Three-dimensional geologic map of the Hayward fault, northern California: Correlation of rock units with variations in seismicity, creep rate, and fault dip

Graymer, R. W.; Ponce, David A.; Jachens, Robert C.; Simpson, Robert W.; Phelps, Geoffrey A.; Wentworth, Carl M.

doi:10.1130/g21435.1

Cited by 36 publications

(34 citation statements)

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“…Partially creeping behavior on the Hayward fault may be associated with complex lithologically modulated variations in frictional behavior of the rocks on either side of the Hayward fault. The region of partial creep we observe between San Leandro and Fremont is spatially coincident with a 25 km long gabbro body on the east face of the Hayward fault [ Graymer et al , 2005] (Figure 9). The adjacent west face consists of gabbro above 6 km depth and metagreywacke below.…”

Section: Discussionmentioning

confidence: 99%

“…Fault surface geology reproduced from Graymer et al [2005] with coupling rate contours. Jurassic gabbro (gb) shown in red.…”

Section: Discussionmentioning

confidence: 99%

“…The green bar represents the observed surface trace of the 1868 Hayward earthquake. Rock types are Czs, Cenozoic sedimentary rocks; Ku, Upper Cretaceous sandstone, shale, and minor conglomerate; cro, undivided Jurassic serpentinite, gabbro, basalt, and keratophyre, with minor sedimentary rocks; gb, Jurassic gabbro; fn, Upper Cretaceous sandstone and shale; fsr: melange; fyb, Cretaceous metagreywacke; mixed, tectonically interleaved sandstone, metasandstone, melange, and serpentinite [ Graymer et al , 2005]. …”

Section: Discussionmentioning

confidence: 99%

“…InSAR data near the trace of the Hayward fault [ Schmidt et al , 2005; Bürgmann et al , 2006; Funning et al, submitted manuscript, 2011] are spatially dense enough to enable us to constrain spatial variations in fault coupling in this region. Although nearly vertical for most of its trace, the Hayward fault dips east south of Fremont, California, and likely merges with the Calaveras fault at depth [ Waldhauser and Ellsworth , 2002; Manaker et al , 2005; Graymer et al , 2005; Hardebeck et al , 2007]. The geometry of the Hayward fault is represented by a three‐dimensional mesh of 1006 triangular dislocation elements [ Comninou , 1973; Jeyakumaran et al , 1992; Thomas , 1993; Meade , 2007], derived from relocated seismicity and geologic mapping [ Murray‐Moraleda and Simpson , 2009].…”

Section: Geodetic Observations and Reference Block Model Geometrymentioning

confidence: 99%

“…The Hayward fault is both geometrically [ Graymer et al , 2005; Waldhauser and Ellsworth , 2002; Hardebeck et al , 2007] and kinematically complex [ Lienkaemper et al 2001; Simpson et al , 2001; Schmidt et al , 2005; G. J. Funning et al, The source of major earthquakes on the Hayward fault, California, submitted to Geophysical Research Letters , 2011]. Nearly vertical along most of its trace, the Hayward fault dips eastward south of Fremont, as illuminated by relocated seismicity [ Waldhauser and Ellsworth , 2002; Manaker et al , 2005; Hardebeck et al , 2007], and likely merges at depth with the Calaveras fault immediately to the east [ Ponce et al , 2004; Williams et al , 2005; Graymer et al , 2005]. Surface creep observations from creepmeters [ Bilham and Whitehead , 1997] and alignment arrays [ Lienkaemper et al , 2001; Simpson et al , 2001] show that sections of the Hayward fault creep aseismically with surface creep rates ranging from <4 mm/yr on the northern Hayward fault to 8 mm/yr near Fremont.…”

Section: Introductionmentioning

confidence: 99%

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Geodetic constraints on San Francisco Bay Area fault slip rates and potential seismogenic asperities on the partially creeping Hayward fault

Evans¹,

Loveless²,

Meade³

2012

J. Geophys. Res.

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[1] The Hayward fault in the San Francisco Bay Area (SFBA) is sometimes considered unusual among continental faults for exhibiting significant aseismic creep during the interseismic phase of the seismic cycle while also generating sufficient elastic strain to produce major earthquakes. Imaging the spatial variation in interseismic fault creep on the Hayward fault is complicated because of the interseismic strain accumulation associated with nearby faults in the SFBA, where the relative motion between the Pacific plate and the Sierra block is partitioned across closely spaced subparallel faults. To estimate spatially variable creep on the Hayward fault, we interpret geodetic observations with a three-dimensional kinematically consistent block model of the SFBA fault system. Resolution tests reveal that creep rate variations with a length scale of <15 km are poorly resolved below 7 km depth. In addition, creep at depth may be sensitive to assumptions about the kinematic consistency of fault slip rate models. Differential microplate motions result in a slip rate of 6.7 AE 0.8 mm/yr on the Hayward fault, and we image along-strike variations in slip deficit rate at $15 km length scales shallower than 7 km depth. Similar to previous studies, we identify a strongly coupled asperity with a slip deficit rate of up to 4 mm/yr on the central Hayward fault that is spatially correlated with the mapped surface trace of the 1868 M W = 6.9-7.0 Hayward earthquake and adjacent to gabbroic fault surfaces.

