[SVC46-P04] Estimation of the re-equilibrium depths of the Sakurajima vulcanian eruption magma from 2010 to 2015
Keywords:melt inclusion, Sakurajima volcano, Vulcanian eruption
Based on the geohygrometry of Putirka (2008), the equilibration between MIs and their host plagioclase was finally established at water contents of 1.3–2.8 wt %; this range is higher than the directly analyzed water contents of MIs, and the corresponding saturation depths were calculated to be 0.5–1.7 km. The difference from the final water reequilibration depth (< a few hundred meters) shows that the growth of plagioclase did not catch up with the magma ascent and resultant decompression and degassing prior to the explosions.
The depths of pressure sources of explosion earthquakes were estimated at 1–3 km from the crater (Iguchi, 2013), which is in between the water-reequilibration and plagioclase-reequilibration depths. Because the magma residence time at this depth is shorter than that required for the plagioclase reequilibration, degree of magma outgassing might be limited. This suggests a possibility that degassing of stagnated magma may causes pressurization to drive vulcanian explosions.