California at risk? Scientists say undersea volcano 700 miles offshore could erupt by year’s end

California – Scientists say a highly active and closely monitored submarine volcano off the Pacific Coast could erupt before the end of 2025 — but there’s no need to panic onshore. Known as Axial Seamount, this undersea giant lies nearly a mile beneath the surface and about 700 miles northwest of San Francisco. Despite its remote location and silent presence, it’s becoming the focus of intense scientific scrutiny.

Discovered in the 1980s, Axial Seamount has erupted three times in the past three decades — in 1998, 2011, and 2015 — and experts believe another eruption is likely within months. Bill Chadwick, a research associate at Oregon State University and one of the world’s leading experts on Axial, is among those predicting a new event based on the volcano’s increasing inflation pattern. “At the rate of inflation it’s going, I expect it to erupt by the end of the year,” Chadwick said.

Fortunately for California and the Pacific Northwest, an Axial eruption poses no tsunami threat. Unlike explosive land volcanoes such as Mt. St. Helens or Mt. Vesuvius, Axial releases fluid lava in a slow, oozing manner — more akin to the eruptions seen at Hawaii’s Kilauea. “The magma is very fluid and doesn’t trap much gas, so it doesn’t explode violently,” Chadwick explained.

Still, an underwater eruption is far from uneventful. The volcano, located on the boundary between the Juan de Fuca and Pacific tectonic plates, releases hot lava that forms thick crusts as it cools — sometimes giving the appearance of snowy landscapes due to microbial growth on the surface. Life on the ocean floor can be buried or killed by lava flows, and valuable scientific instruments used to monitor the area may also be destroyed. But marine animals like whales swim closer to the surface and are unlikely to be affected.

Axial Seamount is now the best-monitored submarine volcano in the world, thanks to a web of sensors installed by the University of Washington’s Ocean Observatories Initiative. These instruments provide real-time inflation, heat flow, and seismic activity data. The volcano’s relatively frequent eruptions and clear geophysical signals make it a rare opportunity for scientists to test eruption forecasting models.

Chadwick and colleague Scott Nooner previously predicted Axial’s 2015 eruption seven months in advance. Although predictions since then have proven trickier, Chadwick believes the current signs point toward another eruption before the end of this year. “If it’s not erupting, it’s getting ready for the next one,” he said.

Despite the mounting evidence, there’s no indication that the eruption is imminent. Seismic activity remains moderate, and no immediate sign of the heightened earthquake frequency typically preceding an eruption. But for scientists, Axial Seamount is a tantalizing laboratory that might help unlock new ways to forecast eruptions at more dangerous volcanoes on land.