Hinterland Green

Monday, October 26, 2009

Study Finds Giant Pool of Magma May Feed Three Washington Volcanoes -- Mt. St. Helens, Mt. Adams & Mt. Rainier

Aerial view of Mount St. Helens' crater and lava dome, 
as seen from the south on Nov. 10. Credit: USGS/John Pallister

A research study led by Graham Hill of GNS Science in New Zealand, suggests that there is a vast pool of magma beneath southwestern Washington state that supplies Mount St. Helens, Mount Rainier and Mount Adams. Some scientists beg to differ. The study was published in the journal Natural Geosciences and hints that the setup could be akin to the known supervolcano at Yellowstone. The journal concludes that, "If confirmed by additional methods, this could be one of most widespread magma-bearing areas of continental crust discovered thus far."
Hill and colleagues measured the electrical conductivity in the rocks under the northern Cascade Mountain range, where the three mountains sit. Their data confirmed previous hints that there is a widespread layer of material with low conductivity below the range. They also found that narrow fingers of this material rise towards the surface, below the Mount St. Helens and Adams volcanoes.

Molten rock has a lower electrical conductivity than solid rock, so the researchers suggest there is a zone of partially molten rock that has pooled in the continental crust. According to Hill and colleagues, the small fingers probably indicate areas where the molten rock is moving up towards the magma chambers of the volcanoes, feeding future volcanic activity.

"Their interpretation is open to disagreement," Seth Moran , a volcano seismologist with the USGS Cascades Volcano Observatory in Vancouver, Wash, is quoted by McClatchy Newspapers. "Other geophysical studies don't support this theory." Researchers have long predicted that the Yellowstone supervolcano will eventually erupt again, with devastating consequences for much of the United States. Half the country could be covered in ash up to three feet (one meter) deep, one study predicts. But those same researchers say nothing suggests such an eruption is imminent. They point out, however, that Yellowstone seems to blow its top about every 600,000 years. Source: LiveScience
This is rather fascinating and we will see if the study's findings are substantiated or they are struck down in later studies.
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