INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616 Probabilistic Seismic Hazard Assessment of Major Dams of Chhattisgarh State (India) Ashish Kumar Parashar and Sohanlal Atmapoojya Abstract— The rapid tremor of the earth’s outer layer, as an outcome of breaking and shifting of rocks underneath, creates seismic waves, resulting in destructions and disasters to the manmade structures existing, commonly known as earthquake. The intensification of consciousness in this area has been monitored in the current years to a great extent. The present paper tries to describe the seismic hazard analyses of the Major Dams of Chhattisgarh state, using the Probabilistic method. In gradual progress of research on the Probabilistic Seismic Hazard Assessment (PSHA) in the earlier period, a framework has been developed, that could be used for assessment of probability of occurrences of earthquakes, at certain return periods on each site. The principal gain of the PSHA over alternative representations of the earthquake risk is that, PSHA incorporate over all probable tremors of occurrence and ground motions to compute a combined probability of exceedance that incorporates the relative frequencies of event of different tremors and ground-motion characteristics. Features of PSHA allow the ground-motion hazard to be articulated at many sites consistently in terms of the tremor sizes, frequencies of occurrence, attenuation, and associated ground motion in terms of topographical and seismological records. Likely seismic sources, seismicity models, Ground Motion Prediction Equations (GMPE) and site effects are the mainly vital factors in seismic peril studies. An effort has also been made, to formulate a detailed catalogue of ancient and the recent seismicity, for generation of a new seismotectonic map for the major dam regions. The earthquake data is analyzed statistically and the seismicity of the regions around Major Dam sites (Ravishankar Sagar Dam, Sikaser Dam, Dudhawa Dam and Sondur Dam) of Chhattisgarh India, has been evaluated, by defining ‘b’ parameters of Gutenberg- Richter recurrence relationship. The Maximum value of Peak Ground Acceleration (P.G.A.) for recurrence period of 100 years, for Ravishankar Sagar Dam site was found as 0.02655g, for 50 percentile and 0.04226g, for 84 percentile. On the other hand the Maximum values of Peak Ground Accelerations (P.G.A.) for same recurrence period for Sikaser Dam site found to be 0.01235g for 50 percentile and 0.01966g for 84 percentile. The Maximum value of Peak Ground Acceleration (P.G.A.) for recurrence period of 1000 years, for Ravishankar Sagar Dam site, was found to be as 0.03507g, for 50 percentile and 0.05508g, for 84 percentile. The Maximum values of Peak Ground Accelerations (P.G.A.), for same recurrence period for Sikaser, Dam Sites was found to be equal to 0.01572g for 50 percentile and 0.02503g for 84 percentile. The PGA at Dam site corresponding to 2 %, probability of exceedence in the life span of 50 years, with a return period of 2475 years, for Ravishankar Sagar Dam is 0.0096g and for Sikaser Dam is 0.0075g. The outcome of the study is presented in terms of seismic design criteria and can be used for design of vital Civil Engineering structures. Index Terms— Dams, Seismic Parameters, Seismic Sources, Peak Ground Acceleration, Probabilistic Approach, Recurrence Period, Probability of Exceedence. —————————— —————————— 1 INTRODUCTION He potentially damaging phenomena associated with typically are ambiguous at best. The probabilistic T earthquakes, ground shaking, liquefaction, landslides and methodology quantifies the hazard at a site from all tsunami can be broadly described by a single term Seismic earthquakes of all possible magnitudes, at all significant hazard. To be more specific, seismic hazard can be described distances from the site of interest, as a probability by taking as the likelihood or probability, of experiencing a specified into account their frequency of occurrence. intensity of any damaging phenomenon at a particular site or The present paper therefore, is focused to estimate the a region, in the period of interest. The methodology for tremor ground motion hazard. In the study, Probabilistic assessing the probability of seismic perils grew out of an Seismic Hazard Analysis (PSHA) has been used to assess Peak engineering need for better designs in the perspective of Ground Acceleration for major Dam sites of the state of structural reliability (Cornell 1968), since such evaluations are Chhattisgarh i.e. Ravishankar Sagar Dam, Sikaser Dam, frequently made, for the purpose of guiding decisions related Dudhawa Dam and Sondur Dam sites. Dams