Abstract
The internal properties within and adjacent to fault zones are reviewed, principally on the basis of laboratory, borehole, and seismic refraction and reflection data. The deformation of rocks by faulting ranges from intragrain microcracking to severe alteration. Saturated microcracked and mildly fractured rocks do not exhibit a significant reduction in velocity, but, from borehole measurements, densely fractured rocks do show significantly reduced velocities, the amount of reduction generally proportional to the fracture density. Highly fractured rock and thick fault gouge along the creeping portion of the San Andreas fault are evidenced by a pronounced seismic low-velocity zone (LVZ), which is either very thin or absent along locked portions of the fault. Thus there is a correlation between fault slip behavior and seismic velocity structure within the fault zone; high pore pressure within the pronounced LVZ may be conductive to fault creep. Deep seismic reflection data indicate that crustal faults sometimes extend through the entire crust. Models of these data and geologic evidence are consistent with a composition of deep faults consisting of highly foliated, seismically anisotropic mylonites.
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References
Aki, K, andLee W. H. K. (1976),Determination of three-dimensional velocity anomalies under a seismic array using first P arrival times from local earthquakes: 1. A homogenous initial model. J. Geophys. Res.81, 4381–4399.
Allen, C. R. (1968), ‘The tectonic environments of seismically active and inactive areas along the San Andreas fault system’, in Proc. Conf. Geol. Problems San Andreas Fault System, W. R. Dickinson and A. Grantz (eds.). Stanford Univ. Publ. Geol. Sci.11, 70–80.
Allen, C. R. (1981), ‘The modern San Andreas fault’, inThe Geotectonic Development of California, W. G. Ernst (ed.), Prentice-Hall, Engelwood Cliffs, New Jersey, p. 512–534.
Bamford, D. andNunn, K. R. (1979),In situ measurement of crack anisotropy in the Carboniferous limestone in northwest England. Geophys. Prosp.27, 322–338.
Birch, F. (1960),The velocity of compressional waves in rocks to 10 kilobars: Pt. 1. J. Geophys. Res.65, 1083–1102.
Birch, F. (1961),The velocity of compressional waves in rocks to 10 kilobars: Pt. 2. J. Geophys. Res.66, 2199–2224.
Blümling, P., Mooney, W. D., andLee, W. H. K. (1985),Crustal structure of the southern Calaveras fault zone, central California, from seismic refraction investigations, Bull. Seis. Soc. Am. 75, 193–209.
Boken, A. andMooney, W. D. (1982)A refraction study of the Santa Cruz Mountains, west-central California (abstr.). Trans. Am. Geophys. Union, EOS63, 1036.
Brewer, J. A., Matthews, D. M., Warner, M. R., Hall, J., Smythe andWittington, R. J. (1983) BIRPS deep seismic reflection studies of the British Caledonides. Nature305, 206–210.
Christensen N. I. (1966),Elasticity of ultramafic rocks. J. Geophys. Res.71, 5921–5931.
Christensen, N. I. (1978),Ophiolites, seismic velocities and oceanic crustal structure. Tectonophys.47, 131–157.
Christensen, N. I. (1984)Pore pressure and oceanic crustal seismic structure. Geophy. J. Roy. Astr. Soc.79, 411–424.
Christensen, N. I. andWang, H. F. (1985)The influence of pore pressure and confining pressure on dynamic elastic properties of Berea sandstone. Geophysics50, 207–213.
Cormier, V. F. andSpudich, P. (1984)Amplification of ground motion and waveform complexity in fault zones: Examples from the San Andreas and Calaveras Faults. Geophys. J. Roy. Astr. Soc.79, 135–152.
Crampin, S. (1978),Seismic wave propagation through a cracked solid: Polarization as a possible dilatancy diagnostic. Geophys. J. Roy. Astr. Soc.53, 467–496.
Crampin, S. (1984a),An introduction to wave propagation in anisotropic media. Geophys. J. Roy. Astr. Soc.76, 17–28.
Crampin, S. (1984b),Effective anisotropic elastic constants for wave propagation through cracked solids. Geophys. J. Roy. Astr. Soc.76, 135–145.
Crampin, S. McGonigle, R. andBamford, D. (1980),Estimating crack parameters from observation of P-wave velocity anisotropy. Geophysics45, 345–360.
Dortman, N. B. andMagid, M. S. (1969),New data on velocities of elastic waves in crystalline rocks as a function of moisture. Int. Geol. Rev.11, 517–523.
Feng, R. andMcEvilly, T. V. (1983),Interpretation of seismic reflection profiling data for the structure of the San Andreas fault zone. Bull. Seis. Soc. Am.73, 1701–1720.
Fountain, D. M., Hurich, C. A. andSmithson, S. B. (1984),Seismic reflectivity of mylonite zones in the crust. Geology12, 195–198.
Hall, N. T. (1984),Holocene history of the San Andreas fault between Crystal Springs Reservoir and San Andreas Dam, San Mateo County, California, Bull. Seis. Soc. Am.74, 281–299.
Healy, J. H. andPeake, L. G. (1975),Seismic velocity structure along a section of the San andreas fault near Bear Valley, California. Bull. Seis. Soc. Am.65, 1177–1197.
