7.7 Magnitude Earthquake Hits Japan: Tsunami and Megaquake Alert Issued

A 7.7 magnitude earthquake on Monday off northern Japan sparked a short-lived tsunami alert and an advisory of a slightly higher risk of a possible megaquake for its coastal areas.

The Cabinet Office and the Japan Meteorological Agency said there was a 1% chance for a megaquake, compared to a 0.1% chance during normal times, in the next week or so following the quake near the Chishima and Japan trenches.

Officials said the advisory was not a prediction but urged residents in 182 towns along the northeastern coasts to raise their preparedness while continuing their daily lives.

Prime Minister Sanae Takaichi urged residents to confirm their designated shelters and evacuation routes and to check emergency food and grab bags so they can run immediately when a megaquake hits. “The government will do its utmost in case of an emergency,” she told reporters.

Authorities have also raised concerns in recent years over the risk of a strong earthquake along the Nankai Trough, an 800km (497-mile) undersea trench south of Japan where the Philippine Sea plate is sliding beneath the continental plate.