There is nearly a 50-50 chance a huge earthquake will flatten coastal areas from central to southern Japan-from the Tokai region to Shikoku-in the next 30 years, a government earthquake panel said Thursday.
If, the panel said, two earthquakes were to hit the area simultaneously, as has happened on more than one occasion, the quake could hit 8.5 on the Richter scale and the damage would be catastrophic.
Not only would the heavily populated industrial areas in central Japan be devastated, severe quakes and tsunami could reach from Kanto to Kyushu, the panel said.
Experts have long warned that the areas near the Nankai trough, which stretches off the coast of Tokai through the Shikoku regions, are danger zones that have historically witnessed a lot of earthquake activity.
An example is the Tonankai Earthquake off the eastern coast of the Kii Peninsula in 1944. More than 900 people died in the disaster.
Two years later the Nankai Earthquake struck south of the peninsula and killed at least 1,300.
A Nankai trough temblor at the close of the 15th century is believed to have killed 40,000 people.
The Nankai trough is blamed for the quakes, with a major temblor hitting an average of every 110 years, experts said.
When the next Tonankai earthquake hits, it is likely to be centered in an area stretching from Lake Hamanako in Shizuoka Prefecture to off the east coast of the Kii Peninsula. According to the Earthquake Research Committee, the quake, if and when it arrives, will have an intensity of about 8.1 on the Richter scale. They said there is a 50 percent chance it will hit within the next 30 years.
The next Nankai earthquake is predicted to hit in an area stretching from the Shiono-misaki promontory in Wakayama Prefecture to the Ashizuri-misaki promontory in Kochi Prefecture.
The scientists says it should have a magnitude of about 8.4 and there is 40 percent chance it will strike in the coming three decades.
If the two earthquakes hit at the same time-a calamity that occurred in both the 17th and 18th centuries-the magnitude could reach 8.5, the panel said.
This compares with 7.3 registered by the 1995 Great Hanshin Earthquake and 7.9 for the 1923 Great Kanto Earthquake.
The government's Central Disaster Prevention Council headed by Prime Minister Junichiro Koizumi has plans to work out ways to make predictions on the size of anticipated tidal waves and other effects from the earthquakes so anti-disaster measures can be put in place.
The Fire Defense Agency said the next Nankai and Tonankai quakes will affect Tokyo and 33 prefectures.