Japan Panel Says 'Megaquake' Probability up to 82 pct

Such a jolt could potentially have a devastating 8-9 magnitude, trigger colossal tsunamis, kill several hundred thousand people, and cause billions of dollars in damage, experts say.

The Earthquake Research Committee said it has increased its estimate of the probability to between 75 and 82 percent from between 74 and 81 percent previously.

It concerns what is known as a subduction megathrust quake along the Nankai Trough, an 800-kilometer undersea gully running parallel to Japan's Pacific coast.

The trench is where the Philippine Sea oceanic tectonic plate is "subducting," or slowly slipping, underneath the continental plate that Japan sits atop.

The plates become stuck as they move, storing up vast amounts of energy that is released when they break free, causing potentially massive earthquakes.

Over the past 1,400 years, megaquakes in the Nankai Trough have occurred every 100 to 200 years, according to the government's Headquarters for Earthquake Research Promotion.

The last one happened in 1946. 

"It's been 79 years since the last quake, and the possibility of another quake occurring is rising every year at a pace of by about one percent," an official of the Earthquake Research Committee's secretariat told AFP.

One estimate by the Nikkei business daily says around 530,000 people could be left shelterless in the event of a megaquake along the Nankai Trough.

That is out of up to 9.5 million people that the government estimates could be displaced by the disaster.

Source: Reuters