life

Certificate of Approval

This thesis by Ahsan ul Haq is hereby approved for submission to the University of the Punjab, Lahore for the partial fulfillment of the requirement for the degree of Doctor of Philosophy in Earth Sciences (Geology).

Dr. Muhammad Nawaz Ch. (PhD, F.P.A.S) Prof. Dr. Jean-Pierre Burg Professor Emeritus, Director, College of Earth and D-ERDW-Institute of Geology, Environmental Sciences, CH-8092 Zurich Quaid-e-Azam Campus, ETH-Zurich - Sonnegstrasse, 5, University of the Punjab, Switzerland. Lahore.

Seismic Hazard Assessment of Eastern Salt Range, Pakistan

Ahsan ul Haq

Abstract

This research investigates neotectonics and seismic risk assessment for the future development in the light of historic recorded earthquakes that caused a huge damage to human life and property. With the help of recent data, geological and neotectonic interpretations were carried out and high seismic areas have been identified. Computer modeling studies with the use of historic and recent seismic data provided peak ground acceleration, peak ground velocity and maximum credible earthquake of the investigated area. This present study indicates that Peak Ground Acceleration (PGA) for soil and rock is 268 gals (0.26 g). Maximum Credible Earthquake (MCE) includes both the low and high values of Peak Ground Acceleration (PGA) which in the context of Joggi Tilla fault and Tilla range fault are 0.26 g and 0.15 g respectively.

The study of earthquake ground motions and associated earthquake hazards and risks plays an important role in the sustainable development of countries like Pakistan, where devastating earthquakes have occurred repeatedly. The devastating earthquake of 8th October, 2005 in Kashmir and adjacent areas produced good neotectonic features on mesoscopic to regional scale therefore, resulting in drawing attention of the worldwide geoscientific researchers.

This present study is particularly valuable as it contributes to mitigation of earthquake risk as well as post-earthquake management of the disasters. The study is in particular concerned with obtaining an estimate of the ground motion parameters of the study area for the purpose of earthquake resistant design or seismic safety assessment.

Lithology, neotectonics and seismic behavior of the Eastern Salt Range was studied. For this purpose, the field analysis of complemented Geological, historical and instrumental earthquake data was carried out. The continuing collision between the Eurasian and Indian plates resulted in compressional forces in the North – West Himalayan Fold and Thrust Belt. Neotectonic features of the study area were studied using satellite image analysis and field observations. Tilting of recent sediments pattern was used as an indicator of neotectonic activity within the study area on satellite images. Field evidences of neotectonic activity along faults present in the study area include, tilting of quaternary sediments, stream offset and dissected sedimentation bars. Another characteristics feature is the change in topographic relief across the trace of fault.

The Eastern Salt Range experienced 190 earthquakes of magnitude 1 to 3.9, 13 earthquakes of magnitude 4.00 to 4.9 and only four events of magnitude from 5.00 to 5.9. On the basis of historical and instrumental records, the area has not experienced moderate to large earthquakes. The investigated area is a part of eastern margin of Salt Range and consists of number of faults. The seismogenic sources and active faults of this zone are Salt Range Thrust, ChoaSayyaidan Shah Fault, KallarKahar Fault, Jhelum Fault, Joggi Tilla fault and Tilla Range faults etc.

In the present study an attempt has been made, for the first time, to identify the surface/subsurface structural pattern for the area of Eastern Salt Range with the help of seismotectonics and neotectonics studies / techniques that are widely known for interpreting structural traps at depth and movements in faults. For this purpose all available earthquake data (during 0900-2008) from international seismological networks and the local seismic observatories have been collected for the compilation of seismicity map of the area.

Acknowledgments

I am greatly thankful to my honorable and most respected supervisor Prof. Dr. Muhammad Nawaz Chaudhry Professor Emeritus, University of the Punjab, Lahore, who took great pain in the field work and research work, extending every possible facility and vast splendid research experience to solve various problems relating to the research work. His personal and professional advice, moral and administrative support may also not be left unmentioned in this regard.

Next, I would like to thank my supervisor Prof. Dr. Jean-Pierre Burg, Director, Institute of Geology, ETH-Zurich, Switzerland, for his enthusiasm and interest in my work, for his patience and support during writing and documentation of the research, for his constant support, for taking time for the many constructive discussions.

I would like to pay my heartiest tribute to officers of Geological Survey of Pakistan, Pakistan Atomic Energy Mineral Centre Lahore, Pakistan Meteorological Department Islamabad, Pakistan Council for Research in Water Resources, Quaid-e- Azam University Islamabad, University of Peshawar, University of Engineering and Technology Lahore, University of the Punjab Lahore, Pakistan etc., for their cooperation and permission to use data from various Geological and Engineering Seismological Technical Reports.

I am deeply grateful to Dr. Ch. Muzaffar Majid and Mr. Imran, College of Earth and Environmental Sciences, University of the Punjab, Lahore and my dear fellows Mr. Kashif Butt, Mr. Kamran Bashir,Mr. Shah Alam and Mr. Shafique for their great cooperation.

Above all, I am grateful to my family for sparing me during the time when my attention towards domestic affairs was urgently required, especially to my mother for her moral support, encouragement and prayers.

May ALLAH bless all those who help me in the duration of my educational career

SEISMIC HAZARD ASSESSMENT OF EASTERN SALT RANGE, PAKISTAN

Contents

Page Number Abstract Acknowledgements List of Figures...... i List of Tables ...... viii List of Maps ...... ix

Chapter One Introduction

1. Introduction ...... 1 1.2 Location and Accessibility ...... 2 1.3 Physiography ...... 3 1.4 Scope of the Work ...... 5 1.5 Objective of the Study ...... 7 1.6 Previous Work ...... 7 1.7 National Data ...... 8 1.7.1 Geological Survey of Pakistan ...... 8 1.7.2 The PMD Historical Database ...... 8 1.7.3 Hydrocarbon Development Institute of Pakistan ...... 9 1.8 International Data ...... 9 1.8.1 The USGS Historical Database...... 9 1.8.2 The ISC Instrumental Database ...... 9 1.8.3 The Harvard Instrumental Database ...... 10 1.8.4 The PDE-NEIC Database ...... 10 1.9 Literature Review ...... 10 1.10 Work Plan and Methodology ...... 13 1.11 Organization of the Thesis ...... 14

Chapter Two Stratigraphy

2. Stratigraphy ...... 21 2.1 Geological Mapping ...... 21 2.2 Regional Stratigraphy of the Study Area ...... 23 2.3 Salt Range Formation ...... 28 2.3.1 Sahiwal Marl Member ...... 28 2.3.2 Bhandar Kas Gypsum Member...... 28 2.3.3 Billianwala Salt Member ...... 29 2.4 Cambrian ...... 29 2.4.1 Khewra Sandstone ...... 30 2.4.2 Jutana Formation ...... 30 2.4.3 Kussak Formation ...... 31 2.4.4 Baghanwala Formation ...... 32 2.5 Carboniferous - Permian ...... 33 2.5.1 Nilawahan Group ...... 33

2.5.2 Tobra Formation ...... 34 2.5.3 Dandot Formation ...... 35 2.5.4 Warchha Sandstone...... 35 2.5.5 Sardhai Formation ...... 36 2.6 Paleocene ...... 37 2.6.1 Indus Basin ...... 37 2.6.2 Upper lndus Basin ...... 37 2.6.3 Makarwal Group ...... 37 2.6.4 Patala Formation ...... 37 2.6.5 Lockhart Limestone ...... 37 2.6.6 Hangu Formation ...... 39 2.7 Eocene ...... 40 2.7.1 Chharat Group ...... 40 2.7.2 Chorgali Formation ...... 40 2.7.3 Nammal Formation ...... 41 2.7.4 Sakesar Limestone ...... 41 2.8 Rawalpindi Group ...... 42 2.8.1 Kamlial Formation ...... 42 2.8.2 Murree Formation ...... 43 2.9 Siwalik Group ...... 45 2.9.1 Chinji Formation ...... 45 2.9.2 Nagri Formation...... 46 2.9.3 DhokPathan Formation ...... 47 2.9.4 Soan Formation ...... 48 2.10 Quaternary ...... 49 2.10.1 Pleistocene ...... 49 2.10.2 Lei Conglomerate ...... 49

Chapter Three Tectonics

3 Tectonics ...... 52 3.1 Regional Tectonics ...... 52 3.2 The Salt Range ...... 54 3.3 Active Thrust System of the Salt Range ...... 55 3.4 Near Regional Tectonics ...... 56 3.5 Structural Geology ...... 58 3.6 Main Boundary Thrust (MBT) ...... 60 3.7 Potwar Plateau Framework ...... 61 3.8 Salt Range and Kirana Hills...... 62 3.9 The Hazara Kashmir Syntaxis and Jhelum Fault ...... 63 3.10 Dill Jabba Fault ...... 64 3.11 Jhelum Fault ...... 64 3.12 Structural Geology of Specific Study Area ...... 65

Chapter Four Neotectonics

4. NeoTectonics ...... 95 4.1 Regional Neotectonics ...... 97 4.2 Near Regional Area Neotectonics ...... 98

4.3 Local NeoTectonics ...... 99

Chapter Five Seismicity and Seismic Risk Evaluation

5. Seismicity ...... 144 5.1 Historical Seismicity ...... 145 5.2 Eastern Potwar and Salt Range ...... 145 5.3 Central Salt Rang-Potwar...... 146 5.4 Kashmir Hills ...... 146 5.5 Punjab Plains...... 147 5.6 Seismotectonic Zoning ...... 147 5.7 Regional Seismotectonic Belts ...... 148 5.8 SeismoTectonic Zones of Pakistan...... 148 5.9 Seismicity of Near Regional Area ...... 149 5.10 Seismicity of Study Area ...... 150 5.11 Seismotectonics of Pakistan...... 150 5.12 Seismology of the Study Area ...... 151 5.13 Earthquake Information ...... 152 5.14 The USGS Historical Database ...... 152 5.15 The PMD Historical Database ...... 152 5.16 The ISC Instrumental Database ...... 153 5.17 The Harvard Instrumental Database ...... 153 5.18 The PMD Instrumental Database ...... 154 5.19 Assessment of Seismic Risk ...... 178 5.20 Seismogenic Sources ...... 178 5.21 Capable Faults ...... 179 5.22 Other Seismogenic Sources ...... 181 5.23 Seismogenic Sources of Study Region ...... 182 5.24 Diffused Seismicity and Floating Earthquake ...... 183 5.25 Seismic Risk Evaluation ...... 184 5.26 Seismogenic Faults of the Area ...... 185 5.27 Maximum Potential Earthquake ...... 186 5.28 Campbell (1997) ...... 186 5.29 Evaluation of Peak Ground Acceleration...... 187 5.30 Sadigh (1997) ...... 187 5.31 Abrahamson and Silva (1997) ...... 188

Chapter Six SUMMARY, CONCLUSIONS AND RECOMMENDATIONS203

References ...... 207 Publication ...... 230

List of Figures

Page Number

Chapter One Introduction

Figure 1.1 Location epicenters of some Major Earthquake in the Region ...... 18 Figure 1.2 Location Map of Study Area ...... 16 Figure 1.3 Satellite view and Physiographic expression of study Area ...... 17 Figure 1.4 Salt Range and adjacent Tectonic Feature ...... 18 Figure 1.5 Geological sketch map of present study area, modified from Gee (1980), of eastern of eastern Salt Range, showing S-bend at Jalalpur north to Chambal Ridge (south of bunha River) and JogiTilla anticline (north of Bunha River). Rawalpindi Group includes Muree and Kamlial Formations (Shah 1977). Lower Siwalik is subdivided into Chinji, nagri, and DhokPathan Formation ...... 19 Figure 1.6 Structural Feature around the study Area ...... 20

Chapter Two Stratigraphy

Figure 2.1 Diagrammatic illustration of the major unconformities in the Ecoambrain to Tertiary sequence of the Salt Range - Surghar Range...... 51

Chapter Three Tectonics

Figure 3.1 Map of Aisa showing topographic and major faults. The two belts, zagros and Himalaya, lie adjacent to stable regions of Arabia and India, where elevation are low, and to higher terrain in the Iranian Plateau, northeast of the Zagros, and in the Tibetan Plateau north and east of the Himalaya. Both plateaus are bounded on their other sides by mountain belts. Tibet is notable higher than Iran, and high terrain extends much farther much farther north and northeast of Tibet than it does from Iran...... 69 Figure 3.2 Regional Tectonic Map of Pakistan and Surrounding ...... 70

Figure 3.3 The Indian plate colliding with the Eurasian plate...... 71

Figure 3.4 The tectonic plate are delineated by the mid-oceanic ridges, trenches and transfor fault that form their boundaries ...... 72 Figure 3.5 Regional plate tectonic setting...... 73 Figure 3.6 Structural sketch map of the western Himalaya, HKS-Hazara-Kashmir Syntaxis; NGT-NathiaGali Thrust ...... 74 Figure 3.7 Section to show the distribution of deep earthquakes related to PAMIR-HINDUKUSH Continental Subduction...... 75 Figure 3.8 Structural cross of North West Pakistan ...... 76 Figure 3.9 Regional location map showing the proximity of the Salt Range (SR) and Potwar plateau (PP) to the main Himalayan Range. Note the gently accurate nature of the main Himalaya in India and Nepal compared to the highly festooned foreland of the Pakistani Himalaya. Also note the sharp bend in structural trends around the hazara Kashmir syntaxis (Hks), just east of the SR/PP. Area shown by bold rectangle. Other abbreviations: ISZ=Indus Suture Zone, JR=Jhelum Reentrant, KF=Kalabaghdault, MBT=Main Boundary thrust, MCT=Main Central thrust, MFF=Main Frontal fault, MKT=Main Karakoram thrust, MMT=Main Mantle thrust, SH=Sargodha High, and SRT=Salt Range thrust ...... 77 Figure 3.10 Generalized map of the upper Indus sub-basin, showing geologic and tectonic features in the potwar, Kohat, Bannu and Mianwali Re-entrant Area ...... 78 Figure 3.11 Interpreted Cross Section Across The Western Salt Range, Potwar Plateau ...... 79 Figure 3.12 Interpreted Cross Section across the Central Salt Range, Potwar Plateau ...... 80 Figure 3.13 (Blank) ...... 81 Figure 3.14 Satellite Image of the study area ...... 82 Figure 3.15 (Blank) ...... 83

Figure 3.16 Interpreted Cross Section across the Eastern Salt Range, Potwar Plateau ...... 84

Figure 3.17 Sketch Fault related topographic fronts ...... 85 Figure 3.18 Fault Propagation geometry of Eastern Salt Range / Potwar Plateau ...... 86 Figure 3.19 Structural Map of Potwar Plateau showing the regional trend of anticlines ...... 87 Figure 3.20 Top: Section across the southeastern fold-an-thrust belt of the Pakistani Himalaya. Location on Figure-3.6. Below: Pseudo template reconstruction. Decisions concerning reconstruction are discussed in the text. Dashed lines are tentative locations of unexposed flats in a thin-skin tectonics interpretation ...... 88 Figure 3.21 Frontal emergence of the MBT separating southward dipping MurreeMolasse sediments of the southward limb of a (ramp) anticline from underlying flat and shallow dipping Molasse beds (par-autochthonous). Note the south-dipping topography marking the southern front of the fold-and-thrust belt of the Western Himalayas. GholaGali ...... 89 Figure 3.22 Structural map of Chamble Ridge-Study area ...... 90 Figure 3.23 Kahankas Fault zone exposed along Waghh Road (North faces camera) ...... 91 Figure 3.24 Highly Crushed Rock along Khan KAS Fault ...... 91 Figure 3.25 Explanation of the terminology used for the different stratigraphic units and structural features in this study. Note that thick salt pad forms the wedge shaped geometry due to the buttressing effects of the northern ramp localized by the basement normal fault. Also note the deformational style of the roof sequence into sharp, salt cored anticlines and broad, flat based synclines ...... 92 Figure 3.26 Schematic diagram showing the successive development ofDilJabba fault. Note that the roof sequence kept on moving forward and only a part of the deformation has been accommodated along the back thrust. Also note that gradual development of a salt wedge in the footwall of the back thrust that altered the geometery of the footwall...... 93 Figure 3.27 Figure showing the Geological Provinces ...... 94

Chapter Four Neotectonics

Figure 4.1 The older rocks are abruptly truncated against Punjab alluvial of recent age, SR = Salt Range,

PP= Punjab Plain, CR=Chambel Ridge ...... 103 Figure 4.2 The older rocks are abruptly truncated against Punjab alluvial of recent age near Jalalpur Village ...... 104 Figure 4.3 Tilting and offset in Recent Sediments Silt / Gravel (Siwaliks) sequence indicating Tectonic activity in ESR near JalalPur Sharif ...... 105 Figure 4.4 Discontinuity of Silt Bed against Gravies Indicating Reverse Fault Indicating Recent Tectonic. Activity in the Area with Throw of About Meter Near, Eastern Salt Range ...... 106 Figure 4.5 Tilting In Recent Silty Clay and Gravelly Beds Near Khewera Village Indicating Recent Tectonic activities in The Area ...... 107 Figure 4.6 Tilting and fracturing within Sub recent to recent silt / gravel sequence indicating Tectonic activity, near Khewera village ...... 108 Figure 4.7 Strong Shearing and Fracturing with in Sub Recent to Recent Silt / Gravel Sequence near Khewera Village ...... 109 Figure 4.8 Tilted Recent deposits lying over Miocene Sandstone in Dag Kas Area ...... 110 Figure 4.9 Sand dyke in Potwar silt / recent deposits near DagKasArea...... 111 Figure 4.10 Fractured silt lying over the concealed trace of Wagh thrust near Dag Kas Area ...... 112 Figure 4.11 Figure showing BhunaKas Fault with in Siwaliks near Chamble ridge, Jalalpur Sharif ...... 113 Figure 4.12 Recent and Sub Recent sediments are tilted in Nathial and PirChak area ...... 114 Figure 4.13 Tilted Potwar Silt Sediment Tilted / Silt (Sediment/Sub Recent) Over Concealed Fault of Near PirChak Area ...... 115 Figure 4.14 Tilted Potwar silt along over concealed fault, near Nathial Village ...... 116 Figure 4.15 A minor neotectonic fault in the recent silt lying close to Wagh Thrust...... 117 Figure 4.16 Shear Fractures with minor offsets in

Recent Silt near Wagh Thrust...... 118 Figure 4.17 Shear fractures in recent silt with minor offset near Wagh Village ...... 119 Figure 4.18 Shear Fracture and minor offset in the Potwar silt (about 5 cm). The small sticks

indicating the offset near Wagh Village ...... 120 Figure 4.19 Sand bed displaced by a minor fault in the recent silt near Wagh Village ...... 121 Figure 4.20 Tilted Recent Silt along Wagh Thrust near Wagh village...... 122 Figure 4.21 KahanKas Fault zone along WaghRaod ...... 123 Figure 4.22 Tilted Recent Silt and Gravel bed near DhokKhair Thrust at ChakShadman ...... 124 Figure 4.23 Recent Silt in Faulted Contact with sub recent Conglomerates along DhokKhair Thrust near south of ChakShadman ...... 125 Figure 4.24 Undistrubed recent sediments (Silt) lying over gently dipping upper Siwaliks, Wagh Village.The upper siwaliks do not show effect of brittle deformation ...... 126 Figure 4.25 Joint sets in recent silts indicating tectonic activities in the area of Hun village near JogiTilla ...... 127 Figure 4.26 Undeformed Recent Sediments lying over a fault in Siwalikes, near Wagh Village ...... 128 Figure 4.27 Undisturbed Recent Silt near DhokNathial village ...... 129 Figure 4.28 Horizontally deposited undeformed silt near DhokNathial village ...... 130 Figure 4.29 Horizontally deposited undeformed Recent Deposits near DhokNathial ...... 131 Figure 4.30 Lateral tiling of joints in silt near Village Jalalpur Sharif ...... 132 Figure 4.31 Cavity in Recent Silt near KahanKas formed by Water Percolation through the Shear Fracture ...... 133 Figure 4.32 Tilt in recent silts along wagh fault in the north Jalalpursharif...... 134 Figure 4.33 Tilted upper Siwaliks along DhokKhair thrust...... 135 Figure 4.34 Scarp of Diljabba Fault near Domeli Village ...... 136 Figure 4.35 Tilted Recent/ Sub Recent Sediments/ Silt Over Concealed Jhelum fault near Jhelum City ...... 137 Figure 4.36 Highly Tilted and Sheared Silts along Jhelum Fault near Dina City ...... 138

Figure 4.37 Tilting of recent terraces and breakage of pebbles along Jhelum Fault ...... 139 Figure 4.38 Highly disturbed and tilted recent sediments nala in close vicinity of Diljabba Fault ...... 140 Figure 4.39 Tectonic fracture in the recent silt, pencils are lying in the direction of fracture Along

Wagh thrust near Jalalpursharif ...... 141 Figure 4.40 Limestone abruptly truncating against recent silt along ChoaSaidan Shah fault near Padrar Village ...... 142 Figure 4.41 SR/PP is generally asesimic due to salt as compared to foreland deformation in India ...... 143

Chapter Five Seismicity and Seismic Risk Evaluation

Figure 5.1 Modern seismicity of central Pakistan CF=Chaman Fault GF=Gardez fault, HF=Hearat fault, HM=Himalaya ranges, HS=Hazara Kashmir Syntaxis, KF=Kunar fault, QTZ=Quetta Transverse Zone, S=Sulaiman range, SKF=Safed-Koho fault, SR=Salt range, GLT=Gilgit, JLD=jalalabad, Lah=Lahore, RWP=Rawalpindi ...... 194 Figure 5.2 Epicentral data of salt range-potowar recorded by mssp from 1976 to 2002. The filled triangles are seismic stations. The site area is marked by microseismic earthquake events of magnitude > 2.9...... 195 Figure 5.3 Regional seismogenic zones ...... 196 Figure 5.4 Seismotectonic provinces of Pakistan. The heavy lines outline the various seismotectonic provinces. The numbers correspond to the embered section in the text. The circular symbols in region 1 represent centers of quaternary volcanism. The bathymetric contour in the Arabian Sea represents a 2 km depth ...... 197 Figure 5.6 Seismicity of the region (Map with the 19 zones overlaid in Google Earth) ...... 198 Figure 5.7 Seismic Zones of Pakistan as used in the present study ...... 199 Figure 5.8 Seismicity of the study region according to the PDE-catalogue ...... 200

Figure 5.9 Earthquakes epicenters shown in red circles (from the ISC-catalogue)...... 201 Figure 5.10 Earthquakes with magnitudes M > 5.0 (red circles) according to the Harvard catalogue...... 202

List of Tables

Page Number

Chapter Two Stratigraphy

Table 2.1 Regional Stratigraphic Succession around

the study Area ...... 26 Table 2.2 Stratigraphic Succession and Seismic velocity of various rock units of Salt Range ...... 50

Chapter Five Seismicity and Seismic Risk Evaluation

Table5.1 Historical Non Instrumental Seismic Data of Northern Part of Pakistan (Around Study Area) ...... 155 Table 5.2 Historical Earthquakes as Collected by Pakistan Meteorological Department ...... 159 Table 5.3 Seismic Events Occurred Around Study Area ...... 168 Table 5.4 Determination of Maximum Potential Magnitude ...... 192 Table 5.5 Peak Ground Accelerations (Horizonal) Due To Different Seismogenic Structure / Faults ...... 193

List of Maps

Map 1 Regional Seismic, Tectonic and Structural Map of The Study Area

Map 2 Litholo Structural Map of The Study Area

Map 3 Geological Map of The Study Area

Chapter One INTRODUCTION

1. Introduction

Innumerable natural and anthropogenic calamities have shaken mankind. The natural afflictions / disasters have cost dearly in terms of lives lost and damage to property. Earthquakes are one group of such calamities that occur suddenly and very often without a warning and last only for a few seconds, the strongest ones are known to have caused colossal damage and wiped out several cultures and civilizations (Ambraseys, et al. 2004).

Pakistan is placed in a seismically highly active region with many disastrous earthquakes which have been documented during historical period (Kazmi, 1982). The earthquakes documented during the last five decades include the 1945 Makran coast earthquake with magnitude 8.01, the Mach earthquake of August 1931, M 7.3, the Quetta earthquake in 1935, M 7.4 and the Pattan earthquake in 1974, M 6.0 (Figure-1.1). The disastrous Muzaffarabad earthquake of 8th October 2005 with magnitude 7.6 has shaken the entire nation. Many active faults exist in Northern and Southern Pakistan. More than half of the total population lives in moderate to strong earthquakes prone areas (Kausar, et al. 2006). The 8 October 2005 Muzaffarabad earthquake, enhanced the attentiveness about the rising vulnerability that the increasing population is confronted. The poorly designed and constructed civil structures in the developing countries are mainly responsible for the large number of victims due to earthquakes (Dominey et al. 2006).The study of strong motion and aftershock series coupled study analysis and interpretation of the damage due to these earthquakes (Bilham, 2006). The earthquakes furnish useful data to the disciplines of seismotectonics, seismology and earthquake engineering which helps these disciplines to draw valid analysis and interpretations. The earthquake data also raise a number of important scientific questions, answers to which will help prevent, minimize or remediate damages in future (Ramachandran et al. 2005). Some examples of Major earthquakes are 1995 “Kobe” Japan earthquake, the 1999 “Chi-Chi” Taiwan,

China earthquake, the 2001 “Gujrat”, India earthquake and October, 2005 “ Muzaffarabad ” earthquake etc.

Earthquakes cause total loss of or damage to civil structures in a number of ways such as collapse of civil structures, ground ruptures and landslides etc. Efforts have been made to minimize the losses (Ahmad et al. 1991). A heap of data shows that most of the causalities were due to collapse of the civil structures (Bilham, 2001). It is therefore imperative that buildings, dams, railways, hospitals and roads etc.are planned and constructed to endure the tremors without becoming dysfunctional.

