The Present and Future of Volcanic Gas Monitoring for Forecasting Volcanic Eruptions

Abstract

Monitoring of volcanic gas composition and flux can provide us the information about the condition of the magma and hydrothermal systems beneath the volcano. Situations of the degassing volcanoes can be classified into two types, one with an underlying hydrothermal system and the other without it discharging the magmatic gases directly from magmas. In order to understand the processes preceding the eruption in the former system, we need theoretical modeling of the hydrothermal system both for physical and chemical responses to the volcanic activity changes. Various techniques are recently developed for monitoring of volcanic gas composition and fluxes directly discharged from magmas, including mini-DOAS for flux measurement and Portable Multi-Sensor System for composition measurement. Comparison of these results with magma discharge rate, volatile contents in magma estimated from melt inclusions enabled to model the degassing processes of volcanoes, such as degassing of convecting magma column. Since the volcanic gas data can show us different aspects of volcanic activities from geophysical monitoring, and interdisciplinary comparison of the data and models will be one of the promising area of volcanology. In order to compare the geophysical data with good time resolution, we also need further development and application of these volcanic gas monitoring techniques.