‘It’s inflating at a pretty good pace’: Underwater volcano off Oregon coast likely to erupt this year, scientists predict

(Update: adding comments from OSU researcher, UO instructor; story airs at Six)

BEND, Ore. (KTVZ) -- An undersea volcano off Oregon's coast will probably erupt by the end of this year, scientists say.

The volcano, known as Axial, is a seamount (large underwater mountain) about 300 miles west of Cannon Beach. It last rumbled to life in 2015 and previously in 1998 and 2011, posing no threat on land.

Recent data shows the volcano is swelling, indicating another upcoming eruption.

"It's inflating at a pretty good pace," Bill Chadwick, a research associate at Oregon State University, told us Thursday. "Plus, the number of earthquakes is way up in the last year. So all those things are pointing toward it building up."

Chadwick and his colleagues have been studying the Axial Seamount for years. He explained that his team uses a remotely operated vehicle, about the size of a minivan, which is controlled from a ship's control room, where scientists can observe the sea floor in real time.

University of Oregon earth sciences instructor Daniele McKay says the volcano's frequent eruptions make it easier to predict its activity.

"It's erupted three times since 1998," McKay said. "It's much more active than Mount St. Helens or the other volcanoes that we think of here in the Pacific Northwest."

It’s also closely monitored with advanced technology.

"The volcano has all this monitoring equipment on it, and then the cables are going directly to land, and they're like a high-speed internet connection," McKay said. "That is actually much better than any monitoring system that we have on the Three Sisters or on Newberry (Volcano)."

The good news is that if Axial Seamount erupts, there won't be any impacts on land.

"There's nothing to worry about for people living on the Oregon coast or anywhere in Oregon," Chadwick said. "It's not going to cause a tsunami."

Predicting eruptions at this underwater volcano can help scientists gain a better understanding of those that pose greater threats.

"Hopefully there's some lessons to be learned for other, more dangerous volcanoes around the world, you know - even the ones in the Cascades." Chadwick said. "We're not saving lives, or it's more like, you know, is this possible? Are there lessons to be learned that we can apply to other volcanoes that are more dangerous?"

Here's our report from April 2015 on the last previous eruption:

Axial Seamount, an active underwater volcano located about 300 miles off the coast of Oregon and Washington, appears to be erupting – after two scientists had forecast that such an event would take place there that year.

Geologists Bill Chadwick of Oregon State University and Scott Nooner of the University of North Carolina Wilmington made their forecast last September during a public lecture and followed it up with blog posts and a reiteration of their forecast just last week at a scientific workshop.

Jillian Fortner is speaking to Chadwick and a local Earth Sciences instructor about what this eruption could mean for the region. Her report at Five on NewsChannel 21.

They based their forecast on some of their previous research – funded by the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA), which showed how the volcano inflates and deflates like a balloon in a repeatable pattern as it responds to magma being fed into the seamount.

Since last Friday, the region has experienced thousands of tiny earthquakes – a sign that magma is moving toward the surface – and the seafloor dropped by 2.4 meters, or nearly eight feet, also a sign of magma being withdrawn from a reservoir beneath the summit. Instrumentation recording the activity is part of the NSF-funded Ocean Observatories Initiative. William Wilcock of the University of Washington first observed the earthquakes.

"It isn't clear yet whether the earthquakes and deflation at Axial are related to a full-blown eruption, or if it is only a large intrusion of magma that hasn't quite reached the surface," said Chadwick, who works out of OSU's Hatfield Marine Science Center in Newport and also is affiliated with NOAA's Pacific Marine Environmental Laboratory. "There are some hints that lava did erupt, but we may not know for sure until we can get out there with a ship."

In any case, the researchers say, such an eruption is not a threat to coastal residents. The earthquakes at Axial Seamount are small and the seafloor movements gradual and thus cannot cause a tsunami.

"I have to say, I was having doubts about the forecast even the night before the activity started," Chadwick admitted. "We didn't have any real certainty that it would take place – it was more of a way to test our hypothesis that the pattern we have seen was repeatable and predictable."

Axial Seamount provides scientists with an ideal laboratory, not only because of its close proximity to the Northwest coast, but for its unique structure.

"Because Axial is on very thin ocean crust, its ‘plumbing system' is simpler than at most volcanoes on land that are often complicated by other factors related to having a thicker crust," said Chadwick, who is an adjunct professor in OSU's College of Earth, Ocean, and Atmospheric Sciences. "Thus Axial can give us insights into how volcano magma systems work – and how eruptions might be predicted."

Axial Seamount last erupted in 2011 and that event was loosely forecast by Chadwick and Nooner, who had said in 2006 that the volcano would erupt before 2014. Since the 2011 eruption, additional research led to a refined forecast that the next eruption would be in 2015 based on the fact that the rate of inflation had increased by about 400 percent since the last eruption.

"We've learned that the supply rate of magma has a big influence on the time between eruptions," Nooner said. "When the magma rate was lower, it took 13 years between eruptions. But now, when the magma rate is high, it took only four years."

Chadwick and Nooner are scheduled to go back to Axial in August to gather more data, but it may be possible for other researchers to visit the seamount on an expedition as early as May. They hope to confirm the eruption and, if so, measure the volume of lava involved.

Evidence that was key to the successful forecast came in the summer of 2014 via measurements taken by colleagues Dave Caress and Dave Clague of Monterey Bay Aquarium Research Institute and Mark Zumberge and Glenn Sasagawa of Scripps Oceanographic Institution. Those measurements showed the high rate of magma inflation was continuing.