Perpustakaan Digital ITB

This research tries to estimate the interplate coupling rate of Indo-Australian plate interface beneath Siberut Island based on SuGAr data between 2010 and 2014. The GPS data are processed by using GAMIT/GLOBK software. The solution is devided into three phases during observation time in order to estimate surface deformation by excluding the presence of coseismic and early postseismic effects due to the 2010 Mentawai Earthquake (Mw 7.7) and the 2012 West Coast of Northern Sumatra Earthquake (Mw. 8.6). This study conducts geodetic inversions to estimate slip deficit rate on the interplate coupling area based on elastic half-space approach (Okada, 1992). The deformation vectors from GPS data from each phase generally show northeast-ward direction for horizontal components and subsidence for the vertical components. The inversion results clearly show a heterogeneous distribution of interplate coupling in both the strike and dip directions. The slip rate varies between -69 to 70 mm/yr in all phases. The negative slip rate indicates the postseismic due to the 2009 Mentawai Earthquake (Mw 7.0) and the 2010 Mentawai Earthquake (Mw 7.7). Since there have been no megathrust earthquake for at least 180 years in this region implies a minimum accumulated seismic moment as much as 1.94 x 1022 Nm or equivalent to Mw 8.8.