Lithological and Structural Control of Hattian Bala Rock Avalanche Triggered by the Kashmir Earthquake 2005, Sub-Himalayas, Northern Pakistan

Journal of Earth Science, Vol. 23, No. 2, p. 213–224, April 2012 ISSN 1674-487X Printed in China DOI: 10.1007/s12583-012-0248-3

Muhammad Basharat*, Joachim Rohn, Dominik Ehret GeoZentrum Nordbayern, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen 91054, Germany Mirza Shahid Baig Institute of Geology, University of Azad Jammu and Kashmir, Azad Kashmir 13100, Pakistan

ABSTRACT: The Kashmir earthquake 2005 (magnitude MW 7.6) triggered thousands of mass movements in northern Pakistan. These mass movements were mainly rock falls, debris falls, rockslides and rock avalanches. The mass movements vary in size from a few hundred cubic meters up to about 100 million cubic meters estimated for the Hattian Bala rock avalanche, the biggest one associated with this earthquake. This mass movement, which moved in southeastern direction, created two natural dams on the valley bottom and blocked the water ways of the Karli and Tung tributaries of the Jhelum River. Topographic, lithologic and structural information were used to investigate the Hattian Bala rock avalanche. Geotechnical and structural maps were prepared to understand relationship between geology and structure of Hattian Bala rock avalanche. The geometry and failure mode of this rock avalanche are controlled by southeast plunging synclinal structures, lithology, a bedding parallel slip surface and a pre-existing old rockslide. The structural map shows that the mass movement failure was due to Danna and Dandbeh synclinal structures plunging southeast on the hanging wall block of the reactivated Muzaffarabad fault. The slip surface of the mass movement followed the bedding planes along mudstone, claystone and sandstone surfaces. The mass movement perfectly followed the pre-existing synclinal morphology of the Danna and Dandbeh synclines. KEY WORDS: Kashmir earthquake 2005, mass movement, rock avalanche, Muzaffarabad fault, northern Pakistan.

INTRODUCTION This study was supported by the University of Azad Jammu The active Himalayan orogenic belt is the result and Kashmir Muzaffarabad, Pakistan. from the collision of the Indian and the Eurasian *Corresponding author: [email protected] plates. The active deformation in the Himalayas © China University of Geosciences and Springer-Verlag Berlin causes frequent earthquakes and coseismic mass Heidelberg 2012 movements. The disastrous Kashmir earthquake 2005

with magnitude MW 7.6 occurred on 8th October 2005 Manuscript received November 21, 2011. in Pakistani Administrated Kashmir (PAK), North Manuscript accepted January 17, 2012. West Frontier Province (NWFP) and the northern areas of Pakistan. The hypocenter was located on the

214 Muhammad Basharat, Joachim Rohn, Dominik Ehret and Mirza Shahid Baig main boundary thrust (MBT) about 18 km northeast of al., 2006; Baig, 2006). Muzaffarabad with the focal depth of 26 km (USGS, The devastating Kashmir earthquake 2005 caused 2006). The earthquake caused the reactivation of the mass movements in an area of more than 7 500 km² Muzaffarabad fault (Baig, 2006). Ground shaking, (Owen et al., 2008). These mass movements caused structural failure, hanging wall collapse, active rup- directly and indirectly approximately 26 200 fatalities tures and large mass movements occurred along this (Petley et al., 2006). The largest mass movement as- fault. The vertical uplift along Muzaffarabad fault sociated with the Kashmir earthquake 2005 was the varies from 3 to 5.5 m (Kaneda et al., 2008; Avouac et Hattian Bala rock avalanche (Fig. 1).

(a)

Badri Gali

Balakot Bheri Talgran Machiara Epicenter 2005^ / Neelum River Heerkotli Panjgran

Brarkot Tithwal Gojra P Kunhar River Muzaffarabad Panjkot DomelMuzaffarabad Langarpura

Leepa

fault

elmRiver Jehlum Garhi Dopatta N Chatter Klass Lamnia

Hattian P Chakhama Chikar Kohala Salmiah Chinari

Katker (b) BAGH Khaliana

020km

Figure 1. (a) General location map of Pakistan, rectangle showing the location of Kashmir earthquake 2005 affected area (Survey of Pakistan, 2005); (b) map of Muzaffarabad district showing the location of the main faults and of Hattian Bala rock avalanche (in red; digitized and modified after map from Department of Planning and Development, Muzaffarabad, 2007).

