Things are heating up hundreds of miles off the Oregon coast, as scientists report that a large undersea volcano is showing signs of a potential eruption. The volcano, called Axial Seamount, lies nearly 1 mile (1.4 kilometers) beneath the surface on a geological hotspot, where intense flows of molten rock rise from the Earth's mantle into the crust. While hotspot volcanoes are common on the ocean floor, Axial Seamount is uniquely situated on the Juan de Fuca Ridge, where the Pacific and Juan de Fuca tectonic plates are continuously moving apart, leading to a gradual accumulation of pressure beneath the Earth's surface.
Researchers from the National Science Foundation’s Ocean Observatories Initiative Regional Cabled Array, managed by the University of Washington, report a significant increase in earthquake activity. This surge is linked to the rising magma within the volcano, indicating that an eruption may be imminent at Axial Seamount.
"Currently, there are several hundred earthquakes occurring each day, which is significantly fewer than what we observed prior to the last eruption," stated William Wilcock, a marine geophysicist and professor at the University of Washington School of Oceanography, who researches the volcano. "I believe it could erupt later this year or early 2026, but it’s entirely unpredictable—it could happen tomorrow."
What occurs during an eruption? In April 2015, during the volcano's most recent eruption, the team recorded approximately 10,000 small earthquakes within a 24-hour timeframe, a pattern likely to repeat in the next event, according to Wilcock. He noted that magma, or molten rock located beneath the Earth's surface, flowed from Axial Seamount for a month, extending roughly 25 miles (40 kilometers) across the ocean floor.
The magma chamber at the center of the volcano has collapsed multiple times in the past, forming a large crater known as a caldera. In this area, marine life flourishes, nourished by the mineral-rich gases that escape through hydrothermal vents, which resemble underwater hot springs. Streams of hot fluid, teeming with billions of microbes and waste particles, rise from fissures in the caldera’s surface, producing white plumes referred to as “snowblowers.” In earlier eruptions, the small plants and animals inhabiting the hydrothermal vents were devastated by lava flows. However, just three months later, their ecosystem rebounded and thrived once again, according to Debbie Kelley, director of the Regional Cabled Array. “I believe this is one of our most significant discoveries,” said Kelley, a professor of marine geology and geophysics at the University of Washington. “Life flourishes in these harsh environments, and volcanoes are likely one of the primary sources of life in our oceans.”
According to Kelley, while nearby marine life, including fish, whales, and octopuses, may sense the heat and vibrations from seismic shifts, they are unlikely to be harmed. People on land are also expected to remain unaware of the eruption. “It’s not a very explosive event. You won’t see ash clouds above the water or anything like that,” she explained. “It’s similar to placing a mile of seawater over Kilauea; you might observe some fountaining, but that’s about it.” In fact, most volcanic activity on Earth occurs at underwater spreading centers like the Juan de Fuca Ridge, which experiences numerous small eruptions daily, Kelley noted.
"The magma is located relatively near the surface, approximately a mile down, which is quite shallow compared to many land volcanoes, where it can be as deep as 8 miles (12.9 kilometers)," Kelley explained. He noted that the viscosity, or thickness, of the magma influences the pressure that accumulates in the magma chamber. Similar to how thick tomato sauce bubbles more vigorously while cooking, the air bubbles in high-viscosity magma burst more dramatically than those in the thinner, more fluid magma of Axial Seamount.
How to Watch
Fortunately, the relatively mild nature of Axial Seamount makes it ideal for close human observation. The observatory plans to livestream the next volcanic eruption, a first in history, according to Kelley. However, observing an undersea volcanic eruption is challenging. Scientists witnessed one for the first time on April 29. Located in the Pacific Ocean, approximately 1,300 miles (2,092 kilometers) west of Costa Rica, researchers from the Woods Hole Oceanographic Institution (WHOI) were conducting a routine submersible dive to gather data on the East Pacific Rise when they discovered that the once-thriving Tica vents were devoid of sea life. Instead, the team encountered what WHOI Emeritus Research Scholar Dan Fornari described as a charred “tubeworm barbeque.” They observed flashes of orange lava seeping through the seafloor and solidifying in the frigid water, signaling an eruption was underway. “This is quite a significant development,” Fornari remarked.
As above, so below. Recent close observations of Axial Seamount have unexpectedly shown that the timing of its eruptions is influenced not only by the activity beneath the surface but also by factors above it. All three of the most recent eruptions—in 1998, 2011, and 2015—occurred between January and April, a period when Earth is moving away from the sun. “I don’t think we fully understand why that is, but it may be related to the gravitational forces from the moon affecting the volcano,” Wilcock noted.
The moon orbits Earth every month, and its gravitational influence causes ocean tides to rise and fall, leading to pressure fluctuations on the seafloor. As the magma chamber of a volcano approaches critical mass, these pressure changes increase stress on the caldera, which is the crater formed by earlier eruptions. According to Kelley, the pressure from high tides also results in more frequent earthquakes, gradually pushing the chamber closer to its breaking point.
