A highest-level warning for a Nankai Trough megaquake would prompt a government evacuation advisory for 670,000 people, but less than half of the affected municipalities are prepared, an Asahi Shimbun survey showed.

Such a quake could generate a towering tsunami that would slam into Pacific coastlines from Kanto to Kyushu.

The Japan Meteorological Agency believes that certain seismic activity could be a precursor to the long-expected megaquake in the Nankai Trough.

Based on Cabinet Office guidelines, if the agency believes there is a strong possibility that such a major earthquake will strike, it will ask residents of 139 municipalities at risk to evacuate one week in advance to acquaintances’ homes or evacuation centers outside the expected flood zones.

The advanced evacuation warning is based on the likelihood that the residents would not have enough time to flee after the actual quake hits.

The survey was conducted in February in areas designated by the Cabinet Office as particularly at risk of tsunami damage from a Nankai Trough earthquake.

The 139 municipalities are in 14 prefectures from Chiba to Kagoshima prefectures.

The Cabinet Office did not have an exact count of the affected residents.

“While listening to the municipalities’ opinions, we also want to grasp the situation as a nation,” an official said.

But the Asahi survey estimated the total number of evacuees at 667,860, while the capacity of available evacuation centers is only 422,676, based on responses from 70 municipalities.

By comparison, around 470,000 people were forced to evacuate after the 2011 Great East Japan Earthquake, while more than 310,000 people fled from their homes after 1995 Great Hanshin-Awaji Earthquake.

The municipalities with the largest targeted populations for evacuation in a Nankai Trough quake are Ise in Mie Prefecture with 81,306 people, followed by Shizuoka city with around 52,000 people, and Matsusaka in Mie Prefecture with roughly 51,000 people.

According to the survey results, only 75 of the 139 municipalities, or about half, have designated areas requiring evacuation and estimated the number of affected residents.

Thirteen municipalities have designated areas requiring evacuation but have not estimated the number of affected residents. Another 13 municipalities said they recognize the need to designate areas and estimate numbers of people but have not yet done so.

Thirty-eight municipalities said such evacuation designations were not necessary. Some of the reasons cited were lack of residences in the targeted areas or construction of tower buildings can be used for evacuation.

Among the municipalities that designated areas for pre-emptive evacuation, only 43 said their evacuation centers would be sufficient.

Twenty-five percent said they would not have enough space for all the evacuees, and 32 percent were uncertain.

“Many public facilities are located in flood-prone areas,” said an official from Shirahama, Wakayama Prefecture.

“It takes time and money to construct new public facilities,” said an official from Makinohara, Shizuoka Prefecture.

TSUNAMI MAY HIT IN MINUTES

During the Great East Japan Earthquake, the tsunami reached shore about 30 minutes after the quake.

But in a Nankai Trough megaquake, a tsunami could hit land within minutes, making pre-emptive evacuation crucial to saving lives.

Takashi Sugiyama, an associate professor of disaster psychology at Kyushu University, warns that many municipalities lack sufficient evacuation centers.

“We need to increase evacuation centers by working with hotels and other facilities while improving overall conditions,” he said. “Establishing a system for large-scale evacuations across municipalities is also urgently needed.”

MORE THAN JUST A NUMBER

Katsuya Yamori, a professor of disaster psychology at Kyoto University, pointed out that simply increasing the number of evacuation centers is a bureaucratic way of thinking.

“What matters is whether the evacuation centers are actually usable, whether people are aware of them, and how those unable to reach them on their own will be supported,” he said.

This became apparent last August when a megaquake advisory was issued for Kuroshio in Kochi Prefecture.

Elderly residents were urged to evacuate, but the local gymnasium that was designated as an evacuation center had no air conditioning amid the extreme heat. They had to use a conference room instead.

Some evacuees slept on cardboard sheets on the floor, and many left the shelter due to health concerns.

LITTLE PREPAREDNESS FOR NON-RESIDENTS

The Noto Peninsula earthquake on New Year’s Day last year affected not only residents but also visitors returning home for the holidays.

With the number of foreign tourists reaching record highs, the risk of non-Japanese being caught in a disaster has also increased.

However, 121 of the 139 municipalities, or nearly 90 percent, said they have no specific plans for the pre-emptive evacuation of non-residents.

Tateyama in Chiba Prefecture, located at the tip of the Boso Peninsula and a popular destination for foreign tourists, has a maximum capacity of about 3,000 people at its designated evacuation centers.

“It’s far from sufficient,” a city official said.

The city has yet to estimate the exact number of residents who would require evacuation in a Nankai Trough megaquake.

“As we are already struggling to ensure adequate support for residents, adding tourists―especially foreign visitors―raises the additional challenge of multilingual support,” an official said. “With limited staff, this inevitably lowers the priority.”