NEW MADRID FAULT GEOMETRY

Based on a review of the geology, seismically and topology of the surrounding area, a plate tear is proposed to explain the New Madrid fault. Reconstructing the tear joins the Ozark and Appalachian Mountains into a continuous mountain range 800mya. With the proposed sequence, some speculation is possible about the original cause of the tear.

The paper deals with the geometry of crustal motion around the New Madrid seismic zone. The existing topography and surface geology are used to reconstruct the proposed motion.

The approach follows conventional forensic analysis of material failures in industrial environments. The basic analogy is to a tear in piece of paper with New Madrid being the blunted point of the active tear. The faults split northeast and northwest from there, tending to arrest the crack.

Age dating from existing geological description suggests the sequencing of the motions. The sharp discontinuities between the age of the Ozark Mountains and the abutting Mississippi embayment suggests a tear edge. The Appalachian Mountains share a similar age, and appearance to the Ozarks, suggesting a similar origin. The Appalachians appear to descend into embayment sediment terminating abruptly in Wash County, Mississipi, suggesting a mate to the east end of the Ozark Mountains. Tension tears on the outside of the rotating Appalachians appear in Cambell County Tennessee and Buchann County, Kentucky. Since the motion occurs in a continuous crustal surface, an opening in one location requires closing in another area. This is proposed as an explanation for seismic activity in Charleston occurring simultaneously with New Madrid activity.

The appearance on a topological map is consistent with this scenario.

Following this understanding of the seismic zone, it is open to speculation as to why and how it occurred. Within the same geologic time frame, the Atlantic spreading zone was active. The forces causing the continental motion could have splayed out such a notch. An additional mechanism that could cause a sudden crack that appears to have arrested itself would be a sharp blow, such as a meteor strike in the Gulf of Mexico.