Scientists who study volcanoes say that while asteroids get all the press -- wiping out dinosaurs is good for your image -- volcanoes pose a more immediate and constant threat to people around the world.

"On any given day there are probably 25 volcanoes erupting around the world," said William Rose, a professor of Geological Engineering and Sciences at Michigan Technological University. "There are volcanic crises every day, there are not meteorite crises every day."

Rose said people need to be more aware that they are living near active volcanic systems. Volcanoes in places like Yellowstone, Valles Caldera in New Mexico and Long Valley Caldera in Southern California are still active systems that could pose a future threat, said Rose, who presented new research at the annual meeting of the American Geophysical Union in San Francisco recently.

"A volcano is like an animal that sleeps almost all the time, but it's still alive," Rose said.

And just as planetary scientists develop ways to predict and mitigate the threat of asteroid impacts, Rose and other geophysicists are working to determine what kinds of risks volcanoes pose. To predict future activity, scientists study past eruptions, try to date them and look for patterns that can tell them how long some of these volcanoes sleep.

Rose hopes that eventually geophysicists will be able to predict volcanic activity years in advance, rather than days or hours, as is typically the case now.

"We are trying to convert risk from a vague concept into a meaningful number," he said.

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