Delano, Jaime E. and Briggs, Richard W. and Thompson Jobe, Jessica and Gold, Ryan D. and Engelhart, Simon E. (2021) 'Quaternary Reelfoot fault deformation in the Obion River valley, Tennessee, USA.', Tectonics, 40 (8).
Blind reverse faults are challenging to detect, and earthquake records can be elusive because deep fault slip does not break the surface along readily recognized scarps. The blind Reelfoot fault in the New Madrid seismic zone in the central United States has been the subject of extensive prior investigation; however, the extent of slip at the southern portion of the fault remains unconstrained. In this study, we use lidar to map terraces and lacustrine landforms in the Obion River valley and investigate apparent broad folding resulting from slip on the buried Reelfoot fault. We compare remote surface mapping results with three auger boreholes in the ∼24 ka Finley terrace and interpret apparent warping as due to tectonic folding and not stratigraphic thickening. We combine our results with historical records of coseismic lake formation that indicate surface deformation dammed the Obion River in the 1812 CE earthquake. Older terraces (deposited at least 35–55 ka) record progressive fold scarps ≥1, ≥2, and ≥8 m high indicating a long record of earthquakes predating the existing paleoseismic record. Broad, distributed folding above the Reelfoot fault into the Obion River valley is consistent with a deep active fault tip along the southern reaches of the fault. Our analyses indicate the entire length of the fault (≥70 km) is capable of rupture and is more consistent with longer rupture scenarios.
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|Publisher Web site:||https://doi.org/10.1029/2019TC005990|
|Publisher statement:||Copyright 2021 American Geophysical Union. Delano, Jaime E., Briggs, Richard W., Jobe, Jessica Thompson, Gold, Ryan D. & Engelhart, Simon E., (2021), Quaternary Reelfoot fault deformation in the Obion River valley, Tennessee, USA, Tectonics, 40:8, 10.1029/2019TC005990. To view the published open abstract, go to http://dx.doi.org and enter the DOI.|
|Date accepted:||02 August 2021|
|Date deposited:||23 September 2021|
|Date of first online publication:||30 August 2021|
|Date first made open access:||02 March 2022|
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