Tsunami warnings have been issued for parts of the Northern California and Oregon coastlines after a 7.0-magnitude earthquake struck off the California coast.

The earthquake hit at 10:44 a.m. PT about 60 miles southwest of Ferndale, California, the US Geological Survey said.

Tsunami activity could impact the California cities of San Fransisco, Crescent City and Fort Bragg, and the Oregon cities of Port Orford, Brookings and Charleston, according to the National Weather Service.

“Tsunami warnings mean that a tsunami with significant inundation is possible or is already occurring. Tsunamis are a series of waves dangerous many hours after initial arrival time. The first wave may not be the largest,” the National Weather Service said.