An underwater volcano in the Pacific Northwest is expected to erupt sometime this year for the first time in 11 years — and it could stir up lots of activity for marine life in the area.
The volcano, Axial Seamount, lies about a mile below the ocean’s surface, about 300 miles from the coast of Astoria, Oregon. It has erupted three times in the last 30 years, with the most recent eruption in 2015, according to Bill Chadwick, an adjunct at Oregon State University who is helping forecast the volcano’s eruption.
Because Axial Seamount is so far from shore and so deep, humans aren’t expected to be impacted. But the pressure from the impending magma flow generates pressure, heating sea water to more than 700 degrees Fahrenheit. As sea water passes through the cracks of volcanic rock, it picks up minerals that spout from the vents, creating plumes of black smoke.
These are known as hydrothermal vents, which are like hot springs on the seafloor. All the warmth and nutrients coming from the vents make it a hotspot for plants and animals, said OSU’s Chadwick.
“The base of the food chain here are microbes that do little chemical reactions that yield energy, and then animals are either symbiotic with them, or they eat them,” he said. “And then there’s this whole chemical energy-based ecosystem around these hydrothermal vents, and lots of weird animals.”
When the eruptions happen, some of the vents may get covered by magma, but they reappear as magma reaccumulates in the earth.
Still, due to the mountain’s depth and distance from the shore, those chemicals won’t make it high enough to affect the atmosphere. And while scientists predict the eruption will trigger small earthquakes (2s and 3s on the Richter scale), they aren’t strong enough to cause major destruction to marine or land life, Chadwick said.
It’s hard to pinpoint when exactly in the year this is all expected to happen.
Although Chadwick and other researchers were right about the last eruption, he notes, “my forecasting has had some success and some failures.”
These forecasts are based on cycles of inflation and deflation. As magma accumulates under the volcano, the seafloor expands. After an eruption, it falls.
“It’s kind of like a balloon inflating with air, and then you let some air out, and it goes back down,” Chadwick said. “And we’ve seen this several times now, and it’s pretty repeatable. It inflates to about the same level each time, and then an eruption is triggered. So this forecasting is based on this pattern that we’ve seen before.”
However, that pattern is not as linear as it once was. Chadwick said scientists have not yet discovered why.
Researchers are able to detect these changes through the Ocean Observatories Initiative, funded by the National Science Foundation. It is a series of cords that stretch from shore to the volcano. They are adorned with more than 140 pieces of equipment, such as pressure sensors.
Because of the program and the volcano’s remote location, Axial Seamount has become a crown jewel in the effort to evolve how underwater volcanoes are forecasted long-term.
Scientists estimate that 80% of volcano eruptions happen underwater, according to the National Oceanic and Atmospheric Administration. But forecasting underwater volcanoes is more difficult than land volcanoes because they don’t make as much commotion, Chadwick said. “We’re kind of experimenting at this place where we can make false alarms,” he said.
The stakes are also lower in monitoring underwater eruptions.
“We can make forecasts, and if they’re wrong, it’s not gonna affect people negatively or not going to cause any economic impact.”
Copyright 2025 NPR