Authorities in communities on the Pacific coast of Japan are woefully ill prepared to evacuate residents in the event of massive tsunami spawned by a megaquake, according to a study by The Asahi Shimbun.

It found that nearly 60 percent of municipalities had failed to designate evacuation centers in such an event, a stunning revelation given persistent predictions published in government reports of a 70-80 percent likelihood that a Nankai Trough megaquake will strike the region within 30 years.

The Nankai Trough is a submarine trench on the Pacific side of the Japanese archipelago that stretches from Shizuoka Prefecture in the main island of Honshu to waters east of Kyushu island in southern Japan.

Scientists predict that up to 231,000 people could be killed or go missing in the tsunami expected to arrive soon after such a quake.

Local authorities were asked by the government to draw up evacuation plans by the end of March to ensure that vulnerable communities would be safe. The emphasis was on plans that provided for evacuation over a week or so after signs emerge of a possible megaquake hitting.

The expected focal area of the megaquake consists of two areas: eastern and western.

Seismologists predict that if a magnitude-8.0 or more class temblor occurs in one area, it is likely to trigger another powerful quake in the other area.

As a result, when the first quake occurs, the government will issue an immediate alert urging residents to evacuate from the area where a second earthquake is expected to strike.

Priority would be given to evacuees who are unable to flee to higher ground and local evacuation centers on their own, including the elderly.

An Asahi Shimbun telephone survey of all 139 municipalities in Tokyo and 13 prefectures from Chiba to Kagoshima found that 81, or 58.3 percent, have yet to designate evacuation areas for tsunami from the envisioned second earthquake.

Thirty-one, or 22.3 percent, said they have, while 27, or 19.4 percent, replied that they do not need to designate ones as nobody lived in the districts projected to be inundated by tsunami.

Authorities blamed a lack of facilities fit to serve as long-term shelters and stalled talks with local communities for the delay in earmarking evacuation centers.

Of the 81 local governments that have yet to devise an evacuation plan, 57, or 70.4 percent, replied that they will do so by the end of fiscal 2020, ending in March 2021.

Twenty-one, or 25.9 percent, said they do not know when they will be able to do so. Three, or 3.7 percent, said they will draw up plans in fiscal 2021, or later.