Fault Slip Rates in the Modern New Madrid Seismic Zone
Karl Mueller,
1
Jocasta Champion,
1
Margaret Guccione,
2
Keith Kelson
3
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.
1 Department of Geological Sciences, University
of Colorado, Boulder, CO 80309-0399, USA.
2 Department of Geology, University of Arkansas,
Fayetteville, AR 72701, USA.
3 William Lettis and
Associates, 1777 Botelho Drive, Suite 262, Walnut Creek, CA 94596, USA.
