( AFP ) - A moderate earthquake measuring 4.9 on the Richter scale jolted the Tokyo region early Monday, swaying buildings, the Japan Meteorological Agency said.
It struck on the start of the day Japan was introducing a world-first early warning system for earthquakes, which gives public utilities and others advance notice that a tremor will strike.
There were no immediate reports of damage from the quake, which struck at 2:21 am (1721 GMT) in Kanagawa prefecture just south of the Japanese capital.
However two elderly people were hospitalised after falls, and some train stations were shut, the Kyodo news agency reported.
Television footage showed a bridge trembling from the quake, which could also be felt in the heart of Tokyo.
Japan experiences 20 percent of the world's powerful earthquakes.