Three-Dimensional Geologic Map of the Hayward Fault Zone, San Francisco Bay Region, California

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

doi:10.3133/sim3045

Cited by 9 publications

(12 citation statements)

References 30 publications

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“…Interestingly, the proposed large locked area includes the San Leandro gabbro (particularly where it forms both faces of the HF (Fig. 4a; Ponce et al, 2003;Graymer et al, 2005;Phelps et al, 2008). The gabbro exhibits the highest coefficient of friction (0.84) of the materials collected along the fault (Morrow et al, 2010).…”

Section: Depth Extent Of Creepmentioning

confidence: 99%

Long-Term Creep Rates on the Hayward Fault: Evidence for Controls on the Size and Frequency of Large Earthquakes

Lienkaemper¹,

McFarland²,

Simpson³

et al. 2012

Bulletin of the Seismological Society of America

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The Hayward fault (HF) in California exhibits large (M w 6.5-7.1) earthquakes with short recurrence times (161 65 yr), probably kept short by a 26%-78% aseismic release rate (including postseismic). Its interseismic release rate varies locally over time, as we infer from many decades of surface creep data. Earliest estimates of creep rate, primarily from infrequent surveys of offset cultural features, revealed distinct spatial variation in rates along the fault, but no detectable temporal variation. Since the 1989 M w 6.9 Loma Prieta earthquake (LPE), monitoring on 32 alinement arrays and 5 creepmeters has greatly improved the spatial and temporal resolution of creep rate. We now identify significant temporal variations, mostly associated with local and regional earthquakes. The largest rate change was a 6-yr cessation of creep along a 5-km length near the south end of the HF, attributed to a regional stress drop from the LPE, ending in 1996 with a 2-cm creep event. North of there near Union City starting in 1991, rates apparently increased by 25% above pre-LPE levels on a 16-km-long reach of the fault. Near Oakland in 2007 an M w 4.2 earthquake initiated a 1-2 cm creep event extending 10-15 km along the fault. Using new better-constrained long-term creep rates, we updated earlier estimates of depth to locking along the HF. The locking depths outline a single, ∼50-km-long locked or retarded patch with the potential for an M w ∼ 6:8 event equaling the 1868 HF earthquake. We propose that this inferred patch regulates the size and frequency of large earthquakes on HF. Online Material: 2007 event creep models, plots of creepmeter data, maps and cross-sections of relocated microearthquakes and active fault traces, and iterative solutions for depth of creep.

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Section: Depth Extent Of Creepmentioning

confidence: 99%

Long-Term Creep Rates on the Hayward Fault: Evidence for Controls on the Size and Frequency of Large Earthquakes

Lienkaemper¹,

McFarland²,

Simpson³

et al. 2012

Bulletin of the Seismological Society of America

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“…3D geologic maps (Figs. 7, 8) can be used for a number of different applications (e.g., Jachens et al 2001;Phelps et al 2008;Moeck et al 2009a). Here, we use the 3D geologic map data to delineate the geothermal potential in 3D.…”

Section: Methods: Geothermal Potential Mappingmentioning

confidence: 99%

“…In this paper, we detail methods for 3D structural and geologic analysis and their use to identify areas of the subsurface with the appropriate characteristics for permeability and the transmission of fluids in geothermal systems. To fully understand the complex 3D geologic relationships in geothermal fields, 1D and 2D data must be synthesized into 3D geologic maps (e.g., Jachens et al 2001;Phelps et al 2008). Hydrocarbon exploration has long relied on the integration of geological and geophysical datasets in 3D for drilling target selection and resource estimation (Calcagno et al 2008;Houlding 2012;Lindsay et al 2013).…”

mentioning

confidence: 99%

Three-dimensional geologic mapping to assess geothermal potential: examples from Nevada and Oregon

et al. 2019

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IntroductionIn this paper, we present a methodology for three-dimensional (3D) analysis of the structural and geologic controls on permeability development and the transmission of fluids in geothermal systems. We present these methods through examples from two geothermal fields, demonstrating the use of these methods in developing data-driven and testable conceptual models of geothermal processes.Faults and interconnected networks of faults and fractures can serve as pathways for upwelling in geothermal fields. This is particularly true in both magmatic and nonmagmatic geothermal systems occupying extensional and transtensional domains in which normal and strike-slip faults serve as fluid conduits (Moeck 2014; Moeck and Beardsmore 2014). The most conductive fault networks typically occur within complex Abstract Geologic structure plays an important role in controlling fluid flow in geothermal systems. In particular, very complex structural settings, consisting of many closely spaced and intersecting faults, host many geothermal systems. To elucidate the key geologic factors that affect fault-controlled geothermal circulation, it is critical to precisely characterize the structural and stratigraphic geometries in these complex settings. Here, we present a methodology and the results of 3D geologic analyses of two geothermal systems in the Basin and Range, USA. This methodology is a quantitative and geologically focused technique that can be used to precisely characterize geothermal areas, in a time when future geothermal growth demands increased exploration precision and efficiency. Surficial and subsurface geologic and geophysical data are synthesized in the construction of detailed 3D geologic maps of geothermal areas. Based on these 3D geologic maps, we examine several geologic attributes that control permeability development and geothermal fluid flow along faults. We use the stress state of faults and the distribution of structural discontinuities (i.e., fault intersections and fault terminations) to identify locations of upflow along faults in these geothermal systems. These results and the methodology presented herein are directly applicable to structurally controlled geothermal fields in the Basin and Range and worldwide. As development focus shifts toward blind geothermal resources, integration of precisely characterized subsurface structural information into exploration methods will be increasingly critical to continued growth in geothermal exploration and development. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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“…We used high‐precision double‐difference relocated seismicity (Figure ) [ Waldhauser and Schaff , ] recorded between 1984 and 2003 to define fault geometries and to identify and characterize potential slip‐transferring structures within the SAF‐CF junction, similar to the methods employed by Phelps et al . [] to map the Hayward and Calaveras Faults and Watt et al . [] to characterize the Mount Lewis fault zone.…”

Section: Methodsmentioning

confidence: 99%

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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Three-Dimensional Geologic Map of the Hayward Fault Zone, San Francisco Bay Region, California

Cited by 9 publications

References 30 publications

Long-Term Creep Rates on the Hayward Fault: Evidence for Controls on the Size and Frequency of Large Earthquakes

Long-Term Creep Rates on the Hayward Fault: Evidence for Controls on the Size and Frequency of Large Earthquakes

Three-dimensional geologic mapping to assess geothermal potential: examples from Nevada and Oregon

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

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