Recent developments in volcano gas monitoring

This chapter examines recent, current, and future developments using volcanic gases to monitor active volcano systems. We first examine the role of ground-based and space-based approaches to measure sulfur dioxide (SO2) fluxes emitted by volcanoes. Then we examine the utility of applying gas ratios to understand volcanic plumbing systems and to forecast eruptive activity. The study of gas ratios during the past two decades has revealed much new information into how volcanoes work. We conclude by looking at several new developments for volcanic gas monitoring. These include the study of hydrothermal systems for new insight into how volcanoes accumulate and lose gas, and also measurements of stable isotopic ratios in volcanic plumes, in particular their changes over different timescales.