Two independent research teams examining opposite ends of California’s San Andreas Fault have arrived at the same unsettling conclusion in the same summer: earthquake risk along America’s most famous fault system is greater than scientists had previously modeled — in ways that matter to the roughly 30 million people who live within reach of its rupture zones.
The more immediately newsworthy finding comes from San José State University geologist Kim Blisniuk, whose research team has spent years mapping displaced landforms at Sanborn County Park near Saratoga — a quiet Santa Clara County reserve where the San Andreas Fault runs directly beneath the surface. Her unpublished findings, reported by the San Francisco Chronicle on August 20, 2026, show that the Santa Cruz Mountains section of the northern fault has been slipping faster than scientists believed, overturning a long-standing assumption about how plate motion distributes itself through the Bay Area fault system.
The second finding, published in June 2026 in the Journal of Geophysical Research: Solid Earth, comes from a team led by Dr. Liliane Burkhard of the University of Bern, with collaborators from the University of Hawaiʻi at Mānoa, the U.S. Geological Survey’s Earthquake Science Center in Pasadena, and the Scripps Institution of Oceanography. Their model, built from 1,000 years of earthquake history, finds that tectonic stress along the southern San Andreas and San Jacinto fault systems has now reached levels not seen at any point in the previous millennium — and that a key geographic junction northeast of Los Angeles is sitting in a configuration associated historically with multi-fault ruptures.
What a Faster Santa Cruz Mountains Slip Rate Means for the Bay Area
The Santa Cruz Mountains section of the northern San Andreas lies south of San Jose, placing it within close seismic range of Silicon Valley, the broader Bay Area, and several million people whose earthquake risk models have relied on specific assumptions about how quickly that section of the fault moves…