Surface displacement during the periods before and after the 2018 northern Osaka earthquake estimated by PSInSAR analysis

Abstract

The 2018 northern Osaka earthquake occurred on June 18, 2018 in Japan, and caused extensive damage. Satellite synthetic aperture radar (SAR) interferometry is effective for observing surface displacements due to earthquakes because it can detect the spatial distribution of surface displacement over a wide area. On the other hand, it is also important to observe the long-term trend of surface displacements around active faults on an annual basis for monitoring the interseismic strain accumulation. In this study, we used persistent scatterer SAR interferometry (PSInSAR) to reveal recent surface displacements, including the period before and after the earthquake, near the Arima-Takatsuki Fault Zone and the epicenter of the earthquake. We validated the estimated surface displacements by ascending orbit data by comparing them with GNSS measurements and previous studies. The estimated surface displacements from Sentinel-1 were compared with results from other satellites in previous studies to understand long-term surface displacements and temporal changes in displacement patterns. Our results suggest that (i) surface displacements in the vicinity of Arima-Takatsuki Fault Zone changed to uplift after the earthquake, which may be caused by changes in the groundwater level, (ii) the uplift in the northern part of the Osaka Plain may be due to groundwater level changes.