Terr. Atmos. Ocean. Sci., Vol. 19, No. 6, 567-578, December 2008 | doi: 10.3319/TAO.2008.19.6.567(PT) |
Yin-Tung Yen, Kuo-Fong
Ma* and Yi-Ying Wen
Institute
Abstract
Teleseicmic vertical P waves of an earthquake doublet occurring on 26 December 2006 offshore southwestern Taiwan are
analyzed to recover spatial slip distribution. Ground-displacement records for period 0.01 - 0.5 Hz are inverted using linear
inversion for finite fault analysis.Waveform inversion results show that a dual segment fault of different strike is necessary for
the first event to explain teleseismic waveforms. The trend in fault geometry, thus, inferred was coincidentally consistent with
the bathymetry in the fault rupture area, suggesting the possible tectonic structure controlling fault propagation. Both
earthquakes show larger slip in the asperities near the hypocenter and there are two main asperities of similar moments. The
first event ruptured along a high angle eastern dipping plane while the second event ruptured along a low-angle western dipping
fault plane. The spatial distribution of the Pingtung earthquake doublet shows a compensative and conjugate relationship, and
the seismic moments of the earthquake doublet were 2.7 x 1026 and 1.8 x 1026 dyne-cm, respectively. The stress drops
corresponding to the asperities of the two earthquakes have values of 3 to 4 bars, individually, similar to the values observed in
other subduction zones.
Keywords: Slip distribution, Teleseismic, Inverison, Earthquake doublet
Citation: Yen, Y. T., K. F. Ma, and Y. Y. Wen, 2008: Slip partition of the 26 December 2006 Pingtung, Taiwan (M 6.9, M 6.8) earthquake doublet determined from teleseismic waveforms. Terr. Atmos. Ocean. Sci., 19, 567-578, doi: 10.3319/TAO.2008.19.6.567(PT)
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