Japan quake magnitude raised to 9.0 from 8.9: USGS

The US Geological Survey on Monday raised the magnitude of the deadly earthquake that struck offshore northern Japan on Friday to 9.0 from 8.9.

Independently, Japanese authorities had also updated their estimate of the quake to 9.O, the USGS said on its website.

"This magnitude places the earthquake as the fourth largest in the world since 1900 and the largest in Japan since modern instrumental recordings began 130 years ago," it said in a message posted at 5.35pm (2135 GMT).

The agency said revisions of magnitude were common after earthquakes and happened as more data became available and more analysis was performed.

Officials say at least 10,000 people were killed in the  earthquake and tsunami that followed it.