Ground motion simulation for earthquakes in Sumatran region

Abstract

The present study aims at developing a model for simulating ground motion for earthquakes in the Sumatran region where one of the most devastating earthquakes took place in 2004 with a moment magnitude (Mw) of 9.1. With advancements in instrumentation, the three-dimensional material properties, topography and bathymetry of the region are available in the global database. These parameters are used as inputs in Spectral Finite Element Method to simulate ground motions. The model is first validated with the IGCAR broadband velocity data for 2012 Mw 8.6 Sumatra Earthquake. Due to favourable comparison, our model is also used to generate ground displacement characteristics of Mw 9.1 event. The source uncertainties are accounted by using three finite fault slip models available in the global database. The simulated time histories showed that the ground motion is sensitive to input slip models. The peak ground displacement (PGD) and ground residual displacement (GRD) in both horizontal and vertical directions are presented as contour plots. PGD obtained from various slip models in the epicentral region is of the order of 14-22 m in horizontal direction and 7-16 m in vertical direction. GRD in the epicentral region is of the order of 6-17 m in East-West (E-W) 4-17 m in the North-South (N-S) directions. The vertical uplift obtained from various slip models is around 2-8 m. The developed model can be used to simulate ground motion time histories, which can be further used in hazard analysis, tsunami simulations, etc.