TOKYO — Japan lifted a rare megaquake advisory for the country’s northeastern coast on Tuesday, one week after a magnitude 7.5 earthquake struck off northern Japan and prompted officials to warn of an increased risk of a much larger tremor.
The decision means residents in the designated coastal areas are no longer being asked to sleep in their day clothes, with helmets, shoes and emergency grab bags by their beds in case a magnitude 8 or stronger quake hit during the night. Those precautionary guidelines had been in place since last Monday, when authorities raised the alert.
At a joint news conference, officials from the Japan Meteorological Agency (JMA) and the Cabinet Office said the probability of a so-called megaquake has “somewhat decreased.” But they stressed that the risk has not disappeared and urged people to maintain a basic level of vigilance and preparedness.
One week after a magnitude 7.5 offshore quake
The JMA issued the megaquake advisory last Monday after the 7.5 magnitude quake struck off the eastern coast of Aomori, Japan’s northernmost prefecture on the main island of Honshu, just south of the island of Hokkaido.
The offshore quake caused light to moderate damage in parts of the region. According to the Fire and Disaster Management Agency, more than 40 people suffered mostly mild injuries and dozens of homes were damaged.
Tsunami alerts and advisories were also issued along the northeastern coast. Waves of up to 70 centimeters (27 inches) were recorded in some areas, but officials said there was no significant tsunami damage.
Authorities noted that municipalities and residents responded calmly to the megaquake advisory, following guidance without signs of widespread panic.
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Lessons from earlier Nankai Trough advisory
The government’s careful messaging this time reflects lessons learned from an advisory issued in the summer of 2024 for a different region.
When Japan released its first-ever “Nankai Trough” megaquake advisory for the southern half of the country’s Pacific coastline, the vague wording and intense media coverage triggered unintended side effects. Officials later reported panic buying of emergency food, the cancellation of events and business closures along parts of the coast as people tried to interpret how seriously to take the warning.
In response, the government refined the mechanism for issuing megaquake advisories, especially for the Hokkaido–Sanriku region along the northeastern Pacific coast. That system was introduced in 2022, shaped by analysis of the 2011 disaster, when a magnitude 9.0 earthquake and devastating tsunami struck the same broad area.
Preparedness remains a priority
With the latest advisory now lifted, officials are trying to strike a balance between avoiding unnecessary alarm and maintaining respect for the seismic risk that defines much of life in Japan.
The JMA and Cabinet Office are continuing to encourage residents to keep emergency supplies on hand, review evacuation routes and remain aware of updated guidance, especially in coastal communities that could face sudden tsunamis.
While the immediate probability of an extreme “megaquake” has eased, the underlying message has not changed: in one of the world’s most earthquake-prone countries, readiness remains essential long after the headlines fade.
Sources:
AP News – “Japan lifts mega-quake advisory after 7.5 magnitude earthquake off Aomori”
Japan Meteorological Agency – Earthquake Information and Evaluation (Hokkaido–Sanriku Region)
