TOKYO - An earthquake with a preliminary magnitude of 5.6 on the Richter scale rocked eastern Japan early Friday but there were no immediate reports of injuries or damage.
The quake jolted the Izu Peninsula and Tokyo at 2.50am (1750 GMT Thursday), the Japan Meteorological Agency said.
Its focus was about 10 kilometers (six miles) below the Pacific Ocean, east of the peninsula, Kyodo News reported the agency as saying.
A weaker tremor with a preliminary magnitude of 3.9 occurred in the same area 16 minutes later. No tsunami warnings were issued.
Japan, which lies at the junction of four tectonic plates, has about 20 percent of the world's powerful earthquakes, frequently jolting Tokyo and other major cities.
On Thursday a moderate earthquake measuring 4.2 on the Richter scale occurred in the central prefecture of Tochigi, 100 kilometers (60 miles) north of Tokyo.
04/20/2006 19:00 GMT