Scientists ponder Japan's black swan

The disaster bureaucrats talk about black swans: calamities from out of the blue, terrible and strange. The world is now transfixed by the black swan disaster of Japan - an earthquake larger than seismologists thought could happen in that part of the country, leading to a tsunami too big for the sea walls, and now a nuclear crisis that wasn't supposed to be possible.

The disaster bureaucrats talk about black swans: calamities from out of the blue, terrible and strange. The world is now transfixed by the black swan disaster of Japan - an earthquake larger than seismologists thought could happen in that part of the country, leading to a tsunami too big for the sea walls, and now a nuclear crisis that wasn't supposed to be possible.

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"People talk about the Big One. This is it," said Tom O'Rourke, a professor.

Japan's nightmare comes in wake of two other events that scientists found surprising in their location and intensity: the highly destructive earthquake in New Zealand, on February 22, which was triggered by a little-regarded fault; and the tsunami-spawning Sumatra earthquake December 26, 2004, on a trench not considered likely to cause such a "mega-quake."

It may seem as if there are more natural disasters these days, but the real issue is that there are more people and more property vulnerable to the violent forces of Earth.

Natural disasters are supplemented by technological disasters - last year's Deepwater Horizon oil spill in the Gulf of Mexico being one example. Disaster planners in the United States have to ask themselves how they would deal not only with the obvious types of calamities - Gulf Coast hurricanes, for example - but also the events that are of low probability but come with high consequences.

(In Exclusive Partnership with The Washington Post)