Surface Displacements Near Active Faults in Hanshin Area Estimated by Persistent Scatterer SAR Interferometry

Abstract

Interferometric SAR analysis is an effective method for clarifying the annual surface displacement tendency. In this study, we used persistent scatterer SAR interferometry to detect surface displacements in the areas around Arima-Takatsuki Tectonic Line, which is the fault group near the epicenter of the 2018 northern Osaka earthquake, and near the Mt. Rokko active segment. As results of our analyses, we found that （i） the subsidence occurred near the Mt. Rokko active segment, （ii） the surface displacements in the wedge-shaped area located between the Arima-Takatsuki Tectonic Line and the Mt. Rokko active segment, and in the vicinity of the Minoh GNSS station were suggested to be changed in the uplift direction after the earthquake, and were possibly caused by changes in the groundwater level, （iii） the groundwater level changes may have caused surface displacement considered to be uplift in the wide area between the Ikoma Fault Zone and Uemachi Fault Zone, and （iv） the slip of the source fault may have caused westward surface displacement around the epicenter of the 2018 northern Osaka earthquake. Furthermore, we validated the estimated surface displacements by comparison with GNSS measurements and previous studies. In order to elucidate surface displacement mechanism around the faults, it is necessary to continue to analyze surface displacements using the analysis of SAR interferometry time series in the same area.