Seismic Potential of the New Madrid Seismic Zone#s Reelfoot Fault: Collaborative Research with the University of Memphis and University of Kentucky

The objective of this proposed research is to ascertain whether the Reelfoot fault within the New Madrid seismic zone is a single 74 km long fault capable of generating a ~ M 7.2 earthquake or whether it consists of two discrete faults - the 49 km Reelfoot North and 25 km Reelfoot South faults - capable of generating a ~ M 6.9 earthquake. This will be undertaken by conducting a geophysical survey and geologic mapping to image the fault at the critical location where the Reelfoot fault appears to separate into two segments. Specifically, we will collect 10 seismic soundings 0.5 km apart to determine if the Reelfoot fault exists at this critical location and we will follow with a 1 km long seismic reflection line if the soundings support the existence of the fault. Additionally, a 5 km long strip map of the top and bottom of the Pliocene Upland Complex (ancestral Mississippi River terrace) will be made within the bluffs of the Mississippi River to determine if the Upland Complex is displaced by the Reelfoot fault. Our expected outcome will be one of the following: 1) the Reelfoot fault is one 74 km long fault with > 70 m of vertical displacement on the top of the Paleozoic, 2) displacement on top of the Paleozoic is zero meters and thus the faults are separate, or 3) displacement histories and magnitudes on the Reelfoot North and Reelfoot South faults differ and thus the faults are connected but are semi-independent. There is no surface fault scarp along the southern portion of the Reelfoot fault (Reelfoot South fault). Thus, identification of two discrete faults would suggest that; 1) the current earthquakes on the Reelfoot South fault are not aftershocks of the February 1812 main shock but a smaller main shock, or 2) that the Reelfoot South fault is experiencing foreshocks.