Fault slip rates in the modern New Madrid seismic zone

Structural and geomorphic analysis of Late Holocene sediments in the Lake C ounty region of the New Madrid seismic zone indicates that they are deforme d by fault-related folding above the blind Reelfoot thrust fault. The width s of narrow kink bands exposed in trenches were used to model the Reelfoot scarp as a forelimb on a fault-bond fold; this, coupled with the age of fol ded sediment, yields a slip rate on the blind thrust of 6.1 +/- 0.7 mm/year for the past 2300 +/- 100 years. An alternative method used structural rel ief across the scarp and the estimated dip of the underlying blind thrust t o calculate a slip rate of 4.8 +/- 0.2 mm/year. Geometric relations suggest that the right lateral slip rate on the New Madrid seismic zone is 1.8 to 2.0 mm/year.