Linking magma to quakes

Rock crystals reveal pulses of underground activity

By Alexandra Witze, 11:55 AM June 15, 2012

Active volcanoes shake, rattle and roll; scientists can’t always be sure whether such activity indicates that molten rock is rising. Now, volcanologists have linked earthquake swarms at Mount St. Helens in Washington state with fresh magma pulses. A team led by Kate Saunders of the University of Bristol in England studied more than 300 rock crystals formed during the 1980–1986 eruption of Mount St. Helens. These crystals (one shown), of a mineral called orthopyroxene, grow in zoned “rims,” ea...

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