Earthquake relocation using HypoDDMethod to investigate active fault system in Southeast Aceh

Abstract

Southeast aceh is one of the most seismically region in the Aceh Province because the existence of the subduction zone and Sumatra Fault Zone (SFZ). In this paper, we present the active fault system that derived from the seismicity distribution and focal mechanisms of earthquakes which occurring along the fault system. In this case, we studied the earthquakes that occurred around the Tripa segment along the Sumatran Fault. The Tripa fault is a segmented fault of SFZ, actively moving, and recently generating some earthquake, this seismic activity was made by the impact from accumulated stress on rock. We use earthquake catalogues including P and S arrival times which collected by BMKG. The earthquake locations were relocated by using double difference method (HypoDD) and the focal mechanisms were obtained from GFZ-Postdam and global CMT solution. The 70 events was obtained from bmkg catalog, only 40 succeeded to be relocated using local velocity models. The earthquakes relocation by using double difference method finally provides sharper lineation of seismicity consisting of three earthquake clusters in the research area. The relocation results show the value change in location and depth which more reliable than the earthquake data from catalogue. The focal mechanisms of earthquakes indicate the right lateral earthquakes similar to fault plane solution of the Sumatran Fault.