Earthquake Generation in Intraplate Seismic Zones: Sources of Stress and Geometric Considerations

Evaluation seismic hazard within intraplate seismic zones is complk:ated the fact that many Of the parameters values needed in the estimation have large uncertainties. Typkal earthquake repeat times and spatial bOlli'1dson possible seismic sources are difficult to constrain observationally because intraplate t1mltsare geologically short-lived, have small cumulative offsets, and their geomorphic expression may be limited. The problem is exacerbated if the intraplate earthquake generation process is transient. In this case, recurrence intervals, earthquake magnitudes, and possible seismic sources are likely to change over time scales ofthousands of years. Under these circumstances, many intraplate seismic zones may, in fact, be quiescent, independent seismic zones might be at different stages in their temporal evolution, and the Holocene behavior of various seismic zones may not be directly comparable. This project will attempt to address these difficulties by developing a greater understanding of earthquake generation processes within intraplate seismic zones. Using a variety of tinite element models, the various mechanisms that act to load faults in intraplate regions will be examined. The numerical analyses will include consideration and integration of length scales ranging from