At least six people have died in an earthquake that struck Japan on New Year's Day as authorities on Tuesday struggled to assess the full extent of a disaster that wrecked buildings and roads and left thousands without power in freezing temperatures. 

The quake with a preliminary magnitude of 7.6 struck in the middle of the afternoon on Monday, prompting residents in some coastal areas to flee to higher ground as tsunami waves about 1 metre (3.3 ft) high hit Japan's western seaboard.

(With inputs from agencies)