Japan Marks Disaster Prevention Day with Nankai Trough M9.1 Earthquake Drill

The Yomiuri Shimbun

13:46 JST, September 1, 2025

The government conducted a comprehensive disaster drill for a Nankai Trough megaquake on Monday, coinciding with Disaster Prevention Day.

The probability of such an earthquake occurring within the next 30 years is estimated to be about 80%. Through the drill, authorities aimed to confirm how relevant agencies would respond to the disaster. They also aimed to strengthen their preparedness to minimize damage in the wake of a major quake.

During the drill, cabinet ministers wearing disaster-response uniforms arrived one after another on foot at the Prime Minister’s Office and convened a meeting of the emergency disaster response headquarters chaired by Prime Minister Shigeru Ishiba. The prime minister instructed the officials to “put the protection of human life first and use every available means to carry out emergency disaster response.”

This year’s drill assumed that a magnitude 9.1 earthquake had struck at 5:10 p.m. on Dec. 1 with its epicenter off the southern coast of Wakayama Prefecture. With a seismic intensity of 7 on the Japanese scale, shaking was assumed to have been recorded in ten prefectures across the Tokai, Kinki, Shikoku and Kyushu regions.

Drawing on the experience of the Noto Peninsula Earthquake in January last year, the scenario also presumed such adverse conditions as the coldest winter temperatures after sunset. During the meeting, officials held a video conference with Shizuoka Gov. Yasutomo Suzuki and others to hear reports on the damage.

The exercise further assumed the spread of false information and rumors on social media. “The malicious circulation of false information is absolutely unacceptable,” Ishiba emphasized at a mock press conference after the meeting. “I strongly urge people to refrain from circulating false information.”

Deaths caused directly by a Nankai Trough earthquake could reach as high as 298,000, while the number of buildings completely destroyed or burned down could total 2.35 million, according to the government’s latest estimates released in March.