A government council on anti-disaster measures proposed Tuesday that all residents of central and western coastal areas of the country should evacuate if the region is hit by a massive earthquake that is likely to occur in the next 30 years.
The council called on the government to issue evacuation orders for all residents, including those not immediately affected, if a magnitude 8 quake occurs in the Nankai Trough, which extends from off the coast of central Japan to the southwest.
Residents would be advised to remain on alert for about a week after the quake, as past records show a second earthquake of a similar scale has followed major quakes in the other hypocentral regions, within 32 hours in the shortest case.
The government says there is a 70 to 80 percent chance of a magnitude 8 to 9 quake occurring along the trough within the next 30 years. In the worst-case scenario, the quake could produce massive tsunami over 30 meters-high and kill up to 323,000 people, according to the estimate.
Based on the proposal, the government is set to compile guidelines on anti-quake measures for municipal governments and businesses that could be affected by the possible disaster, while working on a review of the law on measures against large-scale earthquakes.
The government can issue evacuation orders for municipal governments that are expected to be hit by tsunami higher than 30 cm within 30 minutes of a quake.
Following the guidelines, local governments are expected to prepare their own evacuation plans.
The council also proposed issuing advisories if a smaller, magnitude 7 quakes hit the areas or if abnormal phenomena such as underground deformation were detected together with tremors not strong enough to be felt by residents.