Northern California hit with 5.6 magnitude earthquake

A rural area of Northern California also experienced tremors, reportedly some of the strongest earthquake to hit the area since 1940, causing some injuries but no major damage.

The 5.6 magnitude earthquake hit Mendocino County, 225 kilometres northeast of San Francisco.

The epicentre of the quake was about 12 kilometres northwest of the agricultural town of Willits, according to the U.S. Geological Survey.

Three other quakes under a 2.7 magnitude struck near the epicentre within an hour.

A Mendocino County spokesperson says local hospitals had reported some injuries but offers no details on their nature or extent.

The quake triggered power outages affecting more than 6,000 residents of six towns near the epicentre.

Local residents report picture frames being knocked off walls and shelves rattling.

Authorities are encouraging people to stay off the highways and roads to allow work crews to inspect for damage and make repairs.