oa Estimation of Pre-eruptive Magma Ascent Using a Hydrokinetic Model of Magma Plumbing System

We have developed a hydrokinetic model of magma plumbing system to illustrate pre-eruptive magma migration and accumulation. The pre-eruptive magma flow is not observable but computable using both a magma flow simulation and ground deformation. For this purpose, ground deformation on April 9, 2009 at the Showa crater of Sakurajima Volcano was used because the pre-eruptive magma flow is implied from the observed data, which shows a periodic inflation and deflation event with time lags of 3-6 hours prior to the explosive eruption. Three-phase Poiseuille and permeable flows were adopted to demonstrate the observed data. In consequence, it was found that the data can be reproduced by the permeable model much better than the Poiseuille model. In addition, compressibility of the reservoir, a magma supply rate to the deeper reservoir and a size of the volcanic conduit can be constrained to be ca. 1 GPa, 35 m3/s and 225 m, respectively. Our scheme will be therefore effective to quantitatively evaluate the invisible magma migration preceding an eruption.