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Triggering of the 2024 Fernandina, Galapagos eruption by rainfall.

Falk Amelung, Jonathan Quartin, Giacomo Di Silvestro

Abstract

It is well known that increasing precipitation related to global warming will lead to increases in volcanic hazards because of  (i)  explosive interactions between magma and external water at active lava domes, (ii) mudflows,  and (iii) rainfall-triggered landslides.  However, whether the precipitation infiltrated from the surface can impact the volcanic system at depth  is less understood.  The 2018 eruption and caldera collapse of Kilauea volcano, Hawaii, occurred after several months of anomalously high precipitation suggesting that it was facilitated by surface-induced pore-fluid pressure increases (Farquharson & Amelung, 2020), but this remains controversial. Here we  present InSAR data of Fernandina volcano in the Galápagos Islands  showing that the March 2024 eruption occurred without any precursory inflation,   in contrast to previous eruptions that were preceded by several tens of centimeters of inflation in the years prior to eruptions.  The 2024 eruption occurred during the rainy period, exacerbated by the 2023-2024 El Niño, suggesting that infiltrated rainfall could have been the trigger.  We investigate eruption triggering by rainfall using satellite-measured precipitation data of the Global Precipitation Measurement mission and the Tropical Rainfall Measurement Mission since 2000  and gauge data from Santa Cruz Island  since 1960. We show that 7 of the 16 Fernandina eruptions since 1960 occurred during the tertile of days with the highest 90-day cumulative precipitation, a factor of 1.3 more eruptions than expected by random, strongly indicating that Fernandina eruptions are impacted by precipitation.