Magma found under volcanoes thought dormant in the Cascade Range

Unlike old soldiers, old volcanoes seemingly don’t even fade away, much less die, with researchers discovering magma chambers under cones previously classed as dormant after thousands of years of inactivity.

In findings published in the journal Nature Geoscience, a team from Cornell University’s Department of Earth and Atmospheric Sciences and the US Geological Survey (USGS) used seismic waves to find magma under active and dormant volcanoes alike in the Cascade Range spanning Washington and Oregon in the US and British Columbia in Canada.

“All of the volcanoes, including dormant ones, have persistent and large magma bodies,” the team reported.

“It appears that these magma bodies exist beneath volcanoes over their whole lifetime, not just during an active state,” said Cornell’s Gaunning Pang.

The results challenge “assumptions” about volcanoes, according to the team, in turn raising the question of whether the widely-used “dormant” category could be redundant.

Not counting the underwater volcanoes along the 16,000-kilometre Mid-Atlantic Ridge, there are anything from 1,350 to over 1,500 “active” volcanoes worldwide, going by estimates from the USGS and the British Geological Survey (BGS), with many located on the Pacific Ring of Fire, which includes the Cascades, site of half of the “very high threat” volcanoes in the US, according to the country’s government.

The BGS says there are 82 volcanoes in Europe, more than a third of them on Iceland, while the USGS reckons the US is home to 170 “potentially active” volcanoes.

More work needs to be done to track where eruptions could occur, according to the Cornell-USGS team. “If we had a better general understanding of where magma was, we could do a much better job of targeting and optimizing monitoring,” said Cornell’s Geoffrey Abers, who warned of a “great many volcanoes that are sparsely monitored or have not been subject to intensive study.”

One place where monitoring is carried out is at Yellowstone National Park, part of which sits atop an enormous 50 kilometre by 70 kilometre caldera.

Last month the journal Nature published work led by USGS seismologists revealing that magma underneath the so-called supervolcano is moving.

A major Yellowstone disaster would likely level and leave no survivors across a radius of hundreds of miles. The potential scale of such an eruption could spew out enough ash to not only blanket the surface of much of North America but also block sunlight and cause multi-year global volcanic winter, according to many scientific assessments.