It’s like a scene from a Hollywood movie: A major earthquake along the San Andreas fault ripples through Los Angeles, decimating infrastructure, sparking fires and triggering landslides. For decades, scientists have been investigating when and how this disaster could unfold.Now, researchers report that such a quake could be more widespread and damaging than previously thought. Their study found that southern portions of the San Andreas fault and parts of the adjacent San Jacinto fault line are locked and loaded to their highest stress levels in 1,000 years — increasing the probability of a significant earthquake. If a strong earthquake hits either fault zone, the researchers say the seismic rumbles could cascade into its neighbor through an “earthquake gate” and spread damage from north of Los Angeles through San Bernardino, Riverside and the Coachella Valley simultaneously.“We talk loosely about faults being ‘overdue,’ but it’s important to see a physics-based estimate that the system is sitting at a 1,000-year high,” said Matthew Weingarten, a geologist at San Diego State University who was not involved in the study.AdvertisementAdvertisementEarthquakes happen when a sudden slip along a fault — a fracture in Earth’s crust where rock masses move against one another — releases energy built up over time. Stress accumulates as tectonic forces move the crust, but parts of the fault are locked and unable to slip freely.Less than 60 miles northeast of downtown Los Angeles, stress has been accumulating for more than a century along the southern San Andreas and San Jacinto fault systems. Both fractures make up the boundary of the Pacific and North American tectonic plates, which have been sliding past each other a few centimeters each year while other zones are locked. As a result, some segments of the faults have been building up tension like a coiled spring with nowhere to move.The Cajon Pass can act as an “earthquake gate” that can transmit large ruptures between thetwo faults, increasing the area of potential …
