Report

Fault Slip Rates in the Modern New Madrid Seismic Zone

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Science  05 Nov 1999:
Vol. 286, Issue 5442, pp. 1135-1138
DOI: 10.1126/science.286.5442.1135

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Abstract

Structural and geomorphic analysis of late Holocene sediments in the Lake County region of the New Madrid seismic zone indicates that they are deformed by fault-related folding above the blind Reelfoot thrust fault. The widths of narrow kink bands exposed in trenches were used to model the Reelfoot scarp as a forelimb on a fault-bend fold; this, coupled with the age of folded 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 relief across the scarp and the estimated dip of the underlying blind thrust to 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.

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