DOI: 10.5176/2251-3353_GEOS14.18
Authors: Perveiz Khalid, Shahid Ghazi, Qamar Yasin, Shahzada Khurram
Abstract: The Kalam-Asrit Dam is located in Kohistan arc, Swat District of Khyber Pakhtoon Khwa (KPK), Pakistan. Due to the high seismicity delimited by active tectonic zones, project site is selected for seismic hazard analysis. In this study, the analysis of seismic source contribution to seismic hazard and seismic hazard analysis of Kalam – Asrit Dam site is performed by taking into account the entire available database on seismicity, tectonics, geology and attenuation characteristics of the seismic waves in this area. For this purpose, about 250 km2 area around the dam site is taken. Peak horizontal accelerations have been anticipated for the site of Kalam-Asrit Dam using probabilistic and deterministic approaches. In deterministic hazard analysis, three seismic line sources: Main Mantle Thrust (MMT), Main Karakoram Thrust (MKT), and Kohistan Fault (KF) having PGA 0.17, 0.08, and 0.18 with maximum potential magnitude 7.5, 7.6 and 7.7 respectively are considered active seismic sources contributing to hazard in the area. Based on the analysis of maximum magnitude and closest distance, MMT and KF were identified the most critical sources with earthquake potential of 7.5 and 7.7 at a distance of 36 and 36.5 km respectively. For the maximum design earthquake in the study area, the resulting peak ground acceleration is 0.46 g. The conclusion of probabilistic analysis shows that peak horizontal ground acceleration with 50{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} probability of exceedance in 500 years (about 144 years return period) is 0.26g. So the operational basis earthquake associated acceleration recommended for the design of the project is 0.26g corresponds to rock site with shear wave velocity of 760 m/s.
Keywords: seismic hazard; PSHA; DSHA; active seismic sources; PGA; Pakistan
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