06/17/2026
Tectonic stress along Southern California’s San Andreas and San Jacinto fault systems has reached — and in some areas exceeded — the highest levels seen in the past 1,000 years, according to new research led by Earth scientists at the University of Hawaiʻi at Mānoa.
Researchers say the system is not showing signs of an imminent rupture, but is operating under unusually high stress in a long-term seismic cycle that could support large earthquakes, including multi-fault events.
The study, published in the Journal of Geophysical Research: Solid Earth, suggests the region is in a “critically loaded state,” with stress building across multiple fault segments. One key area of focus is Cajon Pass, a junction between the two fault systems that may act as an “earthquake gate,” either blocking ruptures from crossing between faults or allowing them to link into a single larger event.
Right now, with stress at historically high levels across the region and more than 160 years elapsed since the last major rupture, the system is in a critically loaded state.
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Scientists say the San Andreas and San Jacinto faults are more stressed than at any time in 1,000 years, raising questions about future California quakes.
