[S-SS11] Strong Ground Motion and Earthquake Disaster

[SSS11-16] ESTIMATE TIME AND SPATIAL EVOLUTION OF THE RUPTURE PROCESS OF THE 2021 OFF-FUKUSHIMA BASED ON THE FINITE-FAULT SOURCE INVERSION

*Kenichi Tsuda¹, Chen Ji³, Ralph J Archuleta^3,4, Toshiaki Sato² (1.Institute of Technology, Shimizu Corporation, 2.Ohsaki Research Institute, Inc., 3.University of California, Santa Barbara, 4.RJA Ground Motion Analysis, Inc.)

Keywords:2021 Off-Fukushima Earthquake, Finite-Fault-Inversion

The rupture process of large earthquakes is very essential to understand the physic of faulting process as well as to mitigate the seismic hazard for the future events. Furthermore, if such earthquake occurs on the ocean, the risk for generating tsunami needs to be considered. Usually, right after the occurrence of large earthquakes, many dislocation models to understand the rupture process have been released based on the analysis of various kinds of observed data, such as the seismic waveform including on the regional, near-field and the far-field data, the geodetic such as GPS and the geological field data. On other hand, these models are dependent on the assumption about how the fault ruptures, then, the choice of slip-rate functions that specify how fault ruptures is very important.
In this study, we have developed the source model of the mainshock of the 2021 Off-Fukushima earthquake (Mw 7.1) based on the finite-fault inversion method developed by Ji et al. (2002). We constructed the 1D velocity structure representing the source area of this event with consideration to the results by the seismic tomography (Matsubara et al., 2019). We have used the waveform data at close stations by K-NET and KiK-net with the range of 0.05-0.2 Hz. Our preliminary results of the inversion show that the rupture extend to the southern side of the hypocenter.