Axial Seamount, an underwater volcano about 300 miles off the Oregon coast, is showing signs of an imminent eruption. Scientists monitoring the site believe it could erupt at any time, with forecasts narrowing the window to between now and late 2026.
The volcano sits about a mile beneath the Pacific Ocean surface. It is one of the most active volcanoes on the planet, having erupted at least 50 times in the last 800 years and three times in the past 30 years. It is currently inflating as magma accumulates beneath the seafloor.
Axial Seamount is monitored through a network of cables and more than 140 instruments connected to the shore. This system, part of the Ocean Observatories Initiative, gives researchers real-time data on seismic activity, ground deformation, and magma movement. The current inflation has reached levels comparable to those observed before previous eruptions in 1998, 2011, and 2015.
The volcano is located on the Juan de Fuca Ridge, where two tectonic plates are pulling apart, and it also sits above a mantle plume known as the Cobb hot spot. This dual geological setting makes it highly active and relatively predictable compared to other volcanoes.
Scientists do not expect the eruption to threaten coastal communities. The volcano is too deep and too far offshore to generate a dangerous tsunami or significant ashfall. The main impact will be on the seafloor and the ecosystem that surrounds the vents.
That ecosystem is unusual. The volcano hosts hydrothermal vents that release superheated, mineral-rich water. Communities of tubeworms, crabs, bacteria, and other organisms thrive in these extreme conditions. Past eruptions have buried these communities under fresh lava, but new life typically returns within months as new vents open.
The 2015 eruption was captured in detail by the monitoring network. The ground swelled, thousands of small earthquakes were recorded, and lava poured from miles-long cracks before the seafloor inside the crater collapsed. That event provided a baseline for predicting future activity.
Forecasts initially pointed to an eruption in 2025, but the volcano stalled. The ground continued to rise and small earthquakes continued, but the magma did not reach the surface. Researchers now believe the magma is filling the chamber more slowly than it did a decade ago, or that the surrounding rock is holding the pressure differently. The revised timeline now extends to late 2026.
A larger accumulation of magma could mean a bigger eruption than 2015, which raises concerns about the monitoring equipment. The instruments and cables located on the seafloor could be damaged by new lava flows. Researchers also note that if prediction models fail at Axial, the best-monitored underwater volcano in the world, it would raise questions about forecasts elsewhere.
Scientists hope to capture the next eruption on live cameras, which would make it the first underwater eruption broadcast in real time. The exact timing remains uncertain, but the monitoring network is expected to provide several hours of warning.
The Hunga Tonga–Hunga Haʻapai volcano in the South Pacific erupted on January 15, 2022, in one of the most powerful volcanic events recorded by modern instruments. The eruption was preceded by smaller activity in December 2021. It sent an ash plume high into the atmosphere and triggered tsunamis that reached as far as Peru, Japan, and the California coast. Four people were reported dead as a result of the event.
The explosion caused a pressure wave that traveled around the world and generated tens of thousands of lightning flashes. The eruption also sent roughly 150 million tons of water vapor into the stratosphere, an amount large enough to fill tens of thousands of Olympic-sized swimming pools.
That water vapor was unusual because most large eruptions release sulfur dioxide, which has a cooling effect. The 1991 eruption of Mount Pinatubo in the Philippines, for example, measurably cooled the planet for several years. The Hunga Tonga eruption released relatively little sulfur dioxide. Its water vapor may have a slight warming effect, but scientists have not observed significant temperature changes tied to it. One study suggested the vapor could contribute to regional weather shifts, including colder winters in northern Australia and Scandinavia, though these projections remain uncertain.
Researchers also identified a potential early warning signal after the eruption. Two seismic stations located more than 450 miles away detected a surface wave about 15 minutes before the main explosion. That signal was likely caused by a fracture on the ocean floor where magma and seawater interacted. Scientists believe such signals could help improve early warning systems for underwater eruptions in the future.
In 1815, Mount Tambora in Indonesia produced the largest eruption in recorded history. The blast killed an estimated 10,000 people directly, with tens of thousands more dying from illness and famine in the aftermath. The eruption ejected vast amounts of sulfur dioxide into the stratosphere, leading to the so-called “year without a summer” in 1816. Crop failures and cold weather affected Europe and North America, and historians have linked the conditions to the invention of the bicycle, as oat prices for horses rose sharply.