The Hattian Bala rock avalanche lies on the 2007; Harp and Crone, 2006). A detailed geological hanging wall block of the reactivated Muzaffarabad and structural characterization of the Hattian Bala fault (Fig. 1). The volume was estimated to be about rock avalanche is lacking. In this article, we describe 100 million cubic meters. It destroyed five villages, the relation of geology and structure of the Hattian killed 575 people and formed two landslide dammed Bala rock avalanche. Therefore it was geologically lakes. The Hattian Bala rock avalanche was investi- and structurally mapped. Furthermore, cross profiles gated by other scientists in term of its characteristics and longitudinal profiles were prepared to characterize (Owen et al., 2008; Schneider, 2008; Dunning et al., the rock avalanche.

The Lithological and Structural Control of Hattian Bala Rock Avalanche Triggered by the Kashmir Earthquake 2005 215

KASHMIR EARTHQUAKE 2005 after shocks (maximum MW 6.3) till the end of 2005 The devastating Kashmir earthquake happened (EERI, 2006). The after shocks were concentrated on 8th October 2005 at 8:50:40 am, local time northwest of Muzaffarabad within the Indus-Kohistan (03:50:40 am, Universal Coordinated Time (UTC)) seismic zone (IKSZ; cf., Fig. 2) (Baig, 2006; JSCE, with magnitude MW 7.6 and at location 34.493°N, 2006; Rao et al., 2006). 73.629°E. The main shock was followed by a series of

72o 74o E

37 N Eurasian plate

thrust (MKT) Karakorum

Main

Kohistan island arc

Nangasyntaxis Parbat

Indus-Kohistan seismic (MMT) mantle zone (IKSZ) thrust

35 Main

Hazara Kashmir syntaxis (HKS) Hinterland basement and covered rocks Panjal thrust Jammu and Kashmir Peshawar Panjal thrust Hazara Hattian (PT) thrust boundary (MBT) Main Jhelum fault Himalayan (MBT) Kohat Islamabad Muzaffarabad

Kohat Northern Potwar basin deformed zone (NPDZ) frontal Soan syncline fault Surghar (MF) range Bannu thrust (HFT)

o depression

Kalabagh fault 33 Southern Potwar platform zone Marwat range Salt range thrust (SRT) Active basement Sargoda 050km Indian shield basement

Figure 2. Regional tectonic map showing the major fault systems in northern Pakistan. The investigated area is located near Muzaffarabad fault and marked by a rectangle (compiled after Avouac et al., 2006; Baig, 2006; Yeats et al., 2006; Greco, 1991; Baig and Lawrence, 1987; Calkins et al., 1975; Wadia, 1931).

According to Peiris et al. (2006) and USGS northern areas of Pakistan. The economic loss includ- (2006), official sources reported that about 86 000 ing reconstruction and rehabilitation cost was esti- people were killed, 69 000 were injured, 32 000 mated to be 5.2 billion U.S. $ according to Asian De- buildings were destroyed and approximately 2.8 mil- velopment Bank and World Bank, 2005. lion people were displaced in Pakistani administered The main boundary thrust and Panjal thrust (PT) Kashmir, North West Frontier Province (NWFP) and were not activated during Kashmir earthquake 2005.