Designing civil structures requires an assessment of the seismic potential of the concerned area (Khalid at.al, 2002). The requisite assessment is made by taking into consideration geological, neotectonic as well as seismological data (Khalid at.al, 2002). The data are comprehensively utilized to develop the worst probable seismic scenario.

1.2 Location and Accessibility

The location of the study area is village Jalalpur (25 km radius), Eastern Salt Range (Figure - 1.2). The corner coordinates of the study area is

320 25’’00 N 320 45’’00 N

730 30’’00 E 730 30’’00 E

320 45’’00 N 320 25’’00 N

730 20’’00 E 730 20’’00 E

and the corner coordinates of regional (100 km radius)area , around the study specific area is

330 30’’00 N 310 45’’00 N

740 15’’00 E 740 15’’00 E

330 30’’00 N 310 45’’00 N

720 45’’00 E 720 45’’00 E

1.3 Physiography

The Physiography of an area, particularly in seismically active regions, provides useful information regarding deformation and potential of permanent ground displacements under earthquake loading (Bilham et al. 2001). The physiography of the present study area is mainly controlled by the ongoing tectonic activity of Sub Himalayas that include Eastern Salt Range and some part of Potwar Plateau.

The studied area is marked by three distinct physiographic units.

I. Plains Punjab Plains

2. Range Salt Range

3. Plateau Potwar Plateau

The northern boundary of the Punjab Plains falls within the study limits of the area. It comprises of thick alluvium i.e. silt, clay and sand laid down by the Jhelum and Chenab River system. The plains are abruptly truncated in the north by a narrow chain of low elevation mountains known as Salt Range. In the northeast, alluvium thickness gradually decreases to terminates against the Kashmir Hills. The plains adjoining the Sub Himalaya represent prograding alluvial fans at the foot of these hills.

The Salt Range extends over a length of about 170 km. The Elevation varies from 563 meters to 1400m (MSL). Highest summit of the range is 1422 meters (MSL) at Sakessar, which is located beyond the limits of the present study area. In the study area the elevation varies from 215m to 636m (Figure- 1.3).The extension of Salt Range known as Jogi Tilila Range, is located to the east of the study area.

In Kharian area, the Pabbi Hills (Figure-1.3 and 1.4) emerge out of Punjab Plains between the Jhelum Plains and the main Punjab Plains. The northeastern part of the investigated area (Kashmir Hills) is marked by low

elevation, parallel hills and narrow, elongated valley that occupy synclines e.g. Mangla Dhodial, Gulpur Sehnsa and Kotli valleys (Peter, et al. 2007).

The Salt Range, Tilla Range and Kashmir Hills are dissected by tributaries of Jhelum and Chenab Rivers resulting in rugged topography on their southern slopes. The northern slopes of Salt Range are gentle to moderate and merge into Potwar Plateau.

The Potwar Plateau (Figure-1.4) is represented by peneplained land, covered by Potwar Silt (Peter, et al. 2007). Topography along deep cutting streams and anticlines is relatively rough. The western part of the plateau in the investigated area is drained by Soan River whereas the eastern parts are drained by Jhelum River.

The study area is located at the eastern extreme of northwest trending segment of the Salt Range, where the Range takes a sharp bend at Jalalpur to trend NS to NNW (Peter, et al. 2007). This segment is represented by Chambal Ridge (Figure 1.5). Across the Bunha River, the ENE trending Jogi Tilla Range is an extension of Salt Range. The southern slope of the Salt Range is steep and it is marked by cliffs along the ridge top locally called Mangal Dev Ridge. This Salt Range escarpment extends up to Kahan Kas near Jalalpur. Further to the north, the escarpment of Chambal Ridge faces west (Figure-1.6) whereas the eastern slopes are marked by low altitude arcuate ridges and narrow strike valleys, that extend up to the right bank of Jhelum River.

1.4 Scope of the Work

The study of seismotectonics, neotectonics, tremor hazard, and risk analysis plays a significant role in modern seismology. It is of great societal importance (Bilham et al. 2006). Seismic risk assessment needs categorization of the seismic sources that can be likely to affect a chosen place in terms of area, magnitude, and frequency of happening of potentially destructive earthquakes. Seismic hazard also has a major impact on the earthquake resistant plan / design of civil structures by providing justified

estimates of hazard factors, such as Peak Ground Acceleration “PGA” or response spectrum amplitudes at dissimilar natural periods (Campbell, et al. 2006).PGA has been a widely used hazard parameter, partly because it can easily be read from analogue accelerograms. However, PGA is often ill correlated with the damage potential of ground motion, which has led to more frequent use of events i.e. Peak Ground Velocity “PGV”, or spectral acceleration “SA”, that reflect also other wavelengths, or frequencies (Bilham, 2006).

Taking into account the available databases on seismicity, tectonics, geology and attenuation characteristics of the seismic waves in the area of interest, the seismic hazard analysis provides estimates of the spot specific design ground motion (IAEA Safety Guide line, 2003).

Seismic design codes aim at providing building instructions for the reduction of both property and life losses due to the seismic events. These codes describe standards for the seismic resistant design and construction of new buildings as well as for the retrofit of the existing ones. Safety guidelines are prepared based on theoretical and physical modeling, in addition to the observed damages after major earthquakes (IAEA Safety Guide line, 2003). The lessons given by historical / past earthquakes facilitate promoting the preparation of design techniques, the knowledge of materials performance and the improvement of construction practices. Principally, a seismic code includes specifications for the seismic hazard, including soil and possible near fault effects (Bilham, 2006). In Europe there has been an enormous work on launching a set of so called Euro codes (EC), which contain complete guidelines for the construction industry including the seismic provisions (EC 8, 2004). Eurocode 8 defines two goals:

1. The civil structure shall be planned to survive the design seismic action without local or general collapse. 2. The civil structure shall be planned and constructed to resist a seismic activity with a higher probability of incidence than the design seismic action.

Modern codes, notably the “1997” Uniform Building Code (ICBO, 1997) and the EC-8, 2004, are based on the specification of a base shear that depends on the seismic hazard intensity of the area of interest, effects coming from geology, near fault effects, weight, fundamental period, lateral forces, and the resisting system of the building (IAEA Safety Guide line, 2003). In regions of high seismicity, a sufficient ductile aspect to accommodate the inelastic demand is needed (Bachman et al. 2000).

Unfortunately, the seismic awareness in the study area is still low. Seismic risk analysis and seismotectonic studies for the use of civil engineers / geologist, have not been prepared by any agency, group or individual, in the Salt Range.

This study is the first step in this direction. A large amount of seismological data was obtained from various agencies, to carry out neotectonics, lithostructural and geological studies for the seismic risk analysis of the region.

1.5 Objective of the Study

The major objective of present study is summed up in the title namely to establish “Seismic Hazard Assessment of Eastern Salt Range” using historical and instrumental earthquake data. For this purpose it was decided to carry out seismic risk studies in the eastern Salt Range with the consideration that it would be very helpful in establishing seismic codes for civil structures i.e. high rise buildings, dams, roads, bridges etc.

Other objectives of the study are,

1. Carry out geological mapping on scales of 1:250,000, 1:50,000 and 1:10000 to study the geological and lithostructural set up of the region.

2. Carry out neotectonic studies to recognize active faults that may cause earthquake and to know the tectonic stability of the area. The regional neotectonic framework was established through available literature, maps and satellite images.

1.6 Previous Work

Very little research and publications related to seismic hazard assessment are available for the study area.

However, the following organizations have produced indirectly related to the present research.

a) Geological survey of Pakistan (GSP) b) Pakistan Meteorological Department (PMD) c) Hydrocarbon Development institute of Pakistan (HDIP)

1.7 National Data

1.7.1 Geological Survey of Pakistan

In Pakistan, geological and seismic maps are prepared by the Geological Survey of Pakistan (GSP). Its maps and reports are useful for general geological assessment of a certain area and are used by geologists and engineers for general geological information; Seismic maps of Pakistan are prepared by the Geophysical Institute Quetta and Geological Survey of Pakistan to provide a broad outline of the seismicity of the country. The main objective of GSP is to explore the potential of mineral resources of Pakistan. Detailed maps of Quaternary geology and profiles are rare.

1.7.2 The PMD Historical Database

The historical earthquake catalogue was compiled by Pakistan Meteorological Department. The historical data base includes 58 earthquakes

from year 25 to 1905 AD. All earthquakes are provided with a short description and estimates of maximum intensity. Important extensions to the original database were made by including data from Quittmeyer and Jacob, (1979; see also Menke and Jacob, 1976). The main scientific reason for using the two catalogues (PDE and PMD) simultaneously was the definitive compilation of earthquake information and readings. The USGS PDE instrumental database just like the historical database of USGS and the instrumental database of the same (NEIC-PDE) was also obtained from the Internet. The PDE catalogue contains the data from 1973 to February 2007. Both historical and instrumentally recorded data were extracted from the catalogue in the spatial window from 200to 400 N and 580 to 830 E. The instrumental portion of this catalogue consisted of 14000 earthquakes with magnitude types such as Mb, ML, Mw, and Ms. Such reports and data provide useful background information for historic earthquake studies but are often of little direct use. Historical data base describes 143 events with assigned Ms magnitudes of up to 8.6 from the year 765 to 1992.Each earthquake in the data base is detailed according to source, data, time latitude,longitude, magnitude, intensity,and other seismic-related information.

1.7.3 Hydrocarbon Development Institute of Pakistan:

HDIP is a government organization under the Ministry of Petroleum and Natural Resources. Its main objective is to explore the potential of hydrocarbon resources of Pakistan. HDIP has prepared geological reports showing important geological features and characteristics of different areas at different scales. Most of the reports and data are related to hydrocarbon exploration. They provide useful background information for seismotectonic studies but are often of little direct use.

1.8 International Data

As stated earlier, most of the world's developed countries have recorded earthquake data and prepared seismotectonic maps and reports, which primarily are intended for the use of geologists/ geophysics and seismologists.

1.8.1 The USGS Historical Database

The historical database of USGS was obtained from the Internet. The data in the spatial window was selected ranging from 20°to 40°N and 58° to 83°E. This data base comprised 143 events with assigned Ms Magnitudes up to 8.6. The seismological events dating from the year 765 to 1992 were in chronological order.

1.8.2 The ISC Instrumental Database

Each earthquake in the data base is specified according to its origin, date, time, coordinates, intensity on scale, and other seismic related information. It is a large database in a 31 typical mode, the ISC (http://www.isc.ac.uk)1991 receives more than 200,000 recordings from worldwide stations. The analysis of these digital records leads to the identification of an average of 10,000 seismic events per month. Out of these almost 4,000 require manual review.

1.8.3 The Harvard Instrumental Database

The reason for selecting the Harvard catalogue as one of our study tools is that it contains three consistent magnitude types (Mb, Ms and Mw) f or each of events as well as the standard place (coordinates), depth, time, half duration, moment tensor, scalar moment, and mode of faulting (strike, dip and slip). Altogether 550 seismic events from January 1977 to September 2006, with magnitude equal or greater than 5.0 were analyzed and plotted on the map. Due to their magnitude these events are all significant, showing that large parts of Pakistan are quite vulnerable to earthquakes, especially the northern and south-western regions.

1.8.4 The PDE-NEIC Database

PDE catalogue is considered to be the most reliable data base regarding the completeness since 1973. It contains all information for location, date, origin time and magnitude of the earthquakes. The data file selected from the PDE data base for the study region contains 40,000 events.

1.9 Literature Review

Most of the previous studies of the Salt Range / Potwar Plateau have been carried out to explore the oil potential and work out regional structures with focus on the control of salt on the thrust geometry (Wynne, 1878; Cotter, 1933; Wadia, 1945a, 1945b, 1957; Gee, 1945, 1947, 1980; Martin, 1961; Sokolov & Shah, 1966; Shah, 1977; Farah, 1977; Coskresenskily, 1978; Fatmi et at.., 1987; Baker et al. 1987). However, resulting interpretations were speculative in the third dimension due to lack of published seismic and well data.

Molnar (1973) published preliminary geological and seismic hazard observations on the North West Himalayas and the Salt Range. Shah (1973) gave a preliminary introduction to the Salt Range. He subdivided the surface litho-logical units in the different formation (discussed in chapter 2).

Ambruster (1973) published a preliminary description of earthquake mechanism studies. Farah and De Jong (1979) published “Geodynamics of Pakistan” which focuses on the structural geology, seismology and seismotectonic zones of Pakistan.

The first isoseismic map of Pakistan was prepared by Geological Survey of Pakistan in 1976 for presentation at the Earthquake Minimization Seminar held at Tehran. It displays seven zones with “g” values ranging from < 0.01g to 0.31g.

Yeats et al. 1978; studied the surface effects of the March 16, 1978 earthquake. It is a meaningful and useful contribution showing that earthquake damage was limited to the pressure ridges and to the alluvial fans. This publication is of special significance as it explicitly brings out of the societal benefits that can occur from the study of the geodynamic setting of the area.

Leonardo (1979) published his “Seismicity of the Hazara Arc in Northern Pakistan”. It showed that, the seismicity in the Trans-Indus Salt Range is associated with a set of parallel strike slip faults striking north-

northwest. Faulting involves the entire thickness of the crust which is about 35 km and can be traced at the surface across the Trans Indus Salt Range. The seismicity in the Potwar Plateau and Banu Basin is generally low, and occasionally large earthquakes associated with the décollement.

Quittmeyer et al. (1979) described historical and modern seismicity of Pakistan and its vicinity and examined. Its relation to mapped surface faults. They described three categories of seismicity.

1. Earthquakes with large source dimensions that are associated with huge destruction, defines a trend consistent with a mapped fault. 2. Narrow, elongate zones that possibly related to movement along a continuous single fault or a gap of similarly oriented slighter fault. 3. Diffuse activity not clearly related to any individual fault.

PGA and PGV contour maps of Pakistan of return period 100 and 200 years was prepared by Ghalib (1985). The seismic risk map of northern Pakistan was prepared by Mirza et. al. 1988 and published by the Geological Survey of Pakistan.

Bhatia (1999) produced seismic Hazard Map of India sponsored by the Global Seismic Hazard Assessment Program (GSHAP). This map also includes Pakistan and Afghanistan.

Chaudhary and Ghazanfar 2014; summarized the deformation in salt ranges as follows.

1. E-W imbricate thrusts, the lowest of which is the Salt Range thrust, carries the whole sequence over the recent fanglomerates.

2. N-S or oblique transverse normal faults related to extension. These bring up the oldest Salt Range Formation to the surface providing easy dissection and creation of the well known gorges.

3. Strike slip dextral high angle faults on the margins of the salt range providing for southward transport of the range.

4. Salt diapirs forming salt plugs along the strike slip fault in the west and eastwards providing the upward push under the low pressure regions created by the erosion of deep gorges. This latter push has created tight N-S salt cored anticlines separated by broad synclines.

Khalid Perviz et al. (2002) included research work on seismotectonic zoning of Pakistan and developed methodology of seismic risk evaluation.

Warwick et al. (2007) multidisciplinary regional framework assessment covered 32000 km2, of the Salt Range and Potwar Plateau.

Jan et al. (2007) described the seismicity related to the collusion between Indian and Eurasian Plates as well as active tectonic features of the Pakistan.

The present study is more detailed than previous work and adds new insights to seismic risk assessment of the Salt Range.

It is the first attempt to specially address the seismic hazards assessments of the Eastern Salt Range, based on historical and instrumental seismological data and neotectonics studies.

1.10 Work Plan and Methodology

The adopted methodology is in accordance with IAEA safety guide 50 SG. S1-Rev 1.This safety guide requires that the database is developed on three scales, i.e., regional, near regional and study area specific vicinity. The database has been prepared by considering stratigraphy, tectonics, neotectonics, historical and instrumental seismicity.

Field studies are supported by remote sensing, geophysical techniques and available geoscientific information.

Regional scale studies are conducted in a radial extent of 100 km around the study area. The data source is historical and instrumental seismicity catalogues, specifically processed satellite images and published information augmented by selected field traverses. Computerized

database linked to a Geographical Information system (GIS) has been used with the facility to combine and manipulate the geographically distributed data and prepare different maps. Use of GIS has made this report very flexible, which can be updated easily. For this purpose following maps have been prepared,

1. Regional Seismic, Tectonic and Structural map on scale 1:250,000 2. Geological Map on scale 1:50,000 3. Detailed Lithostructural Map on scale 1:10,000

The resemblance in deformation styles, stress direction and chronology helps defining tectonic zones. Fault geometries, epicentral locations, focal depth and focal mechanism are used to relate seismicity with a specific structural zone. Inside the zone, seismic sources are established on the basis of historical / instrumental seismicity, neotectonics and structure. The maximum possible magnitude for each source is calculated and deterministic Peak Ground Aacceleration at specific locations was assessed with the help of attenuation equations / laws.

1.11 Organization of the Thesis

This thesis is presented in six chapters. Chapter one is the Introduction and physiography, giving introductory background of the study objective, plans and methodology for the study. Chapter two is concerned with regional, semi regional and local stratigraphy of the study area. Chapter three describes tectonics and structural geology of the study area. Chapter four describes the movement of recent sediments during the Holocene period. Chapter five discusses the seismicity, regional seismicity, and maximum potential earthquake, evaluation of seismic risks and assessment and peak ground acceleration. Finally, Chapter six summarizes the conclusions and recommendations drawn from this research.

(Modified from Shah, S.I. G.S.P, 2009)

Figure 1.1 Location of epicenters of some major earthquake in the Pakistan.

Figure 1.2 Location of the study area

Figure 1.3 Satellite view and physiographic expression of the study area.

(Modified from Yeats, 1983)

Figure 1.4 Salt Range and adjacent Tectonic features.

(Modified from Yeats, 1983)

Figure 1.5 Geological sketch map of present study area, modified from Gee (1980), of eastern of eastern Salt Range, showing S-bend at Jalalpur north to Chambal Ridge (south of Bunha River) and Jogi Tilla anticline (north of Bunha River). Rawalpindi Group includes Murree and Kamlial Formations (Shah 1977). Lower Siwalik is subdivided into Chinji, Nagri, and Dhok Pathan Formation.

(Modified from Jadoon 2004)

Fig-1.6 Structural features around the study area

Chapter Two 21 Stratigraphy

Chapter 2 STRATIGRAPHY

2. Stratigraphy

The knowledge of rocks present in an area is a prerequisite for determination of peak ground acceleration as well as for foundation designing of any proposed civil structure (IAEA Safety Guide 50SG.S1-Rev 1). Rock composition, hardness, density and endurance greatly influence the velocity of seismic waves (Emmerson et al. 2007). The seismic waves are also refracted and reflected at lithological boundaries between contrasting rock units. The seismic waves are attenuated or sometime amplified by the softer or loose sediments.

2. 1 Geological Mapping

Regional geological studies have been carried out within 100 km radius around Jalalpur – Eastern Salt Range. These studies are mainly aimed at understanding of regional geodynamic setup to define the seismic sources that could affect the study area.

Satellite data have been used, which facilitates the recognition of active faults. Available seismological data plotted on tectonic map have led to seismotectonic analysis. Selected field traverses have also been made to study the neotectonic signatures of certain faults. The collected information is presented as regional seismic, tectonic and structural map at a scale 1:2, 50,000 (Map No. 1).

The lithostructural map (Map No 2) has been prepared at 1:50,000 scale for near regional geological studies. Near regional geological studies, within 25 km radius around JalalPur.The published geological map (Gee 1979) has been modified with the help of satellite images and field traverses.

Chapter Two 22 Stratigraphy

Special attentions have been given to the faults to delineate active and capable faults as well as lineaments.

Specific investigations have been carried out within 5 km radius around JalalPur.They provides relatively detailed geological data to assess potential for ground rupture and permanent ground displacement. Each exposed rock unit has been mapped in terms of attitude and aerial extent. These studies are depicted on geological map of the study area (Map No. 02), prepared at scale 1:10000.

The geological and seismological data have been synthesized to construct a seismotectonic model of the study area. The model provides the followings:

a. The seismogenic faults and seismogenic sources that can affect the study area were defined and maximum credible earthquake associated with each source have been assessed. b. The closest distance of seismogenic faults from study area. c. Nature of the fault. d. Location of the study area with reference to the geometry of the fault. e. Nature of the rocks and effective length of active faults have been ascertained for evaluation of study area specific peak ground acceleration (PGA). f. Assessment of potential for permanent ground displacement under earthquake loading. The three geological maps appended to research thesis contain admissible spatial error due to

Chapter Two 23 Stratigraphy

1. Manual mapping procedures. 2. Use of enlarged topographic maps of survey of Pakistan as a base map. 3. Instrumental accuracy error of hand held GPS.

2.2 Regional Stratigraphy of the Study Area

The nomenclature recommended by the Stratigarphic Committee of Pakistan is used in the text. Mapable rocks with similar lithological characteristics are designed as formations and the formations are grouped for simplicity.

A brief account of stratigraphic sequence exposed in neighboring areas is given in Table 2.1. Age of rock units ranges from Pre-Cambrian to Recent and depositional environment is mostly marine, fluvial and lacustrine. Major lithological units are limestone, sandstone, marl, shale, and dolomite. Evaporites like salt and gypsum are exposed along the fringes of Salt Range. The oldest Formation known to lie on top of basement (Indian Shield) is the Eocambrian Salt Range Formation (Fatmi et al, 1984). The Precambrian rocks of the present study area are composed mostly of sedimentary rocks i.e. marl, salt, dolomite and gypsum deposits. They occupy probably the sloping part of the Indian Platform and overly the metamorphic rocks of the Late Proterozoic age (Shah, 2009). Fluvial rocks mainly ranging in age from Early Oligocene to Recent dominate the local stratigraphic succession (Table 2.1).

The Cambrian to Eocene platform rocks in the SR / PP area is similar to those of the rest of Peninsular India. In the Salt Range, the base of this sequence is the Lower Cambrian Jhelum Group consisting of the Khewra, Kussak, Jutana, and Baghanwala Formations (Gee, 1980). The base of the Jhelum Group consists of Talchir Boulder Beds, of Gondwana affinity. This succession becomes thicker and more complete from east to west (Fatmi, et al. 1984; Yeats and Hussain, 1987).

Chapter Two 24 Stratigraphy

The upper zone of the stratigraphic sequence in the SR/PP region comprises the Miocene Rawalpindi Group, and the Plio-Pleistocene Siwalik Group. The Rawalpindi Group comprises of the Murree and Kamlial Formations, while the Chinji, Nagri, Dhok Pathan, and Soan Formations are belongs to Siwalik Group.These strata are non-marine, time transgressive molassic facies that indicate the erosional results of Himalayan Mountains (Molnar, et al. 2009). They lie on progressively older formations to the south, such that they lie on early Eocene carbonates in the Salt Range and directly on top of Cambrian rocks in the Jhelum plain, to the south (Wells, 1984; Yeats and Hussain, 1987).

Johnson et al (Aikman, A.B., 2008) suggest that the fluvial and fluviodeltaic Rawalpindi Group deposits indicate the initiation of Himalayan uplift. The Siwalik Group records continued uplift of the Himalaya. However, while the Lower Siwalik strata are derived from the crystalline and metamorphic terranes of the High Himalaya, Upper Siwalik deposits consist of recycled Lower and Middle Siwalik debris, uplifted and eroded as deformation progressed southward (Shah 2009).

Previous attempts to correlate facies within the molasse have been based on biostratigaphic (Shah, 2009) and lithostratigraphic (Pilgrim, 1910) criteria. More recently, a chronostratigraphic approach, employing magnetostratigraphy and tephrachronology, has permitted age calibration of individual horizons (Shah 2009).These data document the southward advancing deformational front, particularly in the eastern Salt Range / Potwar Plateau.

Due to the recent deformation in the Salt Range / Potwar Plateau, post Siwalik strata are essential for dating deformational events. However, much of these young deposits have been removed by uplift and erosion. Fortunately, local preservation of the Lei Conglomerate provides important timing

Chapter Two 25 Stratigraphy

information. The conglomerate, which has a basal age of about 1.9 Ma (Bemard, 2005), is a valley fill deposit with Eocene clasts. Disregarding the recent alluvial cover, the youngest deposit is the Potwar Silt. Edward (2007) suggests that this silt was pounded behind the rising Salt Range. Its age is less than 0.7 Ma (Lamb, 2006) and perhaps as young as 170,000 years (Guillot, 2003).

The stratigraphic succession used in the present study area is:

Chapter Two 26 Stratigraphy

Table 2.1 Regional Stratigraphic Succession around the study Area

ERA AGE FORMATION LITHOLOGY

GROUP Recent Conglomerate, gravel silt and Alluvium sand. Pleistocene Brown and Gray conglomerate and late Lei with sandstone interbeds.

Pliocene conglomerate Light colored sandstone and Soan Formation conglomerate, light red and gray clay. Pliocene Red Brown clays with gray Dhok Pathan

and Late sandstone , conglomerate near

Formation

Miocene Indus. Middle Greenish-gray sandstone and Nagri Formation Miocene clay, conglomeratic near Indus.

Siwalik Group Chinji Formation Bright red clay with sandstone.

Early Kamlial Massive sandstone red clay Miocene Formation

C E N O Z O I Massive sandstone dark red and Murree Group purplish clay-shale: basal

Rawalpindi Formation conglomerate. Early Chor Gali Olive green shale with bedded

Eocene Formation limestone. Sakessar Massive and nodular limestone Limestone with marl, chert in upper part. Nammal Light gray calcareous shale,

Cherat Group Formation limestone.

Chapter Two 27 Stratigraphy

Paleocene Patala Green shale with coal seams, thin

Formation limestone. Lockhart Grey semi-nodular and marly lime Formation stones. Impure limestone, sandstone Hangu Formation Makarwal Group and shale often carbonaceous.

UNCONFORMITY

MESOZOIC Early Sardhai Dark purple and lavender clay with Permian Formation subordinate sandstone.

Warcha Red and light colored sandstone and grit, Sandstone in parts arkosic, clay interbreeds. Dan dot Olive-green and gray sandstone and Formation shale occasionally carbonaceous.

