Will Yellowstone do us in?

Geologists have called for a taskforce to be set up to consider emergency management in the event of a massive volcanic eruption, or super-eruption...Experts say such an event would have a colossal impact on a global scale.  A super-eruption is also five to 10 times more likely to happen than an asteroid impact, the report claims.

The effects, say the authors, "could be sufficiently severe to threaten the fabric of civilisation" - putting events such as the Asian tsunami into the shade.  The fallout from a super-eruption could cause a "volcanic winter", devastating global agriculture and causing mass starvation...the frequency of equivalent super-eruptions is [at least] about once every 100,000 years.

Here is the full story.  Here is more background information.  Here are some apocalyptic worries of a religious nature.