216 Muhammad Basharat, Joachim Rohn, Dominik Ehret and Mirza Shahid Baig

However, seismic movement during this earthquake The Hazara Kashmir syntaxis is built up of Pre- occurred along the NW-SE trending Muzaffarabad cambrian to Tertiary rocks which are imbricated and fault, a reverse fault. Surface rupture occurred over a folded (Greco, 1991; Bossart et al., 1988; Baig and distance of 75 km (Kaneda et al., 2008; Avouac et al., Lawrence, 1987; Wadia, 1931). The core of the syn- 2006) or 80–90 km (Baig, 2006; JSCE, 2006). Satel- taxis consists of red beds of sandstone, mudstone, lite imagery analysis indicated that maximum ground shale and claystone of Early Miocene age belonging to displacement of up to 5.5 m occurred on the hanging the Murree Formation. These sediments lie in the wall of the fault during this earthquake (JSCE, 2006). footwall of the main boundary thrust. Precambrian, Surface rupture appear to be limited to the area around Cambrian, Paleocene and Eocene rocks are exposed in Bagh but not elsewhere along the fault line (JSCE, the external part of the syntaxis (hanging wall of the 2006), although this is disputed by synthetic aperture main boundary thrust). radar (SAR) data from Envisat imagery (Thakur, The rock sequence includes the Precambrian 2006). However, Baig (2006) first documented surface Hazara Formation, Precambrian Salkhala Formation, rupture parallel to the reactivated Muzaffarabad fault Cambrian Muzaffarabad Formation, Paleocene– from Balakot to Bagh area. Eocene limestone and shale sequence (Hangu Forma- tion, Lockhart Formation, Patala Formation, Margalla GEOLOGICAL AND TECTONIC SETTING Hill Formation, Chorgali Formation and Kuldana The geological and tectonic outline of the north- Formation), Early Miocene Murree Formation, Late ern area of Pakistan from various sources is summa- Miocene Kamlial Formation and Quaternary alluvium rized as follows (Fig. 2). Main boundary thrust and (Fig. 3). Hazara Formation and Panjal Formation lie in Panjal thrust are folded to form an antiformal structure the hanging wall block of the main boundary thrust, known as Hazara Kashmir syntaxis (HKS) (Greco, whereas Hangu Formation, Lockhart Formation, 1991; Baig and Lawrence, 1987; Wadia, 1931). Patala Formation, Margalla Hill Formation, Chorgali Muzaffarabad fault and Jhelum fault (JF) lie along the Formation and Kuldana Formation lie in the foot wall western limb of the Hazara Kashmir syntaxis (Nakata block of main boundary thrust and mapped collec- et al., 1991; Baig and Lawrence, 1987; Calkins et al., tively as Paleocene–Eocene sequence because the rock 1975). The main boundary thrust, Panjal thrust, Jhe- unit contains undifferentiated strata. lum fault and Muzaffarabad fault are the important ac- In the south of Muzaffarabad, the Murree Forma- tive tectonic features in the Hazara Kashmir syntaxis tion is overlain by the Kamlial Formation and is di- (Baig, 2006; Yeats et al., 2006; Baig and Lawrence, vided into a lower and an upper part due to different 1987; Armbruster et al., 1978). The Indus-Kohistan lithology. The lower Murree Formation is composed seismic zone is the blind fault zone in Hazara and Ko- of hard, fine grained interbedded sandstone, mudstone histan areas (Baig, 2006; Armbruster et al., 1978). The with shale and claystone. It varies from undeformed Muzaffarabad fault or Himalayan frontal thrust (HFT) competent beds to tightly folded and highly fractured extends southeast through Jhelum valley, Bagh and strata. Compressional forces are responsible for the Poonch City (Indian Administrated Kashmir) areas occurrences of these joints. Joints are generally open (Baig, 2006; Baig and Lawrence, 1987). Indus- especially in sandstone with weathering surface. The Kohistan seismic zone is the zone of active seismicity joint planes are smooth and slightly covered and filled trending northwest-southeast (Parsons et al., 2006; with soft rock. The shear surface of the detachment Bossart et al., 1988; Armbruster et al., 1978). During zone of Hattian Bala rock avalanche was within these the Kashmir earthquake 2005, the Muzaffarabad fault interbedded sandstone beds. These beds consist of al- cut the active Jhelum fault (Baig, 2006) by merging ternating laminae of medium to fine sand and laminae with Jhelum fault east of Hazara and separating north of claystone. The upper part of Murree Formation of Hazara at the bend of Hazara Kashmir syntaxis (Fig. consists of soft, coarse grained interbedded sandstone, 2). mudstone with shale and claystone (Wadia, 1931).

The Lithological and Structural Control of Hattian Bala Rock Avalanche Triggered by the Kashmir Earthquake 2005 217

350 000 370 000 390 000

N ^ Epicenter (

( ( River ( (

3 830 000 ( ( (((Thrust fault ( ( Balakot ( (( Quaternary (( ( Stream bed depositsand

( ( alluvium (

( ( Late Miocene ( Epicenter 2005

( ^ ( ( Main boundary( Panjal thrust (PT) JF ( ( ( Sandstone, shale, clayand ( ( ( conglomerate Neelum ( ( ( River ( ( (Kamlial Formation) ( ( ( ( thrust (MBT)

( ( Early Miocene

( ( ( ( ( (

( Interbedded sandstone, mudstone with Kunhar River ( 3 810 000 ( ( (

( ( ( Shale and clay (Murree Formation)

