University of Hawaiʻi scientists map record stress on San Andreas faults
A new geoscience study says Southern California's major fault network is critically loaded, without predicting when an earthquake will strike.
In 30 seconds
- The University of Hawaiʻi at Mānoa-led study says stress is at or above reconstructed 1,000-year highs on key Southern California faults.
- The study says Cajon Pass can sometimes block, and sometimes transmit, rupture between the San Andreas and San Jacinto systems.
- The researchers stress that their model is not a prediction of when the next earthquake will occur.
- The U.S. Geological Survey's UCERF3 model already treats multifault ruptures as important for California hazard assessment.
The San Andreas Fault (California's major strike-slip boundary between the Pacific and North American plates) is one of the world's best-known seismic hazards. The San Jacinto fault system (a highly active Southern California fault zone branching from the San Andreas system) runs through the inland region east of Los Angeles. Cajon Pass (a mountain corridor between the San Bernardino and San Gabriel ranges) is where the two systems can interact. The University of Hawaiʻi at Mānoa (public research campus in Honolulu) led the new modelling work. Journal of Geophysical Research: Solid Earth (American Geophysical Union peer-reviewed geoscience journal) published the study. The U.S. Geological Survey (US federal science agency) produces national earthquake hazard models. UCERF3 (2013 Uniform California Earthquake Rupture Forecast) is California's official multi-institution earthquake rupture model. Los Angeles, San Bernardino, Riverside and the Coachella Valley are Southern California population and infrastructure zones exposed to major shaking scenarios.
Background
The U.S. Geological Survey's UCERF3 report, first posted in 2013, says California earthquake forecasting had already moved away from rigid single-fault assumptions by including multifault ruptures observed in nature. The 1857 Fort Tejon earthquake, commonly estimated at about magnitude 7.9, ruptured a long southern San Andreas section and remains the key historical benchmark for the region. The 1906 San Francisco earthquake showed the same fault system's destructive potential farther north. The USGS ShakeOut Scenario, published in 2008, modelled a magnitude 7.8 southern San Andreas earthquake to test emergency, economic and infrastructure consequences.
Why now
The immediate trigger is publication of a new peer-reviewed modelling study led by University of Hawaiʻi at Mānoa researchers and publicised on 10 June 2026. The news value comes from the study's claim that present-day stress levels are exceptional in a 1,000-year reconstruction.
What happens next
Watch whether USGS, California Geological Survey or Southern California Earthquake Center researchers incorporate, challenge or refine the model in future hazard products. The practical signal will be whether the work changes scenario planning, infrastructure priorities, building-code discussions or public preparedness messaging in Southern California.
What to do
For Belgian readers travelling to or working with California, the practical takeaway is preparedness rather than alarm: check local emergency guidance, know earthquake procedures and consider business-continuity dependencies. For Belgian and EU institutions, the study is a reminder that probabilistic hazard science should be built into infrastructure, procurement, travel-risk and supply-chain planning.
How we got here
- 1857-01-09
The Fort Tejon earthquake ruptured a long southern section of the San Andreas Fault and became the main historical benchmark for the region.
- 1906-04-18
The San Francisco earthquake demonstrated the destructive potential of the San Andreas system in northern California.
- 2008
The USGS ShakeOut Scenario modelled a major southern San Andreas earthquake for preparedness planning.
- 2013-11-05
The USGS posted UCERF3, a California rupture forecast that incorporated multifault rupture modelling.
- 2026-06-10
The University of Hawaiʻi announced the new stress-modelling study.
EvidenceWell established · 1 primary source + 2 official documents + 1 independent reporting source · Academic sources: 1Explore evidence →Hide evidence ↑
- Published:
- 12 Jun 2026, 02:00
- Retrieved by ODIN:
- 12 Jun 2026
- Published:
- 10 Jun 2026, 02:00
- Retrieved by ODIN:
- 12 Jun 2026
- Published:
- 10 Jun 2026, 02:00
- Retrieved by ODIN:
- 12 Jun 2026
- Published:
- 5 Nov 2013, 01:00
- Retrieved by ODIN:
- 12 Jun 2026
- Publication date unavailable
- Retrieved by ODIN:
- 12 Jun 2026
Continue reading
This story was assembled from verified evidence, with its sources and reasoning recorded as it was written.
This briefing was prepared with AI assistance and passed Belgium Impulse source, provenance and publication-quality checks. methodology.