PORTLAND — Magma 2 to 3 miles beneath Oregon’s highest peak is nearly solid stuff, sort of like peanut butter kept in a refrigerator, that’s not expected to erupt anytime soon, according to a new study.
If and when Mount Hood does erupt, it’s likely to be less violent and dramatic than the May 1980 eruption of Mount St. Helens to the north, Oregon State University Professor Adam Kent said.
“A big glob kind of plops out the top, but in the case of Mount Hood — it doesn’t blow the mountain to pieces,” he said. “Our study shows that most of the time it’s pretty solid magma.”
Kent has been studying Mount Hood for a decade, The Oregonian reported. His latest research was funded by the National Science Foundation and published this week in the journal Nature.
Kent and co-author Kari Cooper of the University of California-Davis wanted to know how long Mount Hood’s magma chamber had been there. They used carbon dating to study the age of the crystals in the magma that rose into the chamber.
That process led to the discovery about the consistency of the magma, Kent said. “It just isn’t very mobile,” he said.
Heating and melting the nearly solid magma to the point of eruption would take a couple of months, he said.
The heating happens when much hotter magma from deeper beneath the mountain rises and mixes with the colder magma.
That mixing is what triggered the past two major eruptions on the mountain 1,500 and 220 years ago, Kent said.
If the magma warms, he said, scientists should get an early warning from the latest detection techniques such as monitoring gases, seismic waves emanating from the mountain and recording ground deformation using GPS systems.
The magma has been in cold storage for 100,000 years, and it has been hot enough to start moving for less than 1 percent of that time, Kent said.
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