North American plate dynamics

Deformation within the North American plate in response to various tectonic processes is modeled using an elastic finite element analysis. A coarse grid contains 328 elements and 190 nodes, while a fine grid contains 718 elements and 396 nodes for a spatial resolution of 2°-3°. Information about the present-day state of intraplate stress constrains the modeling. Distributed ridge forces of magnitude 2×10¹² N/m predict deviatoric stresses of the order of 20-40 MPa that are capable of accounting for the dominant observed ENE stress trend. Driving drag models also fit the trend but are not preferred because of a predicted tenfold increase in compressive stress magnitudes from east to west across the plate. -from Authors