Underwater Volcano Off the Oregon Coast Poised to Erupt

Underwater Volcano Off the Oregon Coast Poised to Erupt

The last time I wrote about seismic activity along the Pacific Northwest, it was about updates to emergency response plans related to two volcanoes in Washington.  One of the two, Mt. Adams, has had a noticeable uptick in small quakes, indicative of magma movement.

The other is the infamous Mt. St. Helens.

Now there are reports that Axial Seamount, an underwater volcano located approximately 300 miles off the Oregon coast and nearly a mile beneath the Pacific Ocean’s surface, is showing strong signs of an impending eruption. This volcano is the most active in the Pacific Northwest and one of the best-monitored underwater volcanoes globally.

One expert indicates the eruption could occur quite soon.

The volcano, known as Axial Seamount, is located nearly 1 mile (1.4 kilometers) underwater on a geological hot spot, where searing gushes of molten rock rise from Earth’s mantle and into the crust. Hotspot volcanoes are common on the seafloor. But Axial Seamount also happens to be located on the Juan de Fuca Ridge — an area where two massive tectonic plates (the Pacific and the Juan de Fuca plates) are constantly spreading apart, causing a steady buildup of pressure beneath the planet’s surface.

The frequency of earthquakes has recently picked up dramatically as the volcano inflates with increasingly more magma, signaling an eruption could be near, according to researchers at the National Science Foundation’s Ocean Observatories Initiative Regional Cabled Array, a facility operated by the University of Washington that monitors the activity of Axial Seamount.

“At the moment, there are a couple hundred earthquakes a day, but that’s still a lot less than we saw before the previous eruption,” said William Wilcock, a marine geophysicist and professor at the University of Washington School of Oceanography who studies the volcano.

“I would say it was going to erupt sometime later (this year) or early 2026, but it could be tomorrow, because it’s completely unpredictable,” he said.

Presently, due to the volcano’s nature and remote location, an eruption event is unlikely to pose a hazard to those living along the West Coast.

In addition to being hundreds of miles offshore, the peak is submerged about a mile deep underwater. The volcano is remote enough that even a strong eruption would be undetectable on land.

“There’s no explosion or anything, so it would really have no impact on people,” [Bill Chadwick, a volcanologist and research professor at Oregon State University] said. “Even if you were out on a boat right over the seamount when it’s erupting, you probably would never know it.”

But that doesn’t mean the eruption wouldn’t be a spectacular event. During Axial Seamount’s last eruption in 2015, an enormous amount of magma poured out of the volcano, including one lava flow that was about 450 feet thick, according to researchers.

“For reference, that’s about two-thirds the height of the Space Needle in Seattle,” Chadwick said. “That’s a lot of lava.”

Legal Insurrection readers may recall my 2022 report on the underwater Hunga Tonga-Hunga Ha’apai volcano, which erupted violently in the South Pacific, creating a 300-foot-deep and 5-mile-wide crater. The resulting tsunami reached Tonga within 10 minutes, flooding land up to 60 feet above sea level and causing extensive damage to resort communities and infrastructure.

The good news for those living in Oregon, Washington, and around the Pacific basin is that the Axial Seamount is an entirely different type of volcano. This volcano typically produces highly fluid, basalt-rich lava flows, similar to those in Hawaii, rather than explosive eruptions.

These eruptions cause the seafloor to inflate and then deflate as lava is expelled, but do not result in the kind of violent displacement of water necessary to trigger a tsunami.

Furthermore, previous eruptions, including the significant 2015 event, did not generate tsunamis. The lava flows, while substantial (up to 127 meters thick in places), altered the seafloor but did not cause rapid, massive collapses or explosions that would displace enough water to create a big wave.

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