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Localized fault-zone dilatancy and surface inelasticity of the 2019 Ridgecrest earthquakes

05 June 2023 Editor’s Note: Readers are alerted that the reliability of some analysis presented in this manuscript is currently in question. Appropriate editorial action will be taken once this matter is resolved.

An Author Correction to this article was published on 06 December 2022

This article has been updated


Earthquakes produce a spectrum of elastic and inelastic deformation processes that are reflected across various length and time scales. While elasticity has long dominated research assumptions in active tectonics, increasing interest has focused on the inelastic characteristics of earthquakes, particularly those of the surface fault rupture zone itself, and how they relate to ground rupture hazard and the mechanics of damage zones. Here we present detailed co-seismic surface-strain analysis of the 2019 Ridgecrest, California, earthquakes. We derive three-dimensional high-resolution surface displacements from satellite optical imagery, which we then invert for the co-seismic surface-strain tensors. We show that fault-zone dilation is pervasive throughout these earthquakes and that inelastic failure is present but relatively localized (median width of 31 m). The width of the inelastic failure zone is not correlated to off-fault deformation, surface geology or displacement magnitude. Instead, the extent and kinematics of inelastic failure reflect active, mylonitic deformation of the fault damage zone that is influenced by rupture velocity and fault maturity. These results highlight how a single earthquake contributes to the long-term, permanent geologic record of faulting.

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Fig. 1: High-resolution (2 m) surface-displacement fields of the 2019 Ridgecrest earthquakes.
Fig. 2: Surface-strain overview of the Ridgecrest earthquakes.
Fig. 3: Illustrations of the relationships among displacement, strain-zone width and OFD.
Fig. 4: Surface-strain orientations and mylonite-like surface deformation patterns.

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Data availability

Derived 2 m DSMs used for image orthorectification and vertical differencing are available at Open Topography ( and Horizontal and vertical displacement fields and complete 2D and 3D strain maps are available through the US Geological Survey Science Base-Catalog ( No raw imagery is shown in this manuscript. Raw imagery details are given in the Supplementary Information and can be obtained independently through the appropriate provisions of the NextView license or commercial access.

Code availability

MATLAB scripts used to generate co-seismic strain fields can be accessed through

Change history

  • 05 June 2023

    Editor’s Note: Readers are alerted that the reliability of some analysis presented in this manuscript is currently in question. Appropriate editorial action will be taken once this matter is resolved.

  • 06 December 2022

    A Correction to this paper has been published:


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W.D.B. was supported in part by NSF/USGS SCEC Awards 17086 and 16147. We acknowledge the DigitalGlobe/NextView licensing agreement through which we accessed pre-earthquake and post-earthquake WorldView imagery. Any use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the US Government. This research was supported in part through computational resources provided by The University of Iowa.

Author information

Authors and Affiliations



W.D.B. and R.D.G. designed the study. W.D.B. processed horizontal and vertical displacements fields, derived strain fields and generated interpretable materials. R.D.G. facilitated data access. J.H. processed imagery spanning the Mw 6.4 foreshock. All authors contributed to the writing of the manuscript.

Corresponding author

Correspondence to William D. Barnhart.

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The authors declare no competing interests.

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Peer review information Primary Handling Editor: Stefan Lachowycz.

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

Extended data

Extended Data Fig. 1 North-South Horizontal Displacements.

Mosaic of north-south horizontal displacement field spanning both Mw6.4 foreshock and Mw7.1 mainshock (east-west and vertical displacements are shown in Fig. 1a, b).

Extended Data Fig. 2 Vertical Displacement Comparison between Differencing and ICP approaches.

a) Vertical displacement field generated by differencing pre- and post-seismic DSMs (negative is co-seismic subsidence). b) Vertical displacement field generated by applying a windowed ICP approach to pre- and post-seismic DSMs (negative is co-seismic subsidence). c) Overlapped comparison of vertical displacements from profile X-X’ highlighted in panels a and b. n is the total number of observations within the profile.

Extended Data Fig. 3 2D Horizontal Strain Fields.

a) S1 (greatest principal strain) component of the 2D strain field. b) S2 (smallest principal strain) component of the 2D strain field. c) Shear strain component of the 2d strain field.

Extended Data Fig. 4 3D Complete Strain Fields.

Each component of the full 3D strain field derived from horizontal and vertical displacements. a) S1 (greatest principal strain), b) S2 (intermediate principal strain), c) S3 (smallest principal strain), d) Shear between the north-east directions, e) shear between the north-vertical directions, f) shear between the east-vertical directions, g) dilatation.

Extended Data Fig. 5 Map-view Comparison of Inelastic Strain Zone Width and Off-Fault Deformation Zone.

Map view depictions of fault zone width (FZW) as defined by the inelastic zone width (as defined by dilatation and shear strains exceeding +/- 0.5%) and the off- fault deformation (OFD) zone width that is mapped from across-fault offsets (Fig. 3a, b). The along-rupture location of these measurements are shown in Fig. 2b. a) Dilatation zone width, b) shear zone width, c) off-fault deformation zone width.

Extended Data Fig. 6 Comparison of Rupture Velocity to Inelastic Strain Zone Width.

Comparison of median and 16th/84th percentile inelastic strain zone widths to earthquake rupture velocities (a) reported by Yang et al. (2020) for segments I-III shown in panel b. The strain zone widths show an inverse relationship with rupture velocity. The black star in b indicates the epicenter of the Mw7.1 mainshock.

Extended Data Fig. 7 Comparison of WorldView and Planet Horizontal Displacement Fields.

Comparison of horizontal displacements derived from WorldView imagery in this study to horizontal displacements derived from Planet Labs imagery (Milliner and Donnellan, 2020). All displacements are resampled to the 87-meter resolution of the Planet Labs results. a) E-W component from this study, b) E-W component of Milliner and Donnellan (2020), c) difference between a and b, d) N-S component from this study, e) N-S component from Milliner and Donnellan (2020), f) difference between d and e.

Extended Data Fig. 8 Effects of Strain Cell Size on Surface Strain Characteristics.

Illustration of how strain inversion cell size impacts strain fields from the 2019 Ridgecrest earthquakes. The top row shows the resulting shear strain field when inverted using triangulation (a), and 4x4m (b), 10x10m (c), and 30x30m (d) averaging cells respectively. e) Strains within the black profile box. Regions in the anelasticity zone exceed the expected failure strain (0.5% strain), while regions in the elasticity zone do not fail. Changes in the strain cell resolution serve to create a smoother strain field with smaller peak strain values, but they also do not significantly impact the interpreted permanent strain zone width. The values in the profile are plotted as the absolute value of the shear strain, in logarithmic space.

Extended Data Fig. 9 Effects of Inversion Regularization on Surface Strain Characteristics.

Illustration of the sensitivity of strain inversions to regularization coefficients of 0.01 (a), 0.1 (b), 0.25 (c), and 0.5 (d) for the same region shown in Extended Data Fig. 8. e) Difference between panels d and a (0.5 vs. 0.01) showing that more regularization (0.5) leads to smaller peak strain values than when little regularization (0.01) is imposed, but that the spatial characteristics of strain do not change. f) Strains within the black profile box. Regions in the anelasticity zone exceed the expected failure strain (0.5% strain), while regions in the elasticity zone do not fail. The values for each of the weighting values are similar such that the different strain values are overlapping and cannot be distinguished from each other.

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Barnhart, W.D., Gold, R.D. & Hollingsworth, J. Localized fault-zone dilatancy and surface inelasticity of the 2019 Ridgecrest earthquakes. Nat. Geosci. 13, 699–704 (2020).

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