Tsunami alert as a quake strikes off Japan
A tsunami alert has been issued in Japan after a powerful earthquake struck near the Okinawan coast.
The Japan Meteorological Agency gave the strength as 6.9 while the US Geological Survey put it at 7.3.
It struck at 0531 (2031 GMT), 84km (52 miles) east of Naha, on the island of Okinawa, 29km (18 miles) below the seabed, Reuters news agency reports.
There were no immediate reports of casualties or damage in the country, which is often hit by earthquakes.
In 1995, a magnitude-7.2 quake in the port city of Kobe killed 6,400 people.
On its website, the Japan Meteorological Agency initially warned of a tsunami of 2m (7ft) in height but later revised this down to about 0.5m (1ft 7in).
For a tsunami to be classed as "major", it has to be at least 3m.
BBC News website reader Ivan Brackin, who lives on Yoron Island, said it was the biggest quake he had felt in his 40 years in Japan but there had been no visible effects in his area.
"We're 30 yards [metres] from the sea and no sign of a tsunami," he said.
"I woke up to violent shudders that lasted about six seconds then a pause followed by a couple of sharp jumps. Jumpers are the most dangerous so that sent me under the desk."