Interseismic strain accumulation and the earthquake potential on the southern San Andreas fault system


The San Andreas fault in California is a mature continental transform fault that accommodates a significant fraction of motion between the North American and Pacific plates. The two most recent great earthquakes on this fault ruptured its northern and central sections in 1906 and 1857, respectively. The southern section of the fault, however, has not produced a great earthquake in historic times (for at least 250 years). Assuming the average slip rate of a few centimetres per year, typical of the rest of the San Andreas fault, the minimum amount of slip deficit accrued on the southern section is of the order of 7–10 metres, comparable to the maximum co-seismic offset ever documented on the fault1,2. Here I present high-resolution measurements of interseismic deformation across the southern San Andreas fault system using a well-populated catalogue of space-borne synthetic aperture radar data. The data reveal a nearly equal partitioning of deformation between the southern San Andreas and San Jacinto faults, with a pronounced asymmetry in strain accumulation with respect to the geologically mapped fault traces. The observed strain rates confirm that the southern section of the San Andreas fault may be approaching the end of the interseismic phase of the earthquake cycle.

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Figure 1: Line of sight (LOS) velocity of the Earth's surface from a stack of radar interferograms spanning a time interval between 1992 and 2000.
Figure 2: Average LOS velocities (grey dots) and GPS/EDM data (coloured symbols) projected onto the satellite LOS from the profile A–A′ shown in Fig. 1.


  1. 1

    Sieh, K., Stuiver, M. & Brillinger, D. A more precise chronology of earthquakes produced by the San Andreas fault in Southern California. J. Geophys. Res. 94, 603–623 (1989)

    ADS  Article  Google Scholar 

  2. 2

    Weldon, R. J., Fumal, T. E., Biasi, G. P. & Scharer, K. M. Geophysics—Past and future earthquakes on the San Andreas fault. Science 308, 966–967 (2005)

    CAS  Article  PubMed  Google Scholar 

  3. 3

    Turcotte, D. L. & Schubert, G. Geodynamics 2nd edn (Cambridge Univ. Press, New York, 2002)

    Google Scholar 

  4. 4

    Lyons, S. & Sandwell, D. Fault creep along the southern San Andreas from interferometric synthetic aperture radar, permanent scatterers, and stacking. J. Geophys. Res. 108, doi:10:1029/2002JB001831 (2003)

  5. 5

    Thatcher, W. & Lisowski, M. Long-term seismic potential of the San Andreas fault southeast of San Francisco, California. J. Geophys. Res. 92, 4771–4784 (1987)

    ADS  Article  Google Scholar 

  6. 6

    Bennett, R. A., Friedrich, A. M. & Furlong, K. P. Codependent histories of the San Andreas and San Jacinto fault zones from inversion of fault displacement rates. Geology 32, 961–964 (2004)

    ADS  Article  Google Scholar 

  7. 7

    Working Group on California Earthquake Probabilities. Seismic hazards in southern California: Probable earthquakes, 1994–2024. Bull. Seismol. Soc. Am. 85, 379–439 (1995)

    Google Scholar 

  8. 8

    Johnson, H. O., Agnew, D. C. & Wyatt, F. K. Present-day crustal deformation in southern California. J. Geophys. Res. 99, 23951–23974 (1994)

    ADS  Article  Google Scholar 

  9. 9

    Bennett, R. A., Rodi, W. & Reilinger, R. E. Global positioning system constraints on fault slip rates in southern California and northern Baja, Mexico. J. Geophys. Res. 101, 21943–21960 (1996)

    ADS  Article  Google Scholar 

  10. 10

    van der Woerd, J. et al. Long-term slip rate of the southern San Andreas Fault, from 10Be-26Al surface exposure dating of an offset alluvial fan. J. Geophys. Res 111, B04407, doi:10.1029/2004JB003559 (2006)

    ADS  Article  Google Scholar 

  11. 11

    Fialko, Y. Probing the mechanical properties of seismically active crust with space geodesy: Study of the co-seismic deformation due to the 1992 M w7.3 Landers (southern California) earthquake. J. Geophys. Res. 109, B03307, doi:10.1029/2003JB002756 (2004)

    ADS  Google Scholar 

  12. 12

    DeMets, C., Gordon, R. G., Argus, D. F. & Stein, S. Current plate motions. Geophys. J. Int. 101, 425–478 (1990)

    ADS  Article  Google Scholar 

  13. 13

    Weldon, R. J. & Sieh, K. E. Holocene rate of slip and tentative recurrence interval for large earthquakes on the San Andreas fault, Cajon Pass, southern California. Geol. Soc. Am. Bull. 96, 793–812 (1985)

    ADS  Article  Google Scholar 

  14. 14

    Lisowski, M., Savage, J. & Prescott, W. H. The velocity field along the San Andreas fault in central and southern California. J. Geophys. Res. 96, 8369–8389 (1991)

    ADS  Article  Google Scholar 

  15. 15

    Le Pichon, X., Kreemer, C. & Chamot-Rooke, N. Asymmetry in elastic properties and the evolution of large continental strike-slip faults. J. Geophys. Res. 110, B03405, doi:10.1029/2004JB003343 (2005)