in Chhattisgarh to mitigating risk. However, the probabilistic method has also are constructed on various rivers which flow across the demonstrated the structured outline for the explicit different parts of state. These Dams are built in order to meet quantification of uncertainties involved, in the hazard the intake water requirements of nearby towns and also fulfill estimation process. Uncertainty is inherent in the evaluation of the irrigation purpose. Some of the Dams of Chhattisgarh are earthquake occurrence and the associated perils of destructive situated in the middle of a suitable and lush green natural ground motion, enduring ground displacements and in some setting, which attracts several tourists from different regions cases, seiche and tsunami. The probabilistic methodology of the country. reduces the need for such earthquake definitions, which 2 PROBABILISTIC SEISMIC HAZARD ANALYSIS [PSHA] Ashish kumar Parashar,Department of Civil Engineering, Faculty of IT, GGV, Central University, Bilaspur, C.G., India, PH-09425502572, E-mail: The PSHA process begins with the characterization of [email protected] earthquake occurrence, using historical sources of data as liner Sohanlal Atmapoojya, Department of Civil Engineering, Faculty of faults and magnitudes. The occurrence information is Engineering, K.I.T.S. Ramtek, Maharashtra, India, E-mail: combined with data on the communication of seismic shaking [email protected] 5590 IJSTR©2020 www.ijstr.org INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616 (termed attenuation) to form the seismotectonic model. In Figure 1(b) Sikaser Dam Fault Map probabilistic seismic hazard analysis it is indispensable to identify the sources which produced hazard at sites and also 23 6.7 be acquainted with its characteristics. Objective of present 6.5 ;Amarkantak 4.8 Shear 3.5 Tan 4.3 Central 3.1 (C)LG Shear Indian study is to find out peak ground accelerations of study area. Tan Shear 4.9 Maniari 6.0 Chilpi Bilaspur Shear Piparia 4.8 This process involves collecting geological features of study 22 Raigrh 5.8 Balaghat 4.6 4.0 Tirodi Indian Katgi area such as faults lineaments and collection of previous F Sambalpur 5.3 Bhaili F F5Khairagarh F4 (B)GN Apt Central F7 F8 Mahanadi R F F F ;Raipur Dongargarh F3 F Bhandara Durg Bundeli earthquake data from catalogue. In the present study, a F Nagpur Rajnandgaon F2 21 F6 Binka F9 Mahanadi R. 4.4 Sagara F1 catalogue of past earthquake was collected from United States Tulka Kunjabangarh Geological Survey (USGS) web site and the previous 4.7 Chanda SONDUR DAM Latitude Latitude 20 earthquake sources were identified. Rushikulya R Sorada Gadapur Pranhita R. Adaba F-10 Indravati R. 5.5 2.1 Identification and Characterization of Sources Jagdalpur Sompeta Vamsadhara Fault ; Koraput F-15 19 Parakimidi Nagavall R. 5.0 Godavari Valley F a u l t 3.0 F-13 Tekkali Vamsadhara R. Nagavali Fault 3.3 Parvatipuram- Bobbili Fault As elucidated in theoretical framework for probabilistic 4.7 3.1 3.2 3.0 F-12 Kanada Fault F-14 3.2 F-11 3.0 3.0 3.7 4.3 6.0 3.0 seismic hazard analysis the primary step is identification of all 3.4 6.0 4.0 3.0 Vizianagaram 5.3 3.3 Sileru R. 4.8 18 3.2 4.5 4.3 5.8 the earthquake sources that result in damaging ground Sabari R. Godavari R. motions at a site. In the present analyses, linear sources were 17 considered as major intraplate faults, which are describe in Seismotectonic Atlas of India known as SEISAT (2000), 79 80 81 82 83 84 85 Longitude published by Geological Survey of India (GSI). For Ravishankar Sagar Dam 16 numbers, Sikaser Dam 17 Figure 1 (c) Dudhawa Dam Fault Map numbers, Dudhawa Dam15 numbers and Sondur Dam 15 numbers of linear faults have been identified within an area of 300 km radius, around the Dam site. 3.3 5.7 24 6.5 F2 4.5 F3 4.7 6.7 Fault Bamhni - Chilpa 4.0 4.6 Mahendragarh Jabalpur 3.7 6.7 23 Narmada R. 6.5 Amarkantak Shear Tan 4.8 4.8 Mandla (C)LG Central 3.5 Nainpur Shear Indian 4.3 3.1 Tan Shear Maniari 4.3 4.9 F 6.0 F6 Chilpi F7 Bilaspur 4.8 F4 Shear Piparia F 5.8 Raigrh Balaghat 4.0 22 Gavilgarh Fault F Tirodi Indian 4.8 Katgi 5.3 F F9 Sambalpur Bhaili F1 F Khairagarh (B)GN Apt Central Mahanadi R 4.6 F5 F8 F F Raipur Dongargarh F Bhandara F12Durg Bundeli F Nagpur Rajnandgaon Binka Baudh F10 F11 Mahanadi R. 4.4 21 Sagara Phulbani RAVISHANKAR SAGAR DAM 4.7 4.3 Dhormopur Latitude 4.8 Chanda 20 Gadapur Pranhita R. 5.5 3.0 Indravati R. F13 Jagdalpur Vamsadhara Fault Koraput Godavari Valley F a u l t 19 Nagavall R. 5.0 3.0 F16 Parvatipuram- Bobbili Fault 3.3 3.1 F15 3.2 F14 4.7 3.0 3.2 3.0 4.3 6.0 3.0 3.0 3.7 3.4 Sileru R. 3.4 6.0 4.0 3.0 4.8 5.3 5.0 3.3 18 4.5 4.3 5.8 3.2 Sabari R.