Inside Alaska's Explosive Redoubt Volcano

Mount Redoubt volcano in Alaska as seen from the northwest on March 4, 1990. Steam commonly vents from the dome in the crater in between eruptions. Credit: USGS.

From Live Science:

Mount Redoubt volcano in Alaska could erupt within days to weeks, say scientists at the U.S. Geological Survey, amazing the rest of us with their certainty.

Here's what makes them so sure: Magma rising toward the surface from beneath a volcano like Redoubt can cause earthquakes and other seismic rumblings. And seismic activity at Redoubt, which is 106 miles (170 km) southwest of Anchorage, has increased recently.

"If you're going to bring magma to the surface you've got to break rock, and every time rocks break at the subsurface beneath a volcano, that's an earthquake," said volcanologist Charles Mandeville of the American Museum of Natural History in New York. "They're recording a whole bunch of earthquakes almost continuously right now," he said, referring to scientists at the Alaska Volcano Observatory in Anchorage.

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