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A Mechanical Model for Intraplate Earthquakes: Application to the New Madrid Seismic Zone

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Science  29 Sep 2000:
Vol. 289, Issue 5488, pp. 2329-2332
DOI: 10.1126/science.289.5488.2329

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Abstract

We present a time-dependent model for the generation of repeated intraplate earthquakes that incorporates a weak lower crustal zone within an elastic lithosphere. Relaxation of this weak zone after tectonic perturbations transfers stress to the overlying crust, generating a sequence of earthquakes that continues until the zone fully relaxes. Simulations predict large (5 to 10 meters) slip events with recurrence intervals of 250 to 4000 years and cumulative offsets of about 100 meters, depending on material parameters and far-field stress magnitude. Most are consistent with earthquake magnitude, coseismic slip, recurrence intervals, cumulative offset, and surface deformation rates in the New Madrid Seismic Zone. Computed interseismic strain rates may not be detectable with available geodetic data, implying that low observed rates of strain accumulation cannot be used to rule out future damaging earthquakes.

  • * To whom correspondence should be addressed. E-mail: kenner{at}gps.caltech.edu

  • Present address: Division of Geological and Planetary Sciences, Seismological Laboratory, California Institute of Technology, Mail Code 252-21, Pasadena, CA 91125, USA.

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