(Barrons) – A powerful earthquake struck Thursday off the coast of northern California, sparking a tsunami warning, US seismologists said.

The 7.0-magnitude quake was recorded at a depth of just 10 kilometers (six miles), almost 100 kilometers west-southwest of Ferndale, according to the United States Geological Survey.

“Based on preliminary earthquake parameters… hazardous tsunami are possible for coasts located within 300 KM of the earthquake epicenter,” said a warning issued by the National Weather Service’s Tsunami Warning Center in Honolulu.

The warning noted that no areas had yet experienced any waves, but that anyone near a coastline should be alert to the possibility of danger.

Smartphone users received warnings urging them to move to higher ground immediately, the San Francisco Chronicle reported.

“A series of powerful waves and strong currents may impact coasts near you,” the warning said.

“You are in danger. Get away from coastal waters.”