4:30 PM - 4:45 PM
[SVC45-24] Temporal volume change of deformation sources of Sakurajima volcano during activity at Showa crater
Keywords:Sakurajima volcano, GNSS, tiltmeter, strainmeter, Mogi model, temporal change
We performed combination analysis of GNSS, tilt and strain data for 2011 event assuming 3-pressure-source model. 2 inflation sources are located beneath Aira caldera at a depth of 9.6 km depth (A-source) and beneath Kita-dake at a depth of 3.3 km (K-source), and a deflation source is located beneath Minami-dake at a depth of 0.7 km (M-source) [Hotta et al., 2014 AGU Fall Meeting].
In this study, we estimate temporal volume change of each source after 2009 on the assumption that sources do not change their position at A-, K- and M-sources of 2011 event. A- and K-sources repeat inflation and deflation on a 1- to 1.5-year cycle. However, start of the change of K-source is simultaneous or several months earlier than that of A-source. Overall trend of volume change of A-source is inflation. On the other hand, K-source shows no significant inflation or deflation trend. M-source inflates several months before 2009 and 2011 events and deflates during these events, which is considered to be magma migration and ejection, respectively. M-source is continuing deflation after 2011 event. Assuming DRE of 2500 kg/m3 for magma, we convert amount of ejected magma from weight of ejected ash and then estimate volume of migrated magma between sources. Magma injection progressed in inflation events, but stopped during other periods. It is considered that magma injected intermittently toward A-source. Amount of magma ejection increased in 2009, 2011 and 2013 events, but is less than that of magma injection from A- to K-source. On the other hand, it is in reverse for deflation periods.