Nilawahan Group Tobra Conglomeratic sandstone and shale,

Formation boulders mainly igneous or metamorphic. Middle Baghanwala Blood-red shale and flaggy Sandstone and Early Formation with salt pseudomorphs. Cambrian Jutana Massive light-colored dolomite and

P AL AEOZOIC Formation dolomitic sandstone, subordinate shale Kussak Gray and purplish shale and glauconitic Formation sandstone, pebble-bed at base.

Jhelum Group Khewara Massive maroon fine-textured Sandstone Sandstone, maroon shale. Salt Range Red gypsiferous marl with rock salt; Formation gypsum-dolomite above; occasional oil shale.

Chapter Two 28 Stratigraphy

2.3 Salt Range Formation

Wynne (1878) named and described the formation as 'Saline Series'. Gee (1945) called the same unit as the 'Punjab Saline Series'. Asrarullah (1967) has given the present name “Salt Range Formation”. The lower zone of the Salt Range Formation is consists of red-colored gypseous marl with thick seams of salt, beds of gypsum, dolomite, greenish clay while low-grade oil shale are the constituents of the upper part. A highly weathered igneous body known as "Khewra Trap" has been reported in the upper part of the Formation. The "Khewra Trap", also known as "Khewrite" (Mosebach, 1956), is 6 m thick and is purple to green in color. The red-colored marl consists chiefly of clay, gypsum and dolomite with occasional grains and crystals of quartz of variable sizes. Thick-bedded salt shows various shades of pink colour and well-developed laminations and color bandings up to a meter thick. The gypsum is white to light grey in colour. It is about 5 m thick, massive and is associated with bluish grey, clayey gypsum and earthy, friable gypseous clay. The dolomite is usually light coloured. The Salt Range Formation is divided into three members in the following succession (top to bottom).

2.3.1 Sahiwal Marl Member

It consists of bright red marl and dull red marl beds with irregular gypsum and dolomite beds. In Khewra Trap (3-100 m) Dull red marl beds with salt seams and 10 m thick gypsum bed lie on the top of Sahiwal Marl Member; (> 40 m).

2.3.2 Bhandar Kas Gypsum Member

It is comprised of thick gypsum layers with beds of dolomite and clay; ( > 80 m).

Chapter Two 29 Stratigraphy

2.3.3 Billianwala Salt Member

It is comprised of ferruginous marl of red colour with massive seams of salt (> 650 m). The formation represents evaporite sedimentation (Gee, 1983), which took place in a closed basin in arid conditions. The clastic material was transported from Peninsular India and deposited under oxidizing conditions (Gee, 1983). The Salt Range Formation is exposed along the southern flank of the Salt Range, from Kussak in the east to Kalabagh in the west. In the subsurface, the rock unit has been encountered as far south as Karampur in the Punjab plains and in the north at Dhulian oil field in the Potwar area. The thickness of the Salt Rang Formation in the type section at Khewra Gorge is > 830 m. It has been found by drilling that the thickness is > 2000 m near Dhariala village (Study Area). The base of the Salt Range Formation is only known from the Karampur well, where the formation overlies metamorphic rocks, presumably of Precambrian age. Contact with the overlying Khewra Sandstone is generally normal and conformable. The age of the Salt Range Formation, its paleontological record and its contact with the overlying rocks has long been a controversial topic. Details of this controversy are beyond the scope of the present study. The overlying Khewra Sandstone is probably Early Cambrian (Gee, 1945, Schindcwolf and Seilacher, 1955). The Salt Range Formation is therefore, assigned an Early Cambrian to Late Precambrian age.

2.4 Cambrian

The Cambrian System of Pakistan has been best studied in the Salt and Khisor Ranges, where the sequence is well developed (Figure-2.1). In the study area, the Cambrian rocks consist of sandstone, shale, and dolomite with glauconitic interbeds, which were essentially deposited in shallow water, except for the lower most and uppermost formations, which represent

Chapter Two 30 Stratigraphy

transgressive and regressive facies respectively. The Cambrian Formations in present study area are (Bottom to top),

4. Baghanwala Formation

3. Jutana Formation

2. Kussak Formation

1. Khewra Sandstone

2.4.1 Khewra Sandstone

The "Khewra group" was named by Noetling (1894). Prior to that, Wynne (1878) called the formation "Purple sandstone series". The latter name continued until recently, when the name of the formation was formalized (Fatmi 1973) by the Stratigraphic Committee of Pakistan as "Khewra, Sandstone". The type locality is in Khewra Gorge near Khewra village. The formation consists predominantly of purple to brown, yellowish-brown, fine grained sandstone. Lower most part of the formation is red, flaggy shale. The sandstone is mostly thick bedded to massive. Sedimentary features like ripple marks, mud cracks etc. are common in the formation.Thickness at the type locality is approximately 150 m.

Shah 2009 carried out a detailed study and concluded that Khewra Sandstone represents a deltaic sequence with distinct bottom-set, fore-set and top-set deposits of the ancient Cambrian delta. Khewra Sandstone can be texturally divided into sandstones, silty sand, sandy silt and siltstones, and consequently, may be termed as Khewra Siltstone. The sandstone appears to be a good reservoir for oil, gas and water and may be exploited for its hydrocarbon potential in the subsurface.

2.4.2 Kussak Formation

Wynne (1878) applied the name 'Obolus beds' or 'Siphonotrata beds' to a predominantly greenish grey, glauconitic, micaceous sandstone and

Chapter Two 31 Stratigraphy

siltstone. Waagen and Wynne (1895) used the name "Neobolus beds" for the same unit. Noetling (1894) proposed the name "Kussak group" and finally the Stratigraphic Committee of Pakistan formalized the name of the unit as Kussak Formation (Fatmi, 1973). The type locality is near Kussak Fort where the formation is composed of micaceous sandstone.The colour of sandstone is greenish grey and interbedded with light grey dolomite. At some places dolomite is arenaceous and oolitic.Numerous layers of intraformational conglomerate are present. Lenses of pink gypsum occur near the top. The formation contains 5 to 25 cm long thin lenses of fossil asphalt (gilsonite). The general lithology throughout the Salt Range is uniform. However, thicknesses vary at different places. The formation is widely distributed throughout the Salt Range with its best exposures in the eastern Salt Range. Thickness at the type locality is 70 m but varies down to 6 m at other places.The formation is fossiliferous and contains the following fauna: Neobolus warthi, L. fuchsi, Lingulella wanniecki,Botsfordia granulata, Hyolithes wynnei, Redlichia noetling. Schindewolf and Seilacher (1955) regarded the age as Early Cambrian. However, Teichert (1964) has shown that R. noetling is allied to or perhaps even identical with R forresti that occurs in Australia in beds of late early or early Middle Cambrian.

2.4.3 Jutana Formation

Fleming (1853) named this unit "Magnesian sandstone". Noetling (1894) described it as Jutana stage. The name “Jutana Formation” formalized by the Stratigraphic Committee of Pakistan.In the Eastern Salt Range the Village “Jutana” is the type locality of the formation, where the lower part of the formation consists hard and massive sandy dolomite of light green colour, while dirty white massive dolomite is present in the upper part.In the upper part, brecciated dolomite is also present with matrix and fragments of the same rock. In the study area, the formation is conformably underlain by the Kussak Formation and conformably overlain by the Baghanwala Formation.

Chapter Two 32 Stratigraphy

The formation is thickest in the eastern Salt Range, whereas at the type locality it is 80 m. The formation is fossiliferous; the shale unit in the middle part of formation exposed in the eastern Salt Range contains Redlichia noetlingi, Lingulella fuchsi, Botsfordia granulata, and also gastropod identified as Pseudotheca cf. subrugosa. The age of the formation is late early to early middle Cambrian.

2.4.4 Baghanwala Formation

The name Baghanwala Formation is now assign to the rocks of the"Pseudomorph Salt Crystal Zone" of Wynne (1878) and the "Baghanwala Group" of Noetling (1894), which overlies the Jutana Formation. Holland (1926) called these beds "Salt Pseudomorph beds" and Pascoe (1959) named them "Baghanwala Stage". The type section is located near Baghanwala Village where the formation is composed of shale and clay of red colour with alternate beds of flaggy sandstone that exhibits several colours including pink grey or blue green, especially in the lower part. Sedimentary features i.e ripple marks and mud cracks are common. Numerous pseudomorphic casts of salt crystals, which are found along the bedding planes, are the diagnostic feature of this formation.Casts of salt pseudomorphs and the absence of fossils indicate lagoonal and arid environment of deposition.The formation is mainly developed in the eastern Salt Range. Near Baghanwala village, it is 100 to 116 m thick. A similar thickness has been reported from northeast of Khewra, but it is reduced by erosion to only 40 m in the Khewra Gorge. The formation contains only trace fossils. Since the Baghanwala Formation rests conformably on the Jutana Formation, which is considered as early Middle Cambrian in age, the same age may be assigned to the Baghanwala Formation.

Chapter Two 33 Stratigraphy

2.5 Carboniferous – Permian

Carboniferous and Permian rocks are found more or less in almost all the basins of Pakistan. Rocks known to be restricted to the Permian system are located in the Kohat-Potwar, Axial Belt and at some places in the Northern Sedimentary Province.The rocks are shale, sandstone and limestone as well as metasedimentary lithologies having thicknesses of several hundred metres.

The Permian strata have been divided into two groups, one is the Nilawahan Group and second is the Zaluch Group. The Nilawahan Group represents a dominantly continental deposit consisting of arenaceous and argillaceous sediments in the upper part which passes conformably into the overlying marine Zaluch Group. The lower most Permian beds rest disconformably on Cambrian rocks, while the upper beds are separated from the Triassic rocks by paraconformity

2.5.1 Nilawahan Group

The name "Nilawahan Series" was proposed by Gee (Pascoe, 1959) for rocks conformably underlying the Zaluch Group and disconformably overlying the Cambrian succession of the Salt Range (Figure-2.1). Gee's proposal has been formalized as Nilawahan Group. The group includes the following formations in the sequence; Tobra Formation being the oldest.

4. Sardhai Formation

3. Warchha Sandstone

2. Dandot Formation

1. Tobra Formation

Some of the formations of the group have yielded bryozoans, brachiopods, mollusks, spores, pollens, and micro planktons indicating Early Permian age.

Chapter Two 34 Stratigraphy

2.5.2 Tobra Formation

The name Tobra Formation refers to the lowest formation of Nilawahan Group previously known in the literature as "Talrchir Boulder Bed" also known as "Talchir Stage"( Pascoe 1959) and "Salt Range boulder bed" (Teichert 1967). The type locality is close to “Tobra” Village.The Tobra Formation depicts a very mixed lithology in which the following three facies are recognized (Warrwick, 2007).

a. Tillitic facies exposed in the eastern Salt Range. This rock unit grades into marine sandstone containing Eurydesma and Conularia fauna (Dandot Formation). b. Freshwater facies with few or no boulders. It is an alternating facies of shale and siltstone containing flora. This facies is characteristics of the central Salt Range. c. The unit with complex facies of diamictite, sandstone and boulder bed increases in thickness in western Salt Range.

In the present study area, the Tobra Formation exhibits true tillite characteristics with boulders of granite and fragments of quartz, feldspar, magnetite, garnet, claystone, siltstone, quartzite, bituminous shale, diabase and gneiss. The matrix is generally clayey, sandy and at some places calcareous. A few pebbles and boulders are polished and scratched. According to Teichert (1967) the ice sheet that deposited the tillite in the eastern Salt Range was probably not a part of an extensive inland ice sheet but local glaciation. The formation is about 20 m thick at the type locality. The thickness in the adjoining areas varies greatly and at places it is totally missing. It contains flora and fauna and several species of freshwater ostracods and bivalves (Reed, 1936). The formation grades into the overlying Dandot Formation in the eastern Salt Range. Its lower contact with the Cambrian rocks is discomformable.The maximum thickness of this formation

Chapter Two 35 Stratigraphy

is more than 35m. The lower part, in Zaluch Nala, contains spores and pollens out of which the following have been identified, Punctatisporites cf, P. gretensis, Leiotriletes spp., Acanthotriletes cf. A. tereteangulatus, Apicnlatisporites sp., Protohaploxypinus sp., Striatopodocarpitrs sp., Potonieisporites sp., Kraeuselisporites sp., Nuskoisporites sp.On the basis of Striatopodocarpites and Ptotohaploxypinus the age is Early Permian (Balme, in Teichert, 1967).

2.5.3 Dandot Formation

The name Dandot Formation is formalized after the “Dandot Group" of Noetling (1901) and includes the "Olive Series”, "Eurydesma beds" and "Conularia beds" of Wynne (1878) and the "Speckled sandstone" of Waagen (1879). The type locality is near Dandot Village, where lithology comprises of olive green to light grey yellowish sandstone with irregular thin pebbly beds and subordinate splintery shales of dark grey and greenish in colour.The Formation has a gradational contact with the underlying Tobra Formation and is terminated at a sharp but conformable contact with the overlying Warchha Sandstone.Fossils in the basal part are brachiopods including Discina sp., Martiniopsis sp. and Chonctes sp; bivalves include a rich fauna of Eurydesma and several species of Conularia. Many species of Bryozoa and Ostracoda have also been described.The age of the Dandot Formation is Early Permian.

2.5.4 Warchha Sandstone

The name “Warchha Sandstone” was coined by Hussain (1967), and approved by the Stratigraphic Committee of Pakistan. Prior to the formalization of this name other terms were used such as the "Warchha Group" of Noetling (1901), which included the overlying "Lavender clays" (Sardhai Formation) with it. The names such as "Speckled sandstone" of Gee (1945) and middle speckled sandstone of Waagen (1879) were also prevalent in the literature. Its type section is in the Warchha. It is comprises of medium

Chapter Two 36 Stratigraphy

to coarse grained cross-bedded sandstone. The sandstone is red, purple or shows lighter shades of pink. The sandstone is arkosic. The pebbles of the unit are mostly of granite of pink color and of quartzite. The Formation is locally speckled which caused the previous workers to call it as "Speckled sandstone". The Warchha Sandstone is widely distributed in the Salt Range. Its thickness varies from 26 to 180 m. Variable thickness together with the strong cross bedding suggests that the formation is a fluviatile deposit and was laid down in a large alluvial flat. The Warchha Sandstone conformably overlies the Dandot Formation. It is overlain by the Sardhai Formation with a transitional contact and the contact is placed at the top of the highest massive sandstone bed. Some plant remains have been reported.On the basis of its stratigraphic position with the overlying and underlying Early Permian formations, the same age may also be assigned to it.

2.5.5 Sardhai Formation

The name Sardhai Formation is approved by the Stratigraphic Committee of Pakistan, was given by Gee. Prior to this Gee (in Pascoe 1959) had called it "Lavander clay stage ". Wyyne (1878) had called it "Lavander clays" and Notling (1901) called it "upper zone of Warcha Group". Type section as suggested by Gee is in the Sardhai Gorge in the eastern Salt Range. It is composed of greenish grey and bluish clay, with minor sand and siltstone beds. The Formation also contains carbonaceous shale. The clay prominently displays lavander color and includes copper minerals with chalcopyrite. Small amount of jarosite, gypsum and chert are disseminated in the formation, with irregular calcareous beds in its upper zone. The formation thickness in the eastern Salt Range is about 40 m. It has a lower transitional contact with the Warchha Sandstone. The upper contact is conformable with the Amb Formation.The age is Early Permian.

Chapter Two 37 Stratigraphy

2.6 Paleocene

2.6.1 Indus Basin

In the Indus Basin, the Kohat Potwar Province and major part of the Kirthar Province was the area of deposition during Danian. Soon after the Danian, a dominantly sandstone facies at the base followed by shallow water foraminiferal limestone in most of the Indus Basin was deposited. The end of the Paleocene Epoch, in places, is marked by slight emergence but marine conditions returned soon after (Shah 2009).

2.6.2 Upper lndus Basin

Rocks of Paleocene age constitute Makarwal group of the following Formations.

1. Patala Formation

2. Lockhart Limestone

3. Hangu Formation

2.6.3 Makarwal Group

Three formations are included in this group. The lowest is Hangu Formation, which is mainly composed of sandstone, siltstone, shale, claystone and limestone; average thickness of the formation is 50 m. Overlying Hangu Formation is Lockhart Limestone, which is composed of mostly nodular limestone with marl partings. It is about 66 m thick. The topmost is Patala Formation, composed predominantly of olive greyish green shale with thin bedded sandstone and limestone. At the type locality the Thickness of this formation is about 150 m. The Makarwal Group is well developed all over the Kohat-Potwar Province with gradual pinching of lower zone of the group in the eastern Salt Range.

Chapter Two 38 Stratigraphy

2.6.4 Patala Formation

The name “Patala Formation” was formalized by the Stratigraphic Committee of Pakistan assigned to the "Paatala Shale" of Pinfold and Davies (1937) and its usage was extended to other parts of the Kohat-Potwar and Hazara areas. The formation includes the "Tarkhobi Shale" of Eames (1952), part of the "Hill Limestone" of Wynne (1873) and Cotter (1933), part of the "Nummulitic formation" of Waagen and Wynne (1879), part of the "Nummulitic Series of Middlemiss" (1896) and the "Kuzagali shale" of Latif (1970). Cheema et al. (1977) stated that in the Salt Range the formation contains shale and marl with subordinate sandstone and limestone. The shale is greenish grey selenite-bearing, at some places carbonaceous with marcasite nodules. The nodular limestone is white to light grey in colour. It occurs as interbeds. Coal seams of economic value are present locally (Dandot area). It is 30 m thick at Khewra and 90 m at Patala Nala. The thickness varies between 30 to 75 m in the Surghar Range. The Patala Formation is conformably and transitionally overlain by the Nammal Formation in the Salt Range. It is richly fossiliferous and contains abundant foraminifers, mollusks and ostracodes.

2.6.5 Lockhart Limestone

The name "Lockhart Limestone" was introduced by Davies (1930) for Paleocene limestone unit and this usage has been extended by the Stratigraphic Committee of Pakistan to similar units in other parts of the Kohat-Potwar and Hazara areas. This unit thus represents the "Nummulitic Series" of Middlemiss (1896), the lower part of "Hill Limestone" of Wynne (1873) and Cotter (1933), the "Khairabad Limestone" of Gee (1934) "Tarkhobi Limestone" of Eames (1952) and "Marl Limestone" of Latif (1970).It comprises of light to medium grey, massive, medium to thick bedded, rubbly and brecciated in places. The basal part is dark to bluish grey and flaggy. In the

Chapter Two 39 Stratigraphy

Salt Range,the limestone is grey to light grey,nodular with minor amounts of grey marl and dark bluish grey, calcareous shale in lower half.It is conformably and transitionally overlain by the Hangu Formation as well as the Patala Formation, respectively.

2.6.6 Hangu Formation

The terms proposed by the Davies (1930) Hangu Shale and Hangu Sandstone was formalized by the Stratigraphic Committee of Pakistan in (1973) as “Hangu Formation” and the name is extended to include the "Dhak Pass beds" of Davies and Pinfold (1937), the "Langrial Iron Ore horizon" of Khan and Ahmed (1966), the "Dhak Pass formation" of Danilchik and Shah (1967), and the basal "Mari Limestone" of Latif (1970a) in the Kohat-Potwar Province.The type section has been defined at Fort Lockhart.The formation contains grey, variegated colour shale, sandstone, carbonaceous shale and, argillaceous nodular limestone. A 2 - 3 m thick bed of ferruginous, pisolitic sandstone occurs at the bottom of the unit, which is 90 m thick in the Fort Lockhart. It is conformably overlain by the Lockhart Limestone. Foraminifers with corals, gastropods and bivalves have been reported by Cox (1930), Davies and Pinfold (1937), Hangue (1956) and Iqbal (1972). Davies et al. (1937) recorded the presence of Operculina, cf. O. candalifera, O. subsalsa, Miscellanea miscella, Lockhartia haimei, L. conditi and Lepidocycma (Polylepidina) punjabensis. Hangue (1956) recorded abundant Epistominella dubia from Nammal Gorge, Salt Range. From foraminifer’s content, the formation is assigned an Early Paleocene age. It is correlated with the lower parts of the Dungan, Bara and Rakhshani formations of the Lower Indus Basin, Axial Belt and Balochistan Basin.

Chapter Two 40 Stratigraphy

2.7 Eocene

2.7.1 Chharat Group

The Chharat Series of Pinfold (1918) has been formalized by Stratigraphic Committed of Pakistan as Chharat Group after the Chharat Village in Attock District, Punjab Province. The lower contact of the group with the Patala Formation is conformable. The Chharat Group is uncomformably overlain by rocks of the Rawalpindi Group. The age of the Group is Early to Middle Eocene. The Group comprises of following Formations,

a. Chorgali Formation b. Sakessor Formation c. Nammal Formation

2.7.2 Chorgali Formation

The Stratigraphic Committee of Pakistan formalized the name "Chorgali beds" of Pascoe (1920) as Chorgali Formation. The lower part contains dolomitic limestone and shale. The dolomitic limestone is yellowish grey and white to light grey in color and medium-bedded while the colour of shale is grey to greenish grey, occurs as interbeds in the upper half of the Formation. The upper part of the formation is mainly consists of shale with one massive bed of grey limestone. A bed of argillaceous nodular limestone close to the top is present. The shale is greenish grey, red, occasionally variegated and calcareous. Some grit beds are intercalated. The formation is divided into two zones in the Salt Range. The lower zone contains shale and limestone, while the upper zone is mostly limestone. The shale of the lower part is greenish grey or buff and calcareous, and the limestone is light grey and argillaceous. In the upper part, the limestone is white or cream coloured, porcellaneous and well bedded. The formation conformably overlies the Sakesar Limestone in the Salt Range while, unconformably overlain by the Murree Formation in the Eastern Salt Range.The Formation is rich in fossils

Chapter Two 41 Stratigraphy

including foraminifers, mollusks and ostracodes (Davis and Pinfold.1937 Eeames. 1952, Gil. 1953 and Latif. 1970). The foraminifers include Assilina spinosa, A. granulosa, A. daviesi, A. leymeriei, Flosculina globosa, Globorotalia reissi, G. wilcoxensis, Globigerina prolata, Lockhartia hunti, L. tipperi, L. conditi, Nummulites atacicus, N. mamilla, Orbitolites complanatus and Rotalia cmokshankiana. The fauna indicates an Early Eocene age.

2.7.3 Nammal Formation

The Stratigraphic Committee of Pakistan formally accepted the term Nammal Formation for the "Nammal Limestone and Shale" of Gee (in Fermor, 1935) and "Nammal Marl" of Danilchik and Shah (1967) occurring in the Salt and TranIs Indus ranges. The formation, throughout its extent, comprises shale, marl and limestone: In the Salt Range, these rocks occur as alternations. The shale is grey to olive green.

The limestone is locally argillaceous. In the Surghar Range, the lower part of the formation is comprises of bluish grey marl with interbedded calcareous shale and or limestone. The formation is well exposed in the Salt range. It is approximately 40 m thick in the eastern Salt Range. The Nammal Formation is overlies the Patala Formation and underlies the Sakesar Limestone.The contact with Sakesar Limestone is transitional.

Abundant fossils, mainly foraminifers and mollusks, have been reported assigning an Early Eocene age the formation.

2.7.4 Sakesar Limestone

The term Sakesar Limestone was initiated by Gee (in Fermor, 1935) for the prominent Eocene limestone part in the Salt Range and TransIndus Range. The unit comprises of dominant limestone with subordinate marl. Throughout its extent, the limestone is cream colored to light grey, usually thick and nodular, with significant development of chert in the upper section. The marl is cream coloured to light grey and forms a persistent horizon near

Chapter Two 42 Stratigraphy

the top. Near Daud Khel in the western Salt Range the limestone grades into white to grey and massive gypsum.

In the study area, the upper contact is conformable with the Chorgali Formation and the lower contact also conformable with the Nammal Formation. The formation has yielded a rich assemblage of foraminifers, mollusks and echinoids. Important foraminifers are Assilina leymeriei, A. laminosa, Fasciolites oblonga, Flosculina globosa, Lockhartia conditi, L. hunti, Operculina nummulitoides, Orbitolites complanatus, Sakesaria cotteri and Rotalia trochidiformis.These foraminifers indicate an Early Eocene age.

2.8 Rawalpindi Group

The Stratigraphic Committee of Pakistan has approved the term Rawalpindi Group after the Rawalpindi District, as proposed by Pinfold (written communication, 1964), for the rocks comprising Murree Formation and Kamlial Formation. The group consists of alternating sandstone and shale of fresh water origin. The sandstone is light to dark red, purple and grey in colour, while the shale is purple and red. The sandstone in the Kamlial Formation is characterized by a flood of tourmaline and paucity of epidote while that of the Murree Formation by abundance of epidote. In general, the thickness increases from southwest to north-west and reaches at least 3,330 m in the North. The lower contact of the group with various Eocene formations is discomformable, while the upper contact with the Siwalik Group is conformable. Vertebrate and plant remains including silicified wood indicating Miocene age have been reported from the group.

2.8.1 Murree Formation

The Stratigraphic Committee of Pakistan has approved the name Murree Formation for "Muri Group" of Wyne (1874), "Murree Beds" of Lydeker (1876) and "Murree Series" of Pilgrim (1910). The name “Murree Formation” is derived from the Murree hills of Rawalpindi District. The Formation is

Chapter Two 43 Stratigraphy

consists of a monotonous series of purple and red clay along with purple grey and greenish grey sandstone. Subordinate intraformational conglomerate are also present. The lower stratum of formation consists of calcareous sandstone and conglomerate of light greenish to grey colour. This unit is rich in foraminifers of Eocene age. The main body of the formation is slightly fossiliferous and only some plant remains, silicified wood, fish remains, mammalian bones and frog have been reported. However, the Fateeh jang Member has recognizable mammals indicating Anthracotherium bugtiense, Brachyodus giganteus, B. cf. africanus, Palaeochoerus pascoei, Hemimeryx sp., Teleoceras fatehjangensis etc. The fauna represents an Early Miocene age.

