Japan updates ‘mega quake’ preparedness plan with efforts including constructing embankments

TOKYO – The Japanese government said that much more needs to be done to prepare for a possible “mega quake” to reduce the feared death toll of up to 300,000 people.

Quakes are extremely hard to predict, but in January, a government panel marginally increased the probability of a major jolt in the Nankai Trough off Japan in the next 30 years to 75 per cent to 82 per cent.

The government then released an estimate in March

saying that such a mega quake and subsequent tsunami could cause as many as 298,000 deaths and damages of up to US$2 trillion (S$2.5 trillion).

In 2014, the Japanese Central Disaster Management Council issued a preparedness plan recommending a series of measures that, it was hoped, would reduce deaths by 80 per cent.

But the Japanese government has said that so far, the steps taken would cut the toll only by 20 per cent, Kyodo news agency reported, and an updated preparedness plan was issued on July 1.

This recommended accelerated efforts including constructing embankments and evacuation buildings as well as more regular drills to improve public readiness.

“It is necessary for the nation, municipalities, companies and non-profits to come together and take measures in order to save as many lives as possible,” Japanese Prime Minister Shigeru Ishiba told a government meeting, the local media reported.

The Nankai Trough is an 800km undersea gully running parallel to Japan’s Pacific coast where one tectonic plate is “subducting” – slowly slipping – underneath another.

Over the past 1,400 years, mega quakes in the Nankai Trough have occurred every 100 to 200 years. The last one was in 1946.

In August 2024, Japan Meteorological Agency (JMA) issued its first advisory warning that the likelihood had risen but it was lifted again after a week.

Manga ‘prophesy’

Some foreign tourists have been holding off coming to Japan this summer by unfounded fears spurred on social media that a major quake is imminent.

Causing particular concern is a manga or comic reissued in 2021 which predicted a major disaster on July 5, 2025.

Hong Kong-based Greater Bay Airlines reduced flights to Japan because “demand has rapidly decreased”, a local tourism official told AFP in May.

The number of visitors to Japan from Hong Kong to Japan fell 11.2 per cent in May year on year, according to the tourism office.

Those from China soared 44.8 per cent, however, while arrivals from South Korea rose 11.8 percent.

“It is impossible with current science to predict earthquakes by specifying the location, time, and magnitude of an earthquake, and to say that an earthquake will or will not occur,” Mr Ryoichi Nomura, head of the JMA, said in May.

“We ask the public to take certain steps so that you can cope with earthquakes no matter when they occur. But we also strongly urge the public not (to) make irrational actions driven by anxiety.” AFP