Magnetic susceptibility of volcanic ash: an evaluation in the Shinmoendake 2017-2018 eruption

Abstract

In volcanic rocks, amount of magnetite chiefly changes their magnetic susceptibility behavior. The modal composition of magnetite presumably decreases in post-magmatic processes such as high-temperature oxidation and hydrothermal alteration. This study suggests that magnetic susceptibility is a possible indicator to identify post-magmatic processes and increased proportion of juvenile components when a pure eruption magmatic phase is approaching, on condition that the modal compositions of magnetite phenocryst are constant.