Japan warns of possible major quake after M7.7 tremor, urges seven prefectures to stay alert until April 27

Japan has issued a warning urging residents in seven prefectures to remain vigilant for a potential major earthquake following a strong tremor off the country’s north, NHK World reported on Tuesday (April 21).

The report said a tsunami warning issued after the quake was later lifted, but the Japan Meteorological Agency (JMA) has cautioned that further large earthquakes could still occur, particularly along two undersea trenches in the Pacific.

The advisory follows a magnitude 7.7 earthquake on Monday (April 20). The JMA said people in affected areas should prepare for disasters and continue monitoring official updates.

The warning covers 182 municipalities across Hokkaido, Aomori, Iwate, Miyagi, Fukushima, Ibaraki and Chiba. Residents are asked to follow guidance until 5.00pm on Monday, April 27, though the notice does not call for pre-emptive evacuation.

Authorities urged households to prepare emergency evacuation kits, secure furniture, and ensure they have adequate food, water and portable toilet supplies. The public was also advised to rely on verified information and avoid sharing misinformation.

NHK World reported that the tsunami warning for parts of Iwate and the Pacific coasts of Hokkaido and Aomori—where waves of up to three metres had been expected—has already been cancelled.