San Andreas fault hits dangerous 1,000-year high, study says

Key Points:

• New research indicates that the junction where California's San Andreas and San Jacinto fault systems meet near Cajon Pass has accumulated tectonic stress levels comparable to 1,000-year highs, raising concerns about a major earthquake risk near Los Angeles.
• The study, using computer simulations of the past millennium, found that the San Jacinto Bernardino segment at Cajon Pass is the most heavily stressed, suggesting this area could act as an "earthquake gate" influencing rupture behavior between fault systems.
• Cajon Pass's role as a critical fault junction means it could either halt or facilitate the spread of earthquake ruptures, potentially leading to larger, more complex seismic events that threaten densely populated regions.
• Historically, the San Andreas and San Jacinto faults have produced at least 36 earthquakes of magnitude 6.4 or greater in the last 1,000 years and together accommodate about 90% of the tectonic plate slip in Southern California.
• The prolonged period without a major earthquake along these faults has increased concerns that accumulated stress could result in a devastating seismic event impacting millions of residents in Southern California.