2.8.2 Kamlial Formation

The Formation is well exposed throughout the study area. It consists of purple-gray, gray, light gray, red, yellow, yellowish gray, brown, brownish gray, yellowish brown, brownish red of loose purple shale and yellow and purple intraformational channels. The Formation overlies the Chorgali Formation with mostly transitional contact; however at some places the Formation has gradational contact with Kalabagh Conglomerate. The Kamlial Formation is conformably overlain by the Chinji Formation.The average thickness is 800 m in present study area where, the Formation is divided into three parts, lower, middle and upper Kamlial. In the lower Kamlial the numbers of sandstone beds are stories 8 to 14 and thickness of sandstone beds stories vary from 2m to 30m. The sandstone beds are soft to medium hard and moderate to poorly sorted. The lower kamlial sandstone is medium to coarse grained. Intraformational channels are 2m to 6m thick and 5m to 20m long. The Kamlial Formation makes an abrupt escarpment against the Eocene of Salt Range to the south. This is named lower Kamlial. The middle part of Kamlial Formation makes "V" shaped strike valley. The number of sandstones beds stories in middle Kamlial are 5 to 8. Shales of middle

Chapter Two 44 Stratigraphy

Kamilal are very thick and there is another abrupt escarpment against the middle Kamlial to the south which is named as upper Kamilal. The number of sandstone beds in upper Kamlial is 8 to 15. The upper Kamlial sandstones are generally medium to very hard. Intraformational channels and yellow colored volcanic ash are present in middle and upper parts of the Kamilal Formation. In lower Kamlial the numbers of shale beds are 7 to 14. The colour of shale is generally brick red. The shale consists of lose material. In lower Kamlial one or two beds of siltstone are present. The color of siltstone is yellowish gray and it is 15m to 20m in thickness. The beds of shale of upper Kamlial are red, brick red and light gray in color. Generally, the Kamlial Formation consists of soft to medium hard sandstone which is cross bedded. Cross bedding is frequent. The spheroidal weathering on sandstone is present. Rock pedestals are present is Kamlial Formation, Wooden logs are also present in Kamlial formation. Calcite/Dolomite are very important constituents of cement. They occur mostly as precipitated matter, but calcitic carbonate grains are also present. Muscovite/biotite/sericite occur as fine to very fine grains. Chlorite occurs as small individual flakes, some small aggregates are also seen. Green, volcanic rock fragments may also contain epidote grains, which are generally fine grained. A number of fossil mammals have been recorded form the formation. These fossils are middle to late Miocene.

At the type locality, the Kamlial Formation consists of hard and medium grained sandstone of purple, grey and dark brick red colour. Interbeds of hard purple shales and pseudo conglomerate of yellow and purple colour, occur at different intervals.

Chapter Two 45 Stratigraphy

2.9 Siwalik Group

Nomenclature history indicates that the term "Siwalik" was first used by Meddlicot (1864) for the upper part of the "Sub Himalayan system" of the Siwalik and Simla hills of India, Later, Oldham (1886) and Holland et al. (1913) used the terms "Siwalik Series" and "Siwalik System". Pilgrim (1913) proposed a three-fold division of the "Siwalik System" each of which was, in turn, divided into different faunal zones as shown in Table 2.1. Cotter (1933), following Wynne's (1878) classification, suggested that the "Kamlial Stage" should be grouped with the Murree Formation as the boundary between these two units is quite arbitrary. The suggestion has been accepted by the Stratigraphic Committee of Pakistan, which combined the Kamlial and the Murree in the Rawalpindi Group. The six faunal zones of Pilgrim were used as formal lithostratigraphic units (Leweis, 1937). Stratigraphic Committee of Pakistan following Danilchik and Shah (1967) established the Siwalik Group for the "Siwalik Series System", comprising the following formations, in descending order; Soan Formation (Tatrot and Pinjor), Dhok Pathan Formation, Nagri Formation and Chinji Formation.

2.9.1 Chinji Formation

Pilgrim (1913) proposed the name "Chinji Zone" to designate the upper faunal subdivision of his "Lower Siwalik". Lewis (1937) upgraded it to a formational level calling it "Chinji Formation and the name were accepted by the Stratigraphic Commiittee of Pakistan. The formation contains red clay with minor ash grey or brownish grey sandstone. The sandstone is fine to medium grained, rarely gritty, cross-bedded and soft. Scattered pebbles of quartzite with thin lenses of intraformational conglomerate are found at different horizons. The proportion of clay and sandstone in interbeds is variable from place to place. The formation essentially represents an argillaceous facies where the sandstone horizons rarely attain 16 m thickness but clay bands

Chapter Two 46 Stratigraphy

may be as much as 60 m thick. The formation has yielded abundant vertebrate fossils as listed by Pascoe (1963). The predominant groups in the Chinji fauna are crocodiles, turtles, monitor lizards, aquatic birds, dinotheres, primitive trilophodonts, forest dwelling suidae, Okapilike Giraffokeryx, water deer, few hominoids, plethora of pythons and abundant chelonian remains. Some of the vertebrate species include Sivapithecus indicus, Trilophodon macronathus, Sivacanthion complicatus, Giraffokeryx punjabiensis, Chilotherium intermedium and Sivaelurus chinjiensis. The age of the Chinji Formation is Late Miocene.

2.9.2 Nagri Formation

The Nagri Formation of Lewis (1937) has been accepted by the Stratigraphic Committee Pakistan. Nagri formation signifies the "Nagri Zone" or "Nagri Stage" of Pilgrim (1913, 1926), the "Dandot Sandstone" of Wynne (1877), the "Marwat formation" of Morris (1938), the "Lower Manchhar" of Blanford (1876), parts of the "Sibi group" and "Urak group" of Hunting Survey Corporation (1961) and "Uzhda Pusha formation" of Kazmi et al. (1970). The Nagri Formation consists of sandstone with subordinate clay and conglomerate. The sandstone is greenish grey medium to coarse grained, cross-bedded and massive. In places, the sandstone is bluish grey dull red with "salt and pepper" pattern, calcareous, and moderately to poorly cemented. The clay is sandy or silty chocolate brown or reddish grey and pale orange, the proportion of which varies from section to section. The conglomerate beds have highly variable thickness and composition.

The upper contact of the Nagri Formation with the Dhok Pathan Formation is everywhere transitional. The contact can be easily placed as it is marked by color change from greenish grey to bright red or gleaming white and also by regular interbeds of sandstone and clay of the overlying

Chapter Two 47 Stratigraphy

Dhok Pathan Formation. The formation has yielded a rich assemblage of vertebrate remains described by Pilgrim (1913, 1926); Anderson (1928); Colbert (1933); Lewis (1937); Gill (1952) and others. Pascoe (1963) listed numerous species including crocodiles, chelonians, proboscides rhinoceratides and artiodactyles from the Kirthar Province and Marri-Bugti area of the Sulaiman Province. The fauna indicates late Middle Miocene to Late Miocene age.

2.9.3 Dhok Pathan Formation:

The name "Dhok Pathan" was introduced by Pilgrim (1913) in a biostratigraphic sense for the upper subdivision of the Middle Siwalik in the northeast Punjab. Cheema et al. (1977) described briefly that the formation is typically represented by monotonous cyclic alternations of sandstone and clay beds. The sandstone is commonly grey, light grey, gleaming white or reddish brown and occasionally brownish grey, greenish grey brown or buff colored, thick-bedded, calcareous, moderately cemented, soft and cross bedded. The clay is orange, brown, dull red or reddish brown and occasionally rusty orange, greenish yellow, yellowish grey, chocolate colored, calcareous and sandy. Intercalations of yellowish brown siltstone are common. Conglomerate in the form of lenses and a layer is an essential character of the upper part. The thickness of one sandstone-clay cycle varies from 6 to 60 m. The formation has a widespread distribution in the Indus Basin. The conglomerate intercalations in these areas gradually increase upwards in number and are transitional to the overlying Soan Formation.

A very rich vertebrate fauna has been recorded in the Kohat- Potwar Province (Pascoe, 1963). The Dhok Pathan formation is remarkable for its rich Hipparion assemblage and numerous artiodactyles. The fauna indicates an Early to Middle Pliocene age. However, in the

Chapter Two 48 Stratigraphy

Kohat-Potwar Province, it is reported to be exclusively of Middle Pliocene age.

2.9.4 Soan Formation:

In the northwest Punjab the "Upper Siwalik" of Meddlicot (1864), this was later divided biostratigraphically into the “Tatrot” and “Pinjor” zones or stages by Pilgrim (1913). In (1964) Stratigraphic Committee of Pakistan has been formalized the name "Soan Formation" .The formation consists of compact colossal conglomerate with sub-ordinate interbeds of varicoloured sandstone, siltstone and or clay. The proportion of different rock types varies within short distances. The conglomerate consists of a variety of pebbles and boulders of different sizes. The pebbles and boulders range in size from 5 to 30 cm Claystone and sandstone are intercalated. The claystone is orange, brown, pale pinkish or red and soft, the sandstone is grey, greenish grey, coarse grained and soft (Cheema et al., 1977).In the Lower Indus Basin and Quetta region, the conglomerate is composed of poorly sorted well-rounded to sub-angular boulders and pebbles of limestone (being most abundant and are mainly derived from the Kirthar Formation), sandstone, chert, quartzite and igneous rocks embedded in a clayey or sandy matrix. The intercalations are usually of dull yellowish clay and light brown, occasionally grey sandstone. The formation is widely distributed in the Indus Basin and Quetta region of the Calcareous Zone of the Axial Belt. The formation is underlain by the Dhok Pathan Formation with an apparent disconformity, which is marked by sharp coarsening of clastics and by massive, densely packed conglomerate. The Soan Formation is poorly fossiliferous, Pascoe (1963) has reported vertebrates from the Potwar area, which include Mastodon sivalensis, Stegodon clifti, Elephas (Archidiscodon) cf. planifrons, Sivatherium giganteum, Pmamphibos lachrymans, Dicoryphochoerus

Chapter Two 49 Stratigraphy

durandi and Sivafelis potens. The fauna indicates Late Pliocene to Early Pleistocene age.

2.10 Quaternary

2.10.1 Pleistocene

Quaternary sediments include rocks of Pleistocene age, which occur in isolated areas of Pakistan and mostly as blanket earlier folds:

2.10.2 Lei Conglomerate

The name "Lei Conglomerate" was introduced by Gill (1952) for the post-Siwalik conglomerates of the Soan area, earlier named "Boulder Conglomerate" by Pilgrim (1910), for the uppermost subdivision of his "Upper Siwalik".Lei Conglomerate is essentially a valley fill, laid down as fluviatile, lacustrine and piedmont outwash deposits in the lower parts of structural depressions. The formation is composed of coarse boulder and pebble conglomerates, with minor coarse and cross-bedded sandstone. In the Soan Valley, the conglomerate comprises of slightly sorted pebbles and boulders of generally Eocene rocks. It is thick bedded and usually stained ochre red or yellow. Most of the boulders are of limestone, marl and sandstone derived from Tertiary and older rocks of the neighbouring areas. Interlayered Sandstone is green grey and brown, cross-bedded, crumbly and pebbly. The 300 to 600 m thick conglomerate in the study area usually forms steep or vertical walls and cliffs. The Lei Conglomerate is unconformably underlain by the Soan Formation in most localities. However, in some places the contact is transitional. The upper contact is gradational with Subrecent deposits and is difficult to define. The fauna includes Elephas hysudricus. Sivatherium giganteum, Dicerorhinus platyrhinus, Equus sp., E. namadiscus Bos sp., and Camelus sp. Pascoe (1963) dates the formation as Middle Pleistocenes.

Chapter Two 50 Stratigraphy

Table: - 2.2 Stratigraphic succession and seismic velocity of various rock units of Salt Range

Chapter Two 51 Stratigraphy

(Modified from Ibrahim Shah, 2009)

Figure 2.1 Diagrammatic illustration of the major unconformities in the

Eocambrain to Tertiary sequence of the Salt Range - Surghar Range

Chapter Three 52 Tectonics

Chapter Three TECTONICS

3 Tectonics

3.1 Regional Tectonics

The Asian continent has grown since Paleozoic times, with the collisions of broken fragments from Gondwana (Hatzfeld, et al. 2005). Some fragments, like the Tarim Basin north of Tibet or the Lut Block within the Iranian Plateau (Figure-3.1 and Figure 3.2) are relatively intact blocks apparently sufficiently strong to have resisted deformation since they joined Eurasia (Hatzfeld, et al. 2005).

The mighty Himalayan mountain chain is a geological expression of shortening between the Indian and Eurasian Plates (Figure 3.3). India was part of Gondwanaland that was in southern hemisphere and that fragmented in Permo-Triassic times. The Tethys Ocean that existed between India and Eurasia was closed after the northwards drift of India and subduction of ocean floor under Eurasia (Abdrakhmatoa, et al. 2001) (Figure-3.4 and Figure-3.5).

Collision responsible for the Himalayan Ranges began in middle-to-late Eocene times (Stoneley, 1974; Stocklin, 1974, Molnar P.et al. 1993). Seafloor reconstructions indicate that about 2000 km of convergence has occurred between India and Eurasia since collision, (Patriat and Achache, 1984).

The collision zone has been studied intensely east of Kashmir, where subdivisions of the Himalaya (from north to south: the Tethyan-Himalaya, High-Himalaya, Lesser Himalaya, Sub-Himalaya, and Gangetic foredeep) are based on stratigraphic, morphological, and structural criteria (Gansser, 1981). In the central part of Himalaya, four major structures the Indus-Tsangpo suture, Main Central Thrust (MCT), Main Boundary Thrust (MBT), and Main Frontal Fault (MFF) bound these subdivisions (Gansser, 1981). However, these structures and subdivisions are not clearly traceable around the

Chapter Three 53 Tectonics

Hazara-Kashmir Syntaxis, where the gently arcuate form characteristic of the ranges throughout India and Nepal gives way to the strongly festooned Pakistani Himalaya (Figure-3.5).

The contact between India and Eurasia is the Indus Tsangpo Suture that bifurcates in northern Pakistan (Figure-3.6).The collision in the west is oblique along the Chaman Ornach Nal Fault zone, which connects the collision zone with the Makran Subduction Zone, where the Arabian Plate is being subducted beneath Eurasia (Figure-3.5). Offshore region, the “Murray Ridge” and “Owen Fracture” zone limit the Arabian and Indian plates (Bullen, M.E., et al. 2003).

Another important tectonic feature of the region is the Pamir arc, located to the north of Karakoram (Figure-3.6, Figure-3.7 and Figure- 3.8). It is an intercontinental subduction marked by two subduction zones (Clark, et al. 2006). The northern subduction zone dips southwards while in Hindukush the subduction zone dips northwards (Figure-3.7). To the east and west it is marked by large strike slip faults i.e. Altyn Tag Fault, Karakoram Fault, Hirat Fault and Chaman Fault (DeCelles et al. 2007).

About 2 Ma ago, the major deformation front shifted further south resulting in emergence of Salt Range along the Frontal thrust named as Salt Range Thrust (Molanar et al. 1993) (Figure- 3.8 and Figure- 3.10).

In northern Pakistan the Himalayan trend has been divided into four main subdivisions (Farah et al, 1984; Yeats and Lawrence, 1984.).To the north of the Main Karakoram Thrust (MKT), the Karakoram Ranges and Hindu Kush are terranes of Gondwana affinity sutured to Eurasia (the Turan Block) in Late Triassic to Middle Jurassic times (Molanar et al. 2009). South of the MKT and north of the Main Mantle Thrust (MMT), the Kohistan block, represents an island arc (Jan and Asif, 1981; Tahirkheli, 1982; Farah et al, 1984) docked to Eurasia in late Cretaceous (Windley, 1983) to early Eocene

Chapter Three 54 Tectonics

time (Kennett, 1982). South of the MMT and north of the MBT are the low ranges of Kashmir, Hazara, and Swat analogous to the Lesser Himalaya of India (Ekutzbach, et al. 2001). The outlying Potwar Plateau and Salt Range, bounded on the south by the Salt Range Thrust (Biswas et al. 2007), represent the marginal foreland (fold and. thrust) belt of the Indo Pakistan subcontinent (Molnar et al. 2009), equivalent to the Sub Himalaya in India (Farah et al, 1984). Zeitler et al (1982) suggest that the MMT locked approximately 15 Ma, subsequent to rapid uplift north of the fault between 30 and 15 Ma (Molnar et al. 2009). Following the cessation of movement along the MMT, deformation propagated southward to the vicinity of the MBT where un metamorphosed (Caddick et al. 2007), Lower Tertiary rocks are thrust over Neogene molasse (Fang et al. 2005). In the latest phase in Pakistan, thrusting transferred to the Salt Range Thrust (Green et al.2008), where deformation as young as 0.4 Ma has been documented (Laffaldano et al. 2006). South of small anticlines in front of the Salt Range Thrust, sediments overlying the Punjab Plain are undeformed; the current foredeep to the Pakistan Himalaya lies in this area (Petit et al. 2006).

3.2 The Salt Range

The Salt Range (Figure3.9), part of the Himalayan foreland (fold and thrust) belt, marks the southernmost position of the thrust front in the northwest Himalaya of Pakistan (Figure-3.10).Tectonically; the Salt Range is the Himalayan equivalent of the Jura Mountains in the Alps and the Pine Mountains of the Appalachians. It is bordered by the Potwar Plateau in the north and Punjab plain in the south.

Thin skinned tectonics is now recognized in the forelands of most orogenic belts. Low-angle thrusts with décollement surfaces in rocks of low yield strength, especially shales and evaporites are characteristic features of these orogens (e.g., Caledonian-Appalachians-Ouachita-Marathon fold

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belt (Morley, 1986; Rich, 1934; Harris, 1970; Harris & Milici, 1977; Cook et at, 1979, 1980; Mitra, 1988; Wickham et al., 1976; Lillie, et al., 1983, 1985), the Alpine-Himalayan belt (Argand, 1916; Pierce, 1966; Laubscher, 1971, 1972, 1975; Rybach et al., 1980; Wadia, 1957; Gansser, 1964; Molnar, 1984; Coward & Butler, 1985, Brunel, 1986) and the Cordilleran belt (Mingramm et at, 1979; Price, 1981).

Most of the previous geological and geophysical studies of the Potwar Plateau have been devoted to oil exploration and regional structures (Wynne, 1878; Cotter, 1933; Wadia, 1945a, 1945b, 1957; Gee, 1945, 1947, 1980; Martin, 1961; Sokolov & Shah, 1966; Shah, 1977; Farah, 1977; Voskresenskiy, 1978; Fatmi et at, 1984; Duroy, 1986; Leathers, 1987; Lillie et at, 1987; Baker, 1987; Baker et. al., 1988; Durroy et al., 1989; Pennock, 1988; Pennock et. al., 1989). Butler et. al., (1987) focused on the control of salt on the thrust geometry of the Salt Range.

3.3 Active Thrust System of the Salt Range

The Salt Range is separated from the Himalayan foothills by the Potwar Plateau, nearly 170 km of slightly elevated (about 270 m) land with very little topographic relief. The roughly ENE-WSW trending Salt Range is bounded by the right-lateral Kalabagh Fault in the west (Gee, 1945; 1947; McDougall, 1985; Leathers, 1987; McDougall and Khan, 1990) and the Hazara-Kashmir syntaxis in the east. The Hazara Kashmir syntaxis is formed by several fault blocks bounded by forward-and-rearward verging thrusts at the eastern margin of the Potwar Plateau (Johnson et al., 1986).

The Salt Range Thrust, which is the leading edge of a décollement within Eocambrian evaporites, brings Phanerozoic strata over late Quaternary fanglomerates and Jhelum River alluvium (Yeats et al., 1984). The allochthonous nature of the Salt Range, was recognized by several workers (e. g., Wynne, 1878; Cotter, 1933; Wadia, 1945 a, 1945 b, 1957; Gee, 1945,

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1947, 1980; Voskresenskiy, 1978). Voskresenskiy (1978) argued that preexisting basement faults played a significant role in the tectonic evolution of the Salt Range as well as Potwar Plateau.

3.4 Near Regional Tectonics

The southern margin of Himalayan collision zone in Pakistan is the Salt Range and Potwar plateau (Royer et al. 2006). It is an active fold-thrust belt formed in response to the under-thrusting of cratonic India beneath its own sedimentary cover (Figure-3.8). The basement (Cratonic part of Indian plate) is covered by 12,000 to 15,000 m thick sedimentary sequence ranging from Precambrian to Recent in age (Zhu.et al. 2005). The Precambrian to Early Cambrian rocks are composed of thick salt, gypsum and marl. These low strength evaporites constitute the lubricated zone of décollement that facilitated zone of under thrusting to extend up to more than 100 km south of MBT (Figure-3.8 and 3.10).

At the Salt Range front, the evaporites and overlying strata override synorogenic fan material and alluvium of Punjab Plains along Salt Range Thrust (Lambs, et. al. 2006).

The Salt Range forms monoclinal slope to the north that merges into Potwar Plateau. The plateau is truncated to the north by MBT (Drewes., et al. 1995). It is bounded to the east by left lateral strike-slip fault named as Jhelum Fault (Figure-3.10) Right-lateral Kala Bagh Tear Fault terminates the Salt Range-Potwar in the west (Figure-3.10) (Drewes., et al. 1995).

The northern monocline is a surface expression of a footwall ramp (Baker., D.M., 1988). It is a basement normal fault 1 km down to the north (Figure 3.11 and Figure 3.15). The basement offset acted as buttress that controlled ramping and emplacement of Salt Range Thrust (Baker, 1988; Edwards, 2007). The basement and décollement dip at an angle of 20 to 4° due north. The basement fault is not a linear structure; hence accumulation of

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south flowing salt at décollement is not in linear fashion that resulted in multi directional salt cored folds in the Salt Range. It also controlled the geometry of frontal thrust (Warwick, P.D., 2007).

The Salt Range has experienced less internal brittle deformation due to its thick salt as décollement zone (Gee, E.R., 1989) (Figure-3.11). Major thrusting is confined to the frontal parts. Folds axes are EW trending and anticlines are generally crest faulted. Further to the west the Salt Range takes a swing to trend NNW on the right lateral Kala Bagh Fault (Figure 3.10).

In Central Salt Range, faulting dominates over folding (Gee 1989). Large, open transverse salt cored folds extend into the range from the frontal thrust escarpment (Jaume, et al. 1988). At places the anticlinal folds are crest faulted, which cut by deep gorges. Examples of such anticlines are Chamblanwala, Nilawahan, Sardhi and Khewra gorges. Brittle deformation is manifested by Kallar Kahar Fault, Chumbi Fault, Sarklan Fault and Vasnal Fault (Gee, 1989 and Peter, et al. 2007). These faults have divided central Salt Range into triangular blocks (Gee, E.R., 1989) that coherently glided over the décollement like coherent slabs without significant internal deformation. The near regional area around the study area is a part of eastern Salt Range- Potwar that, where deformation is distributed in a series of northeast trending folds and thrusts. Major anticlines include Rohtas Anticline, Mahesian Anticline, Bakrala Anticline, Lehri Anticline and Pabbi Anticline (Figure-3.16 and Figure 3.18). The anticlines are cored by ductile thickened salt and separated by broad synclines underlain by relatively thin salt. The anticlines are blind thrust cored or thrust cored folds. This structural style is dominant in areas around Grand Trunk Road. The Pabbi anticline emerges out of Punjab Plains at the left bank of Jhelum River. It is a gently asymmetric attributed to dragging of Tertiary sediments along northwest - dipping blind thrusts.The surface

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signature of the thrust is a lineament on satellite images. It is parallel to the Salt Range Thrust. It is a growing structure, whose surface expression is less than 0.4Ma (Burbank et al. 1988).

Major faults of the eastern Salt Range Potwar are Diljabba Thrust, Salt Range Thrust, Waghh Thrust, Tilla Range Thrust and Jhelum Fault. Thrusts converge both to northwest and southeast. Salt is thinning further to east. The thinning of salt resulted in the formation of left lateral Jhelum Fault and fold structures formed by drag along eastern extreme of Salt Range-Potwar. The eastern Potwar rotated up to 300 counter clockwise relative to central and western Potwar.

The Salt Range attained its present topographic expression about 0.3 million years ago (Burbank, et al. 1988). The average shortening rate of Salt Range is 14 mm/years (Jadoon et al. 2005), which is 35% of total Indian Plate convergence rate (Laffaldano et al. 2006). Since the emergence of Salt Range, continued deformation in the area has mainly taken place in the form of creep movement, tilting and rotation. The offsets in the sediments are generally restricted to major thrusts however; in eastern most and northeastern part of Salt Range - Potwar the geological structures are seismically active (Molnar, et al. 2009). The Salt Range Thrust along with all major thrusts of NW Himalayas makes distinct topographic steps in response to young and active tectonism (Molnar, et al. 2009) (Figure-3.12).

3.5 Structural Geology

Earlier works of Wynne (1878), Pinfold (1918), Cotter (1933), Gee (1945, 1947), and Wadia (1945) provide much of the foundation for the modem structural interpretation of the Salt Range and Potwar Plateau. As mapped by Gee (1980), the Salt Range is deformed in several different ways. The stratigraphic section is cut by south trending, imbricate thrust faults in the central and western portions, giving way westward to right-lateral tear faulting

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near the Indus River (Kalabagh fault; McDougall, 1985). Voskresenskiy (1978) indicates that north-verging folds are also common.

Underneath the Salt Range / Potwar Plateau, the major décollement within the Salt Range Formation has carried southwards the entire sedimentary section (Seeber and Armbruster, 1979; Lithe a al, 1987). The Salt Range itself is the topographical expression of this thrust sheet riding up and over a down to the north, basement normal fault (Lillie and Yousuf, 1986; Baker et al, 1988). However, as one moves eastward, away from the central Salt Range, the prominent topographic expression of the thrust front dies out around the Chambal Ridge (Yeats et al, 1984).

