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An updated stress map of the continental United States reveals heterogeneous intraplate stress

Nature Geosciencevolume 11pages433437 (2018) | Download Citation


Knowledge of the state of stress in Earth’s crust is key to understanding the forces and processes responsible for earthquakes. Historically, low rates of natural seismicity in the central and eastern United States have complicated efforts to understand intraplate stress, but recent improvements in seismic networks and the spread of human-induced seismicity have greatly improved data coverage. Here, we compile a nationwide stress map based on formal inversions of focal mechanisms that challenges the idea that deformation in continental interiors is driven primarily by broad, uniform stress fields derived from distant plate boundaries. Despite plate-boundary compression, extension dominates roughly half of the continent, and second-order forces related to lithospheric structure appear to control extension directions. We also show that the states of stress in several active eastern United States seismic zones differ significantly from those of surrounding areas and that these anomalies cannot be explained by transient processes, suggesting that earthquakes are focused by persistent, locally derived sources of stress. Such spatially variable intraplate stress appears to justify the current, spatially variable estimates of seismic hazard. Future work to quantify sources of stress, stressing-rate magnitudes and their relationship with strain and earthquake rates could allow prospective mapping of intraplate hazard.

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J. Hardebeck, M. Zoback and M. L. Zoback provided helpful comments and discussions during preparation of this manuscript. W.L. was funded by the USGS Mendenhall Postdoctoral Fellowship and Earthquake Hazards Program.

Author information

Author notes

    • Will Levandowski

    Present address: Colorado College, Colorado Springs, CO, USA


  1. USGS, Golden, CO, USA

    • Will Levandowski
    • , Rich Briggs
    • , Oliver Boyd
    •  & Ryan Gold
  2. St Louis University, St Louis, MO, USA

    • Robert B. Herrmann


  1. Search for Will Levandowski in:

  2. Search for Robert B. Herrmann in:

  3. Search for Rich Briggs in:

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W.L. managed catalogue compilation, stress inversions, figure generation and manuscript preparation. R.B.H. generated a plurality of the focal mechanisms and aided in the uncertainty analysis for individual data. All authors collaborated on figure generation, drafting and hypothesis testing.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Will Levandowski.

Supplementary information

  1. Supplementary Information

    Supplementary description, figures, tables, and README file

  2. Supplementary Dataset 1

    Focal mechanism database

  3. Supplementary Dataset 2

    Results shown in Fig. 2c

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