POSTSEICMIC RELAXATION FOLLOWING THE 2010 M7.8 MENTAWAI EARTHQUAKE FROM GPS MEASUREMENTS

• Main Author: YUZARIYADI (NIM : 22413013 ), MOHAMMAD
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/20296
• Institution: Institut Teknologi Bandung

Availability of dense GPS network following the 2010 M7.8 Mentawai earthquake provide a wider opportunity to understand the postseismic mechanisms both in the thrust fault and rheology in the transition zone between the lower crust and the upper mantle. This study employed GPS data set from Sumatran GPS Array (SuGAr) network which had recorded the deformation during two years after earthquake. I utilized PSGRN/PSCMP software to investigate viscoelastic relaxation in the upper mantle by applying rheology models of Burger body. The results indicate that afterslip affecting dominantly of displacement in the near field. It is concentrated in the center of fault plane with maximum slip of 2.3 m. Postseismic deformation associated to viscoelastic relaxation affecting in the larger area compared to afterslip effect. During the first two month, the displacement in the near field was dominated by afterslip with maximum displacement of 0.18 m at BSAT site as viscoleastic relaxation dominated the displacement in the far field with maximum displacement of 0.018 at MKMK site. The best fitting from the viscoleastic relaxation model shows upper mantle with a Kelvin viscosity of 1.0±1×1018 Pa s and a Maxwell viscosity of 1.0±1×1018 Pa s. Clearly, the results provide detailed explanations related to postseismic deformation of the 2010 Mentawai earthquake.