Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Simple shear origin of the cross-faults ruptured in the 2019 Ridgecrest earthquake sequence

Nature Geoscience volume 14, pages 513–518 (2021)Cite this article

Subjects

Abstract

Observations in tectonically active areas increasingly reveal sets of high-angle conjugate faults (‘cross-faults’) that apparently contradict theories of faulting based on experimental data. Possible explanations include a low in situ coefficient of friction, dominant control of ductile shear zones in the lower crust, and tectonic rotation. Discrimination between these mechanisms has been hindered by uncertainties in the state of stress, deformation history and fault geometry at seismogenic depths. Here we use a combination of seismic, geodetic and geologic data to demonstrate that ubiquitous cross-faults in the Ridgecrest (California) area, including those ruptured in the sequence of strong earthquakes in 2019, result from rotation from an initially optimal orientation consistent with experimental data. The inferred rotation pattern can be explained by the geodetically measured velocity field. Our model suggests that the observed asymmetric rotation of faults in the Eastern California Shear Zone can result from simple shear. The same mechanism can be responsible for high-angle conjugate faults observed in other tectonic settings.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Aftershocks and coseismic surface displacements due to the 2019 Ridgecrest earthquakes.
Fig. 2: Orientation of the principal stress and strain rate axes in the 2019 mainshock area.
Fig. 3: Fault rotation predicted by extrapolation of the present-day velocity field into the geologic past.
Fig. 4: Finite strain and rotation recorded by offset dikes.

Similar content being viewed by others

Data availability

All data used in this study are open access. The first motion focal mechanism of the 2019 Mw 7.1 mainshock is available at https://earthquake.usgs.gov/earthquakes/eventpage/ci38457511/focal-mechanism. The seismic moment of the 2019 Mw 7.1 mainshock is available at https://earthquake.usgs.gov/earthquakes/eventpage/ci38457511/moment-tensor. The seismic moment of the 2019 Mw 6.4 foreshock is available at https://earthquake.usgs.gov/earthquakes/eventpage/ci38443183/moment-tensor. The waveform-relocated earthquake catalog for southern California from ref. 47 is available at https://scedc.caltech.edu/research-tools/alt-2011-dd-hauksson-yang-shearer.html. The GNSS position time series from the PBO is available at https://doi.org/10.7283/P2HT0Z. The coseismic displacement data and fault slip models from ref. 28 are available at https://doi.org/10.5281/zenodo.4646321.

Code availability

MATLAB codes used to generate results presented in this study are available at https://doi.org/10.5281/zenodo.4646292

References

  1. Anderson, E. M. The Dynamics of Faulting and Dike Formation with Application to Britain (Oliver and Boyd, 1951).

  2. Scholz, C. H. The Mechanics of Earthquakes and Faulting 3rd edn (Cambridge Univ. Press, 2019).

  3. Byerlee, J. Friction of rock. Pure Appl. Geophys. 116, 615–626 (1978).

    Article  Google Scholar 

  4. Sibson, R. H. Rupture nucleation on unfavorably oriented faults. Bull. Seism. Soc. Am. 80, 1580–1604 (1990).

    Google Scholar 

  5. Lockner, D. A., Byerlee, J., Kuksenko, V., Ponomarev, A. & Sidorin, A. in Fault Mechanics and Transport Properties of Rocks (eds Evans, B. & Wong, T.) 3–31 (Academic, 1992).

  6. Walsh, J. & Watterson, J. Dips of normal faults in British Coal Measures and other sedimentary sequences. J. Geol. Soc. 145, 859–873 (1988).

    Article  Google Scholar 

  7. Collettini, C. & Sibson, R. H. Normal faults, normal friction? Geology 29, 927–930 (2001).

    Article  Google Scholar 

  8. Mount, V. & Suppe, J. State of stress near the San Andreas fault: implications for wrench tectonics. Geology 15, 1143–1146 (1987).

    Article  Google Scholar 

  9. Zoback, M. D. et al. New evidence on the state of stress of the San Andreas fault system. Science 238, 1105–1111 (1987).

    Article  Google Scholar 

  10. Wernicke, B. Low-angle normal faults and seismicity: a review. J. Geophys. Res. 100, 20159–20174 (1995).

    Article  Google Scholar 

  11. Wang, K. & Fialko, Y. Observations and modeling of coseismic and postseismic deformation due to the 2015 Mw 7.8 Gorkha (Nepal) earthquake. J. Geophys. Res. 123, 761–779 (2018).

    Article  Google Scholar 

  12. Ron, H., Beroza, G. & Nur, A. Simple model explains complex faulting. Eos 82, 125–129 (2001).

    Article  Google Scholar 

  13. Sibson, R. Reverse fault rupturing: competition between non-optimal and optimal fault orientations. Geol. Soc. Spec. Publ. 367, 39–50 (2012).

