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The Central Disaster Prevention Council has reworked its potential damage estimate for a major quake that could directly strike the Tokyo area, in light of the March 2011 magnitude 9 temblor that spawned the devastating tsunami off Tohoku.

In Thursday’s estimate, the council’s focus was on a magnitude 7-class event and did not squarely address the possibility of a megaquake of magnitude 9 or greater striking.

A critic said the panel’s “underestimated” report may have been motivated by political considerations to avoid stirring anxiety ahead of the Olympics games Tokyo is hosting in 2020.

The members of the government council took on a review of the government’s disaster scenario crafted in 2005, after the March 2011 earthquake and tsunami disaster that left more than 18,500 people dead or missing.

Having seen that the 2011 quake generated tsunami of an unexpected scale and caused many deaths, as well as the core meltdowns at the Fukushima power station, the council initially included in its consideration a massive earthquake anticipated to happen once in a thousand years.

Scenarios about the so-called Nankai Trough earthquake published from last year to this spring assumed an M9 class quake despite its low probability. The worst-case scenario puts economic damage at ¥220 trillion, more than double the ¥95.3 trillion sum for the Tokyo quake in the latest report assuming a M7.3 quake striking beneath the region.

The presumed quake along the Nankai Trough, an undersea trench in the Pacific off central and western Japan, has an estimated death toll of 323,000 in the worst case, compared with the 23,000 deaths estimated in the Tokyo quake report.

A variety of scenarios are known to have been put on the table at the council for the Tokyo area earthquake.

Some experts in the working group compiling disaster scenarios began voicing concerns around the middle of the year that talking about a massive earthquake may cause too much anxiety and also that creating a quake scenario with no imminence may not be meaningful.

Tokyo beat Istanbul and Madrid at the International Olympic Committee meeting in Rio de Janeiro on Sept. 8 to become the host of the 2020 Olympics.

The council eventually shifted its focus to the M7-class quake, said to have a probability of 70 percent in the next 30 years, and decided to mention the M8 class quake as “a reference” in passing.

The Great Kanto Earthquake of 1923, which was estimated to have a magnitude of 7.9, killed more than 70,000 in Tokyo and 32,000 in neighboring Kanagawa Prefecture.

The council excluded greater magnitude quakes from its consideration as their probabilities are deemed even slimmer.

The council assumed in the report that central government offices, which will serve as headquarters for disaster response measures, face only limited risk of collapsing as they are built on solid ground in central Tokyo.

Their ability to function may decline but wouldn’t be entirely stopped, the council said.

But the Finance Ministry and the No. 4 joint government office building housing part of the Cabinet Office do not meet quake-resistance standards and pose a risk of collapsing in an intensity upper 6 quake on the Japanese seismic scale. The Great East Japan Earthquake of 2011 maxed out the intensity scale at 7.

The No. 4 building is scheduled to be reinforced by fiscal 2016, while the Finance Ministry building does not have a definite enhancement plan.

While each government ministry and agency has been reexamining business continuity plans to prepare for emergencies, responses during night hours and on holidays may also prove to be a challenge because an increasing number of government employees have relocated to suburban areas to curb housing costs in the wake of reductions in government-subsidized housing and rising rents.

“Unless staff can report to work, a (contingency) plan is like a fantasy,” a senior official said. “It’s not guaranteed that an earthquake would conveniently occur during business hours,” another official said. “Government functions would almost all be devastated.”

Many experts question the council’s assumption sidelining the M8-class quake from the scenario, with one calling it “arbitrary” and another saying it is “a diversion from the stance right after the (2011) earthquake.”

The council’s scenario also came under criticism at a meeting Thursday of the Liberal Democratic Party. “It’s too modest of an assumption to alert the population,” one participant said.

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