A powerful earthquake jolted northwestern Japan on Tuesday night, and officials warned of a tsunami up to one meter (3.3 feet) high along parts of the coast.

Japan’s Meteorological Agency said the quake registered magnitude 6.8 and was located off the western coast of Yamagata about 50 kilometers (30 miles) southwest of the city of Sakata.

It said the quake was fairly shallow, about 10 kilometers (6 miles) below the sea’s surface. Shallow quakes tend to cause more damage on the Earth’s surface.

The agency predicted a tsunami as high as 1 meter (yard) along the coast of the northwestern prefectures of Yamagata, Niigata and Ishikawa.

Kyodo News agency said service was suspended on two bullet train lines to check for damage.

All seven reactors at the Kashiwazaki-Kariwa nuclear plant in Niigata were off line and no abnormalities were reported.

“Due to the risk of ongoing strong currents, do not enter the sea or approach coastal regions until the advisory is lifted.

“Slight sea-level changes may be observed in coastal regions, but no tsunami damage is expected.”

The US’ National Oceanic and Atmospheric Administration (NOAA) said the tsunami threat did not extend to Hawaii or Guam.

In an information statement it said: “An earthquake wth a preliminary magnitude of 6.8 occurred near the west coast of Honshu, Japan at 10.22pm CHST (2.22pm BST) on Tuesday June 18

Japan is one of the most earthquake- and tsunami-prone areas in the world. On March 11, 2011, a magnitude 9.0 offshore quake hit the northeast coast, causing a tsunami that took more than 18,000 lives and triggered a nuclear disaster at the Fukushima power plant.

This article was edited by TheBL.