(

Muzaffarabad ( ( (

(

( ( Paleocene-Eocene (

( ( ( ( ( Nodular limestone, calcareousand ( (

hlmfut(JF) fault Jhelum ( ( carbonaceous shales, sandstone, Muzaffarabad fault (MF) ( ( ( ( siltstone, laterite, clay and marlstone ( ( (

( (Hangu, Lochart, Patala, Margala, ( ( Chorgali and Kuldana formations) ( Jhelum River( ( ( ( ( Carboniferous-Triassic ( ( Metacarbonates, metasediments,

( (

metavolcanics, quartzite and graphitic ( (

( 3 790 000 schist (Panjal Formation) ( (

( ( Cambrian hlmRiver Jhelum ( ( ( Cherty dolomite-cherty graybands ( Hattian limestone and black shale Chikar ( ( (Muzaffarabad Formation)

( ( ( Precambrian ( (

( ( Metasediments

( ( (Salkhala Formation) Bagh ( Slate, phyllite and shale with ( Data: WGS 1984 minor limestone (Hazara Formation)

UTM zone 43 north 3 770 000 projection: Transverse 010km mercator

Figure 3. Geological map of Jhelum valley, Neelum valley and Muzaffarabad City (compiled and modified after Baig, 2006; Munir et al., 2006; Hussain et al., 2004; Baig and Lawrence, 1987; Calkins et al., 1975; Wadia, 1931).

METHODOLOGY Lawrence (1987), Hussain et al. (2004) and Munir et In order to understand the lithological and struc- al. (2006) was used to characterize the regional structural control of Hattian Bala rock avalanche, extensive ture and lithology of the rock formations. field work was carried out. The pre- and post-earthquake topographic contour lines are derived MASS MOVEMENTS TRIGGERED BY from the ASTER and SRTM based Digital Elevation KASHMIR EARTHQUAKE 2005 Models (DEM). They were used during field investi- Widespread mass movements were reported in gation. Height and location were measured by using the disastrous Kashmir earthquake 2005 (Kamp et al., an ordinary portable global positioning system (GPS) 2008; Owen et al., 2008; Schneider, 2008; Dunning et receiver (Garmin eTrex series) within an accuracy of al., 2007; Harp and Crone, 2006; Petley et al., 2006). ±10 m. A laser distance meter (RIEGL FG21-HA) The rocks of the area are very fragile, highly fractured was used for absolute horizontal measurement within and jointed because of faulting. Many mass move- an accuracy of ±1 m. The field mapping was done in ments cover mostly inaccessible mountain terrain. an area 2.5 km2 at scale of 1 : 10 000. The area was Slope angles vary from 20° to up to 80°. Most of the mapped geologically and structurally in November mass movements occurred in Murree Formation in the 2009. The geological map compiled and modified af- core of Hazara Kashmir syntaxis. The highest mass ter Wadia (1931), Calkins et al. (1975), Baig and movement concentration is along the Muzaffarabad

