ISTANBUL 

Japan cautioned against "strong quakes for a week," after a 7.6 magnitude earthquake struck off Japan's northern coast, the US Geological Survey reported late Monday.

This is the first time Japan issued a Hokkaido-Sanriku offshore quake alert amid a larger risk.

After the quake, recorded at around 11.15 pm local time on Monday (1415GMT), Tokyo issued tsunami warnings and advisories, urging people to seek safety, while the warnings were later lifted.

The earthquake was measured at a depth of 53.1 kilometers (nearly 33 miles) off the coast of northern Aomori prefecture, the US Geological Survey said.

Following the strong quake, Japan also had 5.5 and a 5.0 magnitude jolts, it added.

The Japanese Meteorological Agency later revised the earthquake's magnitude to 7.5, according to the Kyodo News.

Tsunami warnings had been initially issued for prefectures Aomori, Iwate, and Hokkaido's Central Pacific Coast, with tsunami advisories for prefectures Miyagi, Fukushima, and Hokkaido's West and East Pacific Coast.

Later, tsunami warnings for all regions were downgraded to an advisory level.

Waves up to 70 centimeters (27.5 inches) were reportedly seen in Iwate, 50 centimeters (19.6 inches) in Hokkaido, and 40 centimeters (15.7 inches) in Aomori.

One person was injured after a road collapsed in Aomori, and two people in Hokkaido were injured in falls due to the strong jolt.

The earthquake also caused power outages in about 2,700 homes in Aomori. Two separate fires were reported in the area, and it is being investigated whether they are related to the tremors.

No abnormalities have been reported by nuclear plants in Hokkaido or in the northeastern prefectures of Aomori, Miyagi, and Fukushima.

Authorities have halted Tohoku Shinkansen train services in northeastern Japan due to the quake.

The government has also set up an emergency response room in the Prime Minister's Office in response to the earthquake, the office said through US social media company X.