HR: 0800h
AN: S51B-0508    [Abstracts]
TI: Examination on the interaction of the spatial slip distributions of earthquake doublet (M6.9) of the December 26, 2006 PingTung, Taiwan: discrepancy between teleseismic and strong motion data
AU: * Yen, Y
EM: alec@eqkc.earth.ncu.edu.tw
AF: Institute of Geophysics, National Central University, No. 300, Jhongda Rd., Jhongli, 32001, Taiwan
AU: Ma, K
EM: fong@eqkc.earth.ncu.edu.tw
AF: Institute of Geophysics, National Central University, No. 300, Jhongda Rd., Jhongli, 32001, Taiwan
AU: Wen, Y
EM: yiying@eqkc.earth.ncu.edu.tw
AF: Institute of Geophysics, National Central University, No. 300, Jhongda Rd., Jhongli, 32001, Taiwan
AB: An earthquake doublet (M6.9) was occurred at 12:26(UT) and 12:34 (UT) on December 26, 2007 at southwestern offshore of Taiwan near PingTung. These two earthquakes are considered as a doublet due to their close occurrence in time, magnitude and location. The locations of this doublet are near the subducting front where the South China Sea plate subducts underneath the Philippine Sea plate, but the focal depths of these two events lie away from the slab. The focal mechanism shows a normal faulting mechanism for the first event, and a strike-slip mechanism for the second. The locations and the difference in mechanisms give the odd on the occurrence of this earthquake doublet. To investigate the interaction of the two events, we derived the spatial slip distributions of the two events from available geological and seismic data. The teleseismic data were firstly utilized for the verification on the focal mechanism and inverting of the spatial slip distribution. The inland strong motion data and GPS data were not considered in the beginning for the less azimuthal coverage to the offshore events. Though the teleseismic data might have less resolution to the slip distribution, it gives the general spatial slip patterns of the source rupture on the fault planes of the two events. Our results show that two segment faults with different strikes were necessary for the first event to explain the teleseismic waveforms. The asperities of the second event were compensated to the spatial slip distribution of the first event, suggesting the energy interaction of the two events. However, the derived spatial slip distributions from teleseismic data did not explain the inland strong motion data satisfactorily.. To explain the strong-motion data, more detail information on the fault geometry, precise velocity structure and rupture velocity is necessary. Thus, for the determination of the spatial slip distribution, the teleseismic data might provide important information to the general pattern of the spatial slip distribution. However, for the investigation on the scaling of the amount of slips to the earthquake magnitudes, the consistency on the type of data usage is necessary.
DE: 7203 Body waves
DE: 7215 Earthquake source observations (1240)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Seismology [S]
MN: 2007 Fall Meeting