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Geodynamic modeling of the Southeastern United States: Associations between gravitational potential energy, modern tectonism, and inherited structures
  • Michael Brown,
  • Cassidy Jay
Michael Brown
Washington and Lee University

Corresponding Author:[email protected]

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Cassidy Jay
Washington and Lee University
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Abstract

Regional geodynamics studies of the eastern United States (e.g., Ghosh et al., 2019) have shed light on the force balance controlling intraplate, passive margin seismicity. Recent observations of crustal structure in the Southeastern United States (Chen et al., 2018; Hopper et al., 2016; Parker et al., 2016; Savage et al., 2017; Wagner et al., 2018) now allow us to examine the gravitational component of force balance in more detail. Here, we examine the role of gravitational potential energy (GPE) within the crust and upper mantle in ongoing stress, strain, and tectonism in the Southeastern United States. We first calculate GPE differences using density and crustal thickness data from Crust 1.0 (Laske et al., 2013) which are integrated over the thickness of the lithosphere on a 0.5 by 0.5 degree grid (e.g., Flesch et al., 2001). In further models we modify crustal densities using recent seismic observations (e.g., Parker et al., 2016; Wagner et al., 2018). We compare model results to earthquake epicenters and locations of inherited structures within our study area, including the Reelfoot Rift; New Madrid Seismic Zone; Illinois Basin; New York-Alabama Lineament; sutures between sections of accreted terrane; and a region of high seismic velocity beneath central West Virginia interpreted as delaminated, eclogitized crust (Biryol et al., 2016). Whereas in most locations seismicity is associated with higher magnitudes of GPE, inherited structures may explain regions in which earthquakes occur in areas with lower magnitudes of GPE.