Japan Ends Megaquake Alert for Northeast but Advises Ongoing Preparedness

The Japanese government has withdrawn a special megaquake advisory covering portions of the country’s northeastern Pacific coast, one week after a magnitude 7.5 offshore earthquake heightened concerns about a possible larger seismic event. Officials from the Japan Meteorological Agency (JMA) and the Cabinet Office announced the decision at a joint news conference on Tuesday, emphasizing that the likelihood of an magnitude 8 or stronger earthquake has declined but not disappeared.

The advisory, issued last Monday, instructed residents in designated municipalities along the Pacific shores of Aomori Prefecture and neighboring areas of Hokkaido to stay ready for rapid evacuation. People were asked to sleep in day clothes with helmets, sturdy footwear, and emergency bags nearby. With the lifting of the alert, those measures are no longer formally requested; however, authorities urged communities to maintain what they described as an “adequate” state of readiness for any future seismic activity.

The magnitude 7.5 quake occurred off the eastern coast of Aomori, near the boundary between Japan’s main island of Honshu and the northern island of Hokkaido. Although the tremor caused relatively limited damage, it did injure more than 40 people and damaged dozens of homes, according to the Fire and Disaster Management Agency. Most injuries were reported as mild. Tsunami advisories were issued immediately after the quake, and coastal gauges registered waves up to 70 centimeters (27 inches), but officials said no tsunami-related destruction was recorded.

Municipalities within the advisory zone reported that residents reacted calmly throughout the week. Local governments kept shelters on standby, conducted extra patrols of critical infrastructure, and communicated preparedness instructions through community loudspeakers and social media. National officials noted that the orderly response stood in contrast to some reactions in 2024, when Japan released its first-ever Nankai Trough megaquake advisory for the southern half of the country’s Pacific coastline. The earlier notice, issued during the summer of that year, led to episodes of panic buying, the suspension of public events, and temporary business closures.

The current advisory system for the Hokkaido–Sanriku region was introduced in 2022 as part of reforms implemented after the 2011 Great East Japan Earthquake. That magnitude 9.0 event and its resulting tsunami devastated wide sections of the Tohoku coast, claiming nearly 20,000 lives and triggering the Fukushima Daiichi nuclear accident. Authorities said lessons learned from 2011 continue to guide how and when advisories are issued, the language used in public announcements, and the balance between raising alertness and avoiding unnecessary alarm.

During Tuesday’s briefing, the JMA provided an updated assessment of aftershock probabilities based on seismic data gathered since last week’s temblor. While smaller quakes remain possible, the agency no longer considers the conditions sufficient to sustain the formal megaquake advisory. The Cabinet Office added that local disaster response agencies will keep shelters and rapid-response equipment in place until aftershock activity clearly subsides.

Japan sits on the so-called Pacific “Ring of Fire,” a zone of intense tectonic movement responsible for many of the world’s major earthquakes and volcanic eruptions. According to background information from the U.S. Geological Survey, the country experiences hundreds of felt earthquakes each year, and its building codes, early-warning systems, and public education programs are widely regarded as among the most advanced in the world.

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Despite the end of the advisory, local officials in Aomori and Hokkaido reiterated instructions for residents to review household evacuation routes, keep emergency supplies stocked, and stay informed through official channels such as the J-Alert nationwide emergency broadcast system. Public drills scheduled before the end of the year will proceed as planned to maintain community readiness.

Transportation authorities reported minimal lingering disruption from last week’s quake. Rail operators confirmed that bullet train services running through the Tohoku and Hokkaido regions are operating on regular timetables after temporary speed reductions and overnight inspections of tracks and bridges. Airport facilities in Aomori and Hakodate also resumed normal operations within hours of the quake, according to regional aviation offices.

Utility companies said electricity and water services remain stable, though field teams continue monitoring for delayed infrastructure impacts. Structural inspections of schools, hospitals, and public buildings are ongoing, with preliminary surveys indicating only minor superficial damage in most cases.

While the formal megaquake alert has ended, the JMA advised residents across the broader region to remain vigilant for at least several more days, noting that significant aftershocks sometimes occur beyond a one-week window. Emergency officials encouraged the public to rely on verified information from national and local authorities rather than social media rumors.

Crédito da imagem: Associated Press