A group of government-appointed scientists warned Tuesday that a major earthquake in the Nankai Trough off the Pacific coast could leave as many as 1.45 million households in 246 coastal municipalities stranded.
The researchers who studied the effects of a potential mega-quake concluded such an event would affect more than four times the number of households than those forced to evacuate after the March 2011 earthquake and tsunami.
The number of households affected in 2011 is estimated at some 330,000.
The findings also showed that some 227,000 households would need to be evacuated from Aichi Prefecture to more distant areas, followed by some 188,000 in Shizuoka Prefecture. The populace in 30 municipalities including the city of Ise in Mie Prefecture and the town of Kushimoto in Wakayama Prefecture would halve in the event of the mega-thrust quake.
The team predicts such a quake is also likely to cause severe damage in the central Tokai region facing the Pacific.
The researchers also found that Fukuoka and Kanagawa prefectures would be designated as relocation sites as lighter damage is predicted in those areas.
“Given that outflow of population might disrupt sustainability of a region, we need to address the risk from a long-term perspective through introduction of measures and compiling related procedures that would enable us to ensure reconstruction,” said Yu Hiroi, a University of Tokyo professor who was involved in the study.
The study was part of a project conducted by researchers from the University of Tokyo and Kyoto University under the science ministry.
Researchers at a symposium held on Tuesday disclosed the results of a recent four-year study based on previous seismic history.
“The seismic activity has increased since 2001,” said Haruo Hayashi of the Disaster Prevention Research Institute at Kyoto University, stressing the correlation between the recent mega-quake and further seismic activities.
The probability of a huge Nankai Trough quake with a magnitude of 8 to 9 occurring in the next three decades is estimated at 60 to 70 percent, Hayashi said.
The project members warn that Japan has yet to draw on lessons from the 2011 disaster that killed thousands and left tens of thousands displaced.
A government official who spoke on behalf of Toshinori Ogata, the Cabinet’s assistant secretary in charge of disaster management, said that a speedy response following an earthquake and quick delivery of goods to affected areas “remain an issue.”
The researchers also said that if a mega-quake hits the northern part of Chiba Prefecture, Tokyo will see stronger tremors than those in Chiba.
However, Robert Geller, professor of geophysics at the University of Tokyo, criticized the government for focusing on one particular scenario, “when the scientific reality is that the so-called Nankai Trough quake can’t be said to be more likely than any other.”
He said the government’s conclusions based on a premise the predicted mega-thrust earthquake will hit the coastal areas in the Nankai Trough off the Pacific coast sound authoritative but are “based on a wrong model” thus are false.
“They may be right about the scale of damages,” he said, but added the government’s claims ignore the fact that the earthquakes are not cyclical and the earth’s movements are unpredictable.
Geller added the government-appointed researchers focus only on data from past centuries, while the age of the Earth is estimated at around 4.6 billion years.
“It’s absolutely impossible” to predict where and when the next major earthquake will occur, he said, explaining the government’s earlier predictions proved wrong.
Japan needs to be prepared for a sudden earthquake like the one in Tohoku or in Kobe in 1995, he said.
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