Torrential rains triggered the disastrous volcanic eruptions in Hawaii two years ago; Study.

Nature Research
Will a changing climate make such events more frequent? 
The answer? See footnote!

Lava flow from Kilauea south of Hawai'i Volcanoes Nat'l. Park.
Photo by Ekrem Canli.

A paper appearing in Nature today, suggests, the 2018 eruption of the Kīlauea Volcano in Hawai’i may have been activated by extreme rainfall. The findings indicate that rainfall should be taken into account when assessing volcanic hazards.

Rainfall is known to trigger seismic events and can alter volcanic activity. However, observations of such effects are limited to the shallow subsurface of the volcano, and it is unknown whether rainfall can activate deep magma movement. The eruption of the Kīlauea Volcano in Hawai’i was complex and multi-stage, but its trigger has been unknown. From May to August 2018, rifts opened around Kīlauea and the summit exhibited explosive eruptions and caldera collapse. 

Jamie Farquharson and Falk Amelung examined the impact of rainfall on the 2018 eruption. Prior to the eruption, Hawai’i had several months of abnormally high precipitation. The authors show that rainfall had infiltrated the volcano’s subsurface, increasing the pore pressure to the highest level in nearly 50 years immediately before and during the eruption. They suggest that this weakened the volcano’s structure and allowed magma to intrude, resulting in the eruption. The authors conducted statistical analyses of historical eruptions of Kīlauea and found that from 1790 onwards, nearly 60% of eruptions occurred in the rainy season, despite it being shorter than the dry season. This suggests a correlation between rainfall and Kīlauea’s eruptions throughout history. 

The authors indicate that improving our understanding of the relationship between rainfall and volcanic eruptions might help us to forecast future rainfall-induced volcanic activity.

-30-

Planet in Peril reached out to one of the lead authors, Jamie Farquharson to expand on the findings.

PinP - Q: Does this mean that, because manmade climate change is already bringing more severe weather, including torrential rains, we can expect more volcanic eruptions than in past because of it?

Farquharson - A: “Based on our study, it is impossible to answer your question definitively. Our study was solely focused on Kīlauea Volcano and the 2018 eruption in particular---a single, well-studied example---so caution should be taken not to over-generalise these results. A great deal of further research is required to determine whether this is a phenomenon that can be detected in other volcanic environments. 

"Nevertheless, if there are volcanoes that are particularly prone to external forces such as rainfall, then a potential result of our changing climate could be an uptick in their activity in the future. 

"While it's certainly a fascinating prospect, a greater understanding of the potential coupling between rainfall and volcanism is necessary before we can make such broad claims with any confidence.”