Fault slip rates in the modern new madrid seismic zone
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.
Mueller
K
Department of Geological Sciences, University of Colorado, Boulder, CO 80309-0399, USA. Department of Geology, University of Arkansas, Fayetteville, AR 72701, USA. William Lettis and Associates, 1777 Botelho Drive, Suite 262, Walnut Creek, CA 945.
Champion
J
Guccione
M
Kelson
K