桜島火山における繰り返し相対重力測定 (2018年5月-2019年2月)

Abstract

Relative gravity values were repeatedly measured at 19 gravity points in and around Sakurajima Volcano in May 2018, August-October 2018 and January-February 2019, to monitor spatiotemporal mass variations associated with volcanism. The relative gravity values measured from 2006 to 2019 showed a clear increase in the central part of the volcano by up to +4.7μGal/yr. The gravity increase can be explained by the point mass increase of 1.9×10¹ºkg/yr under the Kita-dake summit at the depth of 3 km below sea level. This result implies that volcanic mass continuously increases under Sakurajima Volcano, even during the quiet period of eruptive activities at the Minami-dake crater.