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738,000 Years of Off-fault Deformation at the Volcanic Tablelands, CA

Alba M. Rodriguez Padilla, & Michael E. Oskin

In Preparation August 29, 2021, SCEC Contribution #11679

Comparisons between the inelastic deformation field of a single earthquake and the cumulative deformation history of a fault are challenged by incomplete knowledge of the pre-faulted landscape, sparse data coverage, erosion, and limited chronologies. Using recently collected high-resolution lidar data of the Volcanic Tablelands in Eastern California, we develop a method to quantify permanent bending strains associated with flexure of the hanging wall and footwall of normal faults. We first detrend the regional slope from the landscape and apply 100-400 m window low pass filters to the high-resolution lidar DEM to remove survey artifacts, smooth high-frequency roughness from the landscape, and remove fault scarps and channels, so that only off-fault deformation remains. Based on thin plate theory, we calculate bending strains for the filtered landscape. We estimate average permanent off-fault bending strains on the order of ~10^-2, with permanent strains decreasing with distance away from faults in an inverse power-law with exponent ~0.8. High-strains are localized to narrow zones (100-300 m) surrounding faults and have constant widths along fault strike that narrow at the fault tip following an elliptical distribution. We integrate strain over the plate to estimate the total strain energy absorbed by long-wavelength off-fault deformation at the Tablelands over the lifetime of the Bishop Tuff, obtaining a range of 1x10^16-4.2x10^18 J depending on the low pass filter kernel size and whether an elastic or perfectly plastic rheology is assumed.

Rodriguez Padilla, A. M., & Oskin, M. E. (2021). 738,000 Years of Off-fault Deformation at the Volcanic Tablelands, CA. Geophysical Research Letters, (in preparation).

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM), Stress and Deformation Over Time (SDOT)