TOKYO - A big quake off northern Japan left at least 30 injured, authorities said Tuesday, damaging roads and leaving thousands without power in freezing temperatures.
The Japan Meteorological Agency said the magnitude 7.5 quake at 11:15 pm on Monday (1415 GMT) -- downgraded from 7.6 initially -- raised the chances of similar or larger tremors in the coming days.
Prime Minister Sanae Takaichi said 30 people were injured in the quake off the coast of the Aamori region, which triggered tsunami waves up to 70 centimetres (28 inches) high.
The injured included one person seriously hurt in the main northern island of Hokkaido, according to the Fire and Disaster Management Agency.
Footage showed several crevasses in roads and at least one car in a hole, with broken glass from windows scattered on roads and pavements.
Initially there were reports of several fires. Government spokesman Minoru Kihara said Tuesday that was one confirmed blaze at a house.
Some 28,000 people were advised after the quake to evacuate from their homes, emergency services said, and media reports said some makeshift shelters were full.
With temperatures around freezing point, some 2,700 homes in Aomori were without power, Kyodo News reported in the hours after the quake.
But by Tuesday morning electricity had been restored to most areas, with fewer than 40 homes still without power, according to utility providers.
At first the JMA warned of tsunamis up to three metres (10 feet), 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.
Shinkansen bullet-train service was suspended in some areas while engineers checked for any damage to the tracks.
No abnormalities were detected at the Higashidori nuclear power plant in Aomori or the Onagawa facility in nearby Miyagi, operator Tohoku Electric Power said.
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.