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Italian scientists convicted of manslaughter for earthquake risk report

Destruction in the aftermath of the L'Aquila quake.

A group of six seismologists were convicted of manslaughter by an Italian court today for their role in the preparation of a risk report on seismic activity in L'Aquila, Italy. The report, which was generally regarded as reassuring, was released about a week before an earthquake struck the town, killing over 300 people. Initial reports indicate that the scientists have been sentenced to six years in prison.

The town of L'Aquila sits on a major fault line, and had been struck by several swarms of small magnitude earthquakes. The Italian government had organized a risk-assessment committee, which included seismologists (including the former head of the National Institute of Geophysics) and government officials. In the week before the earthquake struck, the group told the public that the high incidence of smaller earthquakes were not necessarily precursors of a larger quake. They did, however, also mention that earthquakes were unpredictable, and that building codes in the area needed to be adjusted to provide better seismic safety.

Reportedly, one of the Italian government officials took matters a step further, declaring that there was no danger, and suggesting that the smaller earthquakes had relieved stress on the fault.

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Cluster of >8.0-magnitude earthquakes doesn’t indicate Earth is more active

The past few years have seen an unusual number of epically large earthquakes, with several—in Sumatra, Chile, and Japan—reaching magnitudes of roughly 9.0. This has led a number of people to wonder whether large earthquakes cluster and, if they do, whether we should be getting nervous about when the next one will hit. A new analysis in PNAS, however, suggests the elevated activity is nothing unusual, although the long gap between recent activity and past monster quakes was statistically unlikely.

The authors went through the US Geological Survey's historic records, identifying every earthquake above magnitude 7.0 that occurred between 1900 and 2011. To eliminate aftershocks and local strain caused by initial earthquakes, the authors set a cutoff: any smaller earthquakes within three years and 1,000km of a quake were considered its aftershocks, and not incorporated into the analysis. This is a fairly liberal definition of aftershock, and takes two recent monster quakes out of the analysis, both over 8.5 and near the site of the first Sumatran quake. But it is consistent with what we know about how major quakes can add strain to areas at a considerable distance from where the fault actually ruptured.

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