Probabilistic seismic hazard assessment of East Malaysia using proposed empirical GMPE for shallow crustal earthquake

Abstract

East Malaysia has witnessed an increase in low to moderate seismic activities due to a few active fault lines. While damaging earthquakes are fortunately rare, from historical records ranging between 1874 and 2014, the region already experienced devastating earthquake with a magnitude MW 5.2 in Sarawak, MW 5.8 in Lahad Datu and just recently with a magnitude MW 6.0 in Ranau. Over the years, a total of 159 with magnitudes ranging from 2.9 to 6.0 are known to have occurred. The effects of the earthquakes should be anticipated in order to mitigate the catastrophic failure of structures. In the seismic design of structures, the most critical part is the development of seismic design ground motion. In order to develop this ground motion, seismic hazard analysis such as probabilistic seismic hazard analysis (PSHA) is required. This study presents technical research into seismic hazard assessment for East Malaysia based on three objectives. The first objective is to determine the fault characteristics mechanism and layouts for the region. Next, to produce spectral ground motion prediction equation (GMPE) for the region due to scarcity and incompatible equation of GMPE from other region. Then, to determine the peak ground acceleration (PGA) throughout the region to be plot inside hazard map in terms of 10% and 2% probability of exceedance (PE) in design time period of 50 years with respect to 475 and 2,475 years return period. Since there is limited information regarding the fault sources in East Malaysia, the relevant source zones are divided into three different possible earthquake source (far-field and near-field due to background seismicity and local fault). In general, the plot of the new generated GMPE accurately represents an earthquake condition in East Malaysia. The hazard map shows the PGA values for 10% probability of exceedance is in the range of 0 to 250 cm/s2 and 2% probability of exceedance in the range of 20 to 400 cm/s2. In conclusion, the main contributor to hazard is dominated by local fault sources with Sabah has the highest seismic hazard level than Sarawak.