Numerical investigation for earthquake triggering of volcanic eruptions considering heterogeneity

Abstract

A causal relationship between large earthquakes and following volcanic eruptions has been indicated. It is important to understand the triggering mechanism of volcanic eruptions for establishing sustainable secure society because the volcanic eruptions would have large impacts on our society. Since a volcanic eruption requires a change in stress field around a magma chamber, the dynamic, viscous and static stress changes induced by an earthquake are considered to be key issues of the triggering mechanism. At intermediate distances from earthquakes, static stress changes induced by earthquakes can trigger volcanic eruptions. Many researchers have calculated the static stress changes in subsurface induced by the occurrences of earthquakes in order to understand the interaction between large earthquakes and volcanic eruptions taking heterogeneous earth into consideration. In the present study, we investigate the effect of the heterogeneity of around hundreds of meters on the estimation of the static stress changes around a magmatic chamber, in particular, the layered structure of the heterogeneity. Our numerical results show that the ignorance of the heterogeneity has large effect on the static stress field at the chamber wall. The heterogeneity just around the magma chamber is an important parameter rather than the strong heterogeneous zone near the surface.