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چکیده
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The finite-fault stochastic method was applied to simulate the Mw 6.9, 2008 Iwate-Miyagi earthquake at 44 selected KiK-net sites using EXSIM computer code. To investigate the effects of source characteristics on the simulated results, three models were considered: two models with prescribed slip distribution (Model 1 and Model 3) and a model with random slip distribution (Model 2). S-wave regional attenuation indicates an obvious difference between fore-arc and back-arc regions which are formed by volcanic front. Site amplification was determined by corrected surface to borehole spectral ratio and Quarter wavelength methods. The high-frequency decay parameter (kappa) was estimated to be 0.0473 s. The value of 16 MPa for stress drop was calculated by minimizing the absolute residual of 5% damped pseudo-spectral accelerations (PSA). Comparison of the observed and simulated PGAs and PSAs was performed to investigate the capability of our finite-fault models. The residual models represent that the simulated results by Model 2 are in good agreement with the observations in f < 3 Hz, while the other models can better simulate higher frequency motions. We also focused on the effects of slip patches sitting on the fault plane on near-field stations placed in the directions of slip propagation. For these stations, the simulated results by Model 1 and Model 3 were preferred over those of Model 2. Finite-fault models successfully interpreted the real forced motions to AKTH04 where the recorded peak values were abnormal for non-seismological reasons. Finally, the comparison of intensity measures with the GMPEs showed agreement.
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