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)
Understanding the Megaquake Advisory System
Japan’s unique megaquake advisory system was developed to minimize casualties and improve public preparedness for seismic events. These advisories are rooted in decades of seismic research and historical data, leveraging advanced predictive models to assess the likelihood of major tremors following significant earthquakes. The system is particularly critical for regions like the northeastern Pacific coast, which sits along the volatile Ring of Fire tectonic zone.
Experts caution, however, that forecasting earthquakes remains a complex science with inherent uncertainties. “While our models can identify elevated probabilities, predicting the exact timing and magnitude of future quakes is still beyond the reach of current technology,” said Dr. Hiroshi Tanaka, a seismologist at the Earthquake Research Institute at the University of Tokyo.
Economic and Psychological Impacts of Advisory Measures
Extended megaquake advisories can also have ripple effects beyond immediate safety concerns. Businesses in coastal regions often see reduced foot traffic, as residents prioritize evacuation readiness over routine activities. Additionally, prolonged periods of heightened vigilance can lead to psychological stress for communities already familiar with the trauma of past disasters. Mental health professionals have highlighted the importance of providing accessible counseling resources during such advisories to mitigate long-term emotional strain.
Despite these challenges, experts commend Japan’s proactive approach to disaster management. “Japan’s ability to mobilize communities and maintain orderly responses during crises sets a global benchmark,” said Dr. Akiko Nakamura, a disaster resilience specialist at the International Institute for Disaster Risk Reduction.
Next Steps for Preparedness
As Japan steps down from the recent advisory, officials are urging residents to stay informed about emergency protocols and participate in regular disaster drills. Municipalities in northeastern Japan continue to provide educational workshops and distribute updated preparedness kits to ensure readiness for future seismic events. With advancements in early warning technology and community engagement, Japan remains committed to safeguarding lives amid its ever-present earthquake risks.
