California seismic study highlights risk of interconnected fault ruptures

A new study reconstructing 1,000 years of seismic activity in Southern California suggests that the risk of a devastating earthquake depends not only on tension accumulation within individual faults, but also on how ruptures might propagate through connected systems.

Led by geophysicist Liliane Burkhard, researchers used computer models to analyze the complex network of faults in the region, including the San Andreas and San Jacinto faults. The findings indicate that certain sectors of these faults currently hold tension levels comparable to, or even exceeding, those associated with major historical earthquakes.

The study highlights Cajon Pass as a critical connection point that could either dampen a seismic event or facilitate the transfer of a rupture from one fault segment to another. While the research does not predict when the next major earthquake will occur, it emphasizes that a single movement could redistribute stress and trigger a chain reaction across multiple fault lines, potentially leading to a much more extensive sequence of movements.