Keywords:Hypocenter, Oct-tree importance sampling, Fault segment, Sumatra Fault Zone
Sumani and Sianok segments are two of the many fault segments in Sumatra Fault Zone (SFZ) that have a considerable history of seismicity and cause significant impacts. An important effort to overcome this problem is the need to analyze tectonic structures in detail through one of them by elaborating an accurate hypocenter location. In this study, we conducted hypocenter determination by using a non-linear approach with the oct-tree importance sampling method through NonLinLoc software by using local velocity components for earthquakes in Sumani and Sianok Segments in the range of 2009-2017. The results of hypocenter determination in this study indicate an improvement in picking arrival time of P and S wave. The increment is denoted by the results of residual picking P and S wave arrival times using oct-tree sampling method that dominant at frequency of 0.1 seconds and there is a correlation between hypocenter location cluster in this study with a location of major earthquakes that have occurred in Sumani and Sianok Segments.