Plug Formation Imaged Beneath the Active Craters of Sakurajima Volcano With Muography

Abstract Sakurajima Muography Observatory captured the formation of a volcanic plug beneath the Showa crater with a spatial resolution of ∼60 m in accordance with the end of the eruption episode of Showa crater and the reactivation of Minamidake crater. The increase of average density was observed with above 3 σ standard deviation for both above the floor of Minamidake crater and beneath the floor of Showa crater, respectively, being interpreted as volcanic ejecta deposition and the formation of a volcanic plug laterally extended within a few hundreds of meters.