ANALYSIS OF CHANGE OF SEISMIC STRESS ALONG THE SUMATRAN ZONE TO PREDICT POTENTIAL EARTHQUAKE ZONES

Abstract

A seismic stress change analysis is a powerful method to investigate the relationship of earthquakes, sequences, aftershocks, and potential seismic zones. In previous studies, the analysis was demonstrated by studying earthquake activity to assess seismic hazards on strike-slip, normal, and collisional thrust faults. Unfortunately, seismic stress changes in complex systems, such as subduction and intraplate earthquakes, have not been fully observed, to our knowledge. The objective of the research is to investigate seismic stress changes and their potential effects on the Sumatra subduction zone by using Colomb Stress Change Analysis (Colomb 3.3). The investigation is focused on high-accuracy major earthquake events, during the period of 2004 to 2019, and 50 major earthquakes within a period of 15 years are taken into account to investigate potential zones. Different from previous work, we included temporal and spatial analysis in order to estimate possible future significant seismic events. The results show that the 2004 Aceh-Andaman earthquake triggered the 2005 Nias earthquake as also suggested by previous study. Meanwhile, the 2008 earthquake (Mw 7.2) triggered the Padang earthquake (2009). Our new finding suggests that the 2008 earthquake also provided a positive impulse for the 2010 Mentawai earthquake. Several potential earthquake zones are found at depths of 20 to 50 km in Bengkulu, of 60 to 80 km in Mentawai. The results of this study can be a key to understanding the probability of seismic and tsunami hazards in Sumatra, which is also applicable to other potentially hazardous areas in Indonesia.