Intraplate earthquake occurrence and distribution in Peninsular Malaysia over the past 100 years

Abstract

AbstractPeninsular Malaysia is tectonically situated on a stable craton (intraplate) and so far experiences relatively little earthquake activities, thus considered as a region with low seismicity. This study uses earthquake data from 59 events obtained from various sources in the period 1922 to 2020. The overall seismicity in the study area is low as expected due to the general intraplate setting. Earthquakes occurred onshore and offshore of Peninsular Malaysia between latitudes 1° and 7° N and longitudes 99° and 105° E. The seismicity pattern shows that the epicenters are distributed spatially in some parts of the peninsula and in the Malacca Strait with several epicenter zones. Most of earthquakes are associated with several preexisting faults and fault zones indicating that they are the major contributor to the local seismicity. Meanwhile, some further earthquakes were caused by activities related to reservoirs. Magnitudes are ranging from Mw 0.7 to 5.4 with the majority is Mw 1.0 + and 2.0 +. Hypocenters are located in between 1 and 167 km deep (shallow to intermediate earthquakes) with the majority being shallow earthquakes (1–70 km). The deepest earthquake located in the Straits of Malacca can be associated with a slab detachment broken off from the Sumatran Subduction Zone. Finally, this study contributes to the understanding of the intraplate seismicity of Peninsular Malaysia as a basis for seismic hazard and risk assessment.Article Highlights Earthquake assessment over the last 100 year reveals low but clear seismicity with an associated seismic hazard and risk for certain areas. Shallow, low-magnitude earthquakes associated with reservoir activities and preexisting faults reactivated by the nearby subduction zone. A deeper, low-magnitude earthquake can be related to slab detachment from the Sumatran subduction zone toward the east.