“I think the Japanese authorities should do everything to prepare for a possible large earthquake close to the Fukushima nuclear plant,” Dapeng Zhao, a geophysics professor at Tohoku University and lead author of the study, told The Daily Beast.
Zhao said he had submitted the study to the Japanese government and warned them of the impending danger.
Released Tuesday, the study—by scientists from Tohoku and Shanghai’s Tsinghai University—was published in the journal of the European Geosciences Union. It suggested that Japan also should review seismic safety at three other nuclear facilities: Fukushima-Daini, which is near the crippled plant, Onagawa to the north and Tokai to the south.
Subterranean stresses set off the 8.9 magnitude earthquake—Japan’s most powerful ever—and the tsunami that devastated parts of Japan last March. These same geological processes have now cracked open a fault in the Fukushima-Daiichi region, almost under the stricken nuclear plant, says the study.
The power facility suffered one of the worst nuclear disasters in history after being hit by the earthquake and tsunami. But the epicenter of that temblor was about 160 kilometers away; a new earthquake could strike much closer, Zhao said.
He recommended the Fukushima plant be prepared to withstand “strong shaking,” since the next earthquake would likely be inland and not under the sea, as it was 11 months ago.
“If it is a big one, for example, above magnitude 7 and close to Fukushima-Daiichi, it would cause large damage,” said Zhao.
The aftershocks from the March 11 quake have been occurring in increasing proximity to the plant. On April 22, 2011, an earthquake of magnitude 7 shook the Iwaki region. The epicenter was inland, just 60 kilometers southwest of the Fukushima plant.
Japan’s seismic network recorded a dramatic rise in tremors after the tsunami in Iwaki: more than 24,000 in eight months, up from just 1,300 in the nine years before.
Using this data, scientists peered into the earth’s crust using a technique called seismic tomography, akin to using X-rays from a CAT scan to detect fractures in human bones.
Scans below Japan revealed worsening fractures and vast subterranean activity that is, in essence, making the earth less solid and more like jelly.
When might the next big one strike the region?
“I really don’t know,” said Zhao. While X-rays reveal the stresses below the earth, they cannot predict an earthquake. That task will now be handed over to other scientists who will directly monitor chemical and magnetic changes to estimate the timing and magnitude of a future earthquake.
Last year’s earthquake and tsunami killed at least 15,839 people, while 3,643 remain missing. More than 88,000 people still live in shelters across Japan.
Meanwhile, a nuclear reactor at Fukushima heated up again, though the facility as a whole has cooled, the Tokyo Power Company (Tepco) said on Monday.
On Sunday afternoon, the bottom of one of the reactors rose to 82 degrees Celsius (179.6 degrees Fahrenheit), Tepco said.
The temperature has been rising since Feb. 2, 2012, less than two months after the company announced a “cold shutdown” of three reactors that suffered a meltdown in events after the tsunami.
A cold shutdown means a nuclear chain reaction can no longer take place.
It could take 30 years or more to safely shut down the Fukushima nuclear facility, according to expert estimates.