ホモモロフィックフィルタを用いた地震動位相特性の抽出 [in Japanese] IDENTIFICATION OF PHASE CHARACTERISTICS OF STRONG GROUND MOTION USING HOMOMOROPHIC FILTER [in Japanese]
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The cepstrum analysis was applied to deconvolute a seismic wave into a systemresponse function and a train of impulses. Based on several criteria to minimizeerror, we propose a method to identify the source mechanism using identified trainsof impulses. Simulated waves were analyzed in order to examine the validity of theproposed decomvolution method. It was found that arrival time of an impulse wasestimated within the error of two sampling intervals and intensity of impulse wasproportional to the difference between the exact and estimated arrival time of theimpulse.The accelerograms recorded at fourteen stations in El Centro Array are used toidentify the fault mechanism of the 1979 Imperial Valley, California earthquake. Therupture velocity, the starting point of rupture, the direction of the rupture propaga-tion and the rise time can be estimated by minimizing the error between deconvolu-ted trains of impulses and theoretically calculated ones by selecting proper values offault parameters in the rupture process. The multiple rupture process was con-firmed by the fact that five major small events were identified on the fault surface.The identified distribution of seismic moment on the fault surface compares wellwith that investigated from different approach. The analytical algorithm led to thenonlinear system inversion and non-uniqueness of identified parameters. To over-come these problems, we applied Bayes' rule which provided a quantitative errormeasure taking into account the effect of prior information for identifying parame-ters.
京都大学防災研究所年報 (31B-2), p39-66, 1988-04