Monitoring of Volcanic Activity in Kuchinoerabu Island from ALOS-2 Data

Abstract

Synthetic Aperture Radar (SAR) is a very useful tool for detecting surface changes and deformation caused by volcano activities because of its independence from weather and daylight conditions. A volcano in Kuchinoerabu Island, Kagoshima, Japan, erupted explosively and pyroclastic flows reached the coastal area on May 29, 2015. In this study, ALOS-2 PALSAR-2 data were used to analyze surface changes and deformations associated with the eruptive activity. The pyroclastic flows around the Shindake crater were observed by the differences of backscattering coefficients and the coherence values. Changed areas were extracted by a threshold value of the coherence, and were compared with a visual interpretation result conducted by the Geospatial Information Authority of Japan (GSI). The ground deformation due to the eruption was detected by the interferometric analysis, and its vertical component was estimated by combining the results from two InSAR pairs.