Seismic strain map in Malaysia derived from long-term global positioning system data

Abstract

Series of major earthquakes struck the Sundaland plate as a result of convergence with neighboring plates such as Indian, Australian and Philippine plates. Since then, the Sundaland is experiencing significant crustal deformation that implicate reactivation of local fault and embark question on the status of geohazard and seismic risk. In Malaysia, crustal deformation study by using Global Positioning System (GPS) has been conducted for many years. However, the information of crustal deformation was reported separately and difficult to be archived. In addition, continuous estimation of crustal deformation derived from GPS has to be carried out in order to provide present day seismic status. This study aims at generating a seismic catalog map in Malaysia derived from approximately nine (9) years of GPS data. In this study, derived long-term crustal deformation in the form of coordinate time series (CTS) were converted into yearly strain map. The changes of strain with respect to location of old and active fault line in Malaysia were properly analysed. From the result, the highest changes of strain rate for Peninsular Malaysia happened in 2004 until 2005 and 2012 until 2013 prior to 2004 Acheh earthquake event with the moment magnitude (Mw) and 2012 two strike-slip events in Northern Sumatera with the magnitude of 8.2Mw and 8.6Mw. In North Borneo region, the most significant changes of strain rate happened from 2007 to 2009 and 2011 to 2013. It can be expected that the results will be beneficial in augmenting geohazard mitigation in Malaysia.