Teleseismic body wave inversion in determining rupture process of Sumbawa doublet earthquake, November 25th, 2007

Abstract

The rupture patterns of the Sumbawa doublet earthquake that occurred on November 25th, 2007 was estimated using teleseismic body wave inversion. The first event occurred at 16:02:18 UTC with epicenter at 8.292°N and 118.37°E, short after this, the second event occurred at 19:53:08 UTC with epicenter at -8.224°N and 118.467°E. For each event, teleseismic body wave data were retrieved from the Incorporated Research Institutions for Seismology – Data Management Center (IRIS-DMC). The waves were windowed for 70 s which started at 20 s before the P-wave arrival, band-pass filtered between 0. 01 and 0.1 Hz and then integrated into a displacement with a sampling time of 0.5 s. The Green’s function is calculated using the Kikuchi and Kanamori method. The fault geometry is based on the earthquake parameters of the Global Centroid Moment Tensor solution. Strike and dip for first event were 88° and 23°, respectively and those for the second event were 87° and 25°, respectively. The seismic moment (Mo) estimated by the inversion for the first event is 0.617×1019 Nm or equivalent to moment magnitude (Mw) 6.46 with source duration of approximately 55 s. While for the second event, the seismic moment is estimated to be 0.644×1019 Nm (Mw 6.47), with slightly longer source duration. The inversion for both events provided a similar slip pattern. The rupture propagated along the dip direction, and the maximum slip occurred near the hypocenter region. The maximum slip amount for first event and second event were 1.43 m and 1.48 m, respectively.