The eastern Salt Range is dominated by folding. Most of the folds in the eastern Salt Range (Figure 3.19) trend NE-SW, in stark contrast to the E-W trending folds in the central Salt Range / Potwar Plateau, and the NW-SE trending folds on the eastern side of the Jhelum Reentrant (Clark, 2008). Wavelengths of the folds are typically 10 to 12 km. Along their lengths, many individual folds gently plunge into saddles; however, overall fold trends are clearly identifiable for distances of 40 to 60 km. In some instances, the plunging ends of the anticlines coincide with prominent changes in fold trend (e.g., NE end of the Tanwin-Bains anticline) (Kazmi, A.H., 1997). Folding and erosion of most of the anticlines has exposed rocks of the lower Siwalik Chinji Formation (Shah, 2009). Although all of the molasse facies rocks are time- transgressive to the south, a nominal age range for the Chinji Formation is 13.1-10.1 Ma (Johnson et al, 1982). Stripping of the overlying Nagri, Dhok Pathan, and Soan Formations requires structural relief in excess of 1500 m.

Perhaps most important for a structural interpretation of the eastern Salt Range / Potwar Plateau are that

1. The anticlines are tight structures, separated by broad, open synclines

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2. Dips of the axial zones of most of the anticlines are steep to overturned (Martin, 1962; Raynolds, 1980)

3. Despite the intense deformation in the cores of the anticlines, surface faulting is comparatively rare.

Johnson et al (1986) suggest that folds of the eastern Salt Range / Potwar Plateau are cored by blind thrusts. They suggest that these thrusts cut up section due to increased basal friction caused by an eastward thinning of salt along the edge of an extensive Eocambrian salt basin, as predicted by Davis and Engelder (1985). However, Jaurne (1986), and Leathers (1987) suggest that thrusts may cut up-section due primarily to the extremely shallow dip (Butler, et al. 1987) of the basement (<1°), an idea also consistent with the mechanical model developed by Davis and Engelder (1985) for fold and thrust belts that have developed over evaporites. More recently, Butler et al (1987) have suggested that the structures in the eastern Salt Range / Potwar Plateau decouple within the molasse sediments, not within the Salt Range Formation, but this interpretation is inconsistent with observations from reflection profiles across the region.

3.6 Potwar Plateau Framework

Structurally, the Potwar Plateau consists broadly of a number of faulted anticlines, and synclines superimposed on the East-Northeast to west- southwest trending main Soan Syncline (Figure 3.16 and Figure 3.18). The axial planes of the folds and the fault planes are parallel to sub-parallel to the major regional trend (Figure 3.16 and Figure 3.18). In the SW Potwar Plateau, the deformation is mostly localized to south verging thrusting along the Salt Range Thrust (SRT), also referred to as Main Frontal Thrust (MFT). This style contrasts with that of the eastern PP, where deformation is distributed along a broader zone of NE-SW trending, tight to overturned anticlines separated by broader synclines. Tectonically the Potwar Plateau is

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bounded to the north by the Himalayan Thrust (MBT), to the south by the Salt Range Thrust (SRT) and Eocambrian basement rocks (Kirana Hills), to the east by the Hazara Kashmir Syntaxis (HKS) and Jhelum fault and to the West by the Kalabagh Syntaxis and Kalabagh fault.

3.7 Main Boundary Thrust (MBT)

The MBT has marked topographic expression (Burg et al., 2005). The northern boundary of the Potwar is marked by the Hill Ranges i.e. Margalla Hill, Kala Chitta and Attock-Cherat Ranges which represent westward extension of the Main Boundary Thrust (MBT) from India into Pakistan (Kazmi, A.H., 1997). The MBT, is one of a series of more or less parallel faults among the Tertiary strata, building the outer Himalayan Range.

East of the Hill Range, the MBT is correlated with the 50o to 80oE dipping Murree fault, which brings Mesozoic and lower Cenozoic strata of the Margalla Hills over strata of the Potwar Plateau north of Islamabad, including a great thickness of Murree formation. The Murree fault turns northward, west of the Jhelum river and forms the boundary of the Hazara Kashmir Syntaxis(HKS).

The fault dips vary from 500N to nearly vertical (Kazmi and Jan, 1997). In the east, the fault loops around the Hazara Kashmir Syntaxis. However, on the western side of the syntaxis, like the Panjal Fault, it is displaced by the left lateral Jhelum Fault (described later on). Seeber and Armbruster (1979) consider MBT is a northward dipping reverse fault that in the lower crust is connected with the deeply buried faults referred to as the Hazara Lower Seismic Zone. On both sides of the MBT i.e. Hazara region in the North and Northern Potwar/ Kohat plateau in the south, a number of mostly left lateral strike slip faults occur (e.g. Jadoon et al. 1995).

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3.8 Salt Range and Kirana Hills

The Salt Range, trending ENE, extends along strike for approximately 170 Km. Its southern escarpment is rising 800-900 meters above the Jhelum plains (Warwick, et al. 2007). It forms the present southern active frontal thrust zone of the Himalayas. South of small incipient anticlines in front of Salt Range, the alluvium lying over the Punjab plains is undeformed, the current foredeep to the Pakistan Himalaya lies in this area.

As shown by seismic profiles the Salt Range and southern Potwar Plateau represent a large slab being thrusted, with little deformation, over the foreland basin on a mean 20 to 40, bedding plane fault (Salt Range Thrust) along low strength Eocambrian evaporites (Copley, et al. 2010).This typical décollement tectonics is probably related to the decoupling effect of this salt layer as well as drastic difference in the strength of the rocks above and below it. Loading by the thick molasse sequence within the Soan syncline is believed to have caused ductile flow of Eocambrian slat towards the south, which may have resulted in a salt buildup against a basement buttress. As salt growth continued, Cambrian and younger strata on the north side would be lifted until they could be pushed across the basement offset.

Thrusting, which began later than 5.1 Ma in Central Salt Range (Bhaun area), is still in progress (Lillie, et al. 1987) as shown by Kalabagh fan gravels and alluvium, unconformably overlying the Salt Range Thrust sheet at its southern margin, them selves lidded and overridden by Salt Range Thursts.

The Sargodha High is about 80 km SE of Salt Range Thrust, which composed of basement rocks of the Indian Shield. The Indian Shield occupies two-thirds of the southern Indian peninsular. The Indian Shield, the large stable areas of low relief in the Earth’s crust that are composed of

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Precambrian crystalline rocks (Mahadevan, 2008). The age of these rocks is in all cases greater than 540 million years, and radiometric age dating has revealed some that are as old as 2 to 3 billion years (Figure 3.27).

The southern two-thirds of peninsular India, most of the western half of Australia, and the eastern segment of Antarctica are also areas of continental shields (Mahadevan, 2008). These areas of Precambrian rocks are termed, appropriately, the Indian Shield, the Australian Shield, and the Antarctic Shield It is interpreted as a lithospheric flexural bulge related to the northward under thrusting of the Indian plate (Johnson, et al. 1986). The Sargodha High slopes northwards and provides the required taper for the Salt Range Thrust to outcrop, particularly in the Western Salt Range. Instrumental earthquake records shows that it is an area of low to moderate seismicity.

3.9 The Hazara Kashmir Syntaxis and Jhelum Fault

The Hazara Kashmir Syntaxis is one of the most important structures of the Pakistani fold belt. At this bend the regional trends curve through nearly 90° from the NW -SE Himalayan trend to the ENE- trend of the Salt Range (Lillie, et al. 1987), and locally individual faults can be traced through nearly 180°. The Hazara Kashmir Syntaxes is a "half window" of a complex series of overlapping nappes made up of Precambrian, Paleozoic and Mesozoic formations of the Lesser Himalaya. These thrust units have been thrust over Tertiary sediments of the Sub Himalaya (Lillie, et al. 1987), mainly rocks of Murree Formation. The Hazara Kashmir Syntaxes should probably be considered as the result of interaction between three tectonic components,

a. The Himalayas

b. The Indo-Pakistan shield

c. The Salt Range

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Each of these components is moving separately, viewed in another frame of reference. The Salt Range structures are moving SSE with respect to the Indo Pakistan shield, but the shield itself is converging with the Himalayas. Panjal fault is the main boundary fault that wraps around the Hazara Kashmir Syntaxes. The Panjal Fault is a combination of reverse-strikeslip fault which dips from 59 oE to vertical (Seeber, et al. 1979). The axis of the syntaxes is oriented slightly west of north and is the pivot point of the great regional bend that involves the entire width of the Himalaya.

Jhelum fault is trending N-S nearly parallel to the River Jhelum, extending southwards across the Chaj Duaab (the area between Chanab and Jhelum Rivers) down to south of Ravi River on Landsat and possibly continuing northwards into the active, seismically detected, Indus Kohistan Seismic zone (IKSZ).

3.10 Dill Jabba Fault

The Dill Jabba Fault, a northeast trending thrust dipping towards the northwest is located in the eastern part of Salt Range and Potwar Plateau (Figure 3.26). Pennock et al., 1989 referred to the northeastern portion of this thrust as the Domeli Thrust and the southwestern portion as the Dil Jabba backthrust. Sercombe et al., (1998) referred to the Dill Jabba Fault as the left lateral strike slip Domeli Fault. Some unpublished reports of NESPAK based on observed seismicity pattern suggest that the Dil Jabba Thrust is an extension of the left lateral Jhelum Fault.

3.11 Jhelum Fault

The north south striking Jhelum Fault is a distinct tectonic feature on the western margin of the Hazara Kashmir Syntaxis. The fault has steep dips towards the east and a left lateral offset of about

Chapter Three 65 Tectonics

31 km (Baig and Lawrence, 1987). The Jehlum Fault truncates some major structures of the study area like the MBT, Panjal Thrust and Kashmir Boundary Thrust. Rocks along the fault are highly sheared and deformed due to its movement. Also, Baig and Lawrence (1987) have documented uplift and tilting of Quaternary terraces with localized active landslides.

3.12 Structural Geology of Specific Study Area

The study area is situated at the deformation front of Sub Himalaya. It is surrounded by Salt Range Thrust in the south, Kahan Kas Fault zone in east, Dhok Khair Thrust in north and Waghh Thrust in northeast. All these faults are active and are located at a distance of 1 km, 0.3km, 0.9km and 1.5 km from JalalPur respectively.

The northwest oriented Salt Range Thrust takes a swing in Jalalpur area and merges into NNE oriented Kahan Kas Fault zone (Map NO.3, Figure 3.13, Figure 3.14 and Figure 3.15). The Salt Range Thrust brings synorogenic sediments and Siwaliks in contact with Salt Range Formation. The Siwaliks exposed at footwall are also faulted and fractured and slip is mainly accommodated by shale. In west of Jalalpur, Salt Range Thrust dips at an angle of 400 to 450 due NE whereas it is steeper in Jalalpur area, due to its curvature with concave side to north. The Kahan Kas Fault zone (Figure 3.23) is comprised of two major faults and a number of associated synthetic minor faults. The major faults are high angle, oblique slip faults with reverse component. The major faults bound the Salt Range Formation sandwiched by Siwalik and Rawalpindi Group. Salt Range Formation is highly deformed along the fault zone and movement is mainly accommodated by the low strength evaporites. The synthetic minor faults have crushed the sandstone units at places (Figure 3.24).The western main fault of Kahan Kas Fault zone terminates against EW trending, hinterland dipping thrust while the eastern

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fault of the zone merges into Waghh Thrust.

The Waghh Thrust lies at the base of Chambal Ridge (Figure 3.15), which is a thrust-related monocline with escarpment facing west (Figure 3.13). The arcuate trace of Waghh Thrust is concave to west and the foreland dipping thrust zone lies within Salt Range Formation. Peneplained Siwalik Group covered by sub-recent to recent sediments is in contact with Salt Range Formation along Waghh Thrust. Two NW trending thrusts are located to the west of Waghh Thrust (Figure 3.13). Eastward dipping Shadman Thrust lies within Cambrian rocks while the Dhok Khair Thrust brings Salt Range Formation in contact with Siwaliks as shown in Map-3 (Litholstructural Map around study area)

The topography of the studied area is controlled by major thrusts. The hanging walls make positive topographic expression. The Mangal Dev Ridge, Chambal Ridge. Chak Shadman Hill and Dhok Khair Hill mark the hanging walls of the thrusts (Figure 3.13 Figure 3.14 and Figure 3.15).

The study area is distinguished by many minor faults and fractures, whose orientation, frequency and intensity are controlled by major thrusts. Three parallel curvilinear imbricate thrusts are located in the west of the study area (Map No.1, Figure 3.22). In this area the movement and shearing is mainly, accommodated by the shale. Slickensided shear surfaces and deformed shale can be observed along roadside (Figure 3.23 and Figure 3.24). Change in dip of the strata also marks the eastward extension of the thrusts. These thrusts are synthetic to Salt Range Thrust.

Shear fractures in the study area that trend EW or EEW and dip at an angle of 55o to 68o due south (Map No.3 and Figure 3.22). The fracture planes are marked by grooves, polished surfaces and laminations of gouge. The 50oN- 70oN and 10oN – 20oN fracture are conjugate sets to the Salt Range Thrust. The fractures oriented at 200N-300N are extensional in nature

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however; the fracture/ minor faults along Kahan Kas that trend 300N-400N are compressional shear factures/minor faults (Map No.3 and Figure 3.22).

The brittle deformation is more pronounced in competent rock units, while incompetent shale units are highly deformed. The silty parts within the shale are slickensided along the faults. The clayey portions have been deformed to chips with polished surfaces. The contacts of competent lithology with incompetent rock units are generally sheared and deformation is mainly accommodated by the incompetent units. The shale of Baghanwala Formation behaves like a semi-competent rock while the dolomite being hard and tough is the most affected by brittle deformation.

The study area is dominated by faults trending 0800 EW and EW-2800. Majority of these faults dip at angle ranges from 500 to 650 due South. The fault planes are smooth, polished, striated and slickensided. At places, laminations of dark grey gouge have been observed along the fault planes. It is evident that strong shearing and minor slips are associated with these faults.

The slickensides can be observed along roadside in the relatively harder silty part of shale. The structure that caused the deformation is parallel to afore mentioned fractures but it dips to north. These fractures cause change in the amount of dip, however stratigraphic throw is not associated. Jutana dolomite have repeatedly been thrusted over sandstone of Rawalpindi Group along three imbricate thrusts. The thrusts are linked with the Salt Range Ramp. These thrusts lose their throw eastwards and the north dipping shear fractures represent their extension and splays. The north- dipping fractures are synthetic while south dipping fractures are antithetic structures of Salt Range Thrust.

An east west trending high angle fault zone is located along the cliff of Mangal Dev. The fault zone is comprised of north-dipping or vertical reverse

Chapter Three 68 Tectonics

faults lying within dolomite.

The NS to 010°N trending fractures are generally vertical or dip at high angle due west. Frequency of 010°N trending fractures is higher along the Kahan Kas Fault zone. The fractures trending at 320"-340 N and 030°- 055°N are conjugate shear fractures. The NW trending fractures dip at high angle due SW while dip angle of NE trending fractures varies from 500 - 750 Due SE. It is marked by lamination of gouge and dips at 60 due south.

Chapter Three 69 Tectonics

(After Hatzfeld and Molnar, 2010)

Figure-3.1 Map of Aisa showing topographic and major faults. The two belts, Zagros and Himalaya, lie adjacent to stable regions of Arabia and India, where elevation is low, and to higher terrain in the Iranian Plateau, northeast of the Zagros, and in the Tibetan Plateau north and east of the Himalaya. Both plateaus are bounded on their other sides by mountain belts. Tibet is notably higher than Iran, and high terrain extends much farther much farther N and NE of Tibet than it does from Iran.

Chapter Three 70 Tectonics

(After Powel, 1979)

Figure3.2 Regional tectonic map of Pakistan and surrounding areas

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(Modified from Hatzfeld and Molnar, 2010)

Figure3.3 The Indian plate colliding with the Eurasian plate.

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(Source: US Geological Survey)

Figure3.4 The tectonic plate are delineated by the the mid-oceanic ridges, trenches and transfor fault that form their boundaries.

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Figure 3.5 Regional plate tectonic setting

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Figure 3.6 Structural sketch map of the western Himalaya, HKS-Hazara- Kashmir Syntaxis; NGT-Nathia Gali Thrust.

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Figure 3.7 Section to show the distribution of deep earthquakes related to PAMIR-HINDUKUSH Continental Subduction.

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Figure 3.8 Structural cross of North West Pakistan

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(Modified from Lillie et al. 1984) Figure 3.9 Regional location map showing the proximity of the Salt Range (SR) and Potwar plateau (PP) to the main Himalayan Range. Note the gently accurate nature of the main Himalaya in India and Nepal compared to the highly festooned foreland of the Pakistani Himalaya. Also note the sharp bend in structural trends around the Hazara Kashmir syntaxis (Hks), just east of the SR/PP. Area shown by bold rectangle. Other abbreviations: ISZ=Indus Suture Zone, JR=Jhelum Reentrant, KF=Kalabagh fault, MBT=Main Boundary thrust, MCT=Main Central thrust, MFF=Main Frontal fault, MKT=Main Karakoram thrust, MMT=Main Mantle thrust, SH=Sargodha High, and SRT=Salt Range thrust.

Chapter Three 78 Tectonics

(From Iftkhar Ahmad 2012 and Modified from Lillie 1987)

Figure 3.10 Generalized map of the upper Indus sub-basin, showing geologic and tectonic features in the Potwar, Kohat, Bannu and Mianwali Re-entrant Area.

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(After Leathers, 1987)

Figure 3.11 Cross Section of the Western Salt Range, Potwar Plateau.

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(After Leathers, 1987)

Figure 3.12 Cross Section of the Central Salt Range, Potwar Plateau.

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Figure 3.13 Structural features of Salt Range and Potwar Plateau.

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Figure 3.14 Satellite Image of the study area

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Figure 3.15 Geological sketch map of present study area, modified from Gee (1980), of eastern of eastern Salt Range, showing S-bend at Jalalpur north to Chambal Ridge (south of Bunha River) and Jogi Tilla anticline (north of Bunha River). Rawalpindi Group includes Murree and Kamlial Formations (Shah 1977). Lower Siwalik is subdivided into Chinji, Nagri, and Dhok Pathan Formation.

Chapter Three 84 Tectonics

(After Leathers, 1987)

Figure 3.16 Cross Section of the Eastern Salt Range, Potwar Plateau.

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Figure 3.17 Sketch of fault-related topographic fronts

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(Modified from pennock et al. (1989), Jadoon et al. (1997) Figure 3.18 Fault-propagation geometry of Eastern Salt Range / Potwar Plateau.

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(Modified from Warwick, P.D. 2007)

Figure 3.19 Structural map of Potwar Plateau showing the regional fold trend.

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(Modified From Burg, J.Pet 2004)al,

Figure 3.20 Top: Section across the southeastern fold-

an-thrust belt of the Pakistani Himalaya. Location on Figure-3.6. Below: Pseudo

template reconstruction. Decisions concerning reconstruction are discussed in the text. Dashed lines are tentative locations of unexposed flats in a thin-skin tectonics interpretation

Chapter Three 89 Tectonics

(Modified From J.PBurg, et al, 2004)

Figure 3.21 Frontal emergence of the MBT separating southward dipping Murree Molasse sediments of the southward limb of a (ramp) anticline from underlying flat and shallow dipping Molasse beds (par-autochthonous). Note the south-dipping topography marking the southern front of the fold-and-thrust belt of the Western Himalayas. Ghola Gali.

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Figure 3.22 Structural map of Chamble Ridge-Study area.

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Figure 3.23 Kahan Kas Fault zone exposed along Waghh Road (North faces camera)

Figure 3.24 Highly Crushed Rock along Khan KAS Fault

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Figure 3.25 Explanation of the terminology used for the different stratigraphic units and structural features in this study. Note that thick salt pad forms the wedge shaped

geometry due to the buttressing effects of the northern ramp localized by the basement normal fault. Also note

the deformational style of the roof sequence into sharp, salt cored anticlines and broad, flat based synclines.

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Figure 3.26 Schematic diagram showing the successive development of Dil Jabba fault. Note that the roof

sequence kept on moving forward and only a part of the deformation has been accommodated along the back thrust. Also note that gradual development of a salt wedge in the footwall of the back thrust that altered the geometry of the footwall.

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Figure 3.27: Figure showing the Geological Provinces

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Chapter Four NEOTECTONICS

4 NeoTectonics

Neotectonic studies are a very important component of seismic hazard assessment. The terms Neo-tectonic is generally implied for deformations caused during Holocene times i.e. within the last 0.1 million years (IAEA Safety Guid.50).

Subsequent to deposition each sediment is subjected to different geological phenomena such as diagenesis, lithification and deformation (Beaumont, et al. 2000).Sediments are deposited on horizontal or gently inclined surfaces and the tectonic activity leaves its mark as tilt, fracture, fault or other deformational features (Owen, et al. 2008).Such record of deformation is an essential input for seismotectonic analysis and assessment of peak ground acceleration (IAEA Safety Guid.50).

The frequency and intensity of seismicity in a given area is determined through both historical and instrumental record maintained. However, since most faults have recurrence periods longer than that of recorded history, it is necessary to carry out neotectonic studies. Bilham (2005) defines neotectonics as a field of geology that analyzes the seismic hazards on the basis of palaeoseismology i.e. the study of earthquakes that occurred before the known history and witnessed in sediments and landscape.

Stress builds up in response to plate movements and geological phenomena (Pathier, et al. 2006). It is released by brittle failure with subsequent movement. Seismicity is generated by release of stress through movement along faults. The recurrence time for a seismic event may be very long and stress keeps on building during quiescence period till it is released in the form of next seismic event (Akkar and Boor, 2007).

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Neotectonics features such as tilting of recent sediments, liquefaction etc, have been investigated in the study area using the interpretation of satellite images and selected field traverses.

As a first step recent deposits were mapped through detailed study of available maps, interpretation of satellite imageries and consultation of relevant geological literature i.e. tectonics, lithological units, structure etc. Then satellite data interpretation helped to delineate the areas where these deposits come in contact with major structures (Avouac and Helmberger, 2006). Subsequently, these areas were checked in detail to witness any seismic indicators.

Recent sediments are, in the study area, present mainly along stream beds as terraces, on the top of uplifted older rocks, along cliff faces and in intermountain basins. The most common type is terrace deposits at various levels along major streams and their tributaries. Since the investigated area is comprised of different types of rock units such as limestone, sandstone, shale and conglomerate, boulders and pebbles in these terraces are characterized by mixed lithology. Most terraces are poorly indurated and loose; however, the older terraces are locally indurated.

Since any active structure located within 100 km radius around the investigated area may have direct impact on proposed civil structure (IAEA Safety Guide 50SG. SI-Rev-1),all recent deposits within this circum sphere were checked as recommended by Bilham (2005). Special attention was given to deposits located within 10 km radius from the present study area (JalaPur).

No recent sediments examined so far in the region showed any neotectonics signature.Four different terrace levels are present along various major and minor streams.These are lying undisturbed and horizontal above

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gently to steeply dipping older rocks at many places and even in the vicinity of major fault.

4.1 Regional Neotectonics

Any structure / fault that is active and located within 100 km radius around the studied area has direct impact on the civil structures (IAEA Safety Guid.50). The activity of the geological structure / fault does not originate seismicity only but also is a potential source for ground rupture (Ambraseys, et. al2005). Therefore, study of these structures / faults in respect of their activity in recent times is necessary.

A database has been established from available published and unpublished sources and previous work coupled with fieldwork and satellite image interpretations. The obtained data indicates that several structures bear neotectonic features in accordance with instrumental information. These structures are considered active and capable of generating earthquakes in the future.

Salt Range is an active frontal fold and thrust belt (Molnar, et al. 2010). The ongoing deformation is manifested by the neotectonic features associated with the Recent and Subrecent sediments at various places. These sediments include conglomerate, gravel, sand and silt lying over the Siwalik Group and older rocks. The silt deposits predominate and are named Potwar Silt (Yeats, 1984).

The major active tectonic element of the area is the Salt Range Thrust along which Paleozoic rocks are overriding synorogenic gravels (Akhter, et al. 2004). The older rocks are abruptly truncated against Punjab alluvia’s of recent age (Figure 4.1 and Figure 4.2). In Eastern Salt Range near Jalal Pur Shreef, the Siwaliks are in faulted contact with alluvial deposits (Figure4.2). The silt and gravel beds are tilted and offset (Figure 4.3, Figure 4.4 and Figure 4.5) indicating recent

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deformation (Warwick, et. al, 2007).

Recent gravel and gritty sand are tilted near Khewra (Figure 4.6). The progradation fans and denudation deduced from the gravel dispersal suggest continued uplift (Figure 4.7).

Recent terraces in the northwest of Dina and River terraces near Mangla are tilted as a consequence of active movement along the left lateral Jhelum fault. Rocks along the fault are highly deformed (Figure 4.35 and Figure 4.36) uplifting and tiling of rocks also observed. Tilting of recent silt indicating the active nature of the fault.

Unpublished Mangla joint venture Nespak (2003), seismicity pattern suggested that Jhelum fault connected to the Diljabba fault in the Eastern Salt range.

The Diljabba fault is a North-east trending thrust and dipping towards North-West. North eastern portion of this thrust as the Domeli Thrust and South western portion as the Diljabba back thrust (Satti, 2012). Recent Silt deposit also indicates that the fault is active (Figure 4.34, Figure 4.37 and Figure 4.38).

Near Padrar village limestone abruptly truncated against recent silt along Choa Saiden Shah fault (Figure 4.40).

Faults splays out of Jhelum fault (Map No.1) compensate ongoing crustal shortening in Salt Range / Potwar Plateau (Molnar, et al. 2010). Domeli Diljabba Fault is one of them. Recent deposits lying over Miocene sandstone of Murree Formation in Dag Kas area are tilted due to active movement along the fault (Figure 4.8, Figure 4.9 and Figure 4.10).

4.2 Near Regional Area Neotectonics

In near regional area (25 km radius), neotectonic features are associated with Waghh Thrust, Salt Range Thrust, Dhok Khair Thrust,

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Bunha Kas Fault and frontal fault of Tilla Range.

