[J05-2] Crustal dynamics: Multidisciplinary approach to seismogenesis II

[J05-2-02] Rheological Structure Beneath Java Island after the 2006 Java Tsunami Earthquake Based on GPS Data

^○Endra Gunawan¹, Irwan Meilano¹, Hasanuddin Z. Abidin^1,2, N. Rahma Hanifa¹, Rio Raharja¹, Susilo Susilo^1,2, Joni Efendi^1,2 (1.Bandung Institute of Technology, Bandung, Indonesia, 2.Geospatial Information Agency, Cibinong, Indonesia)

We determine postseismic deformation associated with the 2006 Java tsunami earthquake using Global Positioning System (GPS) data located in Java Island. By using an analytical approach of logarithmic and exponential functions, we find decay time in the order of hundred days after the mainshock as observed by eight years data after the mainshock. This result suggests that decay time for magnitude 7 class tsunami earthquake is longer than a general megathrust earthquake event for similar magnitude. In our postseismic deformation analysis, we investigate the contribution of aftersip and viscoelastic relaxation of the 2006 earthquake. We also calculate the effect of using different coseismic fault to the viscoelastic relaxation. By simultaneously calculate viscoelastic relaxation and afterslip, our result of best-fit rheological model comprises a 60 km elastic layer thickness with a viscosity of 2.0 x 1e17 Pa·s in the asthenosphere. We also find that afterslip contribute of more than two-thirds (~80%) of horizontal displacements in the GPS data, in which asesimic slip occurred at deeper part of the coseismic rupture.