Studying the initiation of volcanic eruptions: Time for a petrological perspective.

Volcano monitoring is essential for mitigating the risks associated with volcanic activity. As monitoring becomes more sophisticated and widespread, there is a growing need for understanding the relationship between different monitoring records and magmatic processes occurring at depth. This is particularly relevant to the processes that initiate eruptions after the extended periods of repose and inactivity that characterize many volcanic systems. Petrological studies of erupted materials are critical to this effort as they provide direct insight into the physical and chemical changes that occur in erupted magmas prior to their eruption, and allow investigation of past eruptions. Crucially, petrological approaches can also constrain the timing of processes involved in eruption initiation, and the time that might be expected to elapse between remote detection of increased activity and eventual eruption. Despite this, petrological studies of eruption initiation mechanisms are rarely systematically applied to monitored and other high-risk volcanoes. A literature compilation suggests there are significant differences in the composition, volume, style and timescales between eruptions initiated by different mechanisms. Knowledge of the processes that initiate eruptions at a given volcano may thus have significant predictive power.