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TitleDelineating the rupture planes of an earthquake doublet using source-scanning algorithm: application to the 2005 March 3 Ilan Doublet, northeast Taiwan
AuthorKan, C -W; Kao, H; Ou, G -B; Chen, R -Y; Chang, C -H
SourceGeophysical Journal International vol. 182, 2010 p. 956-966, (Open Access)
Alt SeriesEarth Sciences Sector, Contribution Series 20100020
Mediapaper; on-line; digital
File formatpdf
AreaTaiwan, Province of China
Lat/Long WENS120.5000 122.0000 25.2500 23.4167
Subjectsgeophysics; earthquakes; earthquake studies; earthquake mechanisms; seismology; models; seismic models; modelling
Illustrationslocation maps; plots
ProgramTargeted Hazard Assessments in Western Canada, Public Safety Geoscience
Released2010 06 18
AbstractCorrect identification of the fault plane(s) associated with an earthquake doublet is a very challenging problem because the pair of events often occurs in close space and time with almost the same magnitude. Most long-periodwaveforms of an earthquake doublet are severely
tangled and thus unsuitable for conventional waveform inversion methods. In this study, we try to resolve this issue by utilizing the recently developed Source-Scanning Algorithm (SSA). The SSA systematically searches the model space for seismic sources whose times and locations are most compatible with the observed arrivals of large amplitudes on seismograms. The identification of a seismic source is based on the brightness function, which is defined as the summation of the normalized waveform amplitudes at the predicted arrival times at all stations. By illuminating the spatiotemporal distribution of asperities during an earthquake's source process, we are able to constrain the orientation of the rupture propagation that, in turn, leads to the identification of the fault plane. A series of synthetic experiments are performed to test SSA's resolution under various scenarios including different directions of rupture propagation, imperfect station coverage and short origin time difference between the two events of a doublet. Because only short-period records are needed in the analysis, the proposed method is best suited for an earthquake doublet with a short time gap between the two events. Using the 2005 Ilan doublet (the origin time difference is only 70 s) that occurred in northeast Taiwan as an example, we show that the trace of the brightest spots moves towards the west and infer the E - W-striking plane to be the actual fault plane.