Seismic Hazard Analysis Using Discrete Faults in Northwestern Pakistan: Part I – Methodology and Evaluation

Abstract

This article is the first of two companion articles that evaluate the seismic hazard in northwestern Pakistan. The area, located at the western edge of the Himalayas, has numerous active faults including the Main Boundary Thrust (MBT) and Main Mantle Thrust (MMT). This article describes the methodology used to perform regional deterministic and probabilistic seismic hazard analyses. Here, seismic sources were defined from 32 identified faults while prior studies have been based on diffuse seismicity and areal source zones. Fault parameters were selected using available data and empirical correlations for faults elsewhere. Recurrence relations were constructed for all discrete faults based on both historical and instrumented seismicity in addition to geologic evidence. Due to lack of region specific attenuation relationships, four plate boundary attenuation relations from the Next Generation Attenuation of Ground Motions Project [Abrahamson et al., 2008] were employed to predict ground motions. Predicted ground motion parameters are compared to measurements from the recent 2005 Kashmir earthquake. In the companion article, the methodology developed and evaluated here is used to conduct deterministic and probabilistic seismic hazard analyses for the entire study region.