Steady Crustal Deformation Around Cape Omaezaki Revealed by InSAR Time Series Analysis Method

Abstract

Large-scale earthquakes have occurred repeatedly along the Nankai Trough, southwestern Japan, and the next one is expected to occur in the near future. These large-scale earthquakes are associated with the subduction of the Philippine Sea plate beneath the Eurasian plate. Coupling at the plate boundary is a source of large-scale earthquakes and it also causes crustal deformation in its vicinity. Consequently, an understanding of crustal deformation in the plate boundary area is important for detecting changes in plate coupling and for understanding and monitoring large-scale earthquakes. Here, we present results of an Interferometric Synthetic Aperture Radar (InSAR) time-series analysis that used data from the Advanced Land Observing Satellite (ALOS) Phased Array L-band SAR (PALSAR). Data collected during both ascending and descending orbits from 2007 to 2010 and from 2014 to 2022 were analyzed. Although widespread crustal deformation associated with plate subduction was not detected in the analysis of the former period data, it was seen in the analysis results for the latter period. The enhanced detection during the latter period may be due to the higher accuracy of the satellite orbit during the latter period compared with the former period.