Stress triggering of earthquakes: evidence for the 1994 M = 6.7 Northridge, California, shock

Abstract

A model of stress transfer implies that earthquakes in 1933 and 1952 increased the Conlomb stress at the site of the 1971 San Fernando earthquake. The 1971 earthquake in turn raised stress and produced aftershocks at the site of the 1987 Whittier Narrows and 1994 Northridge ruptures. The Northridge main shock raised stress in areas where its aftershocks and surface faulting occurred. Together, M ? 6 earthquakes near Los Angeles since 1933 have stressed parts of the Oak Ridge, Sierra Madre, Santa Monica Mountains, Elysian Park, and Newport-Inglewood faults by > 1 bar. While too small to cause earthquakes, these stress changes can trigger events if the crust is already near failure, or advance future earthquake occurrence if it is not.

Keywords

• earthquake prediction
• Coulomb stress
• Southern California