USGS is reporting significant seismic activity in California this morning with more than 100 earthquakes being reported across northern California. The largest of the bunch is a magnitude 7.0 event which struck west-northwest of Petrolia, California on the northern coast of the state. Also of note is a significant swarm of earthquakes striking just south of Clear Lake and north of San Francisco, where 77 earthquakes there alone struck within the last 24 hours.

Hundreds of people across California and Oregon have already reported to USGS they felt the strong off-shore earthquake. USGS continues to take people’s reports through their “Did you feel it?” reporting tool on the USGS website located here: https://earthquake.usgs.gov/earthquakes/eventpage/nc75095651/tellus

The largest earthquake triggered a Tsunami Warning which remains in effect as of the publishing of this article; much of northern California and Oregon coasts are within that warning zone.

USGS says there is a better than 99% chance that there will be a magnitude 3.0 or greater aftershock from the 7.0 event, which was initially reported as a magnitude 7.3 quake. USGS says there’s an 87% chance that a magnitude 4 or greater aftershock will strike; the chance for a 5 or greater magnitude aftershock is 36%.