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Date Available

12-7-2011

Year of Publication

2005

Document Type

Thesis

College

Engineering

Department/School/Program

Mechanical Engineering

Faculty

Keith Rouch

Abstract

In intraplate seismic zones (e.g. the New Madrid Seismic Zone, NMSZ, in the southcentral United States), the source of stress that drives earthquake is very complex. Data from the NMSZ indicate 3 earthquake of magnitude M~7, occurring at an approximate interval of 500 years during the last 2000 years. One hypothesis that satisfies these conditions proposes that short-lived bursts of earthquakes may result from perturbations in the local or regional stress field. This causes relaxation of a lower crustal weak zone which drive repeated earthquakes. The number of earthquakes is dependent on the geometry and rheology of the weak zone. Using finite element techniques which employ contact surfaces to model discrete faulting events and a maximum shear stress criteria evaluated at each node. We investigate the relevant parameter space, as it affects the concentration of stress at the base of the seismogenic fault and the number of earthquakes generated over a given time interval. Parameters that can be varied include earthquake stress drop, background tectonic stress, and maximum shear stress at failure. Results show that solutions are non-unique. With the addition of existing observational evidence, however, we can place bounds on the range of parameters which satisfy above observations.

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