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Is this the age of megaquakes?

April 19, 2011


Kyodo / Reuters

Buildings tossed together by the tsunami is seen in Miyagi Prefecture, northeastern Japan March 12, 2011. Scientists are asking if another megaquake will strike in the next six years.

By John Roach

First there was the earthquake and tsunami in Sumatra in 2004. Chile was shaken and lashed violently a year ago. Japan is still reeling from the twin disasters on March 11. It seems as if the Earth has woken from a long slumber and is violently re-jiggering its plates. Is there any truth to the notion?

The question of megaquake clustering, which I explored in the days following the 9.0 earthquake and tsunami in Japan, was a hot topic of conversation Thursday at the Seismological Society of America’s annual meeting in Memphis, Tenn., according to various media reports.

There, Charles Bufe, a seismologist retired from the U.S. Geological Survey in Denver, said the spate of recent megaquakes is very similar to a string of seven magnitude 8.5 or greater quakes that struck between 1950 and 1965. The intervening decades, he noted, were quiet.

Bufe and USGS colleague David Perkins analyzed the clustering and concluded that it’s unlikely just random. “It’s very statistically significant,” Bufe said, according to the Seattle Times. “We think we’re in an increased hazard situation for these very large earthquakes.”

According to their calculation, there’s a 63 percent chance that another magnitude 9 or greater quake will strike somewhere in the world within the next six years. If these megaquakes are random, the chance is about 24 percent.

Other experts at the meeting, however, supported the notion that what seems like a clustering of megaquakes is really just random, except for clusters of aftershocks in the vicinity of the major rupture, such as those continuing in Japan.

For example, seismologist Andrew Michael, who’s with the USGS in Menlo Park, Calif., announced at the meeting that he’s examined databases for evidence of clustering and, as he told me in an email in March, found “there is no evidence of global large-earthquake clustering.”

That said, scientists are far from being able to predict earthquakes and acknowledge there is much to learn about them. It’s possible that entrenched ideas will be proven wrong, said Rick Aster (outgoing president of the seismological society), encouraging scientists to keep asking questions.

  1. April 20, 2011 at 4:11 pm

    Another perspective on the Japanese Tohoku quake. Presented at Seismological Society of America Apr. 14th.


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