Investigation of the 2011 Eruption of Shinmoedake Volcano, Kirishima Volcanic Group, Japan, Using RADARSAT-2 SAR Data

摘要

In January 2011, a magmatic eruption occurred in Shinmoedake Volcano, which is part of the Kirishima volcanic group and is located in Kyushu, southwestern Japan. We employed C-band synthetic aperture radar (SAR) data acquired by RADARSAT-2 to examine ground surface changes caused by the volcanic activities (ash fall and volcanic bombs) for the prediction of sediment-related disaster. Change detection images recorded by the before-eruption and after-eruption SAR data revealed regional and local changes, especially around the craters and distribution area of volcanic ejecta. The Pauli color-coded image was classified into bare ground, forest area, and built-up area on the basis of the differences in the reflecting features, enabling us to detect a distribution of volcanic ejecta. Although our method cannot yield quantitative features, it is suitable for mapping widely distributed volcanic ejecta. Because SAR is an all-weather sensor, we found that our method of using SAR data was more efficient for investigating the volcanic eruption than image comparison using optical sensor data.