水準測量によって測定された桜島火山および姶良カルデラ周辺域の地盤上下変動 : 2013年10月および11月測量の結果

Abstract

We conducted the precise leveling survey in Sakurajima volcano and around Aira caldera in October and November 2013. The obtained survey data are compared with those of the previous surveys conducted in October-December 2007 and November-December 2012, resulting in the relative vertical displacements of the bench marks. The resultant displacements show the ground uplift around Aira caldera as well as the ground subsidence near the central part of Sakurajima. These results indicate that the magma storage at the magma reservoir beneath Aira caldera is still progressing. On the other hand, they also suggest the increase of the amount of ejected magma at the magma reservoir beneath the center of Sakurajima volcano, reflecting the recent increase of the eruptive activity at Showa crater.