Northern California has been hit with a tsunami warning after being rocked by a magnitude-7.0 earthquake, with locals warned to flee inland.
The tremor struck near the coastal town of Eureka at 10:44 a.m. PST on Thursday, promoting a tsunami warning from the National Weather Service.
It was initially reported as a 6.6 quake but was quickly upgraded by USGS.
The tsunami warning is in effect from the Davenport coast to the Oregon-California border, including the San Francisco Bay area.
A potential killer wave is forecast to make landfall around 12:15pm PST.
That area sits around 45 miles southwest of Eureka.
Residents are advised to evacuate inland or to higher ground, move out of the water and off the beach and do not return until local emergency officials declare it safe.
Moments after the quake, a ‘significant’ aftershock that measured 5.8 on the Richter scale rocked Cobb in California.
Residents living along the Northern California coast and in the Golden State’s Central Valley reported feeling a strong shaking throughout the geological event.
Images shared on social media showed water splashing in and out of a swimming pool, while light fittings swayed in a supermarket in Davis.
California is bisected by the San Andreas Fault, the boundary between the Pacific and North American tectonic plates.
The 750 mile fault’s northern end terminates offshore near Eureka.
Earthquakes occur along the border between two tectonic plates – such as the San Andreas fault.
Tectonic plates are constantly moving but sometimes they get stuck together by their edges.
Eventually, the stress of the moving plates will unstick them, with the energy released by this unsticking causing earthquakes.
California has long been braced for a historic earthquake locals have nicknamed ‘The Big One.’
Seismologists say the San Andreas fault produces a quake of magnitude 7.8 or above every 150 to 200 years that would occur inland, rather than offshore like Thursday’s tremor.
California was rocked by a devastating 6.9-magnitude tremor dubbed the Loma Prieta earthquake in October 1989 that killed 63, injured more than 3,700 and caused $6 billion worth of damage.
And in April 1906, San Francisco was famously-destroyed by a 7.9-magnitude whose epicenter sat just two miles off the coast of the City by the Bay.
More than 3,000 people were killed and 80 percent of the city’s buildings were destroyed.
Experts warn the long-feared ‘Big One’ would have an epicenter that sits inland and produce far worse devastation.