Reconciling geologic and geodetic model fault slip-rate discrepancies in Southern California: Consideration of nonsteady mantle flow and lower crustal fault creep
Journal
Geology
Journal Volume
39
Journal Issue
7
Pages
627-630
Date Issued
2011
Author(s)
Abstract
In Southern California, slip rates derived from geodesyconstrained elastic models are lower than geologic rates along the Mojave and San Bernardino segments of the San Andreas fault and the Garlock fault. In contrast, the summed geodetic rate across the Mojave eastern California shear zone (ECSZ) is significantly higher than the summed geologic rate. We show that geodetic and geologic slip rates in Southern California can be reconciled using a viscoelastic earthquake cycle model that explicitly incorporates time-dependent deformation due to nonsteady interseismic fault creep in the lower crust and viscous flow in the upper mantle. To reconcile geologic and geodetic model rates, our model requires that the southern San Andreas fault and the Garlock fault are in the late stages of the earthquake cycle, resulting in lower current deformation rates than the cycle-averaged rate. Our model implies that the ECSZ and the San Jacinto faults are in the early stages of the earthquake cycle, resulting in high current deformation rates. © 2011 Geological Society of America.
Type
journal article