Earthquake hazard potential along the Panjal Thrust and the Zanskar Thrust, NW Himalaya

Abstract

Kashmir basin is considered to be tectonically active where damaging earthquakes (historical and instrumental) and landslides have occurred. These geologic catastrophes make Kashmir valley prone to hazards. The fault bound Kashmir basin is marked by two mountain fronts: MF1 associated with the Panjal Thrust (PT) and Balapor Fault (BF) and MF2 associated with the Zanskar Thrust. These two structural units make Kashmir valley very susceptible to earthquakes. With this in view the whole basin was divided into 22 sub-basins. However only nine extreme north and south sub basins (five extreme southern and four northern extreme north) were studied to carry out relative tectonic activity of these two tectonic units. With the help of K-mean clustering of eight basin-related geomorphic indices (Hypsometric integral (Hi), Asymmetry factor (Af), Mountain front sinuosity (Smf), Basin shape (Circularity ratio (KA) and Elongation ratio (Eb)), Form factor (Ff), Bifurcation ratio (Rb) and Sinuosity index (Si) were calculated. The results of the geomorphic indices were correlated with the structural and seismic data after that they were grouped into low three (Class1), moderate (class2) and high (class3) relative tectonic activity zones based on the quantified geomorphic indices, earthquake data, structural data and field observations. The overall results infer the tectonic activity dies out towards the north of the Kashmir Valley. It was observed that the highest tectonic activity mostly corresponds to the sub basins in vicinity of the PT and BF stretching 100 Km from Shopian to Baramulla. The least tectonic activity was found to be associated with the ZT lying to the north and northeast part of the Kashmir Valley. The seismic frequency and the overall data analysis infer that the south and Southwestern side of the Kashmir has potential of moderate earthquake in future.