Magmatic inflation in 2008–2010 at Mt. Fuji, Japan, inferred from sparsity-promoting L1 inversion of GNSS data

Abstract

Mt. Fuji, the tallest volcano in Japan, has not erupted since the Plinian eruption in 1707, but its volcanic activity has not finished. Here, using GNSS (Global Navigation Satellite System) time-series data, we investigate an inflation event of Mt. Fuji in 2008–2010. Referring to recent studies of igneous processes, we focus on “vertically-extensive” magma systems and estimate depth distribution of geodetic inflation sources. A sparsity-promoting L1 regularization algorithm for inversion analysis allows us to improve performance of data fitting. Our result shows that the inflation sources were mainly distributed in a depth range from 20 km to 15 km, and the total volume change was on the order of 0.01 cubic kilometers (approximately a sphere of radius 100 m). The 15 km depth may correspond to the upper boundary of partial melt of basaltic magma. Our sparsity-promoting method is useful to constrain magma movement from limited observation data.