Are We Prepared for Volcanic Disruption?

Airports in Europe are back in business, although shifting winds have sent plumes of volcanic ash over Scotland and Scandinavia, forcing some airports to close again. Even as Iceland's Eyjafjallajokull volcano calms down, the total damages from this week's eruption continue to mount, as do complaints about the way it's been handled. The airline industry says regulators failed to coordinate and over-reacted. Others suggest that scientists who monitor volcanoes should have predicted the eruption and its likely impact on air travel. Why did they rely on computer models rather than real planes to test the ash cloud? How much do they really know? What about the 57 active volcanoes here in the US and hundreds of others worldwide? Is civilization prepared to deal with a global calamity?