3:30 PM - 3:45 PM
[SGD01-07] Absolute gravity signals at the Sakurajima volcano since 2009 through 2018
Keywords:Absolute Gravity, Sakurajima
Gravity signal after eliminating groundwater disturbance showed remarkable features according to the phase of volcanic activity as described below. During the phase 1 characterized by frequent vulcanian eruptions from the Showa crater, gravity fluctuated about a mean with rather small amplitude of 10 microgals, suggesting dynamic equilibrium is achieved at the magma chamber; magma supply from deeper interior is balanced with mass loss through eruptions. The phase 2 is interpreted as a dyke intrusion event, which causes elastic deformation and short-term gravity change almost simultaneously. In the current phase 3 (2016-2018), gravity shows monotonous increase of 10 microgal/yr, suggesting deflation of magma.