218 Muhammad Basharat, Joachim Rohn, Dominik Ehret and Mirza Shahid Baig fault, main boundary thrust and close to the epicentral Danna Hill region in Hazara Kashmir syntaxis. 2 038 m a.s.l. The mass movements are the result of ground shaking, vertical uplift and gravity collapse in the hanging wall block of Muzaffarabad fault. The quan- tity of mass movements in the hanging wall block of Danna syncline Dandbeh the Muzaffarabad fault is higher compared to the foot wall block. The mass movement failures follow the plunge of fold axes or happen on escarpments along Artificial spillway the active Muzaffarabad fault and have structural and Karli Lake lithological control. 1 307 m a.s.l. Figure 4. View of Hattian Bala rock avalanche DESCRIPTION OF HATTIAN BALA ROCK structurally controlled by southeast plunging AVALANCHE Danna syncline (photo facing northwest). The largest mass movement triggered by Kash- mir earthquake 2005 is known as Hattian Bala rock where it formed a huge embankment around the con- avalanche. It occurred approximately 32 km southeast fluence of Karli and Tung rivers. A nearly planar of Muzaffarabad in a tributary of Jhelum River on sliding surface was exposed parallel to the intersection Danna Hill (34°08′32′′N 73°42′44′′E, altitude 2 038 m of the bedding surfaces. Detailed geotechnical and a.s.l.) close to the town of Hattian (Figs. 1 and 4). structural maps as well as one longitudinal and three Mass movements of this type and size are expected cross profiles (Figs. 7–10) of the Hattian Bala rock from an earthquake of this magnitude (Jibson et al., avalanche describe the initiation mechanism of Hat- 2006; Keefer, 1984). Previous studies (Owen et al., tian Bala rock avalanche. The source of the Hattian 2008; Schneider, 2008; Dunning et al., 2007; Harp Bala rock avalanche, which is initiated at an elevation and Crone, 2006) of Hattian Bala rock avalanche of 2 038 m a.s.l. (Fig. 4) and moved in southeastern showed that it was an old rockslide which was reacti- direction towards Karli River. The rock avalanche vated by the 8th October 2005 earthquake and trans- deposit is up to 1 470 m wide, 2 400 m long and 60 m formed into a rock avalanche. deep in average. The height distance from top to toe is Danna Hill lies on the hanging wall block of the approximately 700 m. The rock face of the top area is reactivated Muzaffarabad fault, about 2 km northeast inclined nearly vertical. of the fault trace. The hanging wall block of the reac- The bed rock from the source area is highly frac- tivated Muzaffarabad fault contains steep slopes in tured and sheared due to faulting and folding. Multiple highly fractured and sheared rock that is highly sus- joint surfaces both parallel and perpendicular to the ceptible to failure during seismic shaking. The strong slope face were exposed at the mass movement source motion of the earthquake instantaneously weakened area. Due to the remoteness and to lack of resources, the brittle shear surface of the detachment zone of no borehole data is available. In order to estimate the Hattian Bala rock avalanche and caused the coseismic average depth of the rock avalanche deposit, we used gravity collapse. According to Jibson et al. (2006), the pre-earthquake contour lines derived from SRTM failure in brittle rock is most sensitive to high accel- based DEM and constructed longitudinal and cross erations of ground motion. profiles in the field and judging from the height of the The geometry of the Hattian Bala rock avalanche shear surface. The average thickness of the mass (Fig. 5) shows that the old rockslide was favored to movement deposit was estimated to be approximately form a large scale rock avalanche during the Kashmir 60 m. Total volume of the mass movement material earthquake 2005. The rock avalanche completely de- was estimated to be about 100 million cubic meters by stroyed five villages in the detachment zone. Most of multiplying the deposit area with the average thick- the rock avalanche material was deposited at the toe, ness (Table 1).

The Lithological and Structural Control of Hattian Bala Rock Avalanche Triggered by the Kashmir Earthquake 2005 219

Danna Hill 0 500 m N

Dandbeh

3 779 000

New mass Old mass Karli Lake Tung Lake New scarp Old mass Tung Lake Old scarp Artificial spillway Artificial spillway Karli River New deposit area 3 778 000 Tung River

Karli Lake Datum: WGS 1984 UTM zone 43 north Projection: Transverse mercator

381 000 382 000 383 000 Figure 5. Picture showing Hattian Bala rock avalanche from 2005. Note position of old rock slide is derived from Schneider (2008).

Table 1 Geometric characteristics of Hattian Bala rock avalanche triggered by Kashmir earthquake 2005 in northern Pakistan

Crown Toe Height Maximum Maximum Height/ Surface Deposit Average Vol ume elevation elevation (m) length width length area (km2) area (km2) thickness (×106 m³) (m a.s.l.) (m a.s.l.) (m) (m) ratio (m) 2 038 1 307 700 2 400 1 470 0.30 2.02 1.64 60 98.4

The crest of the Hattian Bala rock avalanche is highly cracked (Fig. 6). The length of these cracks is 50–60 m and their width can reach up to 2 m. These cracks are associated with the ground shaking and the subsequent extension. In the northwestern part of the main scarp, cracks mostly parallel to the scarp are also present. The shear surface followed to some extent the bedding parallel slip along mudstone, claystone and sandstone surfaces (Figs. 7 and 8). The mass movement trajectory from scarp to toe is 2 350 m long 14/11/2009 (profile A-A in Fig. 8). The rock avalanche material travelled 400–500 m beyond the Karli valley and also Figure 6. Up to two meters, wide multiple exten- buried Dandbeh Village. The geological longitudinal sional ground cracks oriented northeast-southwest and cross profiles (Figs. 8 and 9) show the relation on the crown of Hattian Bala rock avalanche. Posi- between rock type, position of the initial rock slide, tion of location (black arrow) is: 381 357E, slide plane and the thickness of the different of the 3 779 507N (photo facing southeast). rock avalanche.

