About 300 miles off the coast of Oregon, an underwater volcano appears to be rumbling to life.
Scientists who have been monitoring the vast submarine volcano for decades say a flurry of recent activity — including an uptick in earthquakes in the vicinity, and swelling of the structure itself — signals that it’s ready to erupt.
Current forecasts project that the volcano, known as Axial Seamount, could erupt anytime between now and the end of the year, according to Bill Chadwick, a volcanologist and research professor at Oregon State University.
Chadwick and colleagues at the University of Washington and the University of North Carolina Wilmington have been using a network of sensors on the seafloor to eavesdrop on the volcano.
Over the past few months, the instruments have picked up clues that Axial Seamount is stirring. In late March and early April, for instance, researchers were recording more than 1,000 earthquakes a day. The volcano has also been steadily swelling, a telltale sign that it’s filling with molten rock, Chadwick said.
“This volcano is similar to the ones in Hawaii that erupt very fluid lavas,” he said. “They tend to inflate like a balloon in between eruptions. At Axial, the seafloor is actually rising, and that’s a big signal.”
But unlike some of Hawaii’s volcanoes, there’s no real danger to humans if Axial Seamount does blow.
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,” Chadwick 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.”
Axial Seamount formed on what’s known as a hot spot, where plumes of molten rock rise from Earth’s mantle into the crust. This geological process is not uncommon: Hot spot volcanoes dot the seafloor, and some even create island chains like Hawaii and Samoa. But what does make Axial Seamount unusual is that it is located right at the boundary between the Pacific plate and the Juan de Fuca plate, two giant tectonic plates that are moving apart. The separation of the plates, and the resulting pressure beneath the seafloor, is constantly fueling volcanic activity and producing fresh ocean crust in the region.
Map showing where Axial Seamount is located on the Juan de Fuca Ridge, with relation to the Cascadia Subduction Zone and the Mendocino Fracture Zone. (Susan Merle / Oregon State University)
Chadwick has been tracking activity at Axial Seamount for the past 30 years. Over that period, the volcano has erupted three times: in 1998, 2011 and 2015.
As he and his colleagues wait for an impending eruption, they are testing whether repeating patterns of activity at Axial Seamount can produce reliable predictions of when the underwater volcano is ready to go off.
But eruption forecasting is a notoriously tricky business. Volcanoes can behave in unpredictable ways, and depending on the type, they can exhibit very different warning signs.
“It’s much harder than forecasting the weather, even though the weather is a very difficult thing to forecast already,” said Scott Nooner, a professor of geophysics at the University of North Carolina Wilmington. “There’s still so much that we don’t understand about what triggers eruptions and how magma moves around underneath the Earth’s surface.”
Scientists have had some success with short-term forecasts — usually mere hours ahead of an eruption — that have helped local officials decide whether to evacuate areas or take other precautions. Longer-term forecasts, however, have remained challenging.
That’s what makes Axial Seamount such a good natural laboratory for refining tools for eruption forecasting, according to Nooner.
“On land, if you make a forecast that a volcano is going to erupt in a week or a month and you’re wrong, you’ve cost people a lot of money and time and worry,” he said. “But we don’t have to worry about that at Axial Seamount because these eruptions don’t impact anyone. So it’s a nice way to test our models, test our forecast and hold ourselves accountable, but without the same repercussions as with volcanoes on land.”
This article was originally published on NBCNews.com
