USGS records Magnitude 7.6 quake off Aomori as Japan issues tsunami alerts

The United States Geological Survey (USGS) recorded a Magnitude 7.6 earthquake off the coast of Japan on Monday, 8 December 2025. The offshore quake struck at 21:15 Western Indonesia Time, or 23:15 local time, 73 kilometres northeast of Misawa.

USGS data placed the epicentre at a depth of 53.1 kilometres. The strongest shaking reached a VII on the Modified Mercalli Intensity (MMI) scale, with the potential to damage well-built structures and prompt residents to rush outdoors.

According to Japan Times, the Japan Meteorological Agency (JMA) issued an immediate tsunami warning for parts of the country’s northeastern coastline.

The warning forecast waves reaching up to three metres along the coasts of Hokkaido, Aomori and Iwate prefectures.

JMA reported that the earthquake struck east of Aomori Prefecture at approximately 11:15 p.m. local time. Authorities urged residents in affected areas to evacuate immediately to higher ground.

Forecasts indicated the highest waves—up to three metres—along the Iwate coast and the central Pacific coastline of Hokkaido. One-metre waves were expected in Miyagi and Fukushima prefectures and on the Sea of Japan side of Aomori.

Local media reported that a tsunami wave of about 40 centimetres was observed at Mutsu Ogawara Port in Aomori Prefecture at 11:43 p.m. Monitoring systems continue to track water level changes along multiple coastlines.

JMA recorded a seismic intensity of upper-6 on the Japanese shindo scale in the city of Hachinohe, Aomori Prefecture. This level indicates violent shaking capable of seriously damaging walls, roofs and other structural elements.

JMA placed the quake’s depth at around 50 kilometres, consistent with initial readings by international monitoring agencies. The agency warned that strong aftershocks could follow in the hours ahead.

In response to the earthquake and tsunami alerts, the government activated a crisis management office at the Prime Minister’s Office. Authorities are coordinating emergency communication, coastal surveillance and readiness of evacuation facilities.

Transport operators in northern Japan began precautionary inspections of rail lines, ports and coastal infrastructure. Airports in the area remained operational but were placed under heightened monitoring.

Further updates are expected as real-time observations from tide gauges, seismic instruments and local authorities become available. As of the latest reports, there were no immediate confirmations of casualties or significant structural damage.