Rheological controls on fault loading rates in northern California following the 1906 San Francisco earthquake

• Published in: Geophysical research letters Vol. 31; no. 1; pp. L01606 - n/a
• Main Author: Kenner, S. J.
• Format: Journal Article
• Language: English
• Published: American Geophysical Union 01-01-2004; Blackwell Publishing Ltd
• Subjects: Earthquake dynamics and mechanics; Geodesy and Gravity; Mathematical Geophysics; Modeling; Rheology of the lithosphere and mantle; Seismic hazard assessment and prediction; Seismology; Stresses—crust and lithosphere; Tectonophysics
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2003GL018903

To estimate seismic hazard in complex, multiple fault systems, it is necessary to understand how stresses within the system are transferred. Accurate estimates of loading rate due to far‐field tectonic motion and postseismic transients following large earthquakes are required. Using plausible lower crustal rheologies constrained by observations following the 1906 San Francisco earthquake, I show that postseismic relaxation may play a significant role in reloading the coseismic fault, providing 60–80% of the stress released during great earthquakes. Further, postseismic stressing rates along neighboring faults are highly dependent on the geometry and rheology of the lower crust/upper mantle. This implies that tectonic loading rate estimates are also highly dependent on lower crustal/upper mantle structure. Thus, improvement of seismic hazard estimates within complex, multiple fault systems is dependent on a better understanding of structure and rheology at depth.