San Andreas fault at highest stress level in a millennium

California's San Andreas fault is experiencing the highest levels of tectonic stress in 1,000 years, according to research from the University of Hawaiʻi at Mānoa.

According to lead study author Liliane Burkhard, "Our results show that stress levels on multiple fault segments are now at or above the highest values seen in the past millennium and that the region may be capable of a large through-going rupture involving both fault systems." 

The findings are based on a computer model that simulates stress buildup using 1,000 years of earthquake history. "Results from this study suggest that the stress that would normally be released in large earthquakes has continued to accumulate and is now at unprecedented levels. Perhaps most importantly, the study showed that Cajon Pass could facilitate a joint rupture of both the San Andreas and San Jacinto faults simultaneously, which is a scenario that could be significantly more damaging than a single-fault event, and one that affects densely populated areas including Los Angeles, San Bernardino, Riverside and the Coachella Valley."