The quake struck in the Pacific off Chiba prefecture -- 96 kilometres (60 miles) east of the capital -- and was felt across large areas of eastern Japan, the USGS said.

There were no reports of injuries or damage following the tremor, which struck at a shallow depth of 25 km at 12:52 pm (0352 GMT), police and local government officials said.

No tsunami warning was issued but the Japan meteorological agency warned of a possible change in sea levels.

A series of major quakes have jolted the country since a 9.0 magnitude earthquake and tsunami devastated northern Japan on Friday, leaving more than 11,000 people dead or missing.

earlier related report
Japan quake called 1,000-year event
London (UPI) Mar 15, 2011 - A British seismologist says tsunamis on the scale of the one that hit northeast Japan last week may strike the region about once every 1,000 years.

Roger Musson, head of seismic hazard at the British Geological Survey, said there were similarities between the last week's disaster and another giant tsunami that hit the Sendai coast in 869, the BBC reported Tuesday.

Undersea earthquakes causing tsunamis in this part of Japan are not unusual, he said, and offshore temblors in the 19th and 20th centuries sent large waves against this area of coastline.

However, previous research by Japanese scientists shows that in the 869 "Jogan" disaster, tsunami waters moved some 2 1/2 miles inland, causing widespread flooding, as they did following the recent 9-magnitude earthquake.

Analysis of sediments from the Sendai coastal plain indicate the medieval-era tsunami was probably triggered by an 8.3-magnitude offshore quake.

Evidence of two earlier tsunamis on the scale of the Jogan disaster suggested there had been three massive events in the last 3,000 years.

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