    Article  Google Scholar 

  14. Wintsch, R., Christoffersen, R. & Kronenberg, A. Fluid-rock reaction weakening of fault zones. J. Geophys. Res. 100, 13021–13032 (1995).

    Article  Google Scholar 

  15. Faulkner, D. R., Mitchell, T. M., Healy, D. & Heap, M. J. Slip on ‘weak’ faults by the rotation of regional stress in the fracture damage zone. Nature 444, 922–925 (2007).

    Article  Google Scholar 

  16. Noda, H., Dunham, E. & Rice, J. R. Earthquake ruptures with thermal weakening and the operation of major faults at low overall stress levels. J. Geophys. Res. 114, B07302 (2009).

    Google Scholar 

  17. Di Toro, G. et al. Fault lubrication during earthquakes. Nature 471, 494–498 (2011).

    Article  Google Scholar 

  18. Han, R., Hirose, T. & Shimamoto, T. Strong velocity weakening and powder lubrication of simulated carbonate faults at seismic slip rates. J. Geophys. Res. 115, B03412 (2010).

    Google Scholar 

  19. Brown, K. M. & Fialko, Y. ‘Melt welt’ mechanism of extreme weakening of gabbro at seismic slip rates. Nature 488, 638–641 (2012).

    Article  Google Scholar 

  20. Fialko, Y. in Treatise on Geophysics 2nd edn, Vol. 4 (ed. Schubert, G.) 73–91 (Elsevier, 2015).

  21. Chester, J. S., Chester, F. M. & Kronenberg, A. K. Fracture surface energy of the Punchbowl fault, San Andreas system. Nature 437, 133–136 (2005).

    Article  Google Scholar 

  22. Copley, A. The strength of earthquake-generating faults. J. Geol. Soc. 175, 1–12 (2018).

    Article  Google Scholar 

  23. Mitchell, E., Fialko, Y. & Brown, K. M. Velocity-weakening behavior of Westerly granite at temperature up to 600°C. J. Geophys. Res. 121, 6932–6946 (2016).

    Article  Google Scholar 

  24. Angelier, J. Tectonic analysis of fault slip data sets. J. Geophys. Res. 89, 5835–5848 (1984).

    Article  Google Scholar 

  25. Nicholson, C., Seeber, L., Williams, P. & Sykes, L. R. Seismic evidence for conjugate slip and block rotation within the San Andreas fault system, southern California. Tectonics 5, 629–648 (1986).

    Article  Google Scholar 

  26. Ross, Z. E. et al. Hierarchical interlocked orthogonal faulting in the 2019 Ridgecrest earthquake sequence. Science 366, 346–351 (2019).

    Article  Google Scholar 

  27. Chen, K. et al. Cascading and pulse-like ruptures during the 2019 Ridgecrest earthquakes in the Eastern California Shear Zone. Nat. Commun. 11, 22 (2020).

    Article  Google Scholar 

  28. Jin, Z. & Fialko, Y. Finite slip models of the 2019 Ridgecrest earthquake sequence constrained by space geodetic data and aftershock locations. Bull. Seismol. Soc. Am. 110, 1660–1679 (2020).

    Article  Google Scholar 

  29. Magen, Y., Ziv, A., Inbal, A., Baer, G. & Hollingsworth, J. Fault rerupture during the July 2019 Ridgecrest earthquake pair from joint slip inversion of InSAR, optical Imagery, and GPS. Bull. Seismol. Soc. Am. 110, 1627–1643 (2020).

    Article  Google Scholar 

  30. Ponti, D. et al. Documentation of surface fault rupture and ground-deformation features produced by the 4 and 5 July 2019 Mw 6.4 and Mw 7.1 Ridgecrest earthquake sequence. Seismol. Res. Lett. 91, 2942–2959 (2020).

    Article  Google Scholar 

  31. Yang, W. & Hauksson, E. The tectonic crustal stress field and style of faulting along the Pacific North America Plate boundary in Southern California. Geophys. J. Int. 194, 100–117 (2013).

    Article  Google Scholar 

  32. Templeton, E. L. & Rice, J. R. Off-fault plasticity and earthquake rupture dynamics: 1. Dry materials or neglect of fluid pressure changes. J. Geophys. Res. 113, B09306 (2008).

    Google Scholar 

  33. Takeuchi, C. & Fialko, Y. Dynamic models of interseismic deformation and stress transfer from plate motion to continental transform faults. J. Geophys. Res. 117, B05403 (2012).

