Detailed Probabilistic seismic hazard analysis of Kathmandu Valley, Nepal

Abstract

Abstract The Kathmandu Valley, situated in a region with high seismic activity, has experienced numerous earthquakes in the past. The Gorkha earthquake in Nepal has increased the probability of significant earthquakes happening in the future along this orogenic belt, including the Valley. In this study, an effort has been made to conduct a detailed probabilistic seismic hazard analysis of the Kathmandu Valley by considering earthquakes between 1900 and 2023. A complete catalog of the quake was compiled, encompassing entire seismic events within a 300 Kilometers range. The earthquake catalog was employed to homogenize the magnitude into moment magnitude (Mw) scale using global relationships, and Gardner and Knopoff's algorithm for declustering was used to filter dependent events. Catalog completeness was evaluated using Stepp's technique, and recurrence parameters were calculated using Gutenberg-Richter's law, which is necessary for probabilistic seismic hazard analysis. This study uses a seismic hazard analysis tool R-CRISIS. Global attenuation models within a logic tree were employed to evaluate interface events in Nepal. The findings were presented through maps depicting an Arias intensity, peak ground acceleration, and peak ground velocity for 50-year periods with 2% and 10% risk of exceedance. This study of ground motion will assist in future seismological analysis before developing future infrastructures.