SAN FRANCISCO, United States (AFP) — A 6.5-magnitude earthquake struck yesterday off the coast of northern California, but there was no tsunami threat, seismologists said.

The US Geological Survey said there was “a low likelihood of casualties and damage” from the earthquake, which hit on the Mendocino fault.

The Pacific Tsunami Warning Centre said there was no tsunami threat.

The epicentre of the quake, which hit at 6:49 am, was located 97 miles (157 kilometres) west of Ferndale, California at a depth of 6.2 miles (10 kilometres), USGS said.

“Overall, the population in this region resides in structures that are highly resistant to earthquake shaking, though some vulnerable structures exist,” it said.

Residents of the area reported feeling the tremor.

“It started rolling and I could feel it,” Pam Cahill, a retired teacher who lives three miles north of Eureka, told the San Francisco Chronicle. “I had time to jump out of bed and crouch down and call the dog before it stopped.”

An aftershock measuring 4.9 rattled the area some 90 minutes after the quake, the USGS reported.

Seismologists say a quake capable of causing widespread destruction is almost certain to hit California in the next 30 years.