    ADS  Google Scholar 

  16. 16

    Li, V. C. & Rice, J. Crustal deformation in great California earthquake cycles. J. Geophys. Res. 92, 11533–11551 (1987)

    ADS  Article  Google Scholar 

  17. 17

    Kenner, S. & Segall, P. Lower crustal structure in Northern California: Implications from strain rate variations following the 1906 San Francisco earthquake. J. Geophys. Res. 108, 2011, doi:10.1029/2001JB000189 (2003)

    ADS  Article  Google Scholar 

  18. 18

    Fialko, Y., Simons, M. & Agnew, D. The complete (3-D) surface displacement field in the epicentral area of the 1999 M w7.1 Hector Mine earthquake, southern California, from space geodetic observations. Geophys. Res. Lett. 28, 3063–3066 (2001)

    ADS  Article  Google Scholar 

  19. 19

    Fialko, Y., Sandwell, D., Simons, M. & Rosen, P. Three-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip deficit. Nature 435, 295–299 (2005)

    ADS  CAS  Article  PubMed  Google Scholar 

  20. 20

    Prescott, W. H. & Yu, S. B. Geodetic measurement of horizontal deformation in the Northern San Francisco Bay region, California. J. Geophys. Res. 91, 7475–7484 (1986)

    ADS  Article  Google Scholar 

  21. 21

    Freymueller, J. T., Murray, M. H., Segall, P. & Castillo, D. Kinematics of the Pacific North America plate boundary zone, northern California. J. Geophys. Res. 104, 7419–7441 (1999)

    ADS  Article  Google Scholar 

  22. 22

    Fialko, Y. et al. Deformation on nearby faults induced by the 1999 Hector Mine earthquake. Science 297, 1858–1862 (2002)

    ADS  CAS  Article  PubMed  Google Scholar 

  23. 23

    Thatcher, W. Microplate versus continuum description of active tectonic deformation. J. Geophys. Res. 100, 3885–3894 (1983)

    ADS  Article  Google Scholar 

  24. 24

    Ben-Zion, Y. & Andrews, D. J. Properties and implications of dynamic rupture along a material interface. Bull. Seismol. Soc. Am. 88, 1085–1094 (1998)

    Google Scholar 

  25. 25

    Hauksson, E. Crustal structure and seismicity distribution adjacent to the Pacific and North America plate boundary in southern California. J. Geophys. Res. 105, 13875–13903 (2000)

    ADS  Article  Google Scholar 

  26. 26

    Yule, D. & Sieh, K. Complexities of the San Andreas fault near San Gorgonio Pass: Implications for large earthquakes. J. Geophys. Res. 108, doi:10.1029/2001JB000451 (2003)

  27. 27

    Fialko, Y., Rivera, L. & Kanamori, H. Estimate of differential stress in the upper crust from variations in topography and strike along the San Andreas fault. Geophys. J. Int. 160, 527–532 (2005)

    ADS  Article  Google Scholar 

  28. 28

    Richards-Dinger, K. & Shearer, P. Earthquake locations in southern California obtained using source specific station terms. J. Geophys. Res. 105, 10939–10960 (2000)

    ADS  Article  Google Scholar 

  29. 29

    Waters, M. R. Late Holocene lacustrine chronology and archaeology of ancient lake Cahuilla, California. Quat. Res. 19, 373–387 (1983)

    Article  Google Scholar 

  30. 30

    Murray, J. & Segall, P. Testing time-predictable earthquake recurrence by direct measurement of strain accumulation and release. Nature 419, 287–291 (2002)

    ADS  CAS  Article  PubMed  PubMed Central  Google Scholar 

  31. 31

    Weldon, R. J., Scharer, K. M., Fumal, T. E. & Biasi, G. P. Wrightwood and the earthquake cycle: What a long recurrence record tells us about how faults work. GSA Today 14, 4–10 (2004)

    Article  Google Scholar 

  32. 32

    Cisternas, M. et al. Predecessors of the giant 1960 Chile earthquake. Nature 437, 404–407 (2005)

    ADS  CAS  Article  Google Scholar 

  33. 33

    Sharp, R. V. San Jacinto fault zone in the Peninsular Ranges of southern California. Geol. Soc. Am. Bull. 78, 705–730 (1967)

    ADS  Article  Google Scholar 

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I thank R. Weldon and P. Segall for suggestions. This work was supported by the NSF and the Southern California Earthquake Center (SCEC). Original InSAR data are copyright of the European Space Agency, distributed by Eurimage, Italy, and acquired via the WInSAR Consortium. The ERS SAR imagery was processed using the JPL/Caltech software package ROI_PAC. The continuous GPS data were provided by the Scripps Orbit and Permanent Array Center (SOPAC), and the campaign GPS and EDM data were provided by the Crustal Motion Model v3 of SCEC.

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Fialko, Y. Interseismic strain accumulation and the earthquake potential on the southern San Andreas fault system. Nature 441, 968–971 (2006).

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