Just how frequently do >M7 earthquakes occur in our state? Not very often. There have only been 25 in the past 209 years! Bonus question: Do they all occur along the San Andreas Fault? Nope. This one certainly didn't. The San Andreas Fault runs along the coast of Northern California and continues on land thru the southern portion of the state.

Two Mainshocks!

Want an update to better understand the magnitude of yesterday's M7.1 mainshock? Debi Kilb has more annotation for you.  Click here.

CBS News Channel 8 met with Debi Kilb at IGPP to learn more about the Ridgecrest quake. The largest California quake in 20 years occurred along an unknown fault line and offers much to be studied.

IGPP Seismologist Debi Kilb annotated this ANZA network-generated image to better explain yesterday's Independence Day M6.4 earthquake in Ridgecrest, CA.

Learn more about the Ridgequest M6.4 earthquake that shook some 4th of July festivities.  Visit the Vernon Lab's Array Network Facility (ANF) website for an illustrated view of yesterday's seismic activity: http://anf.ucsd.edu/spevents/display.php?event=11974527.