Incorporating the local faults effects in development of seismic ground-motion hazard mapping for the Peninsular Malaysia region

Abstract

The probabilistic seismic ground-motion hazard maps for the Peninsular Malaysia region have been developed by the present study. Despite the earlier seismic hazard maps for this region, which were proposed only based on far-field Sumatran seismic sources, this study has attempted to present the new maps using the combination of the local faults within the region, Sumatran fault, and Sumatran subduction source zones. The composite earthquake catalogue of the study region has been extended to cover an area limited by 10°S–10°N Latitude and 90°–110°E Longitude with the period from 1900 to 2014. The seismic source zones were categorized into subduction and fault sources. Line, area, and background source models were used to model the seismic sources with variable characteristics along them. In order to consider the epistemic uncertainty, logic-tree framework was used to incorporate basic quantities such as different source modelling, maximum magnitudes, and ground-motion prediction equations (GMPEs). The hazard maps are presented over a 12.5 km grid in terms of peak ground acceleration (PGA) for 10 and 2% probabilities of exceedance in 50 years corresponding to 475 and 2475 years return periods (RP), respectively. The proposed new hazard maps give the expected ground motions based on the extended earthquake catalogue, upgraded seismic source parameters, and more compatible GMPEs than applied in the development of previous hazard maps. The estimated PGAs on rock site condition across the Peninsular Malaysia region for RP475 and 2475 years are in the range of 1.0–10.0%g and 2.0–20.0%g, respectively. The horizontal elastic acceleration response spectra on different soil site conditions have been also presented for the region of interest following the principles of Eurocode 8 through the calculated uniform hazard spectra.