220 Muhammad Basharat, Joachim Rohn, Dominik Ehret and Mirza Shahid Baig

Danna Hill N

60 B' 32 ¶

35 C' B 52 72 62

3 779 000 m 62 75 65 35

65 Tung Lake

C 68

3 778 000

A' D 30 ¶ Karli Lake Datum: WGS 1984 UTM zone 43 north 0 400 m Projection: Transverse mercator

381 000 382 000 383 000 m Interbedded sandstones, Mass movement scarp mudstones with shales and claystones Karli Lake (lower Murree Formation) Mass movement body Tung Lake Rock avalanche material 1-10 m3 Extensional crack 20 Attitude of bedding Rock avalanche material 1-5 m3 Artificial spillway Location of bedding Karli River Rock avalanche material <1 m3 Profiles Tung River Figure 7. Geotechnical map of the Hattian Bala rock avalanche. Note frequent GPS measurements were performed during field work to map the geotechnical details.

The Hattian Bala rock avalanche is a deep seated limb dips northeast. The strike along the northeastern earthquake induced mass movement favored by struc- limb of the Danna syncline varies from N44ºW to turally controlled southeast plunging syncline known N80ºW while the strike along the southwestern limb as Danna syncline (Fig. 10). However, it also followed varies from N14ºW to N80ºW. The dip of the north- the bedding parallel slip (Fig. 8) and pre-existing syn- eastern limb varies from 35ºSW to 75ºSW whereas the clinal morphology (Figs. 9a and 9b). The Danna syn- dip of the southwestern limb ranges from 30ºNE to cline is formed by the folding of the Early Miocene 68ºNE. The northeastern limb of the syncline is fur- lower Murree Formation. The lower Murree Forma- ther folded by parasitic small Dandbeh synclinal and tion consists of interbedded sandstones, mudstones anticlinal structures plunging southeast (Fig. 10). with shales and claystones. The mudstones and clay- Trend and plunge of the Danna syncline is 22º/120º, stones dominate the sandstones. The rocks are highly 6º/131º, 25º/118º, 12º/104º and 20º/074º. The attitude sheared and fractured because the area lies in Muzaf- of the axial plane of the syncline is N55ºW/80ºNE, farabad fault zone. The northeastern limb of Danna N52ºW/90ºNE, N48ºW/86ºNE and N72ºW/56ºNE syncline dips southwest whereas the southwestern (Table 2).

The Lithological and Structural Control of Hattian Bala Rock Avalanche Triggered by the Kashmir Earthquake 2005 221

Cross profile

Main scarp Artificial spillway SE NWA A’

Cross profile

Interbedded sandstones, : o mudstones with shales and claystones > 22 o 06: ()Lower Murree Formation 2000 o : o 12 o : : ((( 25 20 am ((((((( ((((((((((((((( ((( Rock valanche aterial 1-10 m3 ((((((( ((((( ((( 1800 ((((((((((((((( ((((((((((((((( ((((((((((((((( Synclinal plunge ((((((((((((((( : o ((((((((((((((( 20 1600 (((((((((((((((( - (((((((((((((((( Pre earthquake profile ( (((((((((((((((( ((((((((((((((((( Elevation (m a.s.l.) ( ((((((((((((((((((((((((((( ( - 1400 ((((((((((((((((((((((((((( ( Post earthquake profile ((((((((((((((((((((((((((( ( ( ( ( ( ( ( ((((((((((((((((((((((((((( ( ( ( ( ( ( ( ( ( ( ( (( ((((((((((((((((((((((((((( ( ( ( Estimated slip surface 1200 ((((((((((((((((((((((((((( ( ( ( (((((((((((((((((((((((((( 0 400 m 500 1000 1500 2000 2500 Distance (m) Figure 8. Longitudinal geotechnical NW-SE profile showing pre-earthquake landscape and the geotechnical situation after the rock avalanche. Note the mass movement is parallel to the southeast orientated synclinal plunge direction and the slip surface follows in many parts the dip direction of the bedding. The mass movement abuts and accumulates against the right steep wall of the former Karli valley.

