Elevated lateral stress in unlithified sediment, Midcontinent, United States - geotechnical and geophysical indicators for a tectonic origin

Edward W. Woolery, Jeffrey A. Schaefer, Zhenming Wang

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Indirect and direct geotechnical measurements revealed the presence of high lateral earth pressure (Ko) in shallow, unlithified sediment at a site in the northernmost Mississippi embayment region of the central United States. Results from pile-load and pressuremeter tests showed maximum Ko values greater than 10; however, the complex geologic environment of the Midcontinent made defining an origin for the anomalous Ko based solely on these measurements equivocal. Although in situ sediment characteristics indicated that indirect tectonic or nontectonic geologic mechanisms that include transient overburden loads (e.g., fluvial deposition/erosion, glacial advance/retreat) and dynamic shear loads (e.g., earthquakes) were not the dominant cause, they were unable to provide indicators for a direct tectonic generation. Localized stresses induced anthropogenically by the geotechnical field tests were also considered, but ruled out as the primary origin. A high-resolution shear-wave (SH) reflection image of geologic structure in the immediate vicinity of the test site revealed compression-style neotectonism, and suggested that the elevated stress was a tectonic manifestation. Post-Paleozoic reflectors exhibit a Tertiary (?) structural inversion, as evidenced by post-Cretaceous fault displacement and pronounced positive folds in the hanging wall of the interpreted faults. The latest stratigraphic extent of the stress effects (i.e., all measurements were in the Late Cretaceous to Tertiary McNairy Formation), as well as the relationship of stress orientation with the orientation of local structure and regional stress, remain unknown. These are the subjects of ongoing studies.

Original languageEnglish
Pages (from-to)139-153
Number of pages15
Issue number1-4
StatePublished - Jun 26 2003

Bibliographical note

Funding Information:
This research was supported by the US Geological Survey, Department of the Interior, under award number 01HQGR0044. Additional support came from the US Army Corps of Engineers and the Kentucky Geological Survey (KGS). The authors wish to thank John McBride and William Stephenson, as well as two anonymous reviewers, for their insightful comments. We also thank Meg Smath (KGS) and Collie Rulo (KGS) for their editorial and graphic arts improvements to the manuscript. The views and conclusions contained in this document are those of the authors, and do not necessarily represent those of the US Government or Commonwealth of Kentucky.


  • Neotectonics
  • New Madrid seismic zone
  • Seismic reflection
  • Stress

ASJC Scopus subject areas

  • Geophysics
  • Earth-Surface Processes


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