Japan Authorities Urge Vigilance After ‘Subsequent Quake Advisory’; Past Warnings Did Not Spur Residents to Action

By Kotaro Yaginuma and Yuko Shiojima / Yomiuri Shimbun Staff Writers

21:00 JST, December 10, 2025

The Cabinet Office is calling for heightened vigilance for the next week, due to the larger earthquakes that have occurred in the past after earlier tremors along the Japan and Chishima trenches.

The government issued a subsequent earthquake advisory for Hokkaido and the Sanriku Pacific coastal areas of northeastern Japan after the magnitude 7.5 earthquake that struck off the eastern coast of Aomori Prefecture late Monday. This is the first time such an advisory has been issued.

The critical challenge now is getting residents to actually take concrete disaster prevention measures.

Probability rises to 1%

“It’s uncertain whether a large-scale earthquake will actually occur, but we ask residents to take disaster prevention measures that prioritize the protection of their own lives,” Cabinet Office official Tsukasa Morikubo said at a press conference early Tuesday. He called on residents in the affected areas to respond calmly.

The subsequent earthquake advisory system was introduced in December 2022, drawing on lessons from the 2011 Great East Japan Earthquake. Advisories are issued when an earthquake of magnitude 7.0 or greater — measured on the moment magnitude scale — occurs within the assumed epicenter areas along the Japan and Chishima trenches.

Such advisories are expected to be announced roughly once every two years.

Historically, larger earthquakes have sometimes followed magnitude 7-class temblors. In 1963, a magnitude 8.5 quake struck 18 hours after a magnitude 7 quake southeast of Etorofu Island. Similarly, a magnitude 7.3 quake hit the Sanriku coast just two days before the magnitude 9.0 Great East Japan Earthquake in 2011.

According to the Japan Meteorological Agency, global statistics suggest the probability of a magnitude 8 or greater earthquake occurring along these trenches within a week of an initial tremor rises from about 0.1% (once in 1,000 times) during normal periods to about 1% (once in 100 times).

The agency noted that this probability “decreases over time.”

182 municipalities affected

Following the advisory, the Cabinet Office called for preparedness measures across 182 municipalities in seven prefectures ranging from Hokkaido to Chiba.

Residents are urged to continue their usual social and economic activities while taking “special precautions” for one week. These include reconfirming daily preparations — such as securing furniture to walls — and being ready to evacuate immediately. The Cabinet Office stated the one-week duration is intended “to balance safety with social and economic activities.”

The call for precautions will end if no similar-sized earthquake occurs by 12 a.m. Tuesday.

Municipalities under the advisory are currently reviewing their preparations. Hachinohe Japan Red Cross Hospital in Hachinohe, Aomori Prefecture — which recorded an upper 6 on the Japanese seismic intensity scale of 7 — confirmed its stockpiles of heating oil, food and water on Tuesday, anticipating prolonged patient stays.

“We mustn’t be caught unprepared for unforeseeable situations,” said Kentaro Fujisawa, vice president of the hospital. “We must protect the safety of the elderly and others requiring medical care.”

Residents’ response

The effectiveness of the advisory depends on whether it prompts residents to take appropriate action.

A key lesson is the first-ever “Nankai Trough Earthquake Extra Information,” which was issued in August last year. That system includes a “mega-earthquake caution,” which is issued after a magnitude 8 or greater quake, and a “mega-earthquake alert,” which is issued after a magnitude 7 or greater quake. In August last year, the caution was issued, requiring similar preparations to the current advisory.

However, a survey by the University of Tokyo’s Center for Integrated Disaster Information Research revealed a gap in action. While 83% of about 4,400 residents in the affected areas saw or heard the announcement, only 6% confirmed evacuation sites and routes, and only 9.8% confirmed family communication methods.

“When the extra information was issued last time, the government’s message was ambiguous regarding whether people should continue their normal lives or take precautions,” said Prof. Naoya Sekiya, director of the center. “The content of the advisory has been improved based on that lesson, but we need to verify how residents perceive and act on the advisory this time.”

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