TOKYO (Kyodo) -- An earthquake with an estimated magnitude of 6.7 hit Tuesday off Japan's northeastern prefecture of Yamagata and a tsunami warning was issued, the weather agency said.
The epicenter of the quake, which occurred at around 10:22 p.m. at a depth of about 14 kilometers, was off the prefecture, the agency said, adding that despite the warning there is no fear of major damage.
The Japan Meteorological Agency said the first small wave of tsunami reached Awashima Island in Niigata Prefecture at 11:05 p.m. and later the coastline of Sakata in Yamagata Prefecture.
There are no immediate reports of major damage.
The quake registered upper 6 on the Japanese seismic intensity scale of 7 in Murakami in Niigata Prefecture.
"It was a shake I had never felt in my life," said a male official at the city, who was sleeping with his child at the time, adding, "At first there was a vertical shake that pushed me up from the bottom, then I felt that the jolt lasted about a minute."
The quake registered lower 6 in Tsuruoka in Yamagata and lower 5 in cities including Yurihonjo in Akita Prefecture, Sakata in Yamagata, and Nagaoka and Kashiwazaki in Niigata.
The Secretariat of the Nuclear Regulation Authority said there are no abnormalities at the Kashiwazaki-Kariwa nuclear complex run by Tokyo Electric Power Company Holdings Inc. The complex's seven units have been idled since March 2012.
Chief Cabinet Secretary Yoshihide Suga, who entered the prime minister's office after 10:40 p.m., said at an urgent press conference he has been informed there are no problems at any of the nuclear plants in Japan.
Prime Minister Shinzo Abe also went to his office following the quake, while the dollar shot up against the yen, coming close to 108.70 yen at one point, compared with 108.25-26 yen at 5 p.m.
Electricity has been cut at nearly 10,000 homes in the two prefectures, according to Tohoku Electric Power Co.
East Japan Railway Co. said it suspended Yamagata, Akita and Joetsu bullet train services, while some highways in the region are closed to traffic.
The coastal region facing the Sea of Japan from Hokkaido to Niigata Prefecture has experienced similar big earthquakes in the past.
Shinji Toda, a professor of seismic geology at Tohoku University said, "Active faults are concentrated (around the area hit by the latest earthquake) and some of them likely moved."
Toda pointed out that there are similarities in scale and mechanism between Tuesday's quake and one that rocked Niigata in 2007.