10,000 Earthquakes in a Day

The Mile-Wide Volcano Oregon Is Still Watching — And Nearly Lost the Tools to Watch It With

By Madame Whiskerstein

Updated July 2026 — Original Report, Autumn 2025

There is a volcano roughly the size of Rhode Island sitting a mile beneath the Pacific Ocean, and for the last two years it has been doing something almost nothing else on Earth does: counting down to an eruption that scientists can actually see coming. Its caldera spans nearly two by five miles at the summit, and when it finally lets go, monitoring equipment is expected to register somewhere in the neighborhood of 10,000 small earthquakes in a single 24-hour period.^1,2 That number is not folklore. It comes directly from what happened the last time this volcano erupted, in April 2015. Scientists have been expecting a repeat ever since.

The volcano is called Axial Seamount. It sits about 300 miles off the coast of Newport, Oregon, on the Juan de Fuca Ridge, where two tectonic plates are slowly tearing apart and letting magma pool in the space between them.³ It is the most active known submarine volcano in the northeastern Pacific, having erupted in 1998, 2011, and 2015, and for years it has been slowly swelling as fresh magma fills its magma chamber, creeping toward the threshold that triggered each of those past eruptions.^3,4

Where the 10,000-Quake Number Comes From

During Axial's last eruption in April 2015, researchers recorded roughly 10,000 small earthquakes in a single 24-hour window as magma pushed toward the seafloor.² University of Washington marine geophysicist William Wilcock has said the team expects a comparable swarm with the next eruption. By contrast, Axial is currently far quieter: fewer than 100 detected quakes on most days, with only occasional spikes into the hundreds.⁶ For that daily quake count to mean what it meant in 2015, researchers now believe it needs to reach and sustain roughly 500 earthquakes per day before the volcano's seismicity-to-inflation ratio approaches the danger threshold — a new framework developed by Chadwick and his colleagues after their previous pattern-recognition methods failed to call the 2025 window correctly.⁷

That is the honest summary from Bill Chadwick, the OSU research associate at the Hatfield Marine Science Center in Newport who has tracked Axial for nearly three decades.⁸ He has been candid that his forecasts have been repeatedly wrong since 2015 — the volcano was expected to erupt in 2025, then mid-to-late 2026 — and is now experimenting with new physics-based prediction models developed by researchers at Uppsala University in Sweden and ETH Zurich in Switzerland, running in parallel against the real-time seafloor data.⁷

A New Clue: The Earthquake-Per-Centimeter Formula

One of the most intriguing findings from Chadwick's December 2025 report to the American Geophysical Union involves not just counting earthquakes, but normalizing them against the rate of seafloor inflation. In the months leading up to the 2015 eruption, sensors recorded approximately 10,000 earthquakes per centimeter of seafloor uplift — and that ratio held at a sustained high level for three months straight before the eruption started.⁷ Right now, despite Axial being fully re-inflated, that normalized ratio has not reached anywhere near that sustained threshold. Scientists are watching both numbers closely: raw daily quake count and the quakes-per-centimeter ratio. When both surge together and hold, that is the signal they have been waiting for.⁷

The Spring 2026 Lull — And What It Might Mean

Since roughly the start of 2026, Axial has gone oddly quiet. The inflation rate, which was running at around 16 cm per year at the caldera center through much of 2025, slowed to about half that by spring 2026.⁶ The daily earthquake count, which had occasionally spiked past 2,000 on individual days in summer 2025, has largely settled back below 100. Chadwick posted in March 2026 that the volcano appeared to be "taking a spring break," and by May 2026 a modest uptick in the inflation rate had resumed, but the longer-term trend still appeared to be slowing down.⁶ What is causing this? OSU's blunt answer: we don't know, but it must reflect changes in how magma is being supplied from deeper in the Earth.⁶

The Fight to Save the Eyes on the Volcano

The most dramatic development of 2026 had nothing to do with the volcano itself — it involved the survival of the instruments watching it. On May 21, 2026, the Trump administration's National Science Foundation announced a sweeping "descoping" of the Ocean Observatories Initiative, the federally funded network of undersea sensors that includes the Regional Cabled Array running from the Oregon coast to Axial Seamount.¹⁰ The announcement would have shut down virtually all of the OOI's ocean monitoring arrays.

What followed was an immediate and fierce response from the Oregon coast community. KLCC, the Eugene-based public radio station serving the central Oregon coast region, ran a series of reports quoting OSU scientists — including Chadwick himself — on what would be lost.¹¹ Oregon Public Broadcasting covered the congressional pushback, including a radio interview with U.S. Senator Jeff Merkley, who led a bipartisan effort in Congress to reverse the decision.¹² Oregon and Washington state lawmakers framed the observatory's dismantling as a direct threat to the coastal communities that depend on the ocean data for fisheries, climate monitoring, and natural disaster warning systems.

On June 18, 2026, the Trump administration reversed course. The Regional Cabled Array — the specific network monitoring Axial Seamount — will continue operating through at least September 2028.¹⁰ The rest of the OOI arrays remain at risk, but the eyes on the volcano stayed open. Chadwick's blog entry that day linked to three separate local and regional news outlets covering the reversal, calling it a relief not just for Axial research but for the broader scientific mission the network serves.¹⁰

What Happens When It Actually Goes

Axial's eruptions are quieter than anything most people picture when they hear the word "volcano." The water pressure at nearly a mile down — over 2,000 pounds per square inch — prevents any explosive detonation. Lava simply oozes out, is instantly chilled by seawater, and forms smooth rounded "pillow lava" mounds across the caldera floor. In 2015, the eruption produced lava flows more than 400 feet thick in places, spread fissures 25 miles from the summit, and lasted roughly a month — all without a single surface ripple detectable above.^3,4

There is one audible signature, however. When seawater gets trapped beneath advancing lava flows, it superheats into steam. That steam escapes, forms a bubble, and then collapses so rapidly it generates a sharp implosion — detectable by hydrophones but not a soul on the surface.⁴ The eruption also kicks off "snowblower" events: columns of warm fluid billowing from the seafloor, carrying clouds of microbes and pale clumps of their waste products, briefly turning the caldera into an underwater blizzard of life.⁴

Geometry of the Thing

To appreciate what Axial Seamount actually is in physical terms: the volcano's summit caldera — the collapsed crater at its top — spans roughly two miles wide by five miles long.⁸ The caldera rim sits nearly a mile below sea level. The summit itself stands about 3,300 feet tall from its base on the seafloor, making it more modest in height than Mount Hood but far more active: it has produced at least 50 eruptions in the last 800 years, averaging one every 15 to 18 years.¹³ By that historical pace, the current 11-year gap since 2015 is not unusual — it just feels longer because, for the first time in history, we have the instruments to watch it breathe in real time.

And those instruments — 150 sensors laced across the seafloor, connected by 660 miles of fiber-optic cable back to the Oregon coast — are still running. For now, that is the most important update of all.^3,10

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