Blaine Harden has an interesting article in the Washington Post about the dangers posed by a volcanic eruption of Mount Rainier in Washington State.

"A monumental threat," said William E. Scott, scientist in charge of the Cascades Volcano Observatory, a USGS center that monitors volcanoes from California to Alaska.

...

About 150,000 people now live atop lahars that have rioted down the slopes of Mount Rainier over the past 5,000 years. The lahars ran all the way to what are now the ports of Tacoma and Seattle, distances, respectively, of 50 and 75 miles.

No volcano in the lower 48 states packs so much risk so close to so many people, Scott said. Mount St. Helens, which erupted in 1980 and killed 57 people, is more active than Rainier, but it is not near large population centers.

Based on the historical pattern Rainier is expected to erupt some time in the next 500 years. The population is growing around the volcano. A really large eruption could send flows running all the way to Seattle.

Thanks to Joe Katzman for the heads-up.