Abstract
Many volcanic hazards—eruptive and otherwise—are driven or worsened by heavy rainfall. For example, heavy rainfall can trigger dome explosions, induce remobilisation of volcanogenic deposits, and initiate flank collapse, all of which constitute substantial hazards. We investigate the propensity for heavy rainfall to increase in the future due to ongoing climate change (in particular, global warming). The study comprises a comparative analysis of nine general circulation models, from which we calculate the forced model response: a metric which describes the percentage change of heavy precipitation for a given unit of global warming, serving as a proxy for the likelihood of extreme rainfall events in the future. We show that heavy rainfall is projected to increase with continued global warming throughout the twenty-first century in most subaerial volcanic regions, increasing the potential for rainfall-induced volcanic hazards. This result persists across a broad range of spatial scales, from countries and volcanic arcs down to individual volcanic systems. Examples include Soufrière Hills Volcano (Montserrat) and Guagua Pichincha (Ecuador), systems where observational and statistical evidence has previously revealed the importance of heavy rainfall events in initiating hazardous volcanic phenomena. Our analysis indicates that heavy rainfall will increase at more than 700 Holocene-active volcanoes over the remainder of the century (around 60% of the subaerial active volcanic inventory), implying a significant and increasing suite of geohazards tied to ongoing global warming. In contrast, less than 10% of the volcano catalogue studied is coincides with regions projected to experience less heavy rainfall by 2100 CE.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)