A more recent eruption occurred in 1883 at Krakatoa in Indonesia. The explosion generated one of the loudest sounds ever recorded and triggered a tsunami. The event became widely known because news of it spread quickly by telegraph.
Supervolcanoes, which produce eruptions far larger than ordinary volcanic events, have shaped the planet at several points in history. The Toba eruption in Indonesia about 74,000 years ago was the largest in the last two million years. It may have caused a volcanic winter lasting up to a decade. Some researchers have suggested the eruption brought early human populations close to extinction, though that theory is debated. Archaeological evidence from sites like Pinnacle Point in South Africa indicates that some human groups survived and continued to thrive after the event.
The Yellowstone supervolcano in the western United States has produced three major eruptions in the last 2.1 million years, the most recent about 640,000 years ago. Scientists estimate the chance of another super eruption at Yellowstone in any given year is extremely low. The magma chamber is currently only 5 to 15 percent molten, which is well below the threshold needed for a large eruption. Ground uplift in the caldera has been observed in recent decades, but researchers regard this as normal behavior for the system.
NASA researchers have proposed drilling into the volcano to extract heat as a way to prevent a future eruption. The plan was estimated to cost $3.5 billion and would require wells drilled several miles deep. The project has not moved forward, largely because of the risk that drilling could destabilize the system and release toxic gases.
The Campi Flegrei caldera near Naples, Italy, is another large volcanic system under close watch. It last erupted in 1538 and has shown increased seismic activity and ground uplift in recent years. Researchers believe much of that activity is driven by steam and gas trapped in a sealed underground reservoir rather than rising magma. Steam-driven explosions are still possible, but they would be less severe than a large magmatic eruption.
Mount Vesuvius, which destroyed Pompeii in 79 CE, remains active and is monitored closely. Other monitored volcanoes include Mount St. Helens and Mount Rainier in Washington State, Mount Pinatubo in the Philippines, and several volcanoes in Iceland.
New Zealand’s Whakaari, also known as White Island, erupted unexpectedly on December 9, 2019, while 47 tourists and guides were on the island. The explosion was a steam-driven event and was difficult to predict. Rescue helicopters evacuated 23 people, some critically injured. Twenty-two people died from the blast or their injuries.
A month before the eruption, monitoring agencies had raised the alert level because of increased sulfur dioxide emissions. Tour operators at the time continued to run trips under a moderate alert level. The island has been closed to visitors since the eruption.
Iceland’s Reykjanes Peninsula has seen repeated volcanic activity in recent years, including an eruption in November 2024 that led to evacuations near the town of Grindavík. Lava flowed from a fissure about two miles long. The event was smaller than previous ones on the peninsula and did not affect air travel.
In 2025, a large iceberg known as A84 broke away from Antarctica’s George VI Ice Shelf. The break revealed a section of seafloor that had been covered by ice and gave scientists access to a previously unseen ecosystem. A research team deployed an underwater robot to explore the area and found communities of corals, sponges, sea anemones, icefish, and octopuses. Some of the species may be new to science.
On land, a growing number of dormant volcanoes are being reclassified as active based on new satellite data. One example is Taftan in southeastern Iran, which had been considered extinct. Satellite images showed the summit rising, suggesting pressure is building underground. Because the volcano is in a remote area with limited ground monitoring, scientists are relying on satellite observations. A steam-driven eruption would be the most likely scenario, although none has occurred yet.
Research into volcano forecasting continues to advance. In Iceland, scientists are building the Krafla Magma Testbed, a project designed to drill about 7,000 feet into a volcanic system and place sensors near a magma chamber. The goal is to observe conditions directly instead of relying only on surface measurements. The project is based on a 2009 drilling accident at Krafla that unintentionally penetrated magma, proving the molten zone was reachable.
At Yellowstone, a helicopter-mounted electromagnetic sensor has been used to map the park’s underground hydrothermal system. The survey produced detailed images to depths of several thousand feet and showed that many surface features share common underground water sources.
Efforts to predict when the next major volcanic event will occur remain limited. Volcanic systems do not follow predictable schedules, and the warning signs for large eruptions are still poorly understood. Scientists generally agree that preparation, including evacuation planning and monitoring, is the most practical approach available.
