Seismologists at Oregon State University predict that the Axial Seamount, Oregon’s most active underwater volcano, could erupt in 2025.  The seamount, located 300 miles from the state’s coast and one mile beneath the Pacific Ocean’s surface, has been swelling at a steady rate for the past six months, with seismic activity totaling hundreds of earthquakes per day, according to an Oregon State University blog that chronicles eruption predictions of the sea volcano.

The good news is that the seamount doesn’t pose a threat to humans. However, observing what happens before and after its potential eruption could help scientists learn about submerged volcanoes and improve the accuracy of their predictions.

In late October, the following was posted on the Oregon State Axial Seamount blog:

The rate of inflation at Axial has been steady for the last 6 months and the rate of seismicity has moderated. An eruption does not seem imminent, but it can’t do this forever… So, no change in our latest eruption forecast of “before the end of 2025”. 

Science News noted that this much advance notice is a big deal, because forecasting eruptions more than hours ahead is “pretty unique,” says geophysicist William Chadwick.  Nevertheless,  Chadwick and his colleagues reported on December 10 at a meeting of the American Geophysical Union in Washington, D.C. that the Axial Seamount ticks all the boxes that hint at imminent activity

For the past decade, a suite of devices have been monitoring Axial’s every action — rumbling, shaking, swelling, tilting — and delivering real-time data via a seafloor cable. It’s “the most well-instrumented submarine volcano on the planet,” says Mark Zumberge, a geophysicist at Scripps Institution of Oceanography in La Jolla, Calif., who was not involved in the work.

But in November, a particular milestone caught Chadwick’s eye: Axial’s surface had ballooned to nearly the same height as it had before its last eruption in 2015 — fortuitously, just months after monitoring began. Ballooning is a sign that magma has accumulated underground and is building pressure.

The 2015 swelling allowed Chadwick, of Oregon State University’s Hatfield Marine Science Center in Newport, and colleagues to predict that year’s eruption — “our best forecasting success,” he says. The recent swelling, along with increased seismic activity that indicates moving magma, has led the researchers to narrow in on the next one.

Oregon undersea volcano likely to erupt in 2025, scientists say