The Bunha Kas Fault is located along the left bank of the stream where it comes out of Chambal Ridge forming a gorge (Figure 4.11). The fault brings subrecent conglomerates in contact with Cambrian rocks (Khewera Formation) and at places; recent alluvium is in sharp contact with Salt Range Formation of Precambrian age. The fault extends in NE direction and eventually joins frontal thrust of Tilla Range. The fault trace up to Tilla Range is buried under alluvium. The alluvial part has well developed drainage, and some of the streams take sharp bend along the buried fault while confluence points of other streams are aligned in the direction of buried faults. A normal fault to the south of this thrust brings alluvium in contact with Siwaliks near Hun village. Joints sets in recent silts also indicate tectonic activities in the area of Hun Village, near Jogi Tilla (Figure 4.25).

4.3 Local NeoTectonics

Neotectonic features associated with Salt Range Thrust, Waghh Thrust and Dhok Khair Thrust were found within the study area.

The Salt Range Thrust is a regional active fault along which Precambrian Salt Range Formation is overriding Punjab alluvium and synorogenic fanglomerates (Figure 4.2). Recent and Sub recent sediments are tilted in Nathial and Pir Chak area (Figure 4.12). The sediments are comprised of gravel, gritty sand and silt (Figure 4.13 and Figure 4.14). The higher angle of repose in the tilted sediments indicates that tilt is tectonic in origin as higher angles are not possible in fluvial system. Higher angles are known to occur in windblown sediments but wind cannot lay down clasts of pebble size (Frenc Schweitzer, et al. 2011). The shape of scouring surfaces and fining upwards sequences confirm the fluvial origin of these sediments. Slope wash or debris flow deposits do not exhibit such sedimentary characteristics (Szekely, et al. 2002). Further

Chapter Four 100 NEOTECTONICS

westwards beyond the limits of study vicinity area, a number of neotectonic features are associated with Salt Range Thrust.

Recent silt is faulted, fractured and sheared along Waghh Thrust (Figure 4.15, Figure 4.30 and Figure 4.39). The fault planes and shear fracture planes are smooth and marked by fine striations and grooves. Offset laminations in silt have also been observed (Figures 4.16, 4.17, 4.18 and 4.19).The silt deposits lying distant from trace of Waghh Thrust do not show such fractures. It is evident that the shearing and faulting has been caused by movement along Waghh Thrust.

Recent silt deposits lying close to the trace of the thrust are tilted in north of Waghh village (Figures 4.20 and 4.32). Tilt is local and restricted to close vicinity of the fault trace only. Cambrian rocks (Khewra Formation) are in faulted contact with Recent alluvium along the thrust in southeast of W aghh village. Dragged sediments along the faulted contact are indicator of post depositional slip in recent geological time.

The geomorphic signature of the Waghh thrust is expressed by abrupt truncation of flat alluvial plain against escarpment face of Chambal Ridge with an absolute relief > 400 m (Figure 4.1 and Figure 4.2). These features suggest that the Waghh thrust is acti ve.

A fault is also regarded as active if it is linked to an active fault in such a way that movement of active fault may cause slip in the linked fault (Bada, et al. 2001). Although no neotectonic feature could be found along Kahan Kas Fault zone, it is regarded as active because it is linked with the active Salt Range Thrust and Waghh Thrust. The movement along these two active faults will be shared with Kahan Kas Fault Zone (Figure 4.21 and Figure 4.31).

Sub recent conglomerate beds are tilted 5 0 to 60 N along the Dhok Khair Thrust (Figures 4.22, 4.23 and 4.33), which takes a swing to

Chapter Four 101 NEOTECTONICS

strike NW, where the fault trace is concealed by conglomerates. Fractures have been observed in cemented conglomerate along the alignment of concealed trace.

Recent silt is in faulted contact with tilted conglomerate near Dhok Khair villag es shown in (Figure 4.23). This minor fault follows the trend of Dhok Khair Thrust. It is high angle fault and silt is dragged and sheared along the fault. Dhok Khair Thrust is an active structure.

Silt deposit lying in the Chak Shadman, Waghh and Dhok Naghial are undeformed. The silt has been thoroughly investigated for slump structures, liquefaction marks and folds (indication of neotectonics) but nothing like those could be found. The silt is lying horizontal (Figure 4.24). Low angle inclination were observed near Chak Shadman The basin configuration, sedimentary slope and angle of scouring are responsible for such low angle inclinations in fluvial systems (Frenc, et al. 2011). Detail checking of these quaternary deposits did not show any sign of shearing and tilting. Only shallow water carving surfaces developed pseudo expressions of jointing / shearing. However further detail study in lateral parts of this deposit did not reveal any tectonic or seismic movements imprint.

In Dhok Khair area, the upper most Siwalik sandstone unconformably rests on middle Siwalik rocks which dip at 600 - 700 NE whereas the upper Siwalik sandstone dips 100 N. The upper Siwalik rocks are overlain by rec ent conglomerate that dip a 3 to 50 N below flat lying silt.

The lower Siwalik rocks (Chinji Formation and Nagri Formation) are highly sheared / fractured. Thes e fractures do not extend into the middle upper Siwalik sandstone (Dhok Pathan

Chapter Four 102 NEOTECTONICS

Formation). Similarly the conglomerate and silt have not been affected by brittle deformation (Figure 4.26). The neotectonic fractures in silt and conglomerates are restricted to the traces of main thrusts only. The recent silt deposits are undisturbed away from the main faults. (Figures 4.27, 4.28 and 4.29).

The neotectonic brittle deformation indicates that slip along the Salt Range Thrust and related thrusts was seismic up to the time of upper most Siwalik deposition (Pleistocene) in Kotal Kund Syncline. During the time of deposition of recent conglomerate, the Salt Range Formation had already emerged to surface along Salt Range Thrust. The seismic slip transformed into aseismic creep later on due to introduction of low strength (Marl, Gypsum and seams of Salt) rocks of the Salt Range Formation all along the fault planes that acted as lubricant.

The association of neotectonic features with Salt Range Thrust, Waghh Thrust and Dhok Khair Thrust indicates that these faults are active. Average slip rate along Salt Range Thrust is estimated to be 14 mm / a (Kondo, et. al 2008). Localization of brittle neotectonic features with the fault traces, tilt of sandstone and conglomerate without brittle deformation (Figure 4.24) are evidence of aseismic creep movement along the faults.

Keeping in view the aseismic (Figure 4.41) creep, it is inferred that the faults are not capable of generating moderate or large seismic events; however, possibility of small seismic events cannot be ruled out.

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Figure 4.1 The older rocks are abruptly truncated against Punjab alluvial of recent age, SR = Salt Range, PP= Punjab Plain, CR=Chambel Ridge

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Figure 4.2 The older rocks are abruptly truncated against Punjab alluvial of recent age near Jalalpur Village

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Figure 4.3 Tilting and offset in Recent Sediments Silt / Gravel (Siwaliks) sequence indicating Tectonic activity in ESR near JalalPur Sharif

Chapter Four 106 NEOTECTONICS

Figure 4.4 Discontinuity of Silt Bed against Gravies Indicating Reverse Fault Indicating Recent Tectonic. Activity in the Area with a Throw of About Meter Near, Eastern Salt Range

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Figure4.5 Tilting of recent silty clay and gravel beds indicating recent tectonic activity near Khewera Village.

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Figure 4.6 Tilting and fracturing within Sub recent to recent silt / gravel sequence indicating Tectonic activity, near Khewera village.

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Figure 4.7 Strong Shearing and Fracturing with in Sub Recent to Recent Silt / Gravel Sequence near Khewera Village.

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Figure 4.8 Tilted Recent deposits lying over Miocene Sandstone in Dag Kas Area.

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Figure 4.9 Sand dyke in Potwar silt / recent deposits near Dag Kas Area.

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Figure 4.10 Fractured silt lying over the concealed trace of Wagh thrust near Dag Kas Area

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Figure 4.11 Figure showing Bhuna Kas Fault with in Siwaliks near Chamble ridge, Jalalpur Sharif.

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Figure 4.12 Recent and Sub Recent sediments are tilted in Nathial and Pir Chak area.

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Figure 4.13 Tilted Potwar Silt Sediment tilted / Silt (Sediment/Sub Recent) Over Concealed Fault of Near Pir Chak Area.

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Figure 4.14 Tilted Potwar silt along over concealed fault, near Nathial Village

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Figure 4.15 A minor neotectonic fault in the recent silt lying close to Wagh Thrust.

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Figure 4.16 Shear Fractures with minor offsets in Recent Silt near Wagh Thrust.

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Figure 4.17 Shear fractures in recent silt with minor offset near Wagh Village.

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Figure 4.18 Shear Fracture and minor offset in the Potwar silt (about 5 cm). The small sticks indicating the offset near Wagh Village

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Figure 4.19 Sand bed displaced by a minor fault in the recent silt near Wagh Village.

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Figure 4.20 Tilted Recent Silt along Wagh Thrust near Wagh village.

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Figure 4.21 Kahan Kas Fault zone along Wagh raod.

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Figure 4.22 Tilted Recent Silt and Gravel bed near Dhok Khair Thrust at Chak Shadman

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Figure 4.23 Recent Silt in Faulted Contact with sub recent Conglomerates along Dhok Khair Thrust near south of

Chak Shadman.

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Figure 4.24 Undisturbed recent sediments (Silt) lying over gently dipping upper Siwaliks, Wagh Village. The upper Siwaliks do not show effect of brittle deformation.

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Figure 4.25 Joint sets in recent silts indicating tectonic activities in the area of Hun village near Jogi Tilla.

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Figure 4.26 Undeformed Recent Sediments lying over a fault in Siwaliks, near Wagh Village.

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Figure 4.27 Undisturbed Recent Silt near Dhok Nathial village.

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Figure 4.28 Horizontally deposited undeformed silt near Dhok Nathial village.

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Figure 4.29 Horizontally deposited undeformed Recent Deposits near Dhok Nathial

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Figure 4.30 Lateral tiling of joints in silt near Village Jalalpur Sharif

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Figure 4.31 Cavity in Recent Silt near Kahan Kas formed by Water Percolation through the Shear Fracture.

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Figure 4.32 Tilt in recent silts along wagh fault in the north Jalalpur sharif

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Figure 4.33 Tilted upper Siwaliks along Dhok Khair thrust

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Figure 4.34 Scarp of Diljabba Fault near Domeli Village

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Figure 4.35 Tilted Recent/ Sub Recent Sediments/ Silt Over Concealed Jhelum fault near Jhelum City

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Figure 4.36 Highly Tilted and Sheared Silts along Jhelum Fault near Dina City

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Figure 4.37 Tilting of recent terraces and breakage of pebbles along Jhelum Fault

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Figure 4.38 Highly disturbed and tilted recent sediments Nala in close vicinity of Diljabba Fault.

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Figure 4.39 Tectonic fracture in the recent silt, pencils are lying in the direction of fracture Along Wagh thrust near Jalalpur sharif

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Figure 4.40 Limestone abruptly truncating against recent silt along Choa Saidan Shah Fault near Padrar Village

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2002)

et.al, Jadoon, From (Modified

SR/PPgenerallyis asesimic to due salt comparedas to foreland deformationinIndia

Figure 4.41

Chapter Five 144 RISK EVALUATION

Chapter Five SEISMICITY AND SEISMIC RISK EVALUATION

5. Seismicity

Earthquakes are analyzed and expressed by both qualitative and quantitative data (Douglas, 2003). The qualitative data is based upon human observation and feelings regarding ground shaking, damage to civil structures and change in landform (Boor, 2010). To evaluate severity of an earthquake at a particular place, human observation and from feeling of ground vibration complement estimates of destruction in change in landform.Resulting grades were quantified and were assigned numerical values from I to XII known as intensity scale (Duroy, et al. 1989).The modified Mercalli intensity scale is commonly used (Based on US Geological Survey Document 2004) to provide qualitative evaluation of earthquake effects. Generally, intensity is greater in epicentral area and diminishes progressively outwards (Campbell, et al. 2006).

Seismic waves a cause ground vibration. Seismographs record wavelength and amplitude of the seismic waves in analogue or digital form. The size of earthquake in term of magnitude, its epicenter and hypocenter are determined on the basis of the quantitative seismic data (Engdahl, et al. 1998). Magnitude is measured in Richter scale and can also be inferred from the intensity (Based on US Geological Survey Document 2004).

Terms used in this text are as per following format.

Great for > 7.8 magnitude Large 7.00 to 7.80 Moderate 6.00 to 6.90 Small 5.00 to 5.90 Macro 4.00 to 4.90 Micro <4.00 (Based on US Geological Survey 2004)

Chapter Five 145 RISK EVALUATION

Before the invention of modern seismographs in early 20th century, earthquake records were available only in qualitative form. These records were based upon the documented history.

5.1 Historical Seismicity

The historic non instrumental seismic events that occurred in the region are summarized in Table-5.1. The records indicate that the investigated area experienced small earthquakes. Moderate events occurred in the north and east where intensity IX was suggested in epicentral area of the biggest events.

The catalogue includes events of magnitude > 3 (Table-5.3) that occurred within 100km radius around Jalalpur. The same have been plotted (Map No-1). The distribution of epicenters in adjoining area is given in (Figures 5.1 and 5.2). 190 earthquakes of magnitude 1-4 have shaken the study area during the last six decades. The majority of these events have magnitude < 3.90 while 13 earthquakes have magnitude 4.00 to 4.9. Four events are of magnitude ranging from 5 to 5.9 (Table 5.3).

The distribution of epicenters shows a variable frequency of occurrence in different parts of Salt Range Potwar. The regional seismotectonic and structural map no.1 indicates that distribution is in accordance with the tectonic subdivision of Salt Range Potwar and location of the tectonic features of study area. The status of seismicity in various tectonic parts of the area is as under,

5.2 Eastern Potwar and Salt Range

The eastern Salt Range and Potwar, between longitude 73.000E to 73.750 E and latitude N32.450 N 33.150 Contains 32 earthquake events of magnitude 3 to 5.2, out of which 22 are of magnitude < 3.9 and four of magnitude 4 to 4.9(Table5.3). Only two events have 5.2 magnitude. Most of events are shallow in accordance with depth of the basal décollement and

Chapter Five 146 RISK EVALUATION

related structures.

The seismic events with focal depths > 10km are associated with basement structures (Thenhaus, et al. 2003). The epicenter with focal depth of 31.9 km and 5.2 magnitude, located to the east of Chakwal is in the basement shield. Another epicenter of same size with focal depth of 14.5 km is probably associated with the upper part of basement. Two events to the north of JalalPur have focal depths > 32 kiln the basement. Two epicenters with focal depths of 10 km are located in Pabbi Hills of Kharian area (Monalisa, et al. 2004). Very shallow epicenters located close to Salt Range Front are associated with Salt Range Thrust. Epicenters are also associated with Dil Jabba Thrust, Missa Kaswal Fault, Jabbar Fault, Kahuta Thrust, Tilla Range thrust, and strike slip faults parallel to Jhelum Fault.

Beyond the limits of the study area a cluster of epicenters is associated with thrust system of Nilore and Simly area (Jhelum Fault). Epicenters are distributed in linear fashion along Jhelum Fault and associated structures.

5.3 Central Salt Rang-Potwar

Central Salt Range and Potwar, between longitudes 72.000E to 72.400E and latitude 32.150 N 33.250 N. It is marked by sparse seismicity of magnitude < 4.9. Only 18 epicenters are located in this part. Generally, the focal depths are shallow (Table 5.3). Seismic events are associated with Salt Range Thrust, Vasnal Fault, Kallar Kahar Fault and lineaments located to the west and north of Chakwal (Ahmed, et al. 2003). Relatively deeper seismic events are associated with the basement. A shallow earthquake is associated with the basement fault in Bhaun area.

5.4 Kashmir Hills

Fourteen events have been triggered in Kashmir Hills. The events are generally shallow (Table 5.3). Seven events are associated with lineament parallel to Jhelum Fault while other events are related to the thrust system and

Chapter Five 147 RISK EVALUATION

basal detachment. The events to the east of Mangla Reservoir with focal depth > 15 km are associated with basement structures.

5.5 Punjab Plains

The Punjab plains are contain 29 epicenters. Three are aligned with the Jehlum River that follows the thrust. The Siwaliks crop out of Punjab plain along this thrust to the south of Lilla Town. The distribution of epicenters is relatively denser to the south near Pindi Bhattian. It is known as Hafizabad Seismic Zone that extends in southeast direction. The events are shallow (Table 5.2) and related with upper part of basement and overlying cover of sedimentary rocks. Nature of structures involved, cannot be ascertained due to lack of subsurface data. Few epicenters are also located to the south and west of the town of Sargodha. These are associated with Sargodha Basement High. The basement rocks are exposed in Sargodha, Chiniot, Shahpur and Sangla Hill. The basement is faulted in Sargodha High area and the earthquakes are associated with these basement structures.

5.6 Seismotectonic Zoning

The geodynamic processes give rise to a tectonic setup that result in unique development of geological structures and their geomorphic expressions (Jain, et al. 2000). The similarity in deformation styles and seismic behavior of a region or area are the basis to discriminate it from other regions I areas with different seismotectonic characteristics (Monalisa, et al. 2003). Keeping in view the similarities, large crustal parts and regions are divided into seismotectonic belts, provinces and zones (Bilham, et al. 2006). The boundaries of such zones are rather clear but sometimes gradational. The boundaries may overlap particularly where deep and shallow earthquakes associated with different structures occur in the same region.

Chapter Five 148 RISK EVALUATION

5.7 Regional Seismotectonic Belts

The Indo-Pak subcontinent and adjoining regions have been divided into 24 seismotectonic belts (Figure-5.3, Met Report 2007) based upon regional plate tectonics and basement structures. The northern part of Potwar is included in the zone that covers all Himalayan fold and thrust belts. The Eastern Salt Range, Potwar and Hafizabad area is placed in zone 15 (Figure- 5.3) characterized by low frequency, small earthquakes.

5.8 Seismo Tectonic Zones of Pakistan

On the basis of active surface faulting, tectonic setup and distribution of seismicity, Pakistan and adjoining areas are divided into 15 zones (Figure-5.4, Khan, et al. 2004). The study area falls in zone-13,characterized by very low frequency of small size earthquakes (M < 6.00, generally < 4.00)

Any major event in surrounding seismotectonic zones may influence the area by ground shaking, permanent ground displacements and damage to weak civil structures.

Zone 7 lies to the west of the study area, occupies part of Northern Suleiman Range. Small to moderate size earthquakes occur in this zone. Zone 10 covers Afghanistan with moderate shallow earthquakes associated with Kunar and Safaid Koh Fault zones (Idriss, 2008).

The Pamir Hindu Kush and eastern Karakoram fall in zone 11. It is highly active with moderate to occasionally large earthquakes associated with the Pamir subduction (Figure 5.5, Nespak. 2003) are of both shallow and intermediate focal depths. About 200 earthquakes of M > 5 have been recorded at intermediate depth whereas 88 at shallow depth.

Zone 14 includes Kaghan, eastern Hazara, Kashmir and eastern Himalayas. Small to moderate size earthquakes are associated with the MBT, Punjal Fault, and Jhelum Fault. On 16 August 2001 an earthquake of

Chapter Five 149 RISK EVALUATION

magnitude 5.2 with focal XZ of Ten km happened in Balakot area along KBT / Muzaffarabad fault. The earthquakes of this region caused ground shaking in the study area. Zone 12 covers Hazara area with small and shallow earthquakes.

Although Salt Range and Potwar are considered a part of an active fold and thrust belt, yet it behaves aseismically due to presence of salt belonging to Salt Range Formation at décollement zone. Micro to occasional small seismic events are associated with basement, décollement, thrusts and strike slips faults at its both Eastern and Western terminations.

5.9 Seismicity of Near Regional Area

Six epicenters are located in a circle of 25 km radius around Jalalpur. An event of magnitude < 3.99 with focal depth of 10 km occurred on 23 October 1976 along Bunha Kas, to the north of the study area. The event was certainly associated with basement structure as Salt Range Thrust cannot attain a depth of 10 km in such a short distance. The magnitude of the event has been taken as floating earthquake for the study area.

Further to north an earthquake of magnitude < 4.99 with focal depth of 32.3 km originated from deep seated structure of basement. Two events of magnitude < 3.99 occurred to the north and northwest of the Study area. These events are very shallow with focal depths of 1.6 and 1.3 km respectively. The area hosting these epicenters lacks rock exposures and is covered by Potwar Silt therefore, those can be associated with any structure. However, NE trending lineaments have been interpreted from the satellite image. These very shallow events are probably associated with NE trending concealed thrusts.

A very shallow earthquake is associated with a lineament along the axis of Pabbi Anticline, located towards east of the study area. The Pabbi Anticline is a growing blind thrust cored fold. It cannot cause surface rupture

Chapter Five 150 RISK EVALUATION

in the Study area as it is located on a different tectonic structure.

An epicenter of magnitude < 4.99 with focal depth of 5 km is located just to the south of Mandi Bahudin that probably originated from some structure within the cover sediments of the shield. It is located on footwall of Salt Range Thrust. The slips along faults of the near regional area are generally aseismic however, concealed structures of basement can generate small events.

5.10 Seismicity of Study Area

The seismic record of PMD from 1975 to 2002 (Figure 5.6) reveals that three micro earthquakes have occurred in the study area. Two events are to the west Jalalpur, where there are imbricate thrusts.Two other epicenters are located at foot wall of Salt Range Thrust along Jhelum River. One micro event has occurred very close to the study area. It is evident from the seismic records that the study area is seismically active where small sized earthquake events may occur.

5.11 Seismotectonics of Pakistan

Pakistan is situated in the North West region of the Indian plate that subducts under the Eurasian plate. The Hindu Kush region generates regularly very large earthquakes, occurring down to 300 km depth, which are also felt in Pakistan. In the Hindu Kush region the earthquake mechanism is generally thrust faulting occasionally normal faulting whereas in Kashmir, the earthquakes mainly show thrust fault mechanism with a clear NE-SW compression(Lefort, et al. 2002). Both the Karakoram and Hindu Kush ranges have formed and rise due to the collision between Indian plate and Eurasian plate. The Indian plate collides and under plates the Eurasian plate. The Hindu Kush and the Pamir constitutes one of the most seismically active earthquake zones in the world (Bilham, 2006). In the Kashmir region we find the important Hazara-Kashmir Syntaxes (HKS), which was formed due to the

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change in the Himalayan thrust interface direction from NE in Kashmir to NW along the Indus (Lillie, et al. 1987). The Punjal thrust and the Main Boundary Thrust (MBT) are folded around this Syntaxes and are subject to a 900 rotation from one side to the other. The Panjal thrust, Main Boundary Thrust (MBT) and KBT / Muzaffarabad thrust are truncated by the active Jhelum fault (Baig and Lawrence, 1987). Beside other faults in this region, the Jhelum fault is an active left lateral oblique reverse fault (Iqbal, et al. 2001). The general seismicity pattern of the Jhelum Ambore zone (Krinitzsky, et al. 2002) is low activity of regular earthquakes with magnitudes ≤ 4.0. The historical and instrumental seismic data from this region show no earthquake with a size exceeding magnitude 6.8.In the western Himalayas (Gilgit Agency), the seismic activity is associated with earthquakes of magnitude 5 and larger. One section of the eastern Himalayan frontal thrust was relatively quiet during the last decades. This is the source zone of the Kangra earthquake (Ms 8.0) which occurred in 1905 and which extended from Kangra to Dehra Dun, i.e. 760E to 780 E (Middlemiss, 1910). The second section of presently low seismic activity is near the eastern flanks of the Kashmir Syntaxes bend . Note that the north western end of the zone of low activity in Kashmir stops against a zone of high activity which is the area of the destructive Pattan earthquake of December 28, 1974 (M=6.0) and the 8th October, 2005 Muzaffarabad earthquake (Mw 7.6).

The seismicity in the Kirther range is relatively diffuse compared to that in the Suleiman range (Patriat, et al. 1984). In the latter, the seismicity falls on or near a well defined fault scarp which offsets the Kirthar Range against the eastward extending Indus basin.

5.12 Seismology of the study area

The seismicity of the area is directly associated to the geo-tectonic processes; however, the quantitative observations of the seismicity only goes back some 100 years. Due to the long term processes in action the short

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seismicity monitoring time is a serious limitation, but a limitation which has to be accepted.

5.13 Earthquake Information

The main data bases for earthquake information in this study are:

PMD, Pakistan Meteorological Department, historical database.

PDE, United State Geological Survey, database.

ISC, International Seismological Centre England, database.

Harvard database.

5.14 The USGS Historical Database

The historical database of USGS was obtained from the Internet (www.usgs.net). The data in the spatial window was selected ranging from 200 to 400N and 580 to 830E. This data base comprised 143 events with assigned Ms magnitudes up to 8.6. The seismological events were in chronological order dating from year 765 to 1992.

5.15 The PMD Historical Database

The historical earthquake catalogue was compiled by Pakistan Meteorological Department (Table 5.1). The historical data base comprises of 58 earthquakes from year 25 to 1905. All earthquakes are provided with a short description and estimates of maximum intensity. Important extensions to the original database were made by including data from Quittmeyer and Jacob, (1979; see also Menke and Jacob, 1976). Figure 5.8 shows these earthquakes.

The main scientific reason for using the two catalogues (PDE and PMD) simultaneously was the definitive compilation of earthquake information and readings.

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The PDE catalogue contains the data from 1973 to February 2007. The data were extracted from the catalogue in the spatial window ranges from 20 0 to 400N and 580 to 830E. The part of this catalogue which was studied consisted of some fourteen thousand earthquakes, having magnitude types such as Mb, ML, Mw, Ms.

5.16 The ISC Instrumental Database

Each earthquake in the data base is comprehensive according to source, date, time, latitude, longitude, magnitude, and seismic-related information. It is a large database and in a typical mode, the ISC (http://www.isc.ac.uk) receives more than 200,000 recordings from worldwide stations. The analysis of these digital records leads to the identification of an average of 10,000 seismic events per month. Out of these almost 4,000 require manual review.

