Estimation of the subsurface structure in Georgetown, Penang Island using single point microtremor observation technique

Abstract

In this paper, the subsurface structure was estimated using single point microtremor observation technique in Penang Island, Malaysia. Malaysia is located out of Pacific Ring of Fire hence no active tectonic activity happens. However, numerous earthquakes that happened at neighbouring countries act contrary to the myth that Malaysia is seismic free. Tremors from far field earthquake events in Sumatra can be felt at Penang Island. The local site condition is investigated in this study in order to predict the damages on buildings when the earthquake strikes. The study area focused on Georgetown as it is the heart of Penang Island where the economy and population concentrated on. The objective of this study is to determine V s,30 substructure of Georgetown area. Microtremor single point measurements were conducted to estimate the V s profile at Georgetown area. For estimating the ground structure, Rayleigh wave ellipticity method was adopted to single point measurements. From the results, it is found that Georgetown area has V s,30 of 216.4 m/s to 286.6 m/s and the predominant frequency ranging from 1.7 Hz to 2.43 Hz. Hence, the ground type of Georgetown area is classified as Class C in accordance to Eurocode 8.