Japan Issues Highest-Level Megaquake Advisory After 7.5 Earthquake

Table of Contents

• Overview
• What Triggered the Advisory
• Current Impact and Damages
• Risk of a Larger Earthquake
• Government Response
• Advice for Residents
• Useful External Resources

Overview

Japan has issued its highest-level earthquake advisory after a powerful 7.5-magnitude quake struck off the coast of Aomori on Monday night. While the damage was limited, officials warn there is a slightly increased chance of a magnitude-8 or larger earthquake over the next week. The advisory covers areas from Chiba to Hokkaido along the Pacific coast.

What Triggered the Advisory

The quake struck around 11:15 p.m., about 80 km off Aomori’s coastline. Tsunami waves up to 70 cm were recorded in Kuji port, with smaller waves affecting nearby towns. The Japan Meteorological Agency (JMA) said the earthquake temporarily increased stresses along the Japan Trench and Chishima Trench, prompting the highest-tier alert.

Current Impact and Damages

Damage from the quake was moderate. At least 34 people suffered mostly mild injuries. Around 800 homes experienced temporary power outages, and Shinkansen services were suspended overnight. Part of a terminal at New Chitose Airport was closed after ceiling panels fell. Nuclear facilities reported no abnormal radiation levels, though a small amount of cooling-water spillage occurred at the Rokkasho plant.

Японд өчигдөр шөнө 7.5 баллын газар хөдлөлт болжээ.. 😳 pic.twitter.com/mL4jrJlN9L

— Kizuna 🇲🇳 (@KizunaJpp) December 9, 2025

Risk of a Larger Earthquake

Officials stress that the advisory is not a prediction. The probability of a magnitude-8 or larger quake is estimated at about 1%, but this is higher than normal. The alert covers 182 municipalities along Japan’s northeastern Pacific coastline. Authorities noted that the 2011 magnitude-9 earthquake also followed a strong offshore quake two days earlier, prompting extra caution.

Government Response

Prime Minister Sanae Takaichi activated an emergency task force to coordinate assessments and response efforts. Defence teams deployed helicopters to survey damage, and municipalities prepared shelters and communication systems. The government urges people to stay calm but prepared.

Advice for Residents

• Prepare an emergency bag with essentials for a few days.
• Keep shoes near your bed and sleep in clothes suitable for quick evacuation.
• Discuss evacuation routes with family members.
• Secure heavy furniture to prevent injuries during aftershocks.
• Follow updates from local authorities and official channels.

Useful External Resources

• Japan Meteorological Agency (JMA)
• Japan Disaster Management
• USGS Earthquake Information

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