About thirty thousand (29,970) seismic events from the ISC database were analyzed during this study. The region from which these events were extracted from the database was the same as in the previous cases. The data cover the period from 1900 through 2006.

These earthquakes from ISC were plotted using the Google Earth software and the map so formed is shown in Figure 5.9.

5.17 The Harvard Instrumental Database

The reason for selecting the Harvard catalogue as one of our study tools is that it contains three consistent magnitude types (Mb, Ms and Mw) for each of the events and the standard location (coordinates), depth, time, half duration, moment tensor, scalar moment, and mode of faulting (strike, dip and slip). Altogether 550 seismic events from January 1977 to September 2006, with magnitude equal or greater than 5.0 were analyzed and plotted on the map (Figure 5.10). Due to their magnitude these events are all significant,

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showing that large parts of Pakistan are quite vulnerable to earthquakes, especially the northern and south-western regions.

5.18 The PMD Instrumental Database

The PMD data base is consist of historical and instrumentally documented earthquakes.

PDE catalogue is considered to be the most reliable data base regarding the completeness since 1973. It contains all information for location, date and origin time magnitude of the earthquakes. The data file selected from the PDE data base for the study region contains near fourteen thousand events.

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Table 5.1 Historical Non Instrumental Seismic Data of Northern Part of Pakistan (Around Study Area)

Sr. Year Date Detail Estimated MM

01 4.B.C Aristobulous of Cassandra, who IX-X accompanied Alexander on his expedition to India, points out that the country above the river Hydspaces (Jhellum) was subject to earthquake which caused the ground to open so that even the bed of river was changed.

02 25AD A destructive earthquake in Northwestern IX Pakistan which laid Taxila in ruins and caused widespread havoc throughout the countryside. The effects of this earthquake can still be seen among the excavated remains. As a result of the earthquake new methods of building construction were introduced. The buildings were reduced from four to two stories with special precautions to make the foundation secure.

03 1552 Damaging in Kashmir V

04 1669 Jun,4 A very Violent earthquake felt all over VI-VIII Kashmir

05 1669 Jun,23 The earthquake felt at Attock caused a VIII-IX fissure of 50 yard long in the ground.

06 1780 Severe shock in Kashmir V-VII

07 1842 Feb,19 Felt at Peshawar and Kabul. At Kabul said VI-VII (Kabul)

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to have lasted for 03 minutes. VII(Peshawar)

At Peshawar very destructive, “earth VI(Ferozepur) trembled like aspen leaf” several killed.

At Ferozpur, sever. At Ludhiana north south. The hot springs of souah (temp140º - 110º) became as cold as the ordinary wells, water diminished greatly and at time the springs were completely dry. These appearances continued for 25 days.

08 1847 Mar,30 Punjab. A shock causing more freight than VI injury.

09 1851 Jan,17 Strongly felt at Multan and in the Punjab, VI-VII (Wazirabad) &VI originating from Fort Munro, shocks (Fort munro) continued for almost a month, some of them felt in Lahore. Damaging earthquake in the Sulaiman Range.

Slight damage at Ferozepur and Wazirabad.

10 1851 Jan,21 Lahore and all Punjab. Similar to Jan 17th VI event but stronger.

11 1851 Feb,4 Lahore, appears to have extended all over V-VI Punjab

12 1851 Feb,6 AS above V-VI

13 1851 Feb,17 Lahore, Multan, not severe. V

14 1853 Nov. Strongly felt at Attock VI

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15 1858 Aug,23 Lahore slight at 6:30 P.M Jacobabad at 2: III-V P.M about imperceptible.

16 1858 Aug,29 Lahore, Sharp Shock. IV

17 1865 Jan, 22 Slight damage and great panic in V-VII Peshawar; long duration

18 18665 Dec,4 Lahore, two small shocks. III-V

19 1868 Aug,11 Damaging in Peshawar; apportion of the VII-VIII fort was shaken down (official record)

20 1868 Nov,12 Violent shocks were felt in Lahore, Dera IV-VI (Attock) Ismail Khan and Attock, followed by many after-shocks, which were felt throughout Punjab.

21 1869 Mar,24 Severe shock in the upper reaches of V-VIII Jhellum.

22 1869 Mar,25 A large earthquake in the Hindukush, V (Kohat,Lahore& strongly felt at kohat, Lahore, Peshawar, Peshawar) and at Khojend and Tashkant; shocking lasting 20 second.

23 1869 April Peshawar, part of fort shaken down VII-VIII (official record)

24 1869 Dec,20 Rawalpindi shock said to have lasted for VII-VIII ½ minutes; cracked walls and caused all people to rush out of houses.

Attock- A series of shocks at intervals of about 20 sec.

Lawrencepur- 1st shock lasted for 20 sec and other lasted for 5 seconds.

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Campbellpur- for half an hour, buildings much damaged.

25 1869 Dec,24 Rawalpindi- Murree some very heavy VII-VIII claps of thunder preceded.

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Table 5.2 Historical Earthquakes as Collected by Pakistan Meteorological Department

Date Lat Lon (E) Intensity Remarks 25 A.D 33.7(N) 72.9 X TAXILA EARTTHQUAKE The main centre of Budhist Civilization at that time was turned into ruins. Epicentre of the earthquake was around 33.7 N and 72.9E. Maximum documented Intensity was x. 50 A.D 37.1 69.5 VIlI-IX AIKHANUM EARHQUAKE

Epicentre of the earthquake was around 37.1 N, and 69.5E. Maximum documented Intensity was VIlI-IX. Caused extensive damage in Afghanistan, Tajikistan and N.W.F.P and was felt upto N.India. 893-894AD 24.8 67.8 VIII-X DABUL EARTHQUAKE

Epicenter of the earthquake was around 24.8 N, and 67.8E. Maximum documented Intensity was VIII-X. An Indian ancient city on the coast of Indian ocean was Completely turned into ruins 1,80,000 people perished.

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URGUN; Quittmeyer and Jacob, 1052-1053 32.85 69.13 VIl-IX 1979

June 1504 34.5 69.0 VI-VIl QUITTMEYER AND JACOB, 1979

6/7/1505 34.6 68.92 IX-X PAGHMAN; QUITTMEYER AND

JACOB, 1979

6/7/1505 34.6 68.9 VIlI-IX HINDUKUSH EARTHQUAKE

Epicenter of the earthquake was around 34.6 N, and 68.9E. Maximum documented Intensity was VIlI-IX. It was an immense Earthquake causing famine and extensive damage & loss of life in Afghanistan.

3/1/15 19 34.8 71.8 VI-VIl JANDOL VALLEY EARTHQUAKE

Jandol valley was severely rocked. Epicentre of the earthquake was around 34.3 N and 71.8E. Maximum documented Intensity was VI-VIl.

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May 1668 24.8 67.6 VIlI-IX SAMAJI OR SAMAWANI

Town of Samaji or Samawani sank into ground. 80,000 houses destroyed. Epicenter of the earthquake was around 24.8 N and 67.6E. Maximum documented Intensity was VIlI-IX.

4/6/1669 33.4 73.2 VI-XI MANDRA EARTHQUAKE

Epicenter of the earthquake was around 33.4 N, and 73.3E. Maximum documented

Intensity was VII.

22/6/1669 34 76 VI-VIl KASHMIR EARTHQUAKE.

23/6/1669 33.87 72.25 VIlI-IX ATTOCK EARTHQUAKE 1780 34 76 V-VII KASHMIR EARTHQUAKE

16/6/1819 23.3 68.9 IX-X RUNN OF CUTCH

It reduced structures to ruins. 2000 people died. Epicenter of the earthquake was around 23.3 N, and 68.9E. Maximum documented Intensity was IX-X.

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24/9/1827 31.6 74.4 VIlI-IX LAHORE EARTHQUAKE

In this earthquake the fort Kolitaran near Lahore was destroyed. About 1000 people perished.

6/6/1828 34.1 74.8 X KASHMIR EARTHQUAKE

In this earthquake 1000 people died and 1200 houses destroyed.

1831 31.75 70.35 VIlI-IX DARABAN; QUITTMEYER AND

JACOB, 1979

1831 33.5 72.0 IV-VII HINDUKUSH EARTHQUAKE

It was severe earthquake felt

from Peshawar to D.G Khan Maximum documented Intensity was VII at Peshawar VI at Srinagar and IV at D.G Khan.

22/01/1832 36.9 70.8 VIlI-IX HINDUKUSH EARTHQUAKE

It was severe earthquake Which rocked Afghanistan, Northern and central parts of Pakistan and NW India. Maximum documented Intensity was VIlI-IX at Kaliljan, Jurm, Kokcha Valley, and VI at Lahore.

Chapter Five 163 Risk Evaluation

21/2/1832 37.3 70.5 VIlI-IX HINDUKUSH EARTHQUAKE

The epicenter of this earthquake was in Badakhshan Province. Earthquake felt at Lahore and

NW India.

26.11840 34.53 69.17 VI-VIlI KABUL; QUITTMEYER AND

JACOB, 1979

19/2/1842 34.3 70.5 VIlI -IX HINDUKUSH EARTHQUAKE

Epicenter of the earthquake was near Kabul. Maximum documented Intensity was VIII-

IX Alingar valley, Jalalabad and Tijri and VI-VIl at Teezeen and VIl- VIlI at Budheeabad. The earthquake was felt from

Kabul to Delhi over an area of 216,000 sq.miles. Jalalabad and Peshawar damaged.

19/6/1845 23.8 68.8 VIl-VIlI RUNN OF CUTCH

Documented epicenter of this earthquake was between 23.8 N, 68.8 E, and Maximum intensity was VIl-VIlI .Lakhpat was badly affected.

Chapter Five 164 Risk Evaluation

17/1/1851 32.0 74.0 VI-VIlI PUJAB PLAIN EARTHQUAKE

Maximum Documented intensity was VIII and VI-VIl at Wazirabad, Ferozpur and Multan, VI at fort Munro. 19/4/1851 25.1 62.3 VII GAWADAR EARTHQUAKE

Epicenter of the earthquake was around 25.1 N, and 62.3E. Maximum documented Intensity was VII at Gwadar. 24/1/1 852 34.0 73.5 VIII MURREE HILLS EARTHQUAKE

Epicenter was in Murree hills and Kajnan about 350 people died. Maximum Documented Intensity was VIII.

1862 29.88 69.22 VIII KOHU VALLEY; QUITTMEYER AND JACOB, 1979.

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Date Lat (N) Lon (E) Intensity Remarks

2/5/1878 33.58 71.4 VIl-VIlI KOHAT-PESHAWAR EARTHQUAKE

The epicenter of earthquake was between Kohat and Peshawar. .Maximum Documented Intensity was VIl-VIlI at

Kohat and Peshawar, VI-VIl at Attock, Abbotabad, Rawalpindi and Jhelum, V-VI at Bannu, Nowshera, Mardan, Lahore and Simla.

1883 28.08 66.08 VI KHALAT; QUITTMEYER AND JACOB, 1979

April 1883 34.0 71.55 VI-VIl PESHAWAR, QUITTMEYER AND

JACOB, 1979 15/1/1885 34.08 74.82 VI-VIl SRINAGAR; QUITTMEYER AND

JACOB, 1979

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30/5/1885 34.1 74.8 IX-X KASHMIR EARTHQUAKE

The epicenter of earthquake was around 34. 1N,74.8E ,Maximum Documented Intensity was IX-X in the epicentral area, VIlI-IX at Sopur. Gulmarg, Gingal and Srinagar.VI-VII at Punch and Muzzafarabad area, Extensive damage was in about 47 sq.miles between Srinagar,Baramula and Gulmarg. Total felt area was 1,00,000 sq.miles. About 3000 people perished and some villages were completely destroyed.

6/6/1885 34,2 75.0 IX-X KASHMIR EARTHQUAKE

The epicenter of earthquake was around 34.2N,75.OE. Maximium Documented Intensity was IX-X.

28/12/1888 30.2 67.0 VIlI-IX QUETTA EARTHQUAKE

The epicenter of earthquake was around 30,2N,67,OE, at Quetta. Maximum Documented Intensity was VIlI-IX.

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1889 27,7 67,2 VIII JHALAWAN EARTHQUAKE

The epicenter of earthquake was around 27,7N,67,2E at Jhalawan , Maximum Documented Intensity was VIII.

1890 30.4 68.6 VII LORALAI EARHQUAKE

The epicenter of earthquake was around 30,4N, 68,6E, Maximum Documented Intensity was VII at Loralai.

20/12/1892 30.9 66.4 VIlI-IX CHAMAN EARTHQUAKE

The epicenter of earthquake was around 30.9N, 66,4E near Chaman. Maximum Documented Intensity was VIII- IX at Chaman and VII at Sanzal. In this earthquake great damage to buildings, bridges, railroads and other structure etc. The earthquake was caused by the movement of Chaman fault on the west bank of Khojak range passing through the north

west railway between Shelabagh and Sanzal, At Shelabagh the railway station building was severely damaged.

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Table 5.3 Seismic Events Occurred Around Study Area

S.# YEAR MONTH DATE LONGITUDE LATTUDE DEPTH MAGNITUDE (km) (Richter’s Scale)

1 2 3 4 5 6 7 8

1 1953 5 1 72.50 33.07 5.0

2 1953 5 11 72.50 33.70 55.0 5.0

3 1962 8 2 73.50 33.40 33.0 4.5

4 1962 5 8 72.30 33.60 49.0 4.5

5 1963 3 6 72.50 33.70 49.0 5.0

6 1967 3 30 73.90 33.20 07.0 4.0

7 1969 5 31 72.70 33.10 96.0 3.0

8 1970 4 30 73.36 33.12 39.0 4.7

9 1972 3 10 72.71 33.75 45.0 4.5

10 1974 12 30 72.60 33.20 33.0 4.4

11 1975 5 7 73.20 32.86 45.0 4.1

12 1976 10 23 73.31 32.76 10.0 3.8

13 1977 4 13 73.54 31.82 15.0 4.5

14 1977 4 9 73.97 32.72 04.0 4.7

15 1977 11 15 72.50 32.64 11.5 3.8

16 1977 11 15 72.96 32.77 08.1 3.0

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17 1977 10 10 73.31 33.51 00.0 3.0

18 1977 2 14 73.21 33.62 14.5 5.8

19 1977 2 14 73.21 33.62 18.1 3.5

20 1977 3 5 73.21 33.63 015 3.2

21 1977 2 15 73.23 33.63 15.1 3.6

22 1977 2 14 73.21 33.64 13.9 3.1

23 1977 4 17 73.21 33.64 14.1 3.2

24 1978 3 31 72.81 32.15 09.6 3.2

25 1978 11 18 72.72 32.89 40.0 4.9

26 1978 6 6 73.35 32.89 01.6 3.0

27 1978 5 7 73.72 33.39 08.8 5.1

28 1978 5 7 73.69 33.48 10.0 3.6

29 1978 5 7 73.77 33.50 10.0 3.5

30 1978 10 22 73.03 33.75 17.9 3.8

31 1978 10 15 73.05 33.75 23.2 4.0

32 1979 2 15 73.57 31.77 15.0 4.0

33 1979 9 12 72.27 32.33 13.8 305

34 1979 11 28 73.91 33.50 10.0 3.3

35 1979 10 5 73.52 33.54 00.0 3.0

36 1979 12 15 72.61 33.69 12.6 3.0

Chapter Five 170 Risk Evaluation

37 1980 2 10 72.59 32.83 10.0 3.0

38 1980 2 29 73.21 33.13 03.0 4.2

39 1980 10 28 73.50 33.64 05.0 3.0

40 1981 7 23 73.35 31.81 15.0 4.8

41 1981 11 2 72.85 33.08 00.0 3.3

42 1981 6 23 73.31 33.66 10.0 4.9

43 1981 12 17 73.26 33.71 10.0 3.7

44 1982 11 9 72.46 31.93 15.0 3.0

45 1982 3 12 74.07 33.05 10.0 3.2

46 1982 4 3 73.39 33.61 14.2 4.9

47 1983 12 18 73.58 31.79 09.1 3.5

48 1983 7 19 72.25 31.91 10.0 3.0

49 1983 10 15 73.03 32.76 01.0 4.1

50 1983 8 21 73.62 32.44 00.0 3.2

51 1983 8 30 73.78 32.85 10.0 3.0

52 1983 8 5 73.64 33.31 14.7 3.0

53 1983 10 4 73.72 33.32 19.7 3.0

54 1983 11 5 73043 33.69 08.1 3.1

55 1983 11 4 72.67 33.74 09.8 3.6

56 1984 4 18 73.85 31.75 09.8 3.3

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57 1984 3 24 72.31 31.88 29.6 3.7

58 1984 5 24 72.44 31.88 16.4 3.6

59 1984 9 22 72.30 32.09 16.3 3.0

60 1984 5 20 72.76 32.43 31.4 3.3

61 1984 1 15 72.76 32.95 04.0 3.3

62 1984 12 26 72.63 32.96 20.0 3.9

63 1984 12 27 72.64 32.96 01.2 4.6

64 1984 12 20 72.65 32.97 00.1 4.6

65 1984 12 20 72.59 32.99 00.4 3.5

66 1984 5 17 73.55 33.29 08.2 3.0

67 1984 3 23 72.67 33.36 20.0 3.4

68 1984 3 10 72.50 33.59 03.2 3.4

69 1985 4 23 73.10 32.42 36.8 4.4

70 1985 5 21 74.15 33.12 12.1 3.4

71 1986 4 18 73.09 31.76 30.3 3.4

72 1986 6 6 73.44 33.34 07.2 3.6

73 1987 10 11 72.93 31.79 18.0 3.7

74 1987 10 3 73.50 31.86 10.0 3.7

75 1987 2 21 73.69 33.44 10.0 3.0

76 1987 9 19 72.94 33.49 05.4 3.8

Chapter Five 172 Risk Evaluation

77 1987 10 6 73.52 33.72 24.2 3.3

78 1988 8 24 72.70 31.76 24.2 3.9

79 1988 9 27 73.71 31.79 05.9 3.3

80 1988 8 16 73.35 31.82 23.9 4.4

81 1988 8 7 72.82 31.87 31.7 3.5

82 1988 8 15 73.24 32.03 17.7 3.4

83 1988 12 8 72.38 32.11 28.1 3.0

84 1988 8 17 73.85 32.39 07.9 3.3

85 1988 11 27 73.35 32.81 32.3 4.4

86 1988 8 10 73.53 33.20 00.5 3.5

87 1988 11 11 73.87 33.23 22.1 4.9

88 1988 8 15 73.79 33.26 15.4 5.0

89 1988 4 10 73.11 33.65 05.9 3.0

90 1988 2 3 72.57 33.66 06.1 3.3

91 1989 5 25 72.67 31.92 24.7 3.3

92 1989 5 7 72.28 32.28 33.4 4.4

93 1989 7 17 72.71 32.45 24.7 3.0

94 1989 4 16 73.45 33.27 00.9 3.0

95 1989 12 10 73.26 33.57 01.3 3.4

96 1989 1 15 73.20 33.60 23.2 3.8

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97 1990 9 16 73.46 31.91 10.0 3.4

98 1990 12 23 72.49 32.41 21.6 3.6

99 1990 3 3 74.06 32.86 10.0 4.4

100 1990 8 29 73.76 33.20 03.7 3.0

101 1990 4 30 73.32 33.29 07.3 4.4

102 1990 3 29 73.80 33.33 10.0 3.0

103 1990 4 1 73.11 33.52 05.7 3.0

104 1991 11 4 73.17 31.75 15.0 3.0

105 1991 6 3 73.38 31.97 00.6 3.3

106 1991 5 20 72.73 32.77 02.1 3.1

107 1992 7 21 73.63 33.20 13.2 3.2

108 1992 10 25 73.85 33.23 15.2 3.5

109 1992 2 14 72.49 33.53 05.3 3.5

110 1993 7 18 73.68 31.88 15.0 3.1

111 1993 2 19 72.35 32.22 10.0 3.7

112 1993 1 22 72.56 32.58 06.1 3.4

113 1993 9 9 73.69 32.96 01.0 3.3

114 1993 1 30 72.90 33.59 00.6 3.0

115 1993 2 17 72.46 33.60 06.5 5.5

116 1993 2 17 72.47 33.63 02.8 3.8

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117 1993 6 8 72.62 33.68 07.6 5.4

118 1993 6 8 72.58 33.75 04.9 3.6

119 1994 2 22 73.67 31.82 10.0 3.2

120 1994 10 15 73.28 31.89 10.0 3.2

121 1994 9 28 73.72 32.67 05.7 3.0

122 1994 1 21 72.31 32.91 10.0 3.0

123 1994 1 28 73.67 33.07 00.5 3.8

124 1994 1 28 73.25 33.46 19.3 3.6

125 1994 10 8 74.21 33.65 10.0 3.0

126 1994 10 7 72.45 33.67 06.5 3.6

127 1995 11 19 73.32 31.57 10.0 3.4

128 1995 6 17 72.36 31.99 18.0 3.3

129 1995 2 19 73.16 33.30 10.0 3.0

130 1995 4 6 73.25 33.65 10.0 3.0

131 1996 4 13 73.30 31.88 16.8 4.8

132 1996 6 18 72.67 31.92 10.0 3.7

133 1996 1 31 72.99 31.92 14.4 3.0

134 1996 10 13 73.44 32.04 05.0 3.7

135 1996 2 1 73.01 32.11 14.6 3.2

136 1996 10 6 72.96 32.47 00.5 3.5

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137 1996 11 11 73.45 32.53 05.0 4.0

138 1996 1 28 73.71 32.83 10.0 3.2

139 1996 3 30 73.43 33.21 05.0 3.2

140 1996 3 25 73.35 33.22 09.1 3.6

141 1996 5 7 73.35 33.22 07.1 3.3

142 1996 3 25 73.32 33.26 10.0 3.9

143 1996 3 25 73.29 33.31 14.5 5.2

144 1996 8 11 73.95 33.35 14.8 3.0

145 1996 12 14 73.31 33.56 10.0 3.7

146 1996 2 28 73.41 33.65 20.4 3.2

147 1997 1 12 72.38 31.83 14.8 3.2

148 1997 12 1 73.31 31.85 23.3 3.1

149 1997 7 31 72.92 31.90 00.4 3.2

150 1997 4 28 73.42 31.91 10.0 3.6

151 1997 9 22 72.34 32.20 25.7 4.3

152 1997 7 29 73.75 33.14 05.0 3.9

153 1997 7 31 73.85 33.17 00.2 3.8

154 1997 7 29 73.55 33.23 10.0 4.8

155 1997 7 29 73.57 33.23 10.0 3.7

156 1997 10 6 73.59 33.38 05.0 3.3

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157 1997 2 11 73.50 33.43 10.0 3.3

158 1997 1 20 72.52 33.60 06.3 3.7

159 1997 1 17 72.31 33.66 05.0 3.2

160 1998 7 28 72.62 31.79 28.4 3.5

161 1998 5 23 73.43 31.86 00.5 3.0

162 1998 3 24 73.89 32.48 01.1 5.1

163 1998 5 29 73.74 32.77 10.1 3.0

164 1998 2 21 73.96 33.10 05.0 3.8

165 1998 5 1 73.45 33.14 23.8 3.0

166 1998 10 7 73.49 32.22 06.5 3.7

167 1998 2 2 73.22 33.52 05.0 3.0

168 1998 12 20 72.49 33.60 05.0 4.1

169 1999 7 15 72.82 32.76 00.3 3.8

170 1999 4 2 73.93 33.03 05.0 3.2

171 1999 2 17 73.56 33.14 03.7 4.2

172 1999 5 14 73.10 33.33 00.2 3.6

173 1999 4 28 73.12 33.33 05.0 4.7

174 2000 9 20 73.67 31.77 10.0 3.0

175 2000 2 2 74.12 31.82 05.0 3.2

176 2000 3 17 73.37 31.89 10.0 3.0

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177 2000 6 2 72.96 32.47 00.2 3.2

178 2000 7 27 74.17 33.70 14.1 3.0

179 2001 10 12 73.20 32.80 01.3 3.7

180 2001 7 16 73.06 32.93 31.9 502

181 2001 5 5 73.14 33.44 10.0 3.7

182 2001 10 20 72.71 33.47 05.0 3.0

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5.19 Assessment of Seismic Risk

The objective of any seismic hazard analysis, whether deterministic or probabilistic, is to determine vibratory ground motion in the form of response spectra for a series of levels of damping. The first stage of this analysis is to identify the potential seismic sources, seismic zones i.e. faults, area sources etc. and the corresponding maximum potential magnitudes. Attenuation laws and relations are then called on to calculate ground motions, taking into account the influence of superficial soil layers (Boor, et al. 2010).

The parameters that required estimate ground motions are: earthquake magnitude, type of faulting, distance and local site conditions. (Campbell, et al. 2006).

The seismic risk of Jalalpur is evaluated in terms of peak ground acceleration.

The potential seismic risk of the area (Jalalpur) is evaluated in terms of peak ground acceleration. The seismogenic sources within a circle of 100 km radius around study area are recognized and defined as seismic waves generated by small to moderate size earthquake that occur beyond this limit are largely attenuated within this range. Maximum potential earthquake associated with each seismogenic source is assessed on the basis of database discussed in previous text. The potential of permanent ground displacements under earthquake loading is inferred by considering geomorphic, lithological, hydrogeological and structural geology of the study area.

5.20 Seismogenic Sources

Any geological structure, feature or phenomenon that can generate an earthquake is called seismogenic source (Boor, et al. 2010). The seismogenic sources are recognized on the basis of geological, tectonic, neotectonic and both historical and instrumental seismic data (Stafford, et al. 2008).

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5.21 Capable Faults

Any fault is considered to be capable / competent if it indicates previous creep movement / rupture of recurring characteristics within Quaternary time or it has exhibited a structural relationship to a capable fault in such a way that movement in one may transfer to the other, is also considered as capable (Stafford, et al. 2008). Internationally accepted any civil structure exclusion criteria state that if an important / sensitive civil structure is located on or in the close locality of capable fault, and any seismic event related to that fault or creep movement along the fault may potentially cause surface rupture at civil structure, the civil structure should be excluded (IAEA Safety Guide 50G.S1- Rev 1).

