[Rockhounds] Balanced boulders on San Andreas fault suggest the 'Big One' won't be as destructive as once thought

[Kreigh Tomaszewski]

Tens of thousands of earthquakes rock California each year. Many of these
shakes originate in a boundary between the Pacific and North American
tectonic plates that run through southern California, known as the San
Andreas fault.

Someday, the Mojave section of this fault is expected to unleash a massive
earthquake to rival any other in Los Angeles' past — dubbed the "Big One."
Up to at least a 7.8 magnitude, this earthquake could wreak havoc on much
of Southern California, potentially toppling buildings or triggering
widespread evacuations.

But it turns out this event may not be as destructive as previously
thought, particularly near Los Angeles, according to *research presented on
Dec. 13* <https://agu.confex.com/agu/fm23/meetingapp.cgi/Paper/1303303> at
a meeting of the American Geophysical Union.

Currently, earthquake
<https://www.livescience.com/planet-earth/earthquakes> risk
models are mainly based on extrapolations from limited historical timescale
and ground motion recordings from past quakes. But fortunately, a different
group of sentinels have witnessed and captured data from these temblors for
much longer than humans: rocks.

In California, a cluster of five precariously balanced rocks that stand
just 9.3 miles (15 kilometers) from the fault in northern Los Angeles
county hold clues to how strong shaking has been over the last 50,000 years.

https://www.livescience.com/planet-earth/earthquakes/balanced-boulders-on-san-andreas-fault-suggest-the-big-one-wont-be-as-destructive-as-once-thought