A moderate earthquake measuring 4.5 on the Richter scale shook western Wakayama prefecture early Monday, the Japan Meteorological Agency said.

There were no immediate reports of injuries or damage from the quake that struck at 1:42 am (1642 GMT).

The quake, which happened some 450 kilometers (280 miles) southwest of Tokyo, was 10 kilometers (six miles) deep, the agency said.

Japan lies at the junction of four tectonic plates and has about 20 percent of the world's powerful earthquakes, frequently jolting Tokyo and other major cities.