Deformation across the Pacific‐North America plate boundary near San Francisco, California

Prescott, W. H.; Savage, J. C.; Svarc, J. L.; Manaker, D. M.

doi:10.1029/2000jb900397

Cited by 55 publications

(79 citation statements)

References 18 publications

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“…Geodetic site velocities and creep rates have been used to infer the existence of a deeply locked seismogenic zone along the San Andreas fault near Parkfield (King et al, 1987;Segall and Harris, 1987) and north of San Francisco (Prescott et al, 2001), andLienkaemper et al (1991) interpreted systematic variations in surficial creep rates as evidence for a deeply locked seismogenic zone along the Hayward fault. Each of these areas may serve as useful analogs for the central creeping segment.…”

Section: Discussionmentioning

confidence: 99%

New slip rate estimates for the creeping segment of the San Andreas fault, California

Titus

DeMets

Tikoff

2005

Geol

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New continuous and differential global positioning system (GPS) measurements of recent slip rates and 30 yr alignment-array offsets from the central creeping segment of the San Andreas fault yield a maximum right-lateral slip rate of 25 ؎ 1 mm/yr. This slip rate is 20% slower than the 30 mm/yr slip rate accepted for this segment of the fault and 35% slower than the 39 mm/yr slip rate predicted between the Sierra Nevada-Great Valley block and the Pacific plate. New continuous GPS measurements between pairs of sites that flank the creeping segment at intersite distances of 1.0 km and 70 km give relative fault-parallel slip rates of 28 ؎ 2 and 30 ؎ 2 mm/yr, respectively. These observations indicate that right-lateral deformation rates increase with distance from the fault. Possible explanations for the gradient observed in the geodetic data are elastic strain accumulation along the creeping segment or significant distributed deformation on off-fault structures.

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Section: Discussionmentioning

confidence: 99%

New slip rate estimates for the creeping segment of the San Andreas fault, California

Titus

DeMets

Tikoff

2005

Geol

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“… Argus and Gordon [2001] showed that the convergence that they inferred in central California acting over ∼5 Myr could account for the present average elevation of the Coast Ranges. Convergence (3.8 ± 2.1 mm yr −1 according to Prescott et al [2001] and 2.4 ± 0.4 mm yr −1 according to Murray and Segall [2001]) perpendicular to the local Pacific plate motion relative to North America (NA) has recently been reported at the east edge of the Coast Ranges in the San Francisco Bay region.…”

Section: Introductionmentioning

confidence: 99%

Strain accumulation across the Coast Ranges at the latitude of San Francisco, 1994–2000

et al. 2004

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[1] A 66-monument geodetic array spanning the Coast Ranges near San Francisco has been surveyed more than eight times by GPS between late 1993 and early 2001. The measured horizontal velocities of the monuments are well represented by uniform, rightlateral, simple shear parallel to N29°W. (The local strike of the San Andreas Fault is $N34°W.) The observed areal dilatation rate of 6.9 ± 10.0 nstrain yr À1 (quoted uncertainty is one standard deviation and extension is reckoned positive) is not significantly different from zero, which implies that the observed strain accumulation could be released by strike-slip faulting alone. Our results are consistent with the slip rates assigned by the Working Group on California Earthquake Probabilities [2003] to the principal faults (San Gregorio, San Andreas, Hayward-Rodgers Creek, CalaverasConcord-Green Valley, and Greenville Faults) cutting across the GPS array. The vector sum of those slip rates is 39.8 ± 2.6 mm yr À1 N29.8°W ± 2.8°, whereas the motion across the GPS array (breadth 120 km) inferred from the uniform strain rate approximation is 38.7 ± 1.2 mm yr À1 N29.0°W ± 0.9°right-lateral shear and 0.4 ± 0.9 mm yr À1 N61°E ± 0.9°extension. We interpret the near coincidence of these rates and the absence of significant accumulation of areal dilatation to imply that right-lateral slip on the principal faults can release the accumulating strain; major strain release on reverse faults subparallel to the San Andreas Fault within the Coast Ranges is not required. INDEX TERMS: 1206

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“…Miller et al [2001bMiller et al [ , 2001a, Prescott et al [2001], Svarc et al [2002aSvarc et al [ , 2002b, Oldow [2003], Savage et al [2004]). Quaternary fault slip rate data [DeMets and Stein, 1990;Wilson, 1993;DeMets et al, 1994;Jennings, 1994;Petersen and Wesnousky, 1994;Plafker and Berg, 1994;DeMets, 1995;Bird, 1996;DeMets and Dixon, 1999;Shen-Tu et al, 1999] ridge spreading rates, and long-term estimates of plate motions from NUVEL-1A [DeMets et al, 1994] are represented as light blue lines.…”

Section: Estimating Depth Integrals Of Deviatoric Stress Differences mentioning

confidence: 99%

Evidence of long‐term weakness on seismogenic faults in western North America from dynamic modeling

Klein¹,

Flesch²,

Holt³

et al. 2009

J. Geophys. Res.

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[1] We investigate the long-term strength of faults within the plate boundary zone of western North America by quantifying the depth-integrated deviatoric stress field acting within the seismogenic portion of the crust. Forcings in the depth-integrated force balance equations are the horizontal gradients in gravitational potential energy per unit area (GPE). Seismic velocity data define the densities we use to determine GPE. We also solve for stress field boundary conditions that, when added to the contribution from GPE differences, provides a best fit to stress indicators. We estimate that the long-term depth-integrated total stress differences within the approximately 20 km thick seismogenic layer are of the order of 0.1-1.4 Â 10 12 N m À1 . Using these stress differences as a proxy for depth integrals of fault strength within the actively deforming regions, we infer that the long-term values of coefficients of friction on faults within the Basin and Range of Nevada and Utah, and most of California, are 0.1-0.2 under long-term hydrostatic pore pressure conditions. We test the sensitivity of these results by considering a range of maximum depths of integration. We show that for depths of integration in excess of 20 km below sea level, there is diminishing contribution to the depth-integrated stress differences, and by proxy depth-integrated fault strength. This is consistent with a brittle-ductile transition in the plate boundary zone at depths less than 20 km below sea level, and with a weaker lower crust.

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Deformation across the Pacific‐North America plate boundary near San Francisco, California

Cited by 55 publications

References 18 publications

New slip rate estimates for the creeping segment of the San Andreas fault, California

New slip rate estimates for the creeping segment of the San Andreas fault, California

Strain accumulation across the Coast Ranges at the latitude of San Francisco, 1994–2000

Evidence of long‐term weakness on seismogenic faults in western North America from dynamic modeling

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