Probabilistic seismic hazard assessment of NW and central Himalayas and the adjoining region

Abstract

The Himalayan region has undergone significant development and to ensure safe and secure progress in such a seismically vulnerable region there is a need for hazard assessment. For seismic hazard assessment, it is important to assess the quality, consistency, and homogeneity of the seismicity data collected from different sources. In the present study, an improved magnitude conversion technique has been used to convert different magnitude scales to moment magnitude scale. The study area and its adjoining region have been divided into 22 seismogenic zones based upon the geology, tectonics, and seismicity including source mechanism relevant to the region. Region specific attenuation equations have been used for seismic hazard assessment. Standard procedure for PSHA has been adopted for this study and peak ground motion is estimated for 10% and 2% probability of exceedance in 50 years at the bed rock level. For the 10% and 2% probability of exceedance in 50 years, the PGA values vary from 0.06 to 0.36 g and 0.11 to 0.65 g, respectively considering varying b-value. Higher PGA values are observed in the southeast part region situated around Kaurik Fault System (KFS) and western parts of Nepal.