“Quakes aren’t predictable in time, space or intensity”

Japan: The ‘Big One’, but not where they thought it would (Excerpt from the Washington Post):

Quakes aren’t predictable in time, space or intensity. Hazard maps give a good sense of where something is most likely to happen, and the theory of plate tectonics, developed largely since the 1960s, is considered a triumph of modern science. But there is an element of chaos in the way the stresses of the earth relieve themselves. And an earthquake in one place can increase strain on a fault some distance away.

“It’s really just a kind of guessing game, and Mother Nature never really puts up with those guessing games,” said seismologist Dave Wald of the U.S. Geological Survey’s National Earthquake Information Center in Golden, Colo.

Susan Hough, a USGS seismologist in Pasadena, Calif., noted that the recent earthquake in Christchurch, New Zealand, happened on an unmapped fault and caught scientists somewhat by surprise.

“We do tend to focus on the expected events. We’re going to get blindsided by unusual events. . . . But uncommon events happen,” Hough said. “The analog that’s worrisome is Boston. Put a 6.1 under Boston. You have all that un-reinforced masonry.”

Robert Geller, a geologist at the University of Tokyo, said by email: “The bottom line is that it’s not possible to identify in detail which specific areas are particularly dangerous. Also, quakes are not in any sense periodic. Unfortunately some earth scientists, including some government officials in both Japan and the U.S., persist in making highly area-specific risk forecasts and also using models based on periodicity of quakes.”