Off-Fault Focal Mechanisms Not Representative of Interseismic Fault Loading Suggest Deep Creep on the Northern San Jacinto Fault
Michele L. Cooke, & Jennifer L. HatchPublished September 14, 2018, SCEC Contribution #8079
Within the San Bernardino basin, focal mechanisms show normal slip events that are inconsistent with the interseismic strike-slip loading of the nearby San Jacinto and San Andreas faults. The discrepancy may owe to deep (> 10 km depth), creep along the northern San Jacinto fault. The enigmatic normal slip events occur to the northeast of the fault and primarily below 10 km depth, consistent with off-fault deformation due to spatially non-uniform deep creep rates. Consequently, if these normal slip events are included in stress inversions from the seismic catalog, the results may provide inaccurate information about fault loading. Here, we show that models with deep creep on the northern San Jacinto fault that match first-order pattern of observed normal slip focal mechanisms in the basin and that this deep creep cannot be detected with GPS data due to the proximity of the San Andreas fault.
Citation
Cooke, M. L., & Hatch, J. L. (2018). Off-Fault Focal Mechanisms Not Representative of Interseismic Fault Loading Suggest Deep Creep on the Northern San Jacinto Fault. Geophysical Research Letters, 45(17), 8976-8984. doi: 10.1029/2018GL078932.
Related Projects & Working Groups
Stress and Deformation Over Time (SDOT), Cajon Pass EGA
