An Alaskan Volcano Is Overdue to Erupt, And We May Finally Know What's Stopping It

The Westdahl Peak volcano was expected to erupt again by 2010, but it is still restless and has flaws in our models.

Trying to accurately warn when a volcano will go boom is a tricky business to protect surrounding people and reduce aviation risks. One factor that has mostly been overlooked is the fact that so many factors must be considered.

Predicting volcanic activity involves a lot of 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.

Between 1991 and 1992 the Westdahl Peak Shield volcano blew in a series of eruptions. The volcano has continued to swell, threatening more action to come, with an active magma chamber bubbling away around 4.2 miles beneath its surface.

Its most obvious feature is that it is covered by an ice cap, unlike many volcanoes in the world.

The presence of an ice cap increases the average repose interval for a magma system according to Lucas and colleagues.

The University of Illinois found a correlation between ice-cap thickness and the volume changes needed to overcome the strength of the volcano. It is dependent on the production rate of magma at a volcano.

The team calculated that the pressure from the ice cap adds 7 years of dormancy to models without ice.

The increases in time seem insignificant on a geologic scale, but they are significant on the human time scale.

The researchers caution that there is still more to the story, even though the ice cap may account for some of the stability. Their study assumed constant flux, which doesn't capture the dynamics of other systems such as those that have been inactive.

We don't know how close the system is to failure, and recent geodetic data have not yet been investigated to update our estimates of the system's flux rate.

If the system remains close to failure, the season may play a larger role than would be expected.

The team explains that when the system approaches a certain threshold, the weight of ice caps comes more into play.

It will be important to consider how climate change and ice melt will affect Westdahl Peak and other high-latitude volcanoes in the future.

Lucas concludes that accounting for overlying pressure from polar ice caps is another critical, yet poorly understood, variable.

The research was published in a journal.