The Salt Range Thrust and décollement zone under entire Potwar are the main tectonic elements of the study region. The movement along Salt Range Thrust and décollement is generally aseismic due to the presence of low strength rocks i.e. Marl, Gypsum, seams of Salt etc., which lubricate the décollement and Salt Range Thrust (PMD and Nosar Norway, 2007). At places, some microseismic events are associated with décollement zone which is not unusual characteristic of lubricated detachments because small resistances at certain places cannot be ruled out even at the lubricated surface (Idrees, 2008). Higher average slip rate (14mm / year) of Salt Range Thrust (Molnar, et al. 2009) with contrasting low frequency of microseismicity indicates that mainly aseismic creep movement is ongoing along Salt Range Thrust (Ali, et al. 2004).

The curvilinear trace of Salt Range Thrust is 170 km in strike length. The movement all along its strike length is not uniform as the fault is segmented by transverse geological features (Khan, et al. 2011). Despite all similarities, each segment exhibits marked differences in deformation style.

The eastern segment is 50 km in length that extends from Jalalpur to

Chapter Five 180 Risk Evaluation

Choa Sayyadden Shah Fault. The trace of Salt Range Thrust is terminated at Jalalpur by NNE trending Kahan Kas Fault zone that links Salt Range Thrust with foreland dipping Waghh Thrust (Leathers, 1987). Microseismicity is associated with this segment and movement along the segment is also evident from neotectonic features and prograding fans as shown in Figure 5.12 and Map No.1.

Central segment of Salt Range Thrust is about 38 km in length and it extends from Choa Sayydden Shah Fault to Vasnal Fault. Microseismicity of shallow depth is related with recent sediments lying under Salt Range Thrust.

Western and western-most segments are 43 km and 59 km in length respectively. Microseismicity is associated with décollement zone and the faults parallel to Kala Bagh Fault. These segments are beyond the limits of present study area.

The association of neotectonic features with Vasnal fault, the presence of microseismic epicenter along the fault, and its structural relationship with Salt Range Thrust and Kallar Kahar Fault are the evidences to categorize it as active and capable (Shah, 2009). A number of neotectonic features are present along this structure however, only one microseismic event is associated as per instrumental data. It can be deduced that generally, the movement along the fault is aseismic due to presence of Marl, Gypsum and seams of salt of Salt Range Formation within the fault zone and at the décollement zone. The transverse structural features of Salt Range have been developed over the basement structures along which salt accumulated. The salt buildup along basement structures led to the formation of transverse anticlines and faults. The focal depth of the epicenter related to vertical or high angle Vasnal Fault is 11.5 km. Keeping in view the geometry of Salt Range Thrust, it is suggested that the epicenter is associated with the basement structure that is responsible for development of Vasnal Fault.

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The Kallar Kahar Fault is an active and capable structure. It is constituted by parallel, overlapping faults and subsidiary transverse faults. Neotectonic features like tilted silt, abrupt truncations and active salt diapirism have been recorded in close locality of the fault. Two very shallow epicenters of microseismic events are also located along the fault. It terminates southwards against active Choa Sayydan Shah Fault.

The Sarkalan Nurpur Fault is regarded as capable fault due to its geomorphic expression and structural relationship with active Vasnal Fault and Salt Range Thrust. (Map.no.1)

Very shallow microseismic events are associated with the Choa Sayydan Shah Fault as shown on (Map.no.1). It terminates in southwest against Salt Range Thrust. Microseismicity is associated with Dil Jabba Thrust and neotectonic features are associated with its northeastern segment. The south dipping thrust joins active and capable Jhelum Fault in northeast (Map.no.1).

Jhelum Fault and lineaments parallel to it are marked by shallow seismic events (Map.no.1). Neotectonic features are also associated with the Jhelum Fault.

Microseismicity is also associated with Missa Kaswal Fault and Dil Jabba Fault as shown on (Map.no.1).

All these evidences suggest that Sarkalan Fault, Choa Sayyaidan Shah Fault, Dil Jabba Fault, Jhelum Fault, Missa Kaswal Fault and Jabbar Fault are active and capable.

5.22 Other Seismogenic Sources

Sargodha High, Hafizabad Seismic Zone, basement faults and Jhelum River Thrust have also been recognized as seismogenic sources within the present study area.

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Sargodha basement high is marked by seismic events of magnitude < 5.3 with focal depths varies from 10 to 35 km. Distribution of epicenters does not indicate a distinct structural pattern or style and due to lack of subsurface structural information, events cannot be related to a particular structure (Gee, 1989). The epicenters are loosely aligned in EW and NS direction. It is inferred that NS and ESN trending concealed faults of Sargodha High generate seismicity.

Hafizabad seismic zone is also marked by seismic event of magnitude < 5.3 with focal depths of 6 to 24 km. Three very shallow earthquakes i.e. 0.5 to 5 km depth, also occurred in this zone indicating that some of the southeast trending active basement structures also extend into cover sediments (Table- 5.3).

The thrust at right bank of Jhelum River is a geophysically recognized structure. Earthquakes of magnitude up to 4.9 with focal depths ranging from 0.5 to 25 km along this fault indicate that microseismic events are also associated with some basement structure that are responsible for the development of the thrust (Lillie, et al. 1987). Some events of intermediate depth in the vicinity are probably related with the basement faults.

5.23 Seismogenic Sources of Study Region

The present study region is situated at eastern segment of Salt Range Thrust, Kahan Kas Fault, Waghh Thrust and Dhok Khair Thrust as shown on map-1 and 2. Microseismic events have been recorded in the present study area and well exhibited seismites are associated with afore mentioned faults. The movement along these faults is generally aseismic due to the presence of low strength rocks. However, small earthquakes cannot be ruled out due to the presence of active structures. Earthquake of magnitude 4.6 dated 27 December 1986 is the maximum instrumental seismicity recorded along Salt Range Thrust. The event occurred in western most Salt Range. Western Salt

Chapter Five 183 Risk Evaluation

Range is more emergent. It is also influenced by the right lateral slip along Kala Bagh fault. The tectonic setup and incipient geological structures in South West Potwar indicate that slip rate is higher in western most Salt Range as compared to Eastern Salt Range(Jaswal and Lillie.,1997). The different rock units of Salt Range are described in Figure 5.11. Taking Salt Range, Potwar as single regional tectonic element, despite all difference in deformation style the Salt Range Thrust is likely expected to produce comparable response in terms of seismicity. The guidelines provided by IAEA in safety series (IAEA Safety Guide 50SG.SI-Rev-1) states that if seismicity is not associated with an active segment of a fault then maximum recorded seismicity of other segment may be assigned to it. Maximum recorded magnitude of 4.6 as shown in Table 5.3 associated with western most segment of Salt Range Thrust is assigned to the faults of the study area.

The study area is located very close to Kahan Kas Fault and Salt Range Thrust that is 500 m and < 1 Km away respectively. The Study region located on the hanging wall of Salt Range Thrust. The Salt Range Thrust dips at an angle of 40° due north just to the west of Jalalpur and at Jalalpur along its bend chambel ridge, dip angle will be relatively higher. Although the faults of the study area are mainly characterized by creep movement yet small seismic events cannot be ruled out. The Salt Range Thrust, Waghh Thrust, Dhok Khair Thrust and Kahan Kas Fault have been recognized as seismogenic sources for the study area.

5.24 Diffused Seismicity and Floating Earthquake

Many earthquake events cannot be related to a particular tectonic structure because of their random distribution in space and focal depths, such seismicity is referred to as diffused seismicity (Boor, 2008). The event with maximum magnitude within a seismotectonic zone is taken as diffused earthquake with the concept that such event may occur at any place in the same tectonic setup (Zhang, et al. 1999).

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Seismic events in the basement cannot be related with particular structure (Wells, et al. 1994).Any seismic event with maximum magnitude that has occurred within 15 km radius circle around Study area is supposed to be floating earthquake and it can occur beneath the study area. A microseismic event of magnitude < 4 with focal depth of ten Km is located in the study area. Floating earthquake of magnitude < 4 with focal depth of ten km is suggested for study area.

Under earthquake loading, permanent ground displacements including rockfalls, landslides, debris flows and liquefactions, sometimes cause greater damage than the earthquake shocks (Bonilla, et al. 1984). The susceptibility to permanent ground displacement is assessed by geomorphology, lithology, hydrogeology and neotectonics.

Rockfall is an abrupt movement of loose blocks of solid rock detached from the steep slope or cliff. The falling masses possess high kinetic energy and rock debris scatter at foot of hill causing damage to any structure located along or near the cliff. Rockfall is caused by gravity in jointed rocks and triggers by earthquakes shocks or manmade slope modification and blasting. Under earthquake loading small blocks can be detached. However, keeping in view the size of maximum potential earthquake, lithology and geomorphology, huge rockfall is not expected.

Chances of landslide, debris flow and talus creep are less in the study area as much loose material is not available on the slope.

5.25 Seismic Risk Evaluation

The objective of any seismic hazard analysis, whether deterministic or probabilistic, is to determine vibratory ground motion in the form of response spectra for a series of levels of damping (Boor, et al. 2010). The first stage of this analysis is to identify the potential seismic sources or zones (faults, aerial sources, and Remote sensing data) and the corresponding maximum potential

Chapter Five 185 Risk Evaluation

magnitudes. Attenuation laws and relations are then called on to calculate ground motions, taking into account the influence of superficial soil layers (Boor, et al. 2010). Lastly, the surface faulting hazard needs to be taken into account. The whole process requires a thorough knowledge of the characteristics of the source zones.

5.26 Seismogenic Faults of the Area

Seismic risk evaluation or hazard assessment of an area requires good knowledge of the potential seismic sources. The following faults / zones have been recognized as active and capable,

. Salt Range Thrust (Eastern Part)

. Wagh Fault

. Dhok Khair Fault

. Kahar Kas Fault

. Choa Saidan Shah Fault

. Dilijabba Fault

. Tilla Range Frontal Fault

. Jogi Tilla Fault

. Jhelum Fault

. Lehri Fault

. Missa Kaswal Fault

. Jabbar Fault

. Hafiz Abad Zone

. Sargodha Zone

In addition, as an international practice, a floating earthquake (M=5.7.

Chapter Five 186 Risk Evaluation

A=0, D=10 Km) compatible with the local seismic environment has also been considered (Boor, et al. 2010).

5.27 Maximum Potential Earthquake

The maximum magnitude earthquake generating capability of an earthquake source is determined on the basis of seismological and geological data. However, such data is not completely available for this area and therefore the maximum potential capability is determined on the basis of physical characterization of the structure, fault and limited seismological data.

For assessing the maximum potential capability of known faults in the study area, the rupture length relations developed by Wells and Coppersmith (1994) were used. Regression analyses permit the determination of moment magnitude (M) from surface rupture length, down-dip rupture width, rupture area and displacement per event of different types of faults. The maximum potential earthquake for the identified faults in the study area was assumed by taking the higher value determined from 50% fault rupture during an earthquake and adding one to the maximum recorded or historic earthquake (IAEA Safety Guide 50G.S1-Rev 1).

The maximum potential magnitude for each seismogenic structures and faults are given in Table-5.4.

5.28 Evaluation of Peak Ground Acceleration

Study area acceleration values are usually estimated using the empirical attenuation relations developed from actual records for different regions of the World. As sufficient strong ground motion data is not available for the Pakistan, it was not possible to derive the study area specific empirical relation. As such attenuation relations developed for different regions of the world for shallow crustal earthquakes in active regions were studied and most suitable ones, rich in database have been used. The peak ground acceleration and shape of spectrum in study area is dependent on the

Chapter Five 187 Risk Evaluation

magnitude, epicentral / hypocentral distance, intervening medium and local area conditions.

5.29 Campbell (1997)

The equation developed by Campbell (1997) is applicable for an area, which has following characteristics.

a. The larger horizontal component of peak acceleration should be at least 0.02g.

b. The moment magnitude should be equal or greater than 5.0.

c. Valid for near field earthquakes (less than 60 Km).

d. Focal depth is less than 25 Km.

e. Accounts for soil, soft rock and hard rock.

In (AH) = -3.512 + 0.904M

2 2 - 1.328 1n RS EIS + [0.149 exp (0.697M]

+ [1.125 – 0.112 In (RSEIS) – 0.0957M]F

+ [0.440 – 0.171 In (RSEIS)]SSR

+ [0.405 – 0.222 In (RSEIS)] SHR + ε

Where AH has units of g, ε is standard deviation, RSEIS is shortest distance (Km.) to the zone of seismogenic rupture, M is magnitude, F = 0 for strike slip = 1 for reverse / thrust faults, SSR = 1 & SHR = 0 for soft rock.

5.30 Sadigh (1997)

The equation developed by Sadigh is applicable for an area, which has following characteristics.

a. Shallow crustal earthquakes (20 – 25 Km).

b. Valid for soils and rock sites.

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c. Strike slip and reverse faulting earthquakes.

d. Earthquakes of moment magnitude M4 to 8+

e. Distances up to 100 Kilometers.

2.5 In (y) = C1 + C2M + C3 (8.35M) + C4 In (R rup + exp C5 + C6M) + C7 1n (R rup + 2)

Where Y is peak horizontal acceleration, M is moment magnitude; R rup is the closest distance to rupture surface and values of C1, C2, C3, C4, C5, C6, C7 are Standard deviations.

The study area accelerations from different seismogenic structures and faults have been estimated using the attenuation relations of Campbell (1997) and Sadigh (1997).

5.31 Abrahamson and Silva (1997)

The attenuation relation developed by Abrahamson and Silva is applicable for an area, which has following characteristics.

a. Mw > 4.5

b. Rocks and Soils

c. All types of faults

d. Area / region on hanging and foot walls

The general functional form is as under,

γ γ In Sa (g) = f1(M, rup) + Ff3(M) + HWf4 (M, rup) + Sf 5 (Pga

rock)

Where Sa(g) is the spectral acceleration in g, M is Moment magnitude, R rup is the closest distance to the rupture plane in km, F is the fault type (1 for reverse and 0.5 for reverse / oblique, and 0 otherwise), HW is the dummy variable for hanging wall regions (1 for

Chapter Five 189 Risk Evaluation

region over the hanging wall and 0 otherwise), and S is a dummy variable for the region class (0 for rock or shallow soil, 1 for deep soil). For the horizontal component, the geometric mean of the two horizontals is used.

r The function f1(M, rup) is the basic functional form of the attenuation for r strike slip events recorded at rock areas. For f1 (M, rup), we have used the following equations,

For M ≤ C1

r n f1(M, rup) = a1 + a2 (M – c1) + a12(8.5 – M) + [a3 + a13(M – c1)]1nR

For M > C1

r n f1(M, rup) = a1 + a4 (M – c1) + a12(8.5 – M) + [a3 + a13(M – c1)]1nR

In this study, a functional form has been used that allows for a magnitude and period dependence of the style of faulting factor,

a5 for M ≤ 5.8

(a6 - a5)

F3 (M) = a5 + for 5.8 < M < c1

c1 - 5.8

a6 for M ≥ c1

γ The magnitude and distance dependence of the functional form f4 (M1 rup)1 for the hanging wall effect is taken and modeled as separable in magnitude and distance.

f4(M,rrup) = fHW(M) fHW(rrup)

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where

0 for M ≤ 5.5

fHW (M) = M - 5.5 for 5.5 < M < 6.5

1 for M ≥ 6.5

and

0 for rrup < 4

rrup -4

fHW(rrup)= a9 for 4 < rrup < 8 4

a9 for 8 < rrup < 18

rrup -18

a9 1 - for 18 < rrup < 24 7

0 for rrup > 25

The nonlinear soil response is modeled by

f5(PGArock) = a10+a11In(PGArock+c5)

The study area accelerations from different seismogenic structures or faults and seismotectonic provinces have been estimated using the attenuation relation of Abrahamson & Silva (1997).

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The estimated ‘g’ values (mean) at study area in Table 5.5 from Salt Range Thrust ( Eastern segment) Waghh fault, Dhok Khair fault and Kahan Kas fault are very high as the present study area is located very close to these active faults.

Most attenuation relations therefore, are not applicable in the present study area. Abrahams on & Silva (1997) and Sadigh (1997), attenuation relationship equations are suitable for this study.

The study area is close to four faults and creep behavior due to the presence of salt and absence of historic seismic events in the study area, maximum potential capability of these faults may be taken as maximum recorded in the

Salt Range + 1, Mw = 4.65 + 1 = 5.65 and not from physical characteristics. This approach will result in a value of 0.55g for study area for any sensitive / important civil structure. It is however recommended that the project area specific spectra (same in vertical) shown in attached figure should be used in the dynamic seismic analysis (elastic) with proper reinforcement design as this would allow the structures to withstand much higher accelerations in the allowable nonlinear range.

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Table: 5.4 Determination of Maximum Potential Magnitude

Fault Maximum Maximum Postulated Seismogenic Length Recorded Magnitude Structure / Faults (km.) (M) +1 50% Rupture Salt Rang Trust 50 4.65 5.65 7.0 (Eastern Segment) Wagg Fault 10 4.65 5.65 6.2 Dhok Khair fault 5 4.65 5.65 6.2 Kahar Kas Fault 2 4.65 5.65 5.7 Choa Saidan Shah Fault 15 4.65 5.65 6.4 Diljabba Fault 70 5.32 6.32 7.1 Tilla Range Frontal Fault 18 5.0 6.0 6.5 Jogi Tilla Fault 24 4.85 5.85 6.6 Jhelum Fault 87 5.2 6.2 7.3 Lehri Fault 20 5.3 6.3 6.5 Missa Kaswal Fault 22 4.65 5.65 6.6 Jabbar Fault 50 5.0 6.0 7.0 Hafiz Abad Zone Diffused 4.9 5.9 - Sargodha High Diffused 5.3 0.3 - Floating Diffused 4.7 5.7 -

Chapter Five 193 Risk Evaluation

Table: 5.5 Peak Ground Accelerations (Horizontal) Due To Different Seismogenic Structure / Faults

Seismogenic Type of Maximum Closest PGA Structure / Faults Fault Potential Distance (Median Value ) (g) Magnitude (km.) Abrahams Sadigh on & Silva (1997) (1997) Salt Range Trust (Eastern Segment) T (HW) 7.0 0.8 * 0.86** Wagh Fault T (FW) 6.2 2.0 * 0.64 Dhok Khair Fault T (FW) 6.2 2.0 * 0.64 Kahar Kas Fault SS 5.7 0.5 * 0.49** Choa Saidan Shah Fault T 6.4 35.0 0.11 0.09 Diljabba Fault T 7.1 35.0 0.16 0.15 Tilla Range Frontal Fault T 6.5 22.0 0.20 0.18 Jogi Tilla Fault T 6.6 11.0 0.45 0.26 Jhelum Fault SS 7.3 60.0 0.08 0.070 Lehri Fault T 6.5 38.0 0.10 0.092 Missa Kaswal Fault T 6.6 45.0 0.09 0.08 Jabbar Fault T 7.0 50.0 0.10 0.09 Hafiz Abad Zone Diffused 5.9 70.0 0.02 0.02 Sargodha High Diffused 6.3 100.0 0.02 0.01 Floating Diffused 5.7 10.0 0.18 0.19 Legends: T - Thrust SS - Strike Slip

N - Normal HW - Hanging Wall

FW - Foot Wall * - Relation Not Applicable in this epicentral distance.

** - Relations are generally not suitable in this epicentral distance.

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Figure 5.1 Modern seismicity of central Pakistan CF=Chaman Fault GF=Gardez fault, HF=Hearat fault, HM=Himalaya ranges, HS=Hazara Kashmir Syntaxis, KF=Kunar fault, QTZ=Quetta Transverse Zone,

S=Sulaiman range, SKF=Safed-Koho fault, SR=Salt range, GLT=Gilgit, JLD=jalalabad, Lah=Lahore, RWP=Rawalpindi

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Figure 5.2 Epicentral data of salt range-potowar recorded by mssp from 1976 to 2002. The filled triangles are seismic stations. The site area is marked by microseismic earthquake events of magnitude > 2.9.

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(Modified from Khattri et al, 1984)

Figure 5.3 Regional seismogenic zones.

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(Modified from Quittmiyer and Jacob, 1979)

Figure 5.4 Seismotectonic provinces of Pakistan. The heavy lines

outline the various seismotectonic provinces. The numbers correspond to the embedded section in the text. The circular symbols in region 1 represent centers of quaternary volcanism. The bathymetric contour in the Arabian Sea represents a 2 km depth.

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Figure 5.6 Seismicity of the region (Map with the 19 zones overlaid in Google Earth)

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Figure 5.7 Seismic Zones of Pakistan as used in the present study.

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Figure 5.8 Seismicity of the study region according to the PDE-catalogue.

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(From the ISC-Catalogue)

Figure 5.9 Earthquakes epicenters shown in red circles (from the ISC-catalogue).

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(From the ISC-Catalogue)

Figure 5.10 Earthquakes with magnitudes M > 5.0 (red circles) according to the Harvard catalogue.

Chapter Six 203 Conclusions

Chapter Six SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

In conclusion, the studies indicate that the area lies in semi-arid zone. The lithologies of the study area are mainly composed of limestone, sandstone, marl, shale and conglomerate / gravel of Eo-Cambrian to Recent age, which play a significant role in the attenuation of the seismic waves. Being erosion resistant, the dolomite forms peaks of Mangal Dev Ridge while sandstone shale sequence constitutes northern dip slope.

The overall structure of the Salt Range, except its easternmost part, involves a fault bend fold geometry modified by the underlying ductile salt.

S-shaped structures, Jogi Tilla and Chambal ridge, mark the eastern termination of the Salt Range Thrust and are the surface expression of the transition zone from fault bend fold to fault propagation fold geometry.

Palinspastic restoration indicates that approximately 23 km of shortening have occurred in the eastern Salt Range /Potwar Plateau since 5.5 Ma. Average shortening rates over the last 2.5 Ma are estimated to be 14 mm/a. This corresponds to roughly 15% of the 40-50 mm/a convergence rate between the Indian and Eurasian plates. The alignment of the structural trends into a NE-SW configuration may be explained in part by drag-induced rotation (Davis and Engelder, 1985). However, the timing of deformation and rotation suggest that folds in the eastern Potwar Plateau may have formed roughly perpendicular to the transport direction. Rotation accompanying ramping in the central SR/PP between 2.1 and 1.6 Ma may have shifted the structures into their present alignment.

Neo-tectonic features are associated with Dhok Khair Thrust, Waghh Thrust and Salt Range Thrust. Tilted silt / Gravel beds, abrupt truncations, active salt diapirism and offset, indicating that deformation is continuing, even

Chapter Six 204 Conclusions

after the deposition of Recent and Sub-recent sediments. The association of neo-tectonic features with Salt Range Thrust clearly indicates that Salt Range Thrust is active. The slips along the Salt Range Thrust are generally aseismic, however, concealed structures of basement can generate small events.

The study area does not exhibit any neotectonic structures. The undisturbed nature of Holocene deposits indicates that the area has not experienced any tectonic activity during Holocene period i.e. since last 100,000 years. The probability of ground rupture are therefore, ruled out in the study area.

The historical record does not reveal any devastating event in the present study / regional or near regional of study area. The instrumental seismic record indicates that Salt Range / Potwar plateau is generally characterized by low frequency of micro seismicity with exception of some small size events. Low frequency of occurrence of micro and small events suggests that movement along Salt Range Thrust is mainly aseismic.

The semi-regional area comprises of a number of regional faults, which have disturbed the strata of various ages. The Holocene deposits located towards north, south and east of the study area were found undisturbed. However, Holocene deposits associated with Kalar Kahar Fault were recognized disturbed. Therefore, semi-regional area is partially stable in terms of tectonic activity.

Regionally, the area comprises of a number of regional faults. These faults were developed as a consequence of collision of the two major plates i.e. Indian Plate and Eurasian Plate. Since this movement is still going on along these faults, as such these are recognized as “active and capable faults”.

The historical record does not reveal any devastating event in the regional and near regional of study area, while the instrumental records

Chapter Six 205 Conclusions

indicate that the Eastern Salt Range has experienced small earthquakes with shallow epicenters. No moderate or large event has been documented. The area is also sparsely populated. So in case of earthquake, there is limited chance of big damage to human life and property. Permanent ground displacement may occur during earthquake i.e. rock fall, rock blocks detachments etc.

The seismogenic sources recognized for the present study area are Salt Range Thrust, Kahan Kas Fault, Dhok Khair Thrust. Waghh Thrust, Choa Sayyadan Shah Fault, Diljabba Fault, Tilla Range Frontal Fault, Jogi Tilla Fault, Missa Ksawal Fault, Jabber Fault, Hafizabad zone and Sargodha High.

The seismic potential of the area was assessed by using different available data. The detailed scrutiny of the same suggests, the studied area lies in seismically active zone due to being proximal to the major tectonic activity i.e. Eastern margin of plate boundary.

Only two attenuation relationships developed by Abrahamson / Silva and Sadigh are applicable for present study area. Peak ground acceleration of 0.26 g anchored on the basis of earthquake ground motion for study area.

The rock units of the study area are highly fractured and shared. Creep movements may occur along weak zones i.e. along thrusts or shear fractures linked with active structures and sandstone / shale contacts.

Negative slope angles at study area and along roadside need to be modified according to requirements of slope stability, to avoid potential geological hazard. Roof subsidence may occur at the upper contacts of shale and along north dipping fractures. It is recommended that for any kind of civil construction in this area dynamic seismic analysis (elastic) with proper reinforcement design should be used.

Chapter Six 206 Conclusions

It is also suggested that, a regulatory body should be constituted in the country, which should define uniform criteria and minimum requirements for determination of Peak Ground Velocities and Peak Ground Accelerations for civil structures. The regulatory body should have legislative powers to enforce its recommendations.