Study Puts San Andreas, San Jacinto Fault Stress at 1,000-Year High
Updated
Updated · Livescience.com · Jun 16
Study Puts San Andreas, San Jacinto Fault Stress at 1,000-Year High
3 articles · Updated · Livescience.com · Jun 16
Summary
A new model of Southern California’s fault system found the San Andreas and San Jacinto faults are now at or above their highest stress levels in the past 1,000 years, raising the risk of a major earthquake.
Cajon Pass emerged as a key “earthquake gate” that can either block or transmit rupture between the faults; because both now show similarly elevated stress, a multi-fault break is considered plausible.
Researchers reconstructed 1,000 years of seismic history from tree rings and displaced sediments, then simulated how stress built, released and spread across the southern San Andreas and San Jacinto systems.
The study points to scenarios ranging from a joint rupture on San Andreas branches to a tripartite event involving San Jacinto, potentially threatening Los Angeles, San Bernardino, Riverside and the Coachella Valley.
The two fault systems have produced 36 earthquakes of magnitude 6.4 or higher in the past millennium, and nearly 170 years have passed since the region’s last 7.9 “big one” in 1857.
While we watch the San Andreas, is another fault system quietly becoming California's next 'Big One'?
A 'double fault' megaquake now threatens California. Are early warnings and building codes enough to save Los Angeles?
Ancient tree rings warn of a megaquake, but could this '1,000-year' prediction be based on a scientific error?
Millennium-High Tectonic Stress Detected on San Andreas and San Jacinto Faults: What It Means for Southern California
Overview
A major new study warns that tectonic stress along Southern California’s San Andreas and San Jacinto faults has reached the highest levels seen in 1,000 years, raising urgent concerns for the region’s seismic safety. Researchers highlight the Cajon Pass as a critical 'Earthquake Gate,' where the unique geological setup controls how stress is transferred and released, potentially affecting the size and spread of future earthquakes. This research provides essential data for experts to reassess earthquake risks and improve disaster planning, emphasizing the need for updated preparedness strategies to protect the densely populated area.