    Google Scholar 

  34. Montesi, L. Fabric development as the key for forming ductile shear zones and enabling plate tectonics. J. Struct. Geol. 50, 254–266 (2013).

    Article  Google Scholar 

  35. Takeuchi, C. & Fialko, Y. On the effects of thermally weakened ductile shear zones on postseismic deformation. J. Geophys. Res. 118, 6295–6310 (2013).

    Article  Google Scholar 

  36. Fialko, Y. & Simons, M. Deformation and seismicity in the Coso geothermal area, Inyo County, California: observations and modeling using satellite radar interferometry. J. Geophys. Res. 105, 21781–21793 (2000).

    Article  Google Scholar 

  37. Nur, A., Ron, H. & Scotti, O. Fault mechanics and the kinematics of block rotations. Geology 14, 746–749 (1986).

    Article  Google Scholar 

  38. Thatcher, W. & Hill, D. P. Fault orientations in extensional and conjugate strike-slip environments and their implications. Geology 19, 1116–1120 (1991).

    Article  Google Scholar 

  39. Dokka, R. K. & Travis, C. J. Role of the Eastern California shear zone in accommodating Pacific-North American plate motion. Geophys. Res. Lett. 17, 1323–1327 (1990).

    Article  Google Scholar 

  40. Chen, J. H. & Moore, J. G. Late Jurassic Independence dike swarm in eastern California. Geology 7, 129–133 (1979).

    Article  Google Scholar 

  41. Savage, J., Gan, W. & Svarc, J. Strain accumulation and rotation in the Eastern California Shear Zone. J. Geophys. Res. 106, 21995–22007 (2001).

    Article  Google Scholar 

  42. Fialko, Y. A. & Rubin, A. M. Thermal and mechanical aspects of magma emplacement in giant dike swarms. J. Geophys. Res. 104, 23033–23049 (1999).

    Article  Google Scholar 

  43. Hudnut, K. W., Seeber, L. & Pacheco, J. Cross-fault triggering in the November 1987 Superstition Hills earthquake sequence, southern California. Geophys. Res. Lett. 16, 199–202 (1989).

    Article  Google Scholar 

  44. Jennings, C. & Bryant, W. Fault Activity Map of California Geologic Data Map No. 6 (California Division of Mines and Geology, 2010).

  45. Fialko, Y. Probing the mechanical properties of seismically active crust with space geodesy: study of the coseismic deformation due to the 1992 Mw7.3 Landers (southern California) earthquake. J. Geophys. Res. 109, B03307 (2004).

    Google Scholar 

  46. Hauksson, E., Yang, W. & Shearer, P. M. Waveform relocated earthquake catalog for southern California (1981 to June 2011). Bull. Seismol. Soc. Am. 102, 2239–2244 (2012).

    Article  Google Scholar 

  47. Fialko, Y., Simons, M. & Agnew, D. The complete (3-D) surface displacement field in the epicentral area of the 1999 Mw7.1 Hector Mine earthquake, southern California, from space geodetic observations. Geophys. Res. Lett. 28, 3063–3066 (2001).

    Article  Google Scholar 

  48. 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).

    Article  Google Scholar 

  49. Tymofyeyeva, E. & Fialko, Y. Mitigation of atmospheric phase delays in InSAR data, with application to the eastern California shear zone. J. Geophys. Res. 120, 5952–5963 (2015).

    Article  Google Scholar 

  50. Wessel, P., Smith, W. H. F., Scharroo, R., Luis, J. & Wobbe, F. Generic Mapping Tools: improved version released. Eos 94, 409–410 (2013).

    Article  Google Scholar 

Download references

Acknowledgements

We thank O. Zielke and M.-H. Huang for their comments. This study was supported by NSF (grants EAR-1841273 and EAR-1945760) and NASA (grant 80NSSC18K0466). Figures were produced using Generic Mapping Tools50 and MATLAB.

Author information

Authors and Affiliations

  1. Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA

    Yuri Fialko & Zeyu Jin

Authors
  1. Yuri Fialko
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Zeyu Jin
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

Y.F. performed the data analysis and wrote the manuscript. Z.J. provided a finite fault model of the 2019 Ridgecrest earthquakes and contributed to the graphics design.

Corresponding author

Correspondence to Yuri Fialko.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Geoscience thanks Olaf Zielke and Mong-Han Huang for their contribution to the peer review of this work. Primary Handling Editor: Stefan Lachowycz.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary methods, Figs. 1–9 and references.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Fialko, Y., Jin, Z. Simple shear origin of the cross-faults ruptured in the 2019 Ridgecrest earthquake sequence. Nat. Geosci. 14, 513–518 (2021). https://doi.org/10.1038/s41561-021-00758-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41561-021-00758-5

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing