TOKYO, Dec. 10 (Xinhua) -- At least 52 people were injured in northeastern and northern Japan following a 7.5 magnitude earthquake that struck the region, local media reported Wednesday.

Authorities in Aomori, Hokkaido and Iwate prefectures have confirmed 37, 11 and 4 people injured, respectively, Kyodo News reported.

Over 300 schools in total were closed on Tuesday in Hokkaido, Aomori, Iwate, Miyagi and Fukushima prefectures, but most of the schools reopened on Wednesday except for some schools damaged by the quake, the report said.

The temblor occurred at 11:15 p.m. local time on Monday off Aomori's Pacific coast, measuring upper 6 on Japan's seismic scale of 7 in parts of Aomori, according to the Japan Meteorological Agency (JMA).

The powerful quake prompted the JMA to issue tsunami warnings for Iwate Prefecture and parts of Hokkaido and Aomori prefectures. Various ports confirmed the arrival of tsunami waves, with Kuji Port in Iwate Prefecture recording a 70-cm wave.

Shortly after the quake, the weather agency issued an alert for a potential mega quake along the trench off the Pacific coast of northeastern Japan, noting there is a one-in-100 chance that a magnitude-8 or larger quake could occur within the coming week.

The advisory covers areas from Hokkaido to Chiba Prefecture, and is the first issued for the region since the mega-quake warning category was introduced in December 2022.

Weather officials advised people to remain vigilant through next week, although a precautionary evacuation is not required. ■