Volcano in Alaska is about to erupt, and we can finally find out what stops it

(ORDO NEWS) — Geologists expected the Westdal Peak volcano to erupt again by 2010, but it is still intact and restless – this points to the shortcomings of our forecasting models.

Trying to accurately predict when volcanoes will erupt is critical, but not easy, to protect those around you and reduce aviation risks. There are many factors to consider, and the absence of an explosion has highlighted one that has been largely overlooked.

“A volcanic prediction includes many variables, including the depth and size of a volcano’s magma chamber, the rate at which magma fills that chamber, and the strength of the rocks that contain the chamber,” says geologist Lillian Lucas.

Located in western Alaska, along the Aleutian Island chain, the Westdal Peak shield volcano last erupted in a series of eruptions in 1991-1992. Since then, the volcano has continued to swell, threatening new eruptions – an active magma chamber seething about 7.2 kilometers (4.47 miles) below its surface.

The most obvious feature of the volcano, which distinguishes it from many other volcanoes in the world, is that Westdal Peak Volcano is covered by a 1 kilometer thick ice cap.

“Our numerical experiments show that the presence of an ice cap (1-3 kilometers thick) increases the mean rest interval of the magma system,” Lucas and colleagues write in their paper.

Using computer simulations, University of Illinois researchers found a linear relationship between the thickness of the ice cap and the volume changes required inside the volcano to overcome the strength of the enveloping rock and explode. It also depends on the rate of magma production in the volcano – the flow of magma.

Given the size of the magma chamber, geometry, and magma flow, the team calculated that for the Westdal system, ice cap pressure adds about 7 years of dormancy compared to models without ice.

“This increase in time may seem insignificant on a geological scale, but it is significant on a human scale,” says geologist Patricia Gregg. “In the future, it will be important to take ice cover into account when making forecasts.”

However, while the ice sheet may explain some of Westdal’s unexpected stability, the researchers caution that it’s not the whole story. Their study assumed a constant flow, which does not reflect the dynamics of other systems, such as those that have been at rest for a long time.

“We do not know how close to destruction the system is currently, and the latest geodetic data has not yet been examined to update our estimates of the system’s flow rate,” they write.

“If inflow into the Westdal magma reservoir has slowed in recent years while the system remains close to collapse, seasonality may end up playing a larger role than might be expected.”

The shape and depth of the volcano are still the biggest delay factors before an eruption; however, when the system approaches a certain threshold and the flow becomes low, the weight of the ice caps comes into play, the team explains, to the point where even seasonal fluctuations in ice can be enough to cause an explosion.

Therefore, “it is important to consider how climate change and glacial ice melt may affect Westdal Peak and other high-latitude volcanoes in the future,” says geologist Yang Zhan.

“Accounting for pressure from the polar ice caps is another important but little-studied variable,” concludes Lucas.


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