Initial reports scored it a magnitude 5.4. It has since been upgraded to a 6.0, though as the map above [ source ] states, the data has yet to be reviewed by human. [Update: It was dowgraded ever so slightly to a 5.9.]

This map suggests the temblor occurred along the Mendocino fault zone. The USGS recorded it at a depth of 6.8 miles. Lots more data here .