Table 2 Structural data of Danna syncline the deposits along the artificial spillway consists mainly of blocks of fine grained sandstone spanning a Northeastern Southwestern Fold Axial plane wide range of sizes, some individual blocks measured limb limb axis more than 5 m3 on a side. The thickness of the deposit N70ºW/60ºSW N14ºW/32ºNE 22º/120º N55ºW/80ºNE generally ranges between 150–200 m. It is thinner N45ºW/35ºSW N60ºW/35ºNE 6º/131º N52ºW/90ºNE where small blocks accumulated and thicker where N44ºW/52ºSW N72ºW/65ºNE 25º/118º N48ºW/86ºNE large block came to rest. The mass movement deposit N80ºW/72ºSW N55ºW/30ºNE 12º/104° N72ºW/56ºNE in the valley bottom has an irregular surface. It has N80ºW/75ºSW N80ºW/68ºNE 20º/074° N73ºW/90ºNE ridges and depressions. These ridges and depression make the surface of the deposit highly irregular. The Danna and Dandbeh syncline is an open, The Hattian Bala rock avalanche moved southeast from Danna Hill and blocked the water ways of southwest vergent and southeast plunging F1 Himala- yan fold. The axial plane of the Danna syncline is the Karli and Tung tributaries of the Jhelum River. It northeast dipping which is parallel to the northeast buried five villages, which caused 575 people deaths. dipping Muzaffarabad fault. Muzaffarabad fault and The Karli dam with an average length and width of Danna syncline are pre-earthquake Himalayan struc- 1 700 and 400 m respectively varies in thickness from tures. These were reactivated during the October 8th 150 to 200 m. In February 2010, Karli dam was over- 2005 earthquake. flown due to heavy rain. The overflow resulted in an The Hattian Bala rock avalanche deposit is com- outburst flood to the down stream in Hattian. The posed of sandstone, siltstone, claystone, shale and flood left one person dead, swept away 50 houses and mudstone debris of the lower Murree Formation. The damaged the Jhelum valley road. total deposit area was calculated to be about 1.64 km2 (Table 1). The material exposed on the surface of the RESULTS AND CONCLUSION mass movement deposit comprises mainly of angular Geometry and failure mode of this mass move- rock fragments having fairly uniform distribution of ment were strongly controlled by tectonics and lithol- particle size ranging from large boulders (1–10 m3) to ogy, bedding parallel slip, southeast plunging syncli- silty and clayey particles (Fig. 9c). The lower part of nal structures, and the pre-existing rock slide are the

222 Muhammad Basharat, Joachim Rohn, Dominik Ehret and Mirza Shahid Baig

(a) (b) -'

’

AA CC’

Stable area

Scarp

Danna syncline

Dandbeh syncline

Dandbeh anticline

Length profile SW Scarp NE

SW NE 1 500 Scarp ((( ((( ( (

BBLength profile ’ Danna syncline ((((((

Scarp 1 400

1 900 1 300

1 800 (((((((((((((( 1 200

1 700 Elevation (m a.s.l.) 1 100

Elevation (m a.s.l.) 200 400 600 200 600 1 000 Distance (m) Distance (m)

( (( Rock avalanche material 1- 10 m Tung Lake

(((( 3 Length profile (((( Rock avalanche material 1- 5 m 1 500 (((( (((((( (((((( Rock avalanche material <1m3 1 400 (((((((((( (((((( ((((((((((((((( () (((((((((((((((( Tung Lake 1 300 (((((((( ((((( 1 200 Pre- earthquake profile

Elevation m1 a.s.l. 100 Post- earthquake profile 200 400 600 800 1 000 0 400 m Distance (m) Estimated slip surface Figure 9. Geotechnical cross profiles (a), (b) showing the pre-earthquake and post-earthquake situation. Note the rock avalanche perfectly follows the pre-existing structure of the Danna and Dandbeh synclines. The third profile (c) is showing the maximum deposit thickness of the Hattian Bala rock avalanche.

Danna Hill A N

60 32 B' 80

35 ' 22o 52 C B Danna syncline 72

3 779 000 62 Dandbeh syncline 90 § 75 X 62 6o 35 § 86 65Dandbeh anticline

o 25 '

90 # D 56 # o o 20 65 12 Tung Lake

C 68

3 778 000

A ' D 30

Karli Lake Datum: WGS 1984 UTM zone 43 north Projection: Transverse mercator

90 § Trend, plung and axial plane of F1 syncline Tung River Mass movement scarp 20o Karli Lake 3 777 000 X F1 anticlinal fold axis Mass movement body § F1 syncline fold axis Tung Lake Location of bedding Artificial spillway 0 1 000 m 20 Attitude of bedding Karli River

381 000 382 000 383 000 Figure 10. Structural map showing the southeast plunging synclinal structural failure of Hattian Bala rock avalanche.

