Magnitude 6.8 Earthquake Rocks Northwestern Japan, Tsunami Warning Issued
— Yamagata, Japan
A tsunami warning has been issued after a magnitude 6.8 earthquake struck close to the coast of Japan.
There were no immediate reports of casualties, but the country's Meteorological Agency issued a warning for a 0.2 - 1 metre tsunami along the northwest coast of the main island of Honshu.
The quake struck around 30 miles southwest of the city of Sakata at 10.22pm on Tuesday, the agency reported, with the coastal areas of Yamagata and Niigata prefectures and the Noto area in Ishikawa Prefecture receiving tsunami advisories.
The quake's epicentre was fairly shallow, about six miles below the sea's surface.
Shallow quakes tend to cause more damage on the Earth's surface, but the agency said the expected "fluctuation" of waves was unlikely to cause damage.
A map provided by the USGS showing the location of the earthquake (USGS) All seven reactors at the Kashiwazaki-Kariwa nuclear plant in Niigata were off line and no abnormalities were reported.
This is is a developing story with more information to follow.