5.3 earthquake shakes Northern California

An earthquake with a preliminary magnitude of 5.3 struck in the Pacific Ocean about 45 miles west-northwest of Petrolia, at 11:21 p.m. Saturday, the U.S. Geological Survey said.   

California earthquake alerts: How to get notified before a quake strikes

After a 7.0 magnitude earthquake rattled areas near Humboldt County and prompted tsunami fears Wednesday morning, residents are being reminded again to not let these earthquakes "catch you off guard" by staying alert and in the know with earthquake warning systems.