Axial Seamount: A model for predicting volcanic eruptions?

For millennia, volcanoes were seen as unpredictable, or even the work of various gods. Over the years, scientists have developed an understanding of the geophysical processes causing eruptions – but when, exactly, a volcano would erupt remained uncertain until days before it happened.

On Thursday, a team of scientists studying Axial Seamount, an underwater volcano, said they could predict eruptions – at least a one location: Axial Seamount.

Discussing their research at the annual American Geophysical Union fall meeting in San Francisco, they said that the rate at which the seafloor was rising, as well as a high rate of earthquakes, allowed them to forecast an eruption months in advance. In September 2014, they projected that the volcano would occur some time in 2015 — and it erupted on cue in April that year.

By studying what causes volcanic eruptions at Axial Seamount, researchers may also be able to predict volcanic activity elsewhere in the world. Knowing when an underwater volcano is going to erupt can also help scientists be ready to study the regional geology and lava flows just after an eruption. If these lessons can be applied to other volcanos, accurately forecasting volcanic activity on land could increase the efficiency of evacuation efforts and save lives.

“Axial Seamount is a great natural laboratory for learning about volcanic eruptions,” said William Chadwick, one of the lead authors from the National Oceanic and Atmospheric Administration (NOAA) and Oregon State, in NOAA's press release. “It has a simple structure, is frequently active, but it doesn’t pose a hazard to people.”

Axial Seamount, the most active underwater volcano in the northeastern Pacific, is located about 300 miles off the coast of Oregon, on the Juan de Fuca ridge. There, two tectonic plates separate, and fresh magma is channeled into a series of underwater volcanoes, including Axial Seamount.

The volcano has been under constant observation for almost two decades. In 1996, the New Millennium Seafloor Observatory was established there. In 2014, it acquired state-of-the-art monitoring technology, thanks to the National Science Foundation’s Ocean Observatories Initiative. The system involves fiberoptic cables that connect monitoring equipment at the volcano to land, relaying high-resolution images and valuable data to researchers on land.

The lava chamber of Axial Seamount is covered by a relatively thin layer of Earth’s crust, National Geographic reported, making it easy to see when the magma chamber was filling. As the chamber filled, the sea level began to rise, and scientists were able to calculate how soon the pressure would cause an eruption. Pressure sensors also picked up on the seafloor rise.

“The volcano works like a balloon, inflating with molten rock between eruptions and then quickly deflating as the volcano erupts,” said Scott Nooner, an associate professor of geology at University of North Carolina in the NOAA press release.

Also connected, the scientists found, was an increase in earth tremors. As the magma chamber filled, it triggered hundreds of small earthquakes per day. As the pressure increased, more and more tremors occurred. By April 2015, when the volcano erupted, there were more than 2000 earthquakes every day. These earthquakes were picked up by seismic sensors.

These observations may help scientists know what to measure in cases where the volcano is more difficult to study.

“Because ships can go everywhere over the volcano we get a lot more data,” Professor Chadwick said in an Oregon State news release. “On land, you have to drill a hole, set off an explosion, and record it with a few scattered seismometers. It’s not nearly as effective.” 

NOAA noted in its press release that the research might be useful for predicting eruptions on land, where volcanoes “pose greater threat to people.”

Professor Nooner is already looking forward to being able to predict Axial Seamount’s next eruption. It’s too early to be sure, but if its magma chamber continues to fill at the current rate, it should erupt some time in the next three years, he told National Geographic.

The eruption will “allow us to do things like organize responses to go and sample the lava flows and look at the water column and the biological communities directly after an eruption, which is a pretty exciting thing to be able to do,” he said.