High risk of major earthquake in Tokyo within 4 years, warn scientists

Japanese researchers warned today that the risk of a big earthquake hitting Tokyo within the next few years could be much higher than previously thought.

The University of Tokyo's Earthquake Research Institute (ERI) said the chances of a 7.0-magnitude quake occurring in the southern Kanto region around Tokyo by 2016 were about 70 percent, reported the Guardian. The scientists believe the chances of a similar disaster within 30 years are as high as 98 percent.

That estimate indicates a far higher risk than the government's forecast, which says the risk of an earthquake that powerful is 70 percent over the next 30 years.

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The institute said the March 2011 earthquake that struck north-east Japan had increased seismic activity, making tremors of all sizes – including major ones – more likely.

"It’s the same as when one person in a line of people holding hands falls – then those around him are likely to get pulled down too," ERI research associate Shinichi Sakai told the Wall Street Journal's Japan blog:

Mr. Sakai said the March 11 quake jerked the fault lines underground in a way that has changed the coastal landscape as well as the sea bed below. It also mounted pressure on nearby sea floors like those beneath Hokkaido and the Kanto region. If the rate of smaller earthquakes persist, it is likely Tokyo will see a big one strike at its doorstep in the near future.

Since March, quakes with a magnitude of more than 3.0 have occurred about five times more frequently than in previous years, according to the Mainichi Daily News.

The new study took account of these latest data, whereas the government's estimate is based on the intervals between large quakes in the past.

According to Agence France Presse, the last time a major earthquake hit Tokyo was in 1923, when the 7.9-magnitude Great Kanto quake killed more than 100,000 people.

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