Fault Loading Processes in the New Madrid Seismic Zone

Our understanding of the tectonic processes which generate earthquakes in intraplate settings such as the New Madrid seismic zone is severely limited. There are, as yet, no widely agreed upon mechanical models for intraplate earthquakes. In collaboration with personnel from Stanford University, we propose research in three areas: 1) formulation of tectonically reasonable finite element models for the generation of intraplate earthquake sequences with specific application to the New Madrid seismic zone; 2) analysis of the effects of glacial unloading on seismicity; and 3) analysis of GPS uncertainties and how these impact our ability to detect strain accumulation and differentiate between competing models of intraplate seismicity. Fully time dependent finite element models which incorporate spatial variations in material behavior, frictional fault slip, and realistic far-field boundary conditions will provide new insights into the mechanics of stress transfer and earthquake generation in intraplate, low strain-rate regimes. Our results will attempt to providen 1) mechanically reasonable models which can be used to interpret existing geological and geophysical data, especially geodetic data and 2) a firm physical basis for seismic hazard estimation in this region. Analysis of stresses induced by glacial advance and recession, and their effect on predicted seismic slip history, will help to test the hypothesis that the observed late-Holocene increase in slip-rate was triggered by post glacial rebound. Finally, we will investigate the uncertainties in Global Positioning System measurements within the New Madrid seismic zone. Based on this analysis, we will provide recommendations on measurement strategies necessary to detect strain accumulation and differentiate between competing hypothesis for the generation of intraplate earthquakes. We will consider the types of surveys (continuous vs. campaign), network geometry, duration of observations, monument stability and how these factors effect uncertainty in strain-rate.