7.5-magnitude earthquake strikes off Japan's northern coast, megaquake alert issued

A powerful earthquake of magnitude 7.5 struck off the coast of Aomori prefecture in Japan, near Hokkaido, on Dec. 8 evening.

At least 30 people have reportedly been injured, and tsunami waves of up to 70cm were recorded.

Tsunami warnings have been downgraded as of Dec. 9 morning, but Japanese authorities have issued a precautionary alert for a megaquake of magnitude 8 or higher.

Tsunami waves recorded

According to the Japan Meteorological Agency, the epicentre of the earthquake is located off the east coast of Aomori prefecture.

The earthquake was recorded at 11:15pm local time (10:15pm Singapore time).

It was followed by a 5.6-magnitude aftershock,  The New York Times wrote.

The quakes triggered tsunami warnings for Aomori, Iwate and Hokkaido prefectures, while tsunami advisories were issued for Miyagi and Fukushima prefectures.

In Hokkaido, a 50cm tsunami swept up the shore of Urakawa Town, while a 40cm wave was observed at Mutsuogawara Port in Aomori prefecture, NHK reported.

A 70cm wave was also recorded in Kuji Port in Iwate.

Parts of the affected areas were also plunged into darkness due to power outages.

About 800 households in Iwate were affected.

Fires were also reported in affected areas.

Japan: The moment the M7.6 earthquake hit Hachinohe City - captured from the Aomori Asahi Broadcasting Hachinohe branch office 👀pic.twitter.com/ppJdYIxwoo

— Volcaholic 🌋 (@volcaholic1) December 8, 2025

バイクは無事でよかった

バイク「は」！

我が家は津波警報が出る前に4つの水槽が大津波よ

右水槽見てわかるけど地震起きても寝ること優先で陰に行くから

ナマズが暴れたら地震来るは嘘 pic.twitter.com/01rTdPqpz8

— Rじゃない方のらいだー (@not_Rrider) December 8, 2025

At least 30 injuries reported

According to NHK, Shinkansen bullet train services have been suspended between Morioka and Shin-Aomori stations and is due to resume after checks for damages.

About 90,000 residents were evacuated, and at least 30 people have been injured so far, the BBC wrote.

Most of the injured were struck by falling objects, Associated Press reported, citing NHK.

While the earthquake was initially recorded at 7.6, it was later downgraded to 7.5.

The epicentre's depth was also slightly deeper than expected at 54km as opposed to 50km.

All tsunami advisories were lifted by 6:20am local time on Dec. 9.

No abnormalities at Fukushima Daiichi nuclear plant

Tokyo Electric Power Company, which oversees the Fukushima Daiichi and Daini nuclear power plants, said that no abnormalities were observed at the plants, according to NHK.

The release of treated and diluted water from the Fukushima Daiichi plant, which was severely damaged during the 2011 earthquake and tsunami, was halted at 11:42pm local time.

Megaquake alert

Following Monday's seismic activity, Japan's Meteorological Agency issued an alert for a potential megaquake with magnitude 8 or higher off the coast of Hokkaido and Sanriku.

It explained that the region where Monday's 7.5-magnitude earthquake occurred is a probable source of megaquakes.

The probability of a megaquake following an earthquake in this area is "relatively high", or about 1/100 based on records.

The powerful 9.0-magnitude Tōhoku earthquake that struck on Mar. 11, 2011, was preceded by a 7.3-magnitude earthquake just two days earlier.

It added that the advisory did not mean that a megaquake would certainly occur, but advised those affected to take precautions.

Top image via ANNnews / YouTube