Geology & Geophysics Research Spotlight

Is the Recent Increase in Earthquakes Random?

A statistical analysis cannot prove with high confidence that the recent global increase in large (M≥5.6) earthquakes could not have happened by random chance.

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The increase in the global rate of earthquakes since 2010, especially during the first few months of 2014, leads many people to wonder whether there is a physical cause for this increase or if this is simply a random process.

To figure this out, Parsons and Geist conducted a statistical analysis of earthquakes in the Advanced National Seismic System (ANSS) catalog. They considered the period from 2010 to present, which experienced rates of large (M ≥ 7) earthquakes that were 65% higher than the ­1979 to present average; they focused especially on the first quarter of 2014, which saw rates twice as high as the 1979 to ​­present average. To determine whether the global earthquake rate increase is related to interactions among large earthquakes far apart from each other, they filtered out local aftershocks from the record before conducting their statistical analysis. They cannot prove with high confidence that the recent global increase in large (M ≥ 5.6) earthquakes could not have happened by random chance. (Geophysical Research Letters, doi:10.1002/​2014GL060513, 2014)

—Ernie Balcerak, Staff Writer

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