火山噴火予知に関する2,3の問題 -桜島火山の場合-

Abstract

In this report some forerunning phenomena of volcanic eruptions of the Volcano Sakura-jimaare introduced and discussed. The crustal movement of Aira-caldera on which somma the volcanois situated was clearly observed in the big event in 1914 flank eruption. It is also recognized thatthe crustal movement is closely related with the activity of the summit eruptions which have beentaken place since 1955. For the seismic events before the summit eruptions, the migration of fociof earthquakes from somewhat deep place to shallow one under the crater is observed. This patternhas sometimes exceptions when the summit eruptions occur violently. The thermal conditions onthe surface ground of flank and around the active crater are derived from their infrared images.