Ethan Johnson/USMC

ScienceShot: Are Major Earthquakes Linked?

Sid is a freelance science journalist.

Two of the six largest quakes since 1900—the magnitude-8.8 temblor that rocked Chile in February 2010, and the 9.0 quake that slammed Japan in March 2011 (damage shown)—occurred just 13 months apart. What's more, a group of four major shocks around the Pacific Rim in the early 1960s occurred within the span of 57 months. Coincidence? Probably, say researchers who analyzed the spacing of temblors with a magnitude of 8.3 or greater that occurred from 1900 through 2011. The chance of two such quakes occurring within 1 year of each other was 9.5%, the researchers report today in the Bulletin of the Seismological Society of America. That's about the same chances of duplicating any particular arrangement of quakes, the researchers say—even a pattern with widely scattered shocks that isn't particularly remarkable. After comparing the actual pattern of temblors in the past 111 years with hundreds of patterns generated by three different statistical distributions, the team says there's no compelling evidence that major quakes are linked. So next time a big quake happens somewhere in the world, rest easy: It doesn't bode ill for your local fault zone.

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Posted in Earth