A New Perspective on the Geometry of the San Andreas Fault in Southern California and Its Relationship to Lithospheric Structure

Fuis, Gary S.; Scheirer, Daniel S.; Langenheim, Victoria E.; Kohler, Monica D.

doi:10.1785/0120110041

Cited by 91 publications

(153 citation statements)

References 62 publications

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“…Other nearby faults are also imaged in the upper 10 km, appearing to form a flower-like structure largely above the SAF. These new images confirm the basic hypothesis of Fuis et al (2012) that the SAF dips northeast in this region, but the change in dip at 6-9 km and possible flower-like structure are new features.…”

Section: Introductionsupporting

confidence: 83%

“…Results in the present study modify the curviplanar shape of the SAF proposed by Fuis et al (2012) for the Coachella Valley region. The SAF does not appear to be planar in cross section in the Coachella Valley, but rather, it is steeper in the upper crust and less steep in the midcrust.…”

Section: Geological and Geophysical Settingsupporting

confidence: 53%

“…Studies of the SAF in southern California by Fuis et al (2012) indicate a propeller shape whereby the SAF dips moderately northeast in the interval from the Salton Sea to the Mojave Desert, steepens to vertical through most of the Mojave Desert, and then dips moderately southwest around the Big Bend where it exits the Transverse Ranges on the northwest. Results in the present study modify the curviplanar shape of the SAF proposed by Fuis et al (2012) for the Coachella Valley region.…”

Section: Geological and Geophysical Settingmentioning

confidence: 99%

“…Since that time, a number of authors have produced data for and modeled a much longer-dipping panel for the southern SAF, including this study. Fuis et al (2012) modeled a northeast-dipping SAF from the Salton Sea to the Mojave Desert. Lindsey and Fialko (2013) modeled a northeast-dipping SAF from Indio to the Salton Sea, and Fattaruso et al (2014) modeled a northeast-dipping SAF from San Gorgonio Pass to the Salton Sea.…”

Section: Ssip Linementioning

confidence: 99%

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Subsurface Geometry of the San Andreas Fault in Southern California: Results from the Salton Seismic Imaging Project (SSIP) and Strong Ground Motion Expectations

Fuis¹,

Bauer²,

Goldman³

et al. 2017

Bulletin of the Seismological Society of America

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The San Andreas fault (SAF) is one of the most studied strike-slip faults in the world; yet its subsurface geometry is still uncertain in most locations. The Salton Seismic Imaging Project (SSIP) was undertaken to image the structure surrounding the SAF and also its subsurface geometry. We present SSIP studies at two locations in the Coachella Valley of the northern Salton trough. On our line 4, a fault-crossing profile just north of the Salton Sea, sedimentary basin depth reaches 4 km southwest of the SAF. On our line 6, a fault-crossing profile at the north end of the Coachella Valley, sedimentary basin depth is ∼2-3 km and centered on the central, most active trace of the SAF. Subsurface geometry of the SAF and nearby faults along these two lines is determined using a new method of seismic-reflection imaging, combined with potential-field studies and earthquakes. Below a 6-9 km depth range, the SAF dips ∼50°-60°NE, and above this depth range it dips more steeply. Nearby faults are also imaged in the upper 10 km, many of which dip steeply and project to mapped surface fault traces. These secondary faults may join the SAF at depths below about 10 km to form a flower-like structure. In Appendix D, we show that rupture on a northeast-dipping SAF, using a single plane that approximates the two dips seen in our study, produces shaking that differs from shaking calculated for the Great California ShakeOut, for which the southern SAF was modeled as vertical in most places: shorter-period (T < 1 s) shaking is increased locally by up to a factor of 2 on the hanging wall and is decreased locally by up to a factor of 2 on the footwall, compared to shaking calculated for a vertical fault.

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Section: Introductionsupporting

confidence: 83%

Section: Geological and Geophysical Settingsupporting

confidence: 53%

Section: Geological and Geophysical Settingmentioning

confidence: 99%

Section: Ssip Linementioning

confidence: 99%

See 2 more Smart Citations

Subsurface Geometry of the San Andreas Fault in Southern California: Results from the Salton Seismic Imaging Project (SSIP) and Strong Ground Motion Expectations

Fuis¹,

Bauer²,

Goldman³

et al. 2017

Bulletin of the Seismological Society of America

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“…[32] has discussed stress accumulation near buried fault in lithosphere-asthenosphere system. The work of [33] can also be mentioned in these connections.…”

Section: Introductionmentioning

confidence: 99%

Stress and Strain Accumulation Due to a Long Dip-Slip Fault Movement in an Elastic-Layer over a Viscoelastic Half Space Model of the Lithosphere-Asthenosphere System

Sen¹,

Debnath²

2013

IJG

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Most of the earthquake faults in North-East India, China, mid Atlantic-ridge, the Pacific seismic belt and Japan are found to be predominantly dip-slip in nature. In the present paper a dip-slip fault is taken situated in an elastic layer over a viscoelastic half space representing the lithosphere-asthenosphere system. A movement of the dip-slip nature across the fault occurs when the accumulated stress due to various tectonic reasons e.g. mantle convection etc., exceeds the local friction and cohesive forces across the fault. The movement is assumed to be slipping in nature, expressions for displacements, stresses and strains are obtained by solving associated boundary value problem with the help of integral transformation and Green's function method and a suitable numerical methods is used for computation. A detailed study of these expressions may give some ideas about the nature of stress accumulation in the system, which in turn will be helpful in formulating an earthquake prediction programme.

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Is there a discrepancy between geological and geodetic slip rates along the San Andreas Fault System?

2014

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Previous inversions for slip rate along the San Andreas Fault System (SAFS), based on elastic half-space models, show a discrepancy between the geologic and geodetic slip rates along a few major fault segments. In this study, we use an earthquake cycle model representing an elastic plate over a viscoelastic half-space to demonstrate that there is no significant discrepancy between long-term geologic and geodetic slip rates. The California statewide model includes 41 major fault segments having steady slip from the base of the locked zone to the base of the elastic plate and episodic shallow slip based on known historical ruptures and geologic recurrence intervals. The slip rates are constrained by 1981 secular velocity measurements from GPS and L-band intereferometric synthetic aperture radar. A model with a thick elastic layer (60 km) and half-space viscosity of 10 19 Pa s is preferred because it produces the smallest misfit to both the geologic and the geodetic data. We find that the geodetic slip rates from the thick plate model agrees to within the bounds of the geologic slip rates, while the rates from the elastic half-space model disagree on specific important fault segments such as the Mojave and the North Coast segment of the San Andreas Fault. The viscoelastic earthquake cycle models have generally higher slip rates than the half-space model because most of the faults along the SAFS are late in the earthquake cycle, so today they are moving slower than the long-term cycle-averaged velocity as governed by the viscoelastic relaxation process.

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A New Perspective on the Geometry of the San Andreas Fault in Southern California and Its Relationship to Lithospheric Structure

Abstract: The widely held perception

Cited by 91 publications

References 62 publications

Subsurface Geometry of the San Andreas Fault in Southern California: Results from the Salton Seismic Imaging Project (SSIP) and Strong Ground Motion Expectations

Subsurface Geometry of the San Andreas Fault in Southern California: Results from the Salton Seismic Imaging Project (SSIP) and Strong Ground Motion Expectations

Stress and Strain Accumulation Due to a Long Dip-Slip Fault Movement in an Elastic-Layer over a Viscoelastic Half Space Model of the Lithosphere-Asthenosphere System

Is there a discrepancy between geological and geodetic slip rates along the San Andreas Fault System?

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