There is a 40 percent to 50 percent likelihood that magnitude 8 earthquakes will hit regions of central and western Japan causing damage to the Pacific belt zone -- the center of the nation's economy -- in the next 30 years, according to a government report released this week.

The report, by the earthquake survey council, focuses on magnitude 8 quakes in the Nankai and Tonankai regions, which occur in 100- and 150-year cycles along the Nankai trough, which runs through parts of central and western Japan.

The quakes would cause damage throughout major economic centers in the Pacific belt zone, according to the report.

It says there is a 50 percent chance that the Tonankai earthquake, which would probably occur in an area between Lake Hamana in Shizuoka Prefecture and Cape Shiono in Wakayama Prefecture, will happen in the next 30 years.

There is about a 40 percent chance that the Nankai earthquake, likely to be focused between Cape Shiono and Cape Ashizuri in Kochi Prefecture, will happen in the next three decades, the report says.

The quakes may occur simultaneously or successively.

The Nankai quake could be as strong as magnitude 8.4, while the Tonankai quake may register magnitude 8.1.

If the two quakes occurred simultaneously, the combined magnitude could be 8.5, the report says.

The most recent Tonankai quake occurred in 1944, leaving more than 1,000 people dead in the central Japan and Kinki regions.

The latest Nankai quake occurred in 1946, also leaving more than 1,000 people dead in western Japan.

Based on earthquake records since 1498, the council predicted that future quakes will be centered in waters between 50 km and 150 km off the Pacific coast and will occur in shorter cycles.

Quakes in the Nankai trough typically cause widespread damage, the report says, adding that the 1946 Nankai quake killed people in areas as far apart as the Sea of Japan coast and Kyushu.

It also caused tsunami the entire length of the coast from the Kanto region to Kyushu.

The government intends to draw up plans to deal with the aftermaths of quakes after simulating damage caused by earthquakes and tsunami at its Central Disaster Prevention Council.

Many experts say that compared to provisions for a large-scale earthquake in the Tokai region, the central government is relatively ill-prepared for temblors in the Nankai and Tonakai regions.

The council's report says that the probability of a large-scale quake occurring in those two regions rises to between 80 percent and 90 percent if the time frame is expanded to the next 50 years. The report is taken as a strong recommendation to relevant authorities to step up countermeasures.

Officials in Kochi and Wakayama prefectures accepted the report calmly, saying that the predictions were nothing new and that they were already preparing for such a disaster.

Tadayuki Sasaoka, head of Kochi Prefecture's fire and disaster prevention division, said that the actions of the central government seemed tardy.

"(With the release of the report) we can expect the central government to take steps in earnest," he said.

Both prefectures said one of the worst problems that could affect them in the event of a large earthquake was that of a tsunami. They expressed hope that the latest report would serve to raise awareness among residents living near the shoreline.