Volcanoes vs. Meteorites

On Monday the Planetary Society will be marking the 100th anniversary of the Tunguska event with a press conference. Tunguska, you may recall, is the mighty fireball meteor that exploded over the ground in Siberia and flattened 2,000 square kilometers of trees. The message on Monday, according to a press release, will be how vulnerable we all are to these sorts of blasts from space. Imagine such an explosion over Los Angeles! Could be worse than the writers strike. So, the reasoning goes, we'd better make sure to keep funding projects that search the skies for Near Earth Objects (NEOs).

The problem is, Earth has always posed more of a danger to herself than extraterrestrial objects. The Geological Society of London published a report a few years ago comparing the relative frequencies of meteor impacts to the climate wrenching eruptions of calderas -- a.k.a. supervolcanoes. Guess what they found? The odds are far greater that Yellowstone (a caldera with a violent  history) or one of its many siblings around the world will threaten civilization than an NEO. But you don't see geologists out there using scare tactics to get funding for caldera science (and there are plenty of calderas out there we know next to nothing about, by the way). So, is it possible that astronomers are crying wolf, just a teeny bit?

Image info: Dendi Caldera, Ethiopia/NASA