But the Japan Meteorological Agency also said the magnitude 7.6 quake which struck at 11:15 pm on Monday (1415 GMT) off the coast of the Aamori region raised the chances of similar or larger tremors in the coming days.

The injured included one person seriously hurt in the main northern island of Hokkaido, according to the Fire and Disaster Management Agency.

In Hokkaido, an AFP reporter said the ground shook violently for around 30 seconds as smartphone alarms rang to alert residents.

Live footage showed shattered glass fragments scattered across roads.

Some 2,700 homes in Aomori were without power, Kyodo News reported in the hours after the quake, and there were numerous reports of fires.

Initially the JMA warned of tsunamis up to three metres (10 feet) could hit, which could have caused major damage, and thousands of residents were urged to go to safe places.

In the end the biggest waves recorded measured up to 70 centimetres and after several hours the warnings were lifted.

Public broadcaster NHK cited a hotel employee in the city of Hachinohe in Aomori as saying there had been some injuries as a result of the quake.

Shinkansen bullet-train service was suspended in some areas while engineers checked for any damage to the tracks.

Shortly after Monday's earthquake, Tohoku Electric Power said no abnormalities were detected at its Higashidori nuclear power plant in Aomori and its Onagawa facility plant in the Miyagi region.

Prime Minister Sanae Takaichi early Tuesday urged residents to be careful.

"Please listen to information from the JMA or local governments for about a week and check if furniture is fixed .... and be prepared to evacuate when you feel shaking," she said.

- 'Megaquake' -

In 2011, a magnitude-9.0 quake triggered a tsunami that left 18,500 people dead or missing and caused a devastating meltdown at the Fukushima nuclear plant.

Japan sits on top of four major tectonic plates along the western edge of the Pacific "Ring of Fire" and is one of the world's most tectonically active countries.

The archipelago, home to around 125 million people, experiences around 1,500 jolts every year.

The vast majority are mild, although the damage they cause varies according to their location and depth below the Earth's surface.

Quakes are extremely hard to predict, but in January a government panel marginally increased the probability of a major jolt in the Nankai Trough off Japan in the next 30 years to 75-82 percent.

The government then released a new estimate in March saying that such a "megaquake" and subsequent tsunami could cause as many as 298,000 deaths and damages of up to $2 trillion.