The southern San Andreas Fault has reached stress levels unseen in at least 1,000 years, according to new research that suggests the fault is ripe for a major earthquake. Scientists at the University of Hawaii found a stretch near Los Angeles that is in a “critically loaded state” after going more than 160 years without a major rupture.
The area of concern is around Cajon Pass, where the 15 freeway crosses the Transverse Range from Riverside to the Mojave Desert. The pass is where the San Andreas and San Jacinto faults meet, making it a tectonically active zone prone to large earthquakes.
The last big quake in the area was in 1857 at Fort Tejon, estimated at 7.9 on the Richter scale. Before that, a large quake of 7.5 struck in 1812. The region has experienced at least 36 quakes of 6.4 or larger in the last millennium. But scientists say records show large ruptures on this stretch of faults occur every 100 years or so. It’s been more than 160 years since the last large-scale quake, and models confirm that the tension observed is unprecedented…