A 6.4 magnitude earthquake hit Northern California early Tuesday.
The quake occurred near Eureka, causing power outages for thousands.
The earthquake struck about 7.4 miles west-southwest of Ferndale.
Over a dozen smaller earthquakes followed in the region.
It is not yet known if anyone was injured in the quake.
Humboldt County's Office of Emergency Services urged residents to only call 911 in an emergency.
The National Weather Service's tsunami warning system has not issued a tsunami warning.
Many people were alerted to the earthquake by the MyShake app.
This quake happened almost exactly a year after a 6.2 magnitude earthquake struck offshore in Cape Mendocino.
The previous earthquake caused no major damage or injuries.