Looking beneath Mount St. Helens

TACOMA, Wash. Ever since Mount St. Helens' cataclysmic eruption 34 years ago this month, scientists have been tracking the volcano's explosive energy to better understand how Washington's most active volcano works.

This summer, the scientists will be the ones setting off the explosions.

Using techniques developed by the oil industry, researchers are preparing to set off explosive charges buried in two dozen 80-foot-deep wells drilled around the mountain. They'll record the seismic energy of the explosions on thousands of portable seismometers placed by an army of volunteers traveling by car, on foot and on horseback.

Their goal is to see with greater clarity the details of how molten rock, or magma, makes its way to St. Helens' crater from the area where tectonic plates collide and the magma is created, some 60 miles beneath the surface.

"We've been looking at what's beneath the volcano through very fuzzy glasses," said Seth Moran, a seismicity expert with the U.S. Geological Survey's Cascade Volcano Observatory in Vancouver, Washington. "This still won't give us anything like 20/20 vision, but it should make things quite a bit clearer."

The explosive experiments, or "active imaging events," scheduled for this summer are one part of a battery of multidisciplinary imaging experiments collectively called iMUSH for "Imaging Magma Under St. Helens." Together, they constitute what researchers say is the one of the most complete and ambitious series of imaging experiments ever conducted on any volcano in the world.

The $3 million project, funded mostly by the National Science Foundation, is headed by Kenneth Creager, a University of Washington professor of earth and space sciences.

The explosive research, which will use about $1 million of the total, is being conducted by a research team from Rice University, headed by earth science professor Alan Levander.

Along with UW, Rice and the USGS, participants include teams of researchers at Oregon State University in Corvallis, the Lamont-Doherty Earth Observatory at Columbia University in New York and Eidgenoessische Technische Hochschule of Zurich.

In addition to the explosive testing, specialists in other disciplines are preparing for experiments using enhanced receptors for naturally occurring seismic activity. They'll also examine the magnetic and electrical properties of rock deep beneath the volcano, which scientists say is a useful guide to identifying magma.

See more here:
Looking beneath Mount St. Helens