Mile-wide volcano set to erupt off the West Coast this year as scientists reveal 'balloon keeps getting bigger'

Axial Seamount, a massive underwater volcano located nearly 300 miles off the Oregon coast, is showing signs of an imminent eruption. 

This 3,600-foot-tall volcano, which spans 1.25 miles across and sits 4,626 feet beneath the Pacific Ocean's surface, is currently experiencing significant swelling and rumbling, indicating a buildup of magma. 

Volcanologists predict an eruption before the end of 2025, but despite its activity, scientists remain unconcerned. 

Mike Poland, a scientist at the Yellowstone Volcano Observatory, expressed excitement about this event, highlighting Axial Seamount as one of the world's best-monitored submarine volcanoes. 

'This particular volcano is probably the best-monitored submarine volcano in the world,' he told Cowboy State Daily. 'It's fascinating and doesn't really pose a hazard.'

Situated along the Juan de Fuca Ridge, a chain of undersea volcanoes extending between Oregon and Alaska, Axial Seamount is a young shield volcano - a broader volcano with a low profile. 

Its resemblance to Mauna Loa, Earth's largest active volcano, and the typical non-explosive nature of shield volcano eruptions, lessens the concern among volcanologists about the imminent eruption. 

'When Axial Seamount erupts, it'll look a lot like a Hawaiian lava flow eruption,' he said. 'It's not an explosive eruption, but calm effusions of lava flowing out of the caldera and across the seafloor.' 

After closely monitoring the volcano's activity, Oregon State University Research Associate Bill Chadwick predicts that Axial Seamount will erupt by the end of 2025 based on its recent increase in activity.

'Because it's had these three eruptions in the last 30 years, that's why we call it the most active volcano in the Pacific Northwest, because most of the ones on land aren't active that frequently, and they spend a lot of their time slumbering, whereas Axial has a pretty active magma supply,' Chadwick told local CBS affiliate KOIN 6 News. 

'So, if it's not erupting, it's inflating and getting ready for the next one. And so that's why we're kind of monitoring what's happening to it all the time.'

Eruptions from Axial Seamount were recorded in 1998, 2011 and 2015, and the volcano has undoubtedly erupted numerous times prior to those events, according to Poland.

Axial Seamount's ongoing inflation has mirrored pre-eruption levels, leading volcanologists to anticipate an imminent eruption. 

Following the 2015 eruption, Axial's seafloor initially rose at a rate of over one meter per year. This rate gradually slowed to about one centimeter per year by 2023. 

But in 2024, Chadwick observed the seafloor beginning to re-inflate at a faster pace, reaching approximately 25 centimeters per year.

'Axial's summit inflates like a balloon as magma is supplied from below and stored in the reservoir beneath the volcano summit,' Chadwick told OregonLive.

'The balloon keeps getting bigger and bigger. And at some point, the pressure becomes too great and the magma forces open a crack, flowing to the surface. When that happens, the seafloor subsides as the "balloon" deflates.' 

In the months before its 2015 eruption, Axial was rocked by escalating seismic activity, culminating in 9,000 earthquakes on the day of the eruption, according to Chadwick's presentation at OSU's Hatfield Marine Center.

'And in the last year, especially, there was the number of earthquakes, which is also monitored by this cable observatory, has really increased,' Chadwick told KOIN 6 News.

'So, all these signs are pointing toward the final stages of the buildup to the next eruption.'

Although shield volcanoes are not typically associated with explosive eruptions, their flowing lava can still cause substantial destruction.

However, Axial Seamount, residing thousands of feet beneath the Pacific Ocean surface, is underneath an immense amount of pressure by the water column above it.

'Deep submarine eruptions are inhibited by the tremendous water pressure of the ocean,' Poland told Cowboy State Daily. 

'Even explosive eruptions struggle against the ocean.'

The immediate contact with frigid ocean water will rapidly cool the magma that will eventually erupt from Axial Seamount, creating a solidified crust that insulates the inner portion of the lava flow.

The OSU research team has employed a suite of tools to monitor Axial Seamount, including a remotely operated vehicle (ROV) for underwater exploration and sample collection named Jason.

Precise pressure sensors track the vertical movement of the seafloor. While battery-powered recorders were used initially, a cutting-edge fiber-optic cable system now provides real-time data transmission from an array of scientific instruments.

'I can look at my laptop and see data that was collected 10 minutes ago at Axial,' Chadwick told Oregon Live, highlighting the unprecedented level of real-time monitoring that makes Axial the most comprehensively studied submarine volcano globally.

Chadwick emphasized that these eruptions pose no threat to the public. Despite its location on the Juan de Fuca Ridge, Axial Seamount does not have the capability of triggering a major earthquake. 

'If you were out there on a ship right over the seamount, you would never know anything was happening unless you dangled a hydrophone, an underwater microphone, into the water, then you might be hearing some commotion from down deep. But there's no effect at the surface,' he told KOIN 6 News.

'You'd have to make a dive with a submersible or remotely operated vehicle or something to see what's happened.'

Chadwick views these eruption forecasts as valuable scientific experiments, free from the constraints and anxieties associated with volcanic events on land. 

'People's lives aren't in the equation,' he told Oregon Live. 'On land, you can't do this forecasting without worrying about false alarms and freaking people out and having economic impacts. You don't want to evacuate towns and all that without knowing for sure that you need to.'

Chadwick's ultimate goal is to translate the insights gained from these eruption forecasts into a broader understanding of volcanic behavior worldwide. 

If the forecast proves accurate, scientists can apply the science to other volcanoes, adds Poland.

Many volcanoes worldwide, both on land and underwater, lack real-time monitoring systems - not to mention that scientists have only recently gained access to the large amounts of data needed to predict volcanic eruptions. 

This makes Axial Seamount, with its three decades of continuous monitoring, a unique and invaluable resource. 

'That we as a society are able to forecast eruptions of a volcano that's offshore and under an awful lot of water, that's amazing,' Poland told Oregon Live. 'If you can develop a model for how this works at Axial, it gives us a starting point that we can apply elsewhere and, with a few tweaks, we can begin working on forecasts of other volcanoes.'