Scientists study Mount St. Helens magma to understand volcano risks

It's an experiment that involved thousands of sensors, underground explosive tests, and routine earthquakes under Mount St. Helens, and it's all to paint a picture of what's happening underground.

A four-year experiment to locate and study the liquid rock known as magma under Mount St. Helens is expected to hit a milestone. 

In about another month scientists will meet to go over different aspects of their findings.

Known as iMUSH, standing for “imaging magma under St. Helens,” the four-year experiment is designed to learn more about the hazards and risks posed by the volcano. The difficulty is that the region scientists are studying extends 30 miles and below the surface of the Earth, where temperatures can range to 2,500 degrees Fahrenheit. 

“What we want to do is know where the magma is and how it’s moving around,” said Ken Creager, a geophysicist at the University of Washington.  “That understanding of one volcano helps us understand all volcanoes at some level. But of course, they are all different.” 

Related: UW seismology lab analyzed quakes before Mount St. Helens eruption

Mount St. Helens is known as a stratovolcano. It shares that distinction with Mount Rainier, Mount Baker, Glacier Peak, Mount Adams and Mount Hood south of the Columbia River. All are capable of explosive eruptions similar to and even greater than the 1980 Mount St. Helens eruption, which killed 57 people. 

St. Helens continued dome building eruptions into 2006 and then erupted again in 2004.

The iMUSH experiment set off 23 small underground explosions called shots into the geology under the mountain.  The vibration of those “shots” picked up by some 6,000 sensors. For two years, seismometers picked up St. Helens’ naturally occurring earthquakes, which along with the “shots” is helping to create an image of the Earth’s crust under St. Helens. 

Creager expects in the wake of iMUSH, other hazardous volcanoes in the Pacific Northwest will also be mapped. 

“One of the things about understanding volcanoes in particular is that they are very complicated,” said Creager. “And the more tools you can bring to bear on them, on the problem, the better.”

Related: Remembering the deadliest U.S. volcanic event 37 years later

© 2017 KING-TV


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