Japan Issues Megaquake Alert, Warns of Possible 98-Foot Tsunami

Japan has issued a rare megaquake advisory following a powerful 7.6-magnitude earthquake that struck the country’s eastern coast on Monday, raising fears of a far stronger tremor that could trigger a devastating tsunami.

The Japan Meteorological Agency (JMA) said the quake has increased the likelihood of a magnitude-8 or stronger earthquake occurring within the next week along the Japan Trench and the Chishima Trench off Hokkaido. Authorities warned such an event could unleash a tsunami as high as 98 feet, with catastrophic consequences.

According to government estimates, a major offshore megaquake in the Hokkaido–Sanriku region could kill as many as 199,000 people, destroy or severely damage up to 220,000 homes and buildings, and cause economic losses estimated at 31 trillion yen (about $198 billion). Officials also warned that winter conditions could leave up to 42,000 people at risk of hypothermia in the aftermath.

Monday’s earthquake injured more than 30 people and sparked at least one residential fire. While major damage was avoided, the scale of the quake prompted heightened concern among disaster authorities.

Prime Minister Sanae Takaichi said the government is closely monitoring the situation and urged the public to remain alert and follow official guidance. The JMA has called on residents, especially those in coastal areas, to be prepared to evacuate immediately if strong shaking or tsunami warnings occur.

The advisory covers a coastal stretch of nearly 800 miles, from Hokkaido in the north to Chiba Prefecture near Tokyo. It marks the first time Japan has issued a warning under the megaquake advisory system introduced in 2022.

Officials stressed that while a larger quake is not certain, preparedness could be critical in reducing casualties if the worst-case scenario unfolds.