Interseismic Ground Deformation and Fault Slip Rates in the Greater San Francisco Bay Area From Two Decades of Space Geodetic Data

Abstract

The detailed spatial variations of strain accumulation and creep on major faults in the northern San Francisco Bay Area (North Bay), which are important for seismic potential and evaluation of natural hazards, remain poorly understood. Here we combine interferometric synthetic aperture radar data from the ERS‐1/2 and Envisat satellites between 1992 and 2010 with continuous and campaign GPS data to obtain a high spatial and temporal coverage of ground deformation of the North Bay. The SAR data from both ascending and descending orbits are combined to separate horizontal and vertical components of the deformation. We jointly invert the horizontal component of the mean velocities derived from these data to infer the deep strike‐slip rates on major locked faults. We use the estimated deep rates to simulate the long‐wavelength deformation due to interseismic elastic strain accumulation along these locked faults. After removing the long‐wavelength signal from the InSAR horizontal mean velocity field, we estimate fault‐parallel surface creep rates of up to 2 mm/year along the central section of the Rodgers Creek fault and surface creep rates ranging between 2 and 4 mm/year along the Concord fault. No surface creep is geodetically resolved along the West Napa and Green Valley fault zones. We identified characteristically repeating earthquakes on the Rodgers Creek fault, the West Napa fault, the Green Valley fault, and the Concord fault. Nontectonic deformation in the Geysers geothermal field and in Late Cenozoic basins (Rohnert Park and Sonoma basins) are also observed, likely due to hydrological and sediment‐compaction processes, respectively.

Widespread Fault Creep in the Northern San Francisco Bay Area Revealed by Multistation Cluster Detection of Repeating Earthquakes

“…We relocate the events in each family separately (e.g., Figure 3), so that only the highest CCC combinations are used. This is a significantly higher number of RE families than identified in the North Bay by "conventional" means- Xu et al (2018), using only long-lived stations, find only 4 RE sequences on the Rodgers Creek fault, compared with 36 in this study (15 confirmed, 7 possible, and 14 pairs; Figure S8)-showing the importance of using the multistation clustering approach. Overall, we find that 59 of our candidate RE families pass this relocation test (hereafter, "confirmed REs"), and that a further 48 families, despite high CCC values, have insufficient data coverage to allow stable relocations ("possible REs").…”

“…Overall, we find that 59 of our candidate RE families pass this relocation test (hereafter, "confirmed REs"), and that a further 48 families, despite high CCC values, have insufficient data coverage to allow stable relocations ("possible REs"). This is a significantly higher number of RE families than identified in the North Bay by "conventional" means- Xu et al (2018), using only long-lived stations, find only 4 RE sequences on the Rodgers Creek fault, compared with 36 in this study (15 confirmed, 7 possible, and 14 pairs; Figure S8)-showing the importance of using the multistation clustering approach.…”

Time‐Dependent Heat Budget of a Thrust from Geological Records and Numerical Experiments

“…We emphasize that the simplified model of seismicity adopted in this study comes at the cost of several limitations, which are summarized below. As friction is not formulated as a rate‐ and state‐dependent variable vanDinther, Gerya, Dalguer, Corbi, et al, ; vanDinther, Gerya, Dalguer, Mai, et al, ), the model does not account for spontaneous nucleation of analog earthquakes and enhanced postseismic creep at high strain rates (Druiventak et al, ; Xu et al, ). This latter process might be influential at the bottom of natural seismogenic zones where viscous dissipation would provide long‐term heating stabilizing the thermal anomaly (Küster & Stöckhert, ; Trepmann & Stöckhert, ).…”

Logarithmic Model Joint Inversion Method for Coseismic and Postseismic Slip: Application to the 2017 Mw 7.3 Sarpol Zahāb Earthquake, Iran

“…Interferometric synthetic aperture radar (InSAR) data have been successfully used to study earthquake cycle deformation, especially when ground‐based data are not available (Elliott et al, ; Fialko et al, ; Fielding et al, ; Li et al, ; Peltzer, ; Raucoules et al, ; Xu et al, ; Xu et al, ; Zhou et al, ). InSAR data can be inverted to derive finite fault slip models, which are important for understanding of fault geometry, fault slip, and fault frictional properties, as well as for assessing potential regional seismic hazards (Elliott et al, ; Marone, ; Xu et al, ).…”