Muography of the Active Sakurajima Volcano: Recent Results and Future Perspectives of Hazard Assessment

Abstract

Sakurajima volcano is one of the world’s most active volcanoes with over 3,000 of explosive eruptions during the last five years. A muography observatory is under construction in international collaboration since 2017 at a distance of approx. 2,800 m in south-west direction from the active craters. Currently, the Sakurajima Muography Observatory is operating with 11 Multi-Wire-Proportional-Chamber-based Muography Observation Systems that are covering a sensitive surface area of 8.25 square meters. This work is focusing on the volcanological implications of muographic monitoring of Sakurajima: (i) tephra deposition, and erosion of the surface region exist due to heavy rains and post-eruptive lahars; (ii) magmatic plug formation was observed beneath the active craters after the deactivation of Showa crater in 2018 and after a dormant period of Central craters in 2020; (iii) machine-learning-based processing of daily muographic images achieved a fair area under the receiver operating characteristic curve score of 0.76.