Near‐surface deformation in the New Madrid Seismic zone as imaged by high resolution SH‐wave seismic methods

Abstract

Over 1.5 kilometers of high‐resolution, SH‐wave refraction and reflection profiles have been performed in the Madrid Bend area of northwestern Tennessee, approximately 8 km north of Tiptonville, Tennessee, to establish the existence of neo‐tectonic, near‐surface deformation. The specific area was chosen because of the access it provided to the Tiptonville dome (a Holocene flexure) and the trend of contemporary seismicity within the New Madrid seismic zone (NMSZ). We believed the highest likelihood of near‐surface deformation to be over these features. Partially reversed refraction/reflection walk‐away tests and common depth point (CDP) seismic profiling, using the non‐traditional SH‐wave method, have traced antiformal flexure and numerous faults into the late Eocene and Holocene sediments of the Tiptonville dome province of the Lake County uplift (LCU). Vertical displacements exhibited across the faults range from approximately 3 to 30 m. These structures have been interpreted to be neo‐tectonic features associated with tensional stresses across the Tiptonville dome.