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Shallow fault slip of the 2020 M5.1 Sparta, North Carolina, earthquake

Frederick Pollitz
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Abstract

The 2020 M 5.1 Sparta, North Carolina, earthquake is the largest in the eastern United States since the 2011 M 5.8 Mineral, Virginia, earthquake and produced a ∼2.5‐km‐long surface rupture, unusual for an event of this magnitude. A geological field study conducted soon after the event indicates oblique slip along a east‐southeast‐trending fault with a consistently observed thrust component. My analysis of regional seismic waveforms, Interferometric Synthetic Aperture Radar, and Global Positioning System survey data yields a compact shallow rupture extending from Earth’s surface down‐dip to the southwest over a ∼3 km fault length. The inferred kinematic rupture is primarily toward the up‐dip and eastward along‐strike directions and has predominantly thrust motion in the west, transitioning to roughly equal thrust and left‐lateral strike‐slip motion in the east. No normal faulting component, as proposed in an earlier geophysical study, is necessary to explain the data. The prevalence of only dip‐slip motions observed at Earth’s surface may demand slip partitioning between dip slip and lateral motions at depth.

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Seismological Research LettersArticle
90° N90° S · 180° W ← longitude → 180° E
Source-reported bounding extent: 35° to 39° latitude; -83° to -77° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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BibTeXRIS

Frederick Pollitz. 2023-09-11. Shallow fault slip of the 2020 M5.1 Sparta, North Carolina, earthquake. https://doi.org/10.1785/0220230127

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