Fukushima Nuclear Reactors Need Reinforcing, Seismic Study Says

Areas around the Fukushima Dai-Ichi nuclear plant appear more prone to large temblors since last year’s magnitude 9 quake, according to a peer-reviewed geological study that recommends reinforcing the reactors.

The March 11 earthquake’s strongest on-shore aftershock, a magnitude 7 quake that struck on April 11, occurred on the Iwaki fault. This suggests the Iwaki fault has been reactivated by the record quake a month earlier, according to the study published yesterday in the journal Solid Earth.

That should prompt closer attention to the seismic safety of Tokyo Electric Power Co. (9501)’s nuclear plant, according to the researchers at Japan’s Tohoku University in Sendai and Tsinghua University in Beijing who wrote the study in the journal published by the European Geosciences Union.

“The similar structures under the Iwaki source area and the Fukushima nuclear power plant suggest that the security of the nuclear power plant site should be strengthened to withstand potential large earthquakes in the future,” they wrote.

Sensors detected 24,108 tremors in the area between the April 11 aftershock and Oct. 27 last year, with 23 of them earthquakes of magnitude 5 or higher, according to the study. That compares to 1,215 recorded between June 3, 2002 and the March 11 quake, the report shows.

To contact the reporter on this story: Jacob Adelman in Tokyo at jadelman1@bloomberg.net

To contact the editor responsible for this story: Peter Langan at plangan@bloomberg.net

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