Abstract
Comparison between local variations in magnetic field, long-term changes in creep rate, and local earthquakes have been made for the seismically active and creeping section of the San Andreas fault between the most southern extent of the 1906 earthquake fault break and the most northern extent of the 1857 break, for the period early 1974 through mid-1977. The data utilized are from stations located near the two ends of this section of the San Andreas fault where strain accumulation is expected. The proton precession magnetometer stations included in this study have recorded local magnetic field variations up to 1.8 γ with durations of a few minutes to several months. The creep data indicated changes in creep rate of up to 10 mm/year lasting for 6 months or more and a close similarity between the changes in creep rate on two adjacent creepmeters about 7 km apart. Earthquakes with magnitudes less than 4.0 do not appear to correspond in time to local changes in magnetic field greater than 0.75 γ or variations in the creep rate. There is no general correspondence between creep events and magnetic field variations. There is, however, an approximate correspondence, in both space and time, between the long-term changes in creep rate and the variations in magnetic field. In order to explain the observations presented in this study, it appears necessary to allow for a substantial amount of deep aseismic slip without any obvious attendant changes in the time distribution or size of the local earthquakes.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Bakun, W.K., C.G. Bufe, and R.M. Stewart, Body wave spectra of central California earthquakes, Bull. Seismol. Soc. Am., 66, 363–384, 1976.
Burford, R.O., Fluctuations in rates of fault creep associated with moderate earthquakes along the central San Andreas fault, EOS, Trans. Am. Geophys. Union, 57, 1012, 1976.
Johnston, M.J.S., Local magnetic field variations and stress changes near a slip discontinuity on the San Andreas fault, J. Geomag. Geoelectr., 30, 511–522, 1978.
Johnston, M.J.S., B.E. Smith, and R.J. Mueller, Tectonic experiments and observations in western U.S.A., J. Geomag. Geoelectr., 28, 85–97, 1976a.
Johnston, M.J.S., S. McHugh, and R.O. Burford, On simultaneous tilt and creep observations on the San Andreas fault, Nature, 260, 691–693, 1976b.
Johnston, M.J.S., B.E. Smith, and R.O. Burford, Local magnetic field measurements and fault creep observations on the San Andreas fault, Tectonophysics, 1978 (in press).
McHugh, S. and M. Johnston, Short period nonseismic tilt perturbations and their relation to episodic slip on the San Andreas fault, J. Geophys. Res., 81, 6341–6345, 1976.
Mortensen, C.E., R.C. Lee, and R.O. Burford, Simultaneous tilt, strain, creep, and water level observations at the Cienega Winery south of Hollister, California, Bull. Seismol. Soc. Am., 67, 641–650, 1977.
Rikitake, T., Earthquake Prediction, pp. 197–211, Elsevier, Amsterdam, 1976.
Savage, J.C. and R.O. Burford, Discussion of paper by C.H. Scholz and T.J. Fitch, Strain accumulation along the San Andreas fault, J. Geophys. Res., 86, 6469–6479, 1971.
Slater, L.E. and R.O. Burford, A comparison of long-baseline strain data and fault creep records obtained near Hollister, California, Tectonophysics, 1978 (in press).
Smith, B.E. and M.J.S. Johnston, A tectonomagnetic effect observed before a magnitude 5.2 earthquake near Hollister, California, J. Geophys. Res., 81, 3556–3560, 1976.
Stacey, F.D. and S.K. Banerjee, The Physical Principles of Rock Magnetization, pp. 146–155, Elsevier, Amsterdam, 1974.
Stuart, W.D. and M.J.S. Johnston, Tectonic implications of anomalous tilt before central California earthquakes, EOS, Trans. Am. Geophys. Union, 56, 1196, 1974.
Talwani, P. and R.L. Kovach, Geomagnetic observations and fault creep in California, Tectonophysics, 6, 69–73, 1972.
Thatcher, W. and T.C. Hanks, Source parameters of southern California earthquakes, J. Geophys. Res., 78, 8547–8576, 1973.
Wesson, R.L., R.O. Burford, and W.L. Ellsworth, Relationship between seismicity, fault creep and crustal loading along the central San Andreas fault, in Proceedings of the Conference on Tectonic Problems of the San Andreas Fault System, edited by R.L. Kovach and A. Nur, pp. 303–321, School of Earth Sciences, Stanford University, Stanford, California, 1973.
Yamashita, P.A. and R.O. Burford, Catalog of preliminary results from an 18-station creepmeter network along the San Andreas fault system in central California for the time interval June 1969 to June 1973, U.S. Geol. Surv. Open File Report, 215 pp., 1973.
Author information
Authors and Affiliations
Editor information
Rights and permissions
Copyright information
© 1979 Center for Academic Publications Japan
About this paper
Cite this paper
Smith, B.E., Johnston, M.J.S., Burford, R.O. (1979). Local Variations in Magnetic Field, Long-Term Changes in Creep Rate, and Local Earthquakes along the San Andreas Fault in Central California. In: Fuller, M., Johnston, M.J.S., Yukutake, T. (eds) Tectonomagnetics and Local Geomagnetic Field Variations. Advances in Earth and Planetary Sciences, vol 5. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-9825-0_9
Download citation
DOI: https://doi.org/10.1007/978-94-010-9825-0_9
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-010-9827-4
Online ISBN: 978-94-010-9825-0
eBook Packages: Springer Book Archive