An earthquake measuring 6.3 on the Richter scale occurred offshore near Chiba Prefecture in eastern Japan at 8:08 a.m. local time Tuesday, according to the Japan Meteorological Agency.

The earthquake poses no tsunami risk, the agency said.

The epicenter of the quake was located some 30 km under the sea of the eastern prefecture in eastern Honshu, said the agency.

There were no immediate reports of casualties or damage to properties.

Runways at Narita airport, an international gateway near Tokyo, was closed for safety checks following the quake, authorities said.