Japan issues megaquake advisory after 7.5-magnitude quake
10 Dec 2025

Japan has issued a megaquake advisory after a 7.5-magnitude earthquake hit off the eastern coast of Aomori, the northernmost prefecture of Honshu on Monday night.

The quake caused minor damage and injuries, with 34 people suffering mostly mild injuries and some roads and buildings sustaining damage.

Officials, however, stressed that the advisory was not prediction and that the likelihood of a magnitude 8 or higher earthquake was just about 1%.

Advisory aims to prepare public for potential megaquake
Public preparedness

The advisory, issued on Tuesday, is aimed at ensuring public preparedness for a potential megaquake similar to the devastating 2011 disaster that killed nearly 20,000 people.

The Japan Meteorological Agency (JMA) said Monday's quake temporarily raised the risk of larger quakes in Hokkaido and the Sanriku coast.

These areas are located above two trenches, the Japan trench and Chishima trench, known for causing large quakes.

2011 quake's aftermath and potential future impact
Historical context

The JMA explained that the magnitude 9.0 quake in 2011 occurred two days after a magnitude 7.3 quake in the Japan Trench off Iwate's eastern coast.

The tsunami from this quake devastated northern coastal towns and damaged the Fukushima Daiichi nuclear power plant.

Another megaquake in Hokkaido-Sanriku could trigger a tsunami up to 30 meters high, kill nearly 199,000 people, destroy up to 220,000 buildings, and cause economic damages of up to ¥31 trillion ($198 billion).

Advisory covers 182 municipalities, urges public preparedness
Advisory details

The advisory covers 182 municipalities from Hokkaido to Chiba prefecture.

Residents have been advised to keep emergency bags with essentials, discuss evacuation plans with family members, sleep in day clothes and not sleep in pajamas, and fix furniture to the floor or wall.

Iwaki city in Fukushima has also urged residents to register for emergency emails while Oarai town officials inspected wireless communication devices.