Effectivity of Combination use of Multiple SAR Satellites for Volcano Monitoring – A Practical Lesson for SAR Constellation

A combination use of multiple SAR satellites can achieve frequent monitoring. This paper exemplified a combination use of ALOS-2 and other satellites for observation of volcanic activities in Japan. SAR data analysis for the 2015 Hakone volcano eruption showed that the time evolution of a local ground deformation could be achieved by combining ALOS-2 observations with those of RADARSAT-2. On the other hand, monitoring lava growth inside the crater of Shinmoedake volcano during its eruption in 2018 was realized by combining the intensity images of ALOS-2 and COSMO-Skymed (CSK) to provide high temporal resolution at a minimum interval of six hours. The interval was achieved by a combination of a noon–midnight orbit (ALOS-2) and a dusk–dawn orbit (CSK). Thus, the limited observation interval and data acquisition times for a single satellite can be effectively solved by the combination use of multiple SAR satellites.