Ground deformation monitoring associated with environmental disaster by InSAR analysis.

Abstract

Interferometric Synthetic Aperture Radar (InSAR) is a technique for mapping subtle surface deformations over two-dimensional areas with high spatial resolution. The aim of this study is to evaluate the capability of InSAR analysis for monitoring the ground deformation caused by the environmental disaster. Differential InSAR (DInSAR) analysis and InSAR time series analysis were performed around disaster areas of the Sanriku district and the Kirishima Mountains in Japan (Fig. 1). The data used in this study were images from the Advanced Land Observation Satellite/Phased Array Synthetic Aperture Radar (ALOS/PALSAR) observed from 2009 to 2011. We performed DInSAR analysis and InSAR time-series analysis with a commercial software and attempted to precisely estimate vertical and horizontal displacements by using the vector composition method from the observation data of up-going and down-going orbits. The results show that InSAR analysis is useful for the disaster monitoring such as earthquakes and volcanic eruptions. Uplift and subsidence were detected around the Kirishima Mountains before the last eruption on January 26, 2011. This suggests that InSAR analysis may be useful for forecasting volcanic eruptions. In the Sanriku district, the huge vertical movement and horizontal movement to the east were clearly detected by the vector composition analysis method from up-going and down-going orbit data.