Massive underwater volcano off Oregon coast could erupt soon; scientists weigh risk of 9.0 earthquake and Pacific tsunami

Economic Times

24-05-2025

TIL Creatives The Axial Seamount lies deep in the Pacific Ocean, drawing increased scientific attention as it shows signs of an imminent eruption (AI generated image)
Beneath the cold waters of the northeast Pacific Ocean, roughly 700 miles northwest of San Francisco, an ominous geological force is rumbling. Scientists warn that the Axial Seamount, one of the most active underwater volcanoes on Earth, could erupt.This wouldn't typically spell disaster, but its location raises bigger questions. Could this undersea eruption spark a chain reaction along the Cascadia subduction zone, resulting in the long-feared magnitude 9.0 earthquake and a catastrophic tsunami striking the Pacific coastlines of Oregon, Washington, and California?
Also read: US may get hit by a 1,000-foot 'Mega-Tsunami' within 50 years, wiping out these cities off the mapExperts say the answer is no. But the timing and intensity of Axial Seamount's activity is still giving them pause.
No tsunami threat, but concerns about earthquake risk remain
Volcanologist Bill Chadwick of Oregon State University has studied Axial Seamount for decades. He says the volcano is far enough from the Cascadia fault that an eruption will not trigger the so-called "Big One", the massive earthquake scientists have long anticipated along the Pacific Northwest coast.
Axial Seamount is located too far away to influence the tectonic plates responsible for Cascadia's seismic threat. 'Mt. St. Helens, Mt. Rainier, Mt. Hood... kinds of volcanoes have more gas and are more explosive,' Chadwick explained. "Axial is more like Hawaii and Iceland."Unlike explosive land-based eruptions, which can kill people and cause widespread destruction, the Axial Seamount's underwater eruptions ooze lava quietly. 'The magma is more fluid, so the gas can get out without exploding,' Chadwick added.Volcano inflation indicates eruption is nearStill, what's happening at the volcano is far from routine. The seafloor surrounding the Axial Seamount has started to inflate again, something scientists have seen before every past eruption. Since 2024 began, the rate of inflation has been steady, and Chadwick is confident enough to go public with his forecast.
Also read: Two quakes in Pacific ocean, but no damages or tsunami warnings issued 'At the rate of inflation it's going, I expect it to erupt by the end of the year,' he said. Chadwick and colleague Scott Nooner, from the University of North Carolina at Wilmington, posted their prediction to their blog in July 2024.The last time they made a similar forecast, in 2015, the volcano erupted seven months later. But predicting eruptions isn't foolproof. "It wouldn't shock me if it erupted tomorrow," Chadwick said, 'but I'm thinking it's not going to be anytime soon on the whole.'
A hot spot for eruptions and data
Axial Seamount sits atop the Juan de Fuca Ridge, where tectonic plates diverge and new seafloor forms. What makes it even more volcanic is that it also rests over a geological hot spot, rising plumes of superheated magma that power frequent eruptions.This double threat of tectonic and hot spot activity makes Axial Seamount one of Earth's most consistently active volcanoes. It erupted in 1998, 2011 and 2015. Its reliable activity has turned it into the best-monitored underwater volcano in the world.'In between eruptions, the volcano slowly inflates—the seafloor rises. Then during an eruption, the volcano deflates and the seafloor drops,' said oceanographer William Wilcock of the University of Washington.
Also read: Earthquake in US: Tremor jolts Massachusetts, New England. Residents share their experiences
Underwater eruptions still reshape marine life
Though it won't create a tsunami or reach the ocean's surface, an eruption can still be dramatic under the sea. Lava flows spread across the seafloor, destroying any sea life in their path and potentially damaging expensive sensor equipment that monitors the area. 'There's all this heat that takes a long time to dissipate,' Chadwick said. 'Microbial mats can grow and it almost looks like snow over a landscape.'Whales and other large sea creatures won't be impacted, as they live near the surface. But deep-sea habitats may not fare as well.
Forecasting a rare glimpse into Earth's inner workings Scientists are optimistic that their work at Axial Seamount will offer broader insight into volcano forecasting, especially for eruptions that pose real danger on land. But they also acknowledge that catching these eruptions live remains a challenge.
Also read: Mega earthquake in USA? 10,000 US residents at risk from underwater fault line in the Pacific 'You have to be in the right place at the right time,' Chadwick said. Eruptions may last only days to a few weeks, and scientific vessels are scheduled years in advance.Although Axial Seamount might erupt before 2025, the next planned expedition to study it is set for the summer of 2026."There's no problem of having a false alarm or being wrong," Chadwick noted, because no communities are directly at risk. Still, he said, 'maybe there's lessons that can be applied to other more hazardous volcanoes around the world.'For now, scientists continue to monitor this restless giant under the sea, one that may erupt quietly, but not unnoticed.