A critical junction where California’s San Andreas and San Jacinto fault systems meet has accumulated tectonic stress levels matching highs not observed in 1,000 years, according to new research. This buildup of stress near Cajon Pass, located approximately 50 miles from downtown Los Angeles, raises concerns about the potential for a major and catastrophic earthquake in one of the United States’ most densely populated regions.
High Stress Levels Found
The study, published this month in the Journal of Geophysical Research, utilized computer simulations to analyze 1,000 years of fault rupture history. Researchers estimated stress levels along key segments of the fault junction. The San Jacinto Bernardino segment of the San Jacinto Fault showed the highest stress, with an estimated level of 3.6. The Mojave South segment of the San Andreas Fault was estimated at 2.8, and the North San Bernardino segment of the San Andreas Fault at 1.8. These findings indicate that significant stress has accumulated across the densely populated area.
The research suggests that these two powerful fault systems may interact when their stress levels equalize. Cajon Pass, where these segments converge, is identified as a critical junction that could potentially act as an “earthquake gate.” This means it can influence how earthquake ruptures propagate, either halting them or allowing them to jump between the San Andreas and San Jacinto fault systems. Such a jump could lead to longer, larger, and more complex earthquakes, especially given the proximity to Los Angeles.
Potential for Cascading Events
Researchers highlighted that Cajon Pass plays a pivotal role in determining whether an earthquake remains confined to a single fault or spreads across multiple connected systems. If a rupture cascades across connected fault systems beyond Cajon Pass, it could threaten the creation of a significantly larger earthquake event.
The study found that several fault segments near Cajon Pass are currently carrying some of the highest stress levels reconstructed over the past millennium. It has been more than 100 years since the San Andreas and San Jacinto faults produced a major earthquake in this region. Historically, over the last 1,000 years, these fault systems have been responsible for at least 36 earthquakes of magnitude 6.4 or larger and accommodate approximately 90% of the North American-Pacific plate slip rate in Southern California. The current period of relative quiet has led to concerns that the next seismic event could be devastating for the millions of residents in the area.
While the study does not predict the timing of the next major earthquake, it underscores the ongoing and dangerous accumulation of stress at this complex fault junction in North America.
Norman Pearlstine is the Chief Editor of News Raise and focuses on Business news. His responsibility is to oversee the editorial content including business, commodities, personal investments and the stock market.
