Underwater volcano eruption predicted months in advance
Nearly two decades of monitoring let geophysicists recognise and decipher Axial Seamount's warning signs. Richard A. Lovett reports.
Geophysicists studying an undersea volcano off the coast of Oregon and Washington predicted an eruption months in advance, scientists reported today at a meeting of the American Geophysical Union in San Francisco and papers in Science.
A forecast that an eruption was likely in 2015 was made in September 2014, says Scott Nooner, a marine geophysicist at the University of North Carolina Wilmington. It occurred seven months later, in April.
Forecasts were made for other volcanic eruptions, but generally only a few weeks ahead.
Predicting volcanic eruptions is tricky business. What made this one possible was the fact that the volcano, Axial Seamount, has been monitored for nearly 20 years via a seafloor observatory. Its instruments transmit real-time data by fibre-optic cable.
In two prior eruptions, the instruments revealed that the volcano’s surface dropped a few metres during the eruption, then rose again as the magma chamber refilled. Each eruption occurred when the surface rose to a certain height.
“Axial Seamount has what appears to be relatively repeatable behaviour,” Nooner says.
“Our model is that the magma chamber will inflate, and once it gets to a certain threshold, it erupts.”
William Wilcox, a researcher from the University of Washington, Seattle, says an undersea volcano such as Axial Seamount is a particularly useful study target because there's no weather to disrupt or damage instruments.
And instruments can be deployed remotely — right on top of the volcano, if desired — with no danger to the researchers.
Ultimately, Nooner says, the goal is to take what’s learnt underwater and apply it to land-based volcanoes near populated areas.
John Delaney, a University of Washington marine geologist who has long championed underwater observing networks such as that at Axial, believes there are many other scientific benefits.
Axial Seamount, he notes, is part of the mid-ocean ridge system, a giant mountain chain that spans much of the world. “Finally,” he says, “we have insights into what goes on in that 70,000-kilometre-long ridge crest.”