The seismogenic source on the deep lateral ramp of Sumatra accretionary wedge inferred from the source model of the 2009 mw 7.6 Padang, Indonesia, earthquake

I. D.M.A. Sanjiwani, K. E. Ching, I. M. Anjasmara

Research output: Contribution to journalConference articlepeer-review

Abstract

The 2009 Mw 7.6 Padang earthquake has been inferred as an intraslab event because it locates at approximately 80 km depth which is within the oceanic slab with maximum curvature. However, the major trench-parallel-striking normal faulting event usually occurs at this tectonic environment but not the trench-normal-striking reverse event like this 2009 Padang earthquake. To solve this enigma, the coseismic displacements were estimated based on the analysis of daily coordinate time series calculated by GAMIT software from 15 continuous GPS stations along the Sumatra region. The maximum horizontal displacement is approximately 58.3 mm toward SW at the MSAI station while the maximum vertical displacement reaches 16.1 mm. The optimized geometry parameters of the source fault were determined by the Markov Chain Monte Carlo using the uniform-slip dislocation model. The optimized strike and dip of fault plane are 80circ and 57circ, respectively. The coseismic slip distribution was then estimated using the distributed-slip dislocation model in terms of optimized fault geometry. The geodetic moment of 1.35 x 1027 dyne-cm in our best-fit model is equivalent to Mw 7.39. The coseismic slip mainly ranges 28-70 km in depth with the maximum slip of 2000 mm. The optimized source fault plane is also comparable to the relocated aftershock distribution. Comparing to the location of interface, our source fault is mainly located at the place above the interface. We therefore proposed that this 2009 Padang earthquake occurred in the deep part of accretionary wedge, but not with the slab. In addition, we also proposed this 2009 event as a lateral ramp event because its strike is normal to the trench, such as the 2010 Jaishian earthquake in Taiwan. Finally, we proposed that a thick-skinned deformation may be also represented in the prism of Sumatra subduction zone.

Original languageEnglish
Article number012026
JournalIOP Conference Series: Earth and Environmental Science
Volume389
Issue number1
DOIs
Publication statusPublished - 2019 Dec 13
Event4th Geomatics International Conference 2019, GeoICON 2019 - Surabaya, Indonesia
Duration: 2019 Aug 212019 Aug 22

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

Fingerprint Dive into the research topics of 'The seismogenic source on the deep lateral ramp of Sumatra accretionary wedge inferred from the source model of the 2009 mw 7.6 Padang, Indonesia, earthquake'. Together they form a unique fingerprint.

Cite this