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Section: Discussionmentioning

confidence: 99%

“…Fault surface geology reproduced from Graymer et al [2005] with coupling rate contours. Jurassic gabbro (gb) shown in red.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Geodetic Observations and Reference Block Model Geometrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Geodetic constraints on San Francisco Bay Area fault slip rates and potential seismogenic asperities on the partially creeping Hayward fault

Evans¹,

Loveless²,

Meade³

2012

J. Geophys. Res.

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Subsurface geometry of the San Andreas-Calaveras fault junction: Influence of serpentinite and the Coast Range Ophiolite

et al. 2014

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While an enormous amount of research has been focused on trying to understand the geologic history and neotectonics of the San Andreas-Calaveras fault (SAF-CF) junction, fundamental questions concerning fault geometry and mechanisms for slip transfer through the junction remain. We use potential-field, geologic, geodetic, and seismicity data to investigate the 3-D geologic framework of the SAF-CF junction and identify potential slip-transferring structures within the junction. Geophysical evidence suggests that the San Andreas and Calaveras fault zones dip away from each other within the northern portion of the junction, bounding a triangular-shaped wedge of crust in cross section. This wedge changes shape to the south as fault geometries change and fault activity shifts between fault strands, particularly along the Calaveras fault zone (CFZ). Potential-field modeling and relocated seismicity suggest that the Paicines and San Benito strands of the CFZ dip 65°to 70°NE and form the southwest boundary of a folded 1 to 3 km thick tabular body of Coast Range Ophiolite (CRO) within the Vallecitos syncline. We identify and characterize two steeply dipping, seismically active cross structures within the junction that are associated with serpentinite in the subsurface. The architecture of the SAF-CF junction presented in this study may help explain fault-normal motions currently observed in geodetic data and help constrain the seismic hazard. The abundance of serpentinite and related CRO in the subsurface is a significant discovery that not only helps constrain the geometry of structures but may also help explain fault behavior and the tectonic evolution of the SAF-CF junction.

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Seismogeodesy of the 2014M_w6.1 Napa earthquake, California: Rapid response and modeling of fast rupture on a dipping strike‐slip fault

et al. 2015

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Real‐time high‐rate geodetic data have been shown to be useful for rapid earthquake response systems during medium to large events. The 2014 Mw6.1 Napa, California earthquake is important because it provides an opportunity to study an event at the lower threshold of what can be detected with GPS. We show the results of GPS‐only earthquake source products such as peak ground displacement magnitude scaling, centroid moment tensor (CMT) solution, and static slip inversion. We also highlight the retrospective real‐time combination of GPS and strong motion data to produce seismogeodetic waveforms that have higher precision and longer period information than GPS‐only or seismic‐only measurements of ground motion. We show their utility for rapid kinematic slip inversion and conclude that it would have been possible, with current real‐time infrastructure, to determine the basic features of the earthquake source. We supplement the analysis with strong motion data collected close to the source to obtain an improved postevent image of the source process. The model reveals unilateral fast propagation of slip to the north of the hypocenter with a delayed onset of shallow slip. The source model suggests that the multiple strands of observed surface rupture are controlled by the shallow soft sediments of Napa Valley and do not necessarily represent the intersection of the main faulting surface and the free surface. We conclude that the main dislocation plane is westward dipping and should intersect the surface to the east, either where the easternmost strand of surface rupture is observed or at the location where the West Napa fault has been mapped in the past.

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Three-dimensional geologic map of the Hayward fault, northern California: Correlation of rock units with variations in seismicity, creep rate, and fault dip

Cited by 36 publications

References 5 publications

Geodetic constraints on San Francisco Bay Area fault slip rates and potential seismogenic asperities on the partially creeping Hayward fault

Geodetic constraints on San Francisco Bay Area fault slip rates and potential seismogenic asperities on the partially creeping Hayward fault

Subsurface geometry of the San Andreas-Calaveras fault junction: Influence of serpentinite and the Coast Range Ophiolite

Seismogeodesy of the 2014M_w6.1 Napa earthquake, California: Rapid response and modeling of fast rupture on a dipping strike‐slip fault

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Three-dimensional geologic map of the Hayward fault, northern California: Correlation of rock units with variations in seismicity, creep rate, and fault dip

Cited by 36 publications

References 5 publications

Geodetic constraints on San Francisco Bay Area fault slip rates and potential seismogenic asperities on the partially creeping Hayward fault

Geodetic constraints on San Francisco Bay Area fault slip rates and potential seismogenic asperities on the partially creeping Hayward fault

Subsurface geometry of the San Andreas-Calaveras fault junction: Influence of serpentinite and the Coast Range Ophiolite

Seismogeodesy of the 2014Mw6.1 Napa earthquake, California: Rapid response and modeling of fast rupture on a dipping strike‐slip fault

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Seismogeodesy of the 2014M_w6.1 Napa earthquake, California: Rapid response and modeling of fast rupture on a dipping strike‐slip fault