Hudson, J. A. (1981),Wave speeds and attenuation of elastic waves in material containing cracks. Geophys. J. Roy. Astr. Soc.64, 133–150.
Hurich, C. A., Smithson, S. B., Fountain, D. M. andHumphreys, M. C. (1985),Seismic evidence of mylonite reflectivity and deep structure in the Kettle dome metamorphic core complex, Washington Geology.13, 577–580.
Jones, T. D. andNur, A. (1984),The Nature of seismic reflection from deep crustal fault zones. J. Geophys. Res.89, 3153–3173.
Leary, P. C. andHenyey, T. L. (1985),Anisotropy and fracture zones about a geothermal well from P-wave velocity profiles. Geophysics50, 25–36.
Lynn, H. G. (1979),Migration and interpretation of deep crustal seismic reflection data Ph.D. Thesis, 158 pp. Stanford Univ., Stanford, Calif.
Ludwig, W. J., Nafe, K. E. andDrake C. L., ‘Seismic refraction’, inThe Sea, Vol. 4, Pt. I, A. Maxwell (ed.) Wiley, New York, 1970, p. 53–84.
Mayer-Rosa, D. (1973),Traveltime anomalies and distribution of earthquakes along the Calaveras fault zone. California. Bull. Seis. Soc. Am.63, 713–729.
Mereu, R. F. (1986),An interpretation of the central California profiles for the CCSS Shizooka workshop, submitted to USGS Open-File Rep., 7 pp.
Mooney, W. D. andColburn, R. (1985),A seismic refraction profile across the San Andreas, Sargent, and Calaveras faults, west-central California. Bull. Seis. Soc. Am.75, 175–191.
Mooney, W. D. andLuetgert, J. H. (1982),A seismic refraction study of the Santa Clara Valley and southern Santa Cruz Mountains, west-central California Bull. Seis. Soc. Am.72, 901–909.
Moos, D. andZoback, M. D. (1983),In situ studies of velocity in fractured crystalline rocks. J. Geophys. Res.88, 2345–2358.
Nur, A. andSimmons, G. (1968),The effect of saturation on velocity in low porosity rocks. Earth Planet. Sci. Lett.7, 183–193.
O'Connell, R. J., andBudiansky B. (1974)Seismic velocities in dry and saturated cracked solids. J. Geophys. Res.79, 5412–5426.
Pavoni, N. (1973), ‘A structural model for the San Andreas fault zone along the northeast side of the Gabilan Range’, inProc. Conf. Tectonic Problems San Andreas Fault System, R. L. Kovach and A. Nur (eds.) Stanford Univ. Publ. Geol. Sci.13, 259–267.
Peddy, C. P. (1984),Displacement of the Moho by the Outer Isles thrust shown by seismic modeling. Nature312, 628–630.
Sibson R. H. (1977),Fault rocks and fault mechanism. J. Geol. Soc. Lond.133, 191–213.
Simmons, G. andNur, A. (1968),Granites: Relation of properties in situ to laboratory measurements. Science162, 789–791.
Sjogren, B. (1984),Shallow Refraction Seismics, Chapman and Hall, London, 268 pp.
Smithson, S. B., Brewer, J. A., Kaufman, S., Oliver, J. E. andHurich, C. (1979),Structure of the Laramide Wind River uplift, Wyoming, from COCORP deep reflection data and from gravity data. J. Geophys. Res.84, 5955–5972.
Stierman, D. J. (1984),Geophysical and geological evidence for fracturing, water circulation, and chemical alteration in granitic rocks adjacent to major strike-slip faults. J. Geophys. Res.89, 5849–5857.
Stierman, D. J. andKovach, R. L. (1979),An in situ velocity study: The Stone Canyon well. J. Geophys. Res.84, 672–678.
Thurber, C. H. (1983),Earthquake locations and three-dimensional crustal structure in the Coyote Lake Area, central California. J. Geophys. Res.88, 8226–8236.
Trehu, A. M. andWheeler, W. H. (1986),Possible evidence for subducted sediments beneath central California. Geology (submitted).
Wallace, R. E. (1949),Structure of a portion of the San Andreas rift in southern California. Geol. Soc. Am. Bull.,60, 781–806.
Wang, C. Y. (1984),On the constitution of the San Andreas fault zone in central California. J. Geophys. Res.,89, 5858–5866.
Wang, C. Y., Lin, W. N. andWu, F. T. (1978),Constitution of the San Andreas Fault Zone at depth. Geophys. Res. Lett.5, 741–744.
Wang, H. F. andSimmons, G. (1978),Microcracks in crystalline rock from 5.3 km depth in the Michigan Basin. J. Geophys. Res.83, 5849–5856.
Wu, F. T. (1978),Mineralogy and physical nature of clay gouge. Pure Appl. Geophys.116, 655–689.
Wu, F. T., Blatter, L. andRobertson, H. (1975),Clay gouges in the San Andreas fault system and their possible implications. Pure Appl. Geophys.113 87–96.
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Mooney, W.D., Ginzburg, A. Seismic measurements of the internal properties of fault zones. PAGEOPH 124, 141–157 (1986). https://doi.org/10.1007/BF00875723
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DOI: https://doi.org/10.1007/BF00875723