14:15 〜 14:30
[SGD02-03] Evaluation of Earthquake Potential based on Updated Rheology Structure and GNSS Data in Sumatra, Indonesia
キーワード：Block Motion, Crustal Deformation, Earthquake Potential, GNSS, Sumatra
Evaluating earthquake potential in Sumatra through geodetic observations requires interseismic deformation which is devoid of postseismic deformation signal of multiple M>7 earthquakes since 2004. By applying postseismic velocities correction from the updated rheology structure to the recent GNSS velocities, we evaluated the earthquake potential in the seismogenic faults of Sumatra, Sunda Subduction Zone (SSZ) started from the Sunda Trench (ST), as well as the strike-slip Sumatran Fault Zone (SFZ). The GNSS velocities were processed using the Bernese v.5.2 and the double-difference positioning technique. These velocites were then corrected by the viscoelastic velocities of the the 2004 M9.2 Aceh, the 2005 M8.6 Nias, the 2007 M8.4 Bengkulu, and the 2010 M7.8 Mentawai earthquakes using the robust simpilifed rheology structure model. We utilized these corrected velocities to evaluate the earthquake potential through kinematic crutal block motion modeling using DEFNODE. We investigated two different block configurations: three blocks with one block between ST and SFZ, and four blocks with two blocks between ST and SFZ separated by the strike-slip Mentawai Fault Zone (MFZ). We imposed a strict constraint on the maximum slip rate of the strike-slip at 15 mm/yr to obtain the parameter of block motion and coupling of the seismogenic faults. The result showed that the model without MFZ was better, as indictaed by the lower AIC value. The SSZ could generate an earthquake up to M8.6 in the Mentawai Islands, in the rupture area of the historical 1797 M8.7 earthquake. It was slightly south of the highly presumed aseismic zone of the SSZ. The viscosity difference affected the uncertatinty of the calculated earthquake potential solely near the epicenters of the 2004 and the 2007 earthquakes.