Japan earthquake

An earthquake with a preliminary magnitude of 4.6 hit eastern Japan on Thursday, according to the Japan Meteorological Agency. There were no immediate reports of damage.

The agency said that the epicentre of the quake was located to the north of Tokyo in Saitama prefecture. The quake, which hit at 9.27am (8.27am, Singapore time), was measured at a depth of 50 km.

The authorities said that they did not issue any tsunami warning.

Japan is located at the junction of four tectonic plates and earthquakes are quite common in the country. The country sits on one of the world's most seismically active zone known as the Pacific Ring. But rigid building codes and strict enforcement mean even strong tremors often do little damage.

Reports say Japan accounts for about 20 percent of the world's earthquakes of magnitude-6 or greater.

On March 11, 2011, the north-east coast was struck by a magnitude 9 earthquake, the strongest quake in Japan on record, and a massive tsunami. Those events triggered the world's worst nuclear crisis since Chernobyl a quarter of a century earlier.