GEORADAR PROFILE STUDIES OF QUATERNARY DEFORMATION ASSOCIATED WITH THE FARRENBURG AND COMMERCE GEOPHYSICAL LINEAMENTS IN THE NEW MADRID SEISMIC ZONE

The New Madrid Seismic Zone is located in the central Mississippi Valley and is the most seismically active area in central and eastern United States. Geological and geophysical studies were conducted near the villages of Idalia and Farrenburg, Missouri. The Holly Ridge site, located near Idalia, Missouri, is associated with the Commerce geophysical lineament. The Farrenburg site is associated with the North and South Farrenburg lineaments. These lineaments may be related to microseismicity of the New Madrid Seismic Zone.

Aerial photography, seismic-reflection, paleoseismic trenching, and georadar have been used to determine if these linear geomorphic features are related to deeper structures and if they are possibly of tectonic origin. The Holly Ridge and Farrenburg sites were selected by the presence of photo-lineaments. Comparison of georadar and trenching profiles show that each of the lineaments are related to shallow faulting which in turn appear to be related to deeper faulting observed on seismic reflection profiles. Thus the geological and geophysical studies provide evidence for late Pleistocene to early Holocene deformation that is interpreted to be of tectonic origin. The structures imaged on the geophysical profiles at each site appear to be directly related to the Farrenburg and Commerce geophysical lineaments and therefore may be related to any seismicity associated with those lineaments.