Volcanic Eruptions can Worsen as Heavy Rainfall Persists Near Volcanoes Like Mt. St. Helens, Study Suggests

The damage brought on by volcanic eruptions can get worse when there is a lot of rain, which is predicted to happen more often in some places in the future.

Increased rainfall due to climate change will make volcanic hazards like flank collapses and dome explosions more likely, potentially putting more people in danger who live close to volcanoes like Mount St. Helens. This research was published in the journal Royal Society Open Science.

The specific volcanic hazards that are expected to worsen vary from volcano to volcano.

Jamie Farquharson, a postdoctoral associate from the Rosenstiel School of Marine and Atmospheric Science, University of Miami, said that lahar, which is a destructive slurry of volcanic ash combined with water that typically results from rainfall, is one of the most frequent hazards. Farquharson is a co-author of the paper.

A volcano's slopes and lava domes can become unstable due to heavy rain, which can result in rockfalls, collapses, landslides, and even the possibility of volcanic eruptions as the magma becomes suddenly depressurized.

According to Farquharson, the rapid volumetric growth of the fluid can cause steam-driven explosions if the surface of the lava dome is extremely hot in comparison to an unexpected downpour of rain. A volcano's edifice may also be penetrated by rainfall, which could weaken or fracture the subsurface rock and make it simpler for magma to intrude at a greater depth.

Climate Change and Volcanic Activity

Knowing which volcanic areas may experience more intense precipitation events in the future is crucial in wake of growing climate change because doing so could greatly increase the dangers that locals in the area face. Around 800 million people live within 60 miles of active volcanoes, which is just 6 miles away from over 29 million people worldwide, which is comparable to the width of the state of New Jersey.

According to Farquharson, this study compared the outcomes of nine counts of global-scale "general circulation models" created by various climate research groups around the world to determine where rainfall will be more frequent, which is a result of climate change.

Heavy Rainfall within Volcanic Vicinity

Then, according to Farquharson, they concentrated on the parts of the Earth where most of the models concurred. These models predict that with continued global warming, some regions, including South America, the West Indies, or Indonesia, will experience more extreme rainfall. Additionally, there is a lot of volcanic activity in these areas.

The Soufrière Hills Volcano in the Caribbean, Mount Semeru in Indonesia, and Guagua Pichincha in Ecuador are among the dangerous volcanoes in these areas. Rainfall-related volcanic casualties have increased recently in both Semeru and Guagua Pichincha. Semeru's hardened lava dome was partially eroded by rain, which is thought to have set off the eruption that will take place in 2021.

Additionally, the western seaboard, Alaska, Canada, and some areas of the U.S. are expected to experience increased rainfall. Although U.S. volcanoes were not specifically examined in the study, the authors noted that Mount Rainier and Mount St. Helens may in the future present a greater risk to locals.

Farquharson pointed out that numerous active volcanoes, particularly those in the Cascade Range, pose a lahar threat to significant population centers, including Mount Rainier in Washington. At Mount St. Helens, patterns of steam explosions were also connected to passing downpours. Farquharson contends that in light of current climate change, this justifies further research into the relationship between volcanic activity and rainfall in these systems.

When Mount St. Helens erupted last in 1980, it directly killed close to 60 people. It is anticipated that future eruptions will be even more destructive. In 2019, the population of Skamania County, which includes Mount St. Helens, was estimated at 12,083, Newsweek reports.