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[SSS09-13] Near-Fault Velocity Pulses Simulated by Stochastic Finite-Fault Simulation Method of the 2022 Taitung, Taiwan Earthquake Sequence
キーワード：Near-Fault Velocity Pulse, Stochastic Finite-Fault Simulation Method, 2022 Taitung, Taiwan Earthquake Sequence
On 17th Sep., 2022, a Mw 6.55 earthquake occurred firstly in southeastern Taiwan and was identified as one of the important disaster foreshocks of the Mw 7.0 mainshock event occurred on the next day (18th Sep., 2022) issued by the Central Weather Bureau of Taiwan. Both of the earthquakes in the 2022 Taitung, Taiwan earthquake sequence caused severe damages near-fault such as total collapse of old bridges, total collapse of a 3-story building and severe damages of several building structures within the Huadong Longitudinal Valley. Several velocity pulses were observed by near-fault strong motion stations near those damaged structures. The velocity pulses were extracted from the procedure of Shahi and Baker (2014) that observed pulse periods were identified as approximately 1.2 - 4.2 s for eight stations of a rupture distance within 7 km. We performed a procedure to simulate velocity pulses by incorporating the stochastic Green’s function method with finite-fault process (Boore, 2009), the empirical transfer function method (ETF, Huang et al., 2017) for each site to represent linear site response and a moving random asperity model (Huang et al., 2022, preprint under review) to evaluate most contributed asperity location for simulating near-fault velocity pulses. The results indicating a good similarity of simulated non-filtered velocity time history and extracted velocity pulses compared to observed waveforms. The pulse periods could be captured by the proposed simulation procedure in a reasonable range which covers the observed ones. This means main velocity pulse were mainly controlled by asperity size and location on fault but not sensitive to the random phase setting of point source stochastic method on the first place. The proposed procedure could be used for near-fault evaluation of future possible large earthquake validated by the case study of the 2022 Taitung, Taiwan earthquake sequences showed in this study.