Structure of the California Coast Ranges and San Andreas Fault at SAFOD from seismic waveform inversion and reflection imaging

Bleibinhaus, Florian; Hole, J. A.; Ryberg, Trond; Fuis, Gary S.

doi:10.1029/2006jb004611

Cited by 111 publications

(110 citation statements)

References 40 publications

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“…Direct reflection imaging of steep faults is rare, with only a few examples in California (e.g., Shaw and Shearer, 1999;Hole et al, 2001;Bleibinhaus et al, 2007). The imaging method of Bauer et al (2013) represents a promising tool that can be applied to steep faults worldwide.…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%

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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“…1 A schematic plot of a typical fault zone, after Chester and Logan (1986) Pinto Mountain faults, Southern California (Fialko et al 2002). In addition, many geophysical methods have been applied in deriving FZ properties such as gravity and electromagnetic surveys, seismic reflection and refraction, travel-time tomography, earthquake location, waveform modeling of FZ-reflected body waves, FZ head waves, and FZ trapped waves (e.g., Mooney and Ginzburg 1986;BenZion and Malin 1991;Ben-Zion et al 1992;Hole et al 2001;Prejean et al 2002;Waldhauser and Ellsworth 2002;Li et al 2002;McGuire and Ben-Zion 2005;Bleibinhaus et al 2007;Li et al 2007;Yang et al 2009;Roland et al 2012). In the following, I briefly review a few seismological and geodetic methods that have been used to derive FZ structure.…”

Section: Fz Properties and Their Effectsmentioning

confidence: 99%

Recent advances in imaging crustal fault zones: a review

Yang

2015

Earthq Sci

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Crustal faults usually have a fault core and surrounding regions of brittle damage, forming a low-velocity zone (LVZ) in the immediate vicinity of the main slip interface. The LVZ may amplify ground motion, influence rupture propagation, and hold important information of earthquake physics. A number of geophysical and geodetic methods have been developed to derive high-resolution structure of the LVZ. Here, I review a few recent approaches, including ambient noise cross-correlation on dense across-fault arrays and GPS recordings of fault-zone trapped waves. Despite the past efforts, many questions concerning the LVZ structure remain unclear, such as the depth extent of the LVZ. High-quality data from larger and denser arrays and new seismic imaging technique using larger portion of recorded waveforms, which are currently under active development, may be able to better resolve the LVZ structure. In addition, effects of the alongstrike segmentation and gradational velocity changes across the boundaries between the LVZ and the host rock on rupture propagation should be investigated by conducting comprehensive numerical experiments. Furthermore, high-quality active sources such as recently developed large-volume airgun arrays provide a powerful tool to continuously monitor temporal changes of fault-zone properties, and thus can advance our understanding of fault zone evolution.

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“…For practical applications, severe simplifications must be employed to make the inversion feasible. In controlled-source seismology, the most popular forward solutions are 2D, isotropic, acoustic or viscoacoustic, and FD frequencydomain methods ͑e.g., Hicks and Pratt, 2001;Operto et al, 2004;Ravaut et al, 2004;Operto et al, 2006;Bleibinhaus et al, 2007;Gao et al, 2007;Malinowski and Operto, 2008͒. Validity of this approximation has been established by a study on a physical scale model by Pratt ͑1999͒.…”

Section: Introductionmentioning

confidence: 98%

Effects of surface scattering in full-waveform inversion

Bleibinhaus

Rondenay

2009

GEOPHYSICS

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In full-waveform inversion of seismic body waves, often the free surface is ignored on grounds of computational efficiency. A synthetic study was performed to investigate the effects of this simplification. In terms of size and frequency, the test model and data conform to a real long-offset survey of the upper crust across the San Andreas fault. Random fractal variations are superimposed on a background model with strong lateral and vertical velocity variations ranging from 1200 to 6800 m/s. Synthetic data were computed and inverted for this model and different topographies. A fully viscoelastic time-domain code was used to synthesize the seismograms, and a viscoacoustic frequency-domain code was utilized to invert them. The inversion was focused on early arrivals, which are dominated by P-waves but also contain strong P-Rayleigh wave conversions from the near-field of the receiver. Resulting waveform models show artifacts and a loss of resolution from neglecting the free surface in the inversion, but the inversions are stable, and they still improve the resolution of kinematic models. The extent of deterioration depends more on the subsurface than on the surface structure. Inversion results were improved at no additional expense by introducing a weak contrast along a staircase function above shots and receivers.

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Structure of the California Coast Ranges and San Andreas Fault at SAFOD from seismic waveform inversion and reflection imaging

Cited by 111 publications

References 40 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

Recent advances in imaging crustal fault zones: a review

Effects of surface scattering in full-waveform inversion

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