Publication Date:
2023-06-16
Description:
Estimation of a strain-rate field from spatially discrete geodetic data has been a longstanding issue. On this problem, Okazaki et al. (2021) has recently developed a method based on basis function expansion with smoothness prior. In their method, the relative weight between observed data and the prior are objectively determined by Akaike's Bayesian information criterion (ABIC; Akaike, 1980; Yabuki and Matsu'ura, 1992); bi-cubic B-spline functions are used for basis functions, which makes inversion computation much faster (Nozue and Fukahata, 2022). By applying the method to GNSS data in Japan, strain-rate fields are estimated for three periods: 1997-1999, 2006-2009, and 2017-2020; the number of the used GNSS sites for each period is 880, 1337, and 1340. Except for deformation related with volcanic activities and large earthquakes, the obtained strain-rate fields are roughly stationary in time, while they show large variation in space. In order to interpret such spatially heterogeneous deformation, plate tectonics is considered to be inappropriate, because it basically postulates rigid motion for each plate. Instead, we propose a framework of inter-arc and intra-arc deformation, considering that Japanese Islands are composed of five island arcs (Kuril, northeast Japan, west Japan, Izu-Bonin, and Ryukyu). Using the framework, we can easily classify complicated deformation in Japan into the inter-arc deformation, such as the formation of the Hidaka Mountains, and the intra-arc deformation, such as the Niigata-Kobe tectonic zone.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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