5:15 PM - 5:30 PM
[J05-2-03] Afterslip and Viscoelastic Relaxation Model Following The 2010 Mentawai Earthquake Deduced from Postseismic Surface Deformation
Sumatra, Indonesia, is an island of high tectonic activity due to the northeastward subduction of the Indo-Australia beneath the Eurasian Plates at a rate of ~60 mm/year. This plate convergence causes high seismic activity in the region, and the M7.8 Mentawai earthquake on October 25th, 2010 is just one of those. We study its postseismic viscous relaxation in the upper mantle using geodetic data along the Sumatra subduction zone. Previous studies found that both afterslip and viscoelastic relaxation are responsible for the observed postseismic deformation (e.g. Gunawan et al., 2014). The two mechanisms have different temporal and spatial domains (Wang, 2007). Afterslip occurred up- and down-dip segments of the coseismic fault rupture and generated a crustal deformation in short to medium periods (e.g. Hsu et al., 2002; Freed, 2007). On the other hand, viscoelastic relaxation dominates the deformation over the larger area and the longer period (e.g. Wang et al., 2001; Pollitz et al., 2006).
The analysis in our previous study of the first two years of postseismic surface deformations revealed that afterslip contributed significantly to the postseismic deformation. We first modeled the deformation by the viscoelastic relaxation and isolated the afterslip contribution by subtracting the model from the data. Then we estimated the afterslip distribution on the plate interface. According to Ardika (2015), afterslip caused by the 2007 Mentawai earthquake can be modeled using a logarithmic function and continued for about a half year after the mainshock.
Keywords: Earthquake cycle, Postseismic deformation, Viscoelastic Relaxation, Afterslip
The analysis in our previous study of the first two years of postseismic surface deformations revealed that afterslip contributed significantly to the postseismic deformation. We first modeled the deformation by the viscoelastic relaxation and isolated the afterslip contribution by subtracting the model from the data. Then we estimated the afterslip distribution on the plate interface. According to Ardika (2015), afterslip caused by the 2007 Mentawai earthquake can be modeled using a logarithmic function and continued for about a half year after the mainshock.
Keywords: Earthquake cycle, Postseismic deformation, Viscoelastic Relaxation, Afterslip