A 5.6 magnitude earthquake has hit Tokyo, shaking buildings across the city and causing train services to be suspended.
Radio broadcaster Jason Morrison tweeted events as they happened. He said he felt the earthquake from the high rise hotel he was staying in and that broadcasters were urging people to stay calm.
He added that hotel staff said the earthquake was the biggest they have experienced so far this year.
The earthquake struck 44km north-northeast of Tokyo and was at a depth of 50m.
Japan Meteorological Agency said there is no threat of tsunami from the earthquake, which hit just after midnight local time.
Aaron Low, a student living in Tokyo, said: "I was relatively calm. I thought it was a slow one at first but it got pretty big. We were sent a text message about the earthquake. Buildings were rocking."
Other cities affected by the earthquake included nearby Iwai, Sakai, Ishige and Mitsukaido.
The location of the earthquake was also near to Fukushima, which was devastated by the magnitude 9 earthquake that hit the country in 2011.
Operators of the Fukushima Daiichi nuclear power plant said there were no reports of damage.
Spokesman Keisuke Murakami told AFP: "There was no abnormality in our monitoring at the Fukushima Daiichi nuclear power plant following the earthquake. Also, we have not received any reports of damage from the latest quake."