The Lithological and Structural Control of Hattian Bala Rock Avalanche Triggered by the Kashmir Earthquake 2005 223 main features. The various aspects of Hattian Bala leozoic Orogenesis in the Himalaya. Kashmir Journal of rock avalanche triggered by Kashmir earthquake 2005 Geology, 5: 1–22 were analyzed as follows. Baig, M. S., 2006. Active Faulting and Earthquake Deforma- The reactivation of Hattian Bala rock slide on the tion in Hazara-Kashmir Syntaxis, Azad Kashmir, North- hanging wall block of Muzaffarabd fault was the re- west Himalaya, Pakistan. In: Kausar, A. B., Karim, T., sult of the ground shaking, structural failure, and Khna, T., et al., eds., Extended Abstracts, International hanging wall collapse and escarpment failure. Conference on 8 October 2005 Earthquake in Pakistan: Its The failure of this catastrophic mass movement Implications and Hazard Mitigation. Geological Survey of was due to the southeast plunging Danna and Dandbeh Pakistan, Islamabad. 27–28 synclinal structures. The Danna and Dandbeh syn- Bossart, P., Dietrich, D., Greco, A., et al., 1988. The Tectonic clines were formed by the Himalayan F1 folding of the Structure of Hazara Kashmir Syntaxis, Southern Himala- Murree Formation. yas, Pakistan. Tectonics, 7(2): 273–297, Claystones, mudstones and subordinate sand- doi:10.1029/TC007i002p00273 stones of the lower Murree Formation are prone to Calkins, J. A., Offield, T. W., Abdulla, S. K. M., et al., 1975. mass movements due to inclined layering. The Danna Geology of the Southern Himalaya in Hazara, Pakistan, and Dandbeh southeast plunging synclinal structural and Adjacent Areas. U.S. Geological Survey Professional failure followed the bedding parallel slip along clay- Paper, 716-c: 29 stone, mudstone and sandstone slip surfaces Dunning, S. A., Mitchell, W. A., Rosser, N. J., et al., 2007. The Earthquake deformation contributed in a Hattian Bala Rock Avalanche and Associated Landslides co-seismic gravity collapse of the Hattian Bala mass Triggered by the Kashmir Earthquake of 8 October 2005. movement. Engineering Geology, 93 (3–4): 130–144, The rock avalanche followed the pre-existing doi:10.1016/j.enggeo.2007.07.003 synclinal morphology of the Danna and Dandbeh syn- EERI (Earthquake Engineering Research Institute), 2005. First clines. Special Earthquake Report on the Kashmir Earthquake of October 8, 2005. 1–8 ACKNOWLEDGMENTS Greco, A., 1991. Stratigraphy, Metamorphism and Tectonics of We would like to acknowledge the University of the Hazara-Kashmir Syntaxis Area. Kashmir Journal of Azad Jammu and Kashmir Muzaffarabad, Pakistan Geology, 8–9: 39–66 which is funding the research under Faculty Devel- Harp, E. L., Crone, A. J., 2006. Landslides Triggered by the opment Program. We would also like to acknowledge October 8, 2005, Pakistan Earthquake and Associated the Director of the Institute of Geology for providing Landslide-Dammed Reservoirs. U. S. Geological Survey transport facility during the geological field work. Open-File Report, 1–13 Hussain, A., Iqbal, S., Nasir, S., 2004. Geological Maps of the REFERENCES CITED Garhi Habibullah and Nauseri Area, District Muzaffarabad, Armbruster, J., Seeber, L., Jacob, K. B., 1978. The Northwest- AJK: Geol. Survey of Pakistan, Preliminary Map Series, ern Termination of the Himalayan Mountain Front: Active VI (14), Sheet No. 43 F/7, 11, 1 : 50 000 Tectonics from Microearthquakes. J. Geophys. Res., Jibson, R. W., Harp, E. L., Schulz, W., et al., 2006. Large Rock 83(B1): 269–282 Avalanches Triggered by the M 7.9 Denali Fault, Alaska, Asian Development Bank and World Bank, 2005. Preliminary Earthquake of 3 November 2002. Eng. Geo., 83(1–3): Damage and Needs Assessment (Pakistan Earthquake 144–160, doi:10.1016/j.enggeo.2005.06.029 2005), 1–124 JSCE (Japan Society of Civil Engineers), 2006. Quick Report Avouac, J. P., Ayoub, F., Leprince, S., et al., 2006. The 2005, of the JSCE Mission for Geotechnical Survey along

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