A strong earthquake centred off the coast of northeastern Japan shook buildings as far away as Tokyo and led to a tsunami warning for coastal areas.
The earthquake hit in the same area as a devastating quake and tsunami in March 2011.
The earthquake in 2011 killed nearly 20,000 people and triggered the world's worst nuclear crisis in 25 years.
The quake had a preliminary magnitude of 7.3, the US Geological Survey said, adding that there was no risk of a widespread tsunami.
The quake measured a "lower five" on Japan's scale of one to seven in Miyagi prefecture.
This measurement means there might be some damage to roads and houses that are less quake resistant.
The scale measures the amount of shaking and in that sense gives a better idea of possible damage than the magnitude.
The quake registered a "four" in Tokyo.
A warning of a one-metre tsunami was issued for the coast of Miyagi.
Much of the area is still free of people.
Prime Minister Yoshihiko Noda cancelled campaigning in Tokyo ahead of a 16 December election and was on his way back to his office, but there was no immediate plan to hold a special cabinet meeting.
Public spending on quake-proofing buildings is a big election issue.
The United Nations atomic agency has said it had been informed by Japanese authorities that no problems had been detected at nuclear power plants in the region nearest to the epicentre of today's earthquake.