Estimation of Ground Motion Parameters for Structural Design Using Woo Approach for Pakistan: Preliminary Results

Abstract

Seismic hazard maps for Pakistan have previously been computed through the conventional Cornell approach, characterized by its reliance on subjective decisions made by experts in defining seismic sources. This study aims to generate a seismic hazard map and determine ground motion parameters for Pakistan by employing the Woo smooth seismicity approach.  This alternative method is rooted in the kernel estimation technique, eliminating the need for subjective judgments from the hazard analyst in defining seismic sources. In this method, the kernel smoothing is based on the magnitude size of the event. The seismic hazard maps for Pakistan are being computed using an updated seismic catalogue and newly developed ground motion prediction equations. These maps are generated considering a rock site condition, specifically focusing on peak ground acceleration. The calculations are conducted for a 2% and 10% probability of exceedance (PE), corresponding to 475 and 2475 years return period (RP). The results show that the zone-free approach is useful in areas like Pakistan where seismic activity is non-uniformly distributed across the country and ranges from low to high. The outcomes obtained exhibit a generally favourable concordance with findings from other studies. Within the logic tree framework, this method can effectively handle epistemic uncertainty in the estimation of seismic hazard maps.