What will really happen when the Yellowstone supervolcano erupts?

Lurking beneath Yellowstone National Park is a massive underground reservoir of magma, capped by the park's famous caldera. 640,000 years ago, a super eruption rocked the region. What would happen if another such event blasted the park today? We asked USGS geologist Jake Lowenstern, scientist-in-charge of the… » 5/17/13 2:32pm 5/17/13 2:32pm