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Abstract

Ground‐motion prediction equations (GMPEs) are a reliable and fast means to predict strong ground motions. They play a crucial role in estimating seismic hazards levels for any region using either deterministic or probabilistic approaches. Due to the scarcity of ground motion data, GMPEs are assumed ergodic and are borrowed from the host region and adapted/adjusted to target regions which results in large aleatory variabilities. Development of regional GMPEs is challenging because it requires a lot of data to constrain the uncertainties, which are not always available. Therefore, we developed region specific GMPEs for shallow crustal earthquakes in western Himalayan region. We used data from 80 earthquakes in the magnitude (M_L) range of 3 and 5.5 recorded at 27 strong motion seismic stations. The hypocentral distance range varies between 5km and 262km. We developed GMPEs for PGV, PGA and PGD values employing a non-linear mixed effect regression. We developed the reference model by initially considering the source and medium effects and subsequently incorporate the Vs-30 values to account for the local site effects and obtain the final model. It is emphasized that the model is able to explain the observations even with limited number of parameters without making the equation too complex, which otherwise becomes difficult for engineers to implement while evaluating seismic hazard. The residual values at each station are analyzed to quantify the role of epistemic uncertainties. The inter-event and intra-event residuals are also analyzed with respect to magnitude and distance.