Mile-Deep Underwater Volcano Is Inflating ‘Like a Balloon’ and Could Erupt Soon, Scientists Says

An underwater volcano off the Pacific Northwest coast is showing signs it may erupt soon.

Scientists at Oregon State University (OSU) have been monitoring the Axial Seamount, located about 300 miles off Oregon’s coast and nearly 4,900 feet below the surface. The volcano’s recent activity suggests an eruption could happen in the near future.

Key warning signs include a spike in earthquakes around the seamount and structural changes in the seafloor, researchers said.

In June, OSU recorded more than 2,000 earthquakes in a single day near the site, a number commonly associated with upcoming eruptions. Activity has since slowed to about 100 quakes per day.

William Chadwick, an OSU research associate, told ABC News earlier this year that the seamount has been inflating “like a balloon” as molten rock accumulates beneath the surface. Combined with its seismic activity, researchers believe the volcano is on track to erupt before the end of 2025.

While the eruption is expected to be significant for scientific study, experts emphasize it poses little risk to people, property, or the possibility of triggering a tsunami.

“For the size of eruptions we’ve seen in the last 20 years … if you were on top of it on a boat, you would never know it,” Chadwick said in a 2019 interview with OPB.

The Axial Seamount last erupted in 2015, with previous events in 2011 and 1998. OSU researchers call it the most active submarine volcano in the region, according to their ongoing blog.