7 April 2011 15:32 GMT
The BBC has reported that a magnitude 7.1 earthquake has occurred off the east coast of Honshu, 118 km north of Fukushima, 40 km offshore. A tsunami with a wave height of 2m was predicted. Japanese authorities have ordered an evacuation from the zone at risk from the tsunami. Fukushima Daiichi workers were also evacuated. It is reported that there has been no detectable effect at the Fukushima Daiichi nuclear plant, nor at two other nuclear plants in the area.
For comparison the 1989 earthquake that hit San Francisco, was magnitude 6.9.