Cascadia Subduction Zone: Two Contrasting Models of Lithospheric Structure The subduction of the Juan de Fuca plate beneath North America changes markedly along the length of the subduction zone, notably in the angle of subduction, distribution of earthquakes, volcanism, geologic and seismic structure of the upper plate, and regional horizontal stress. To investigate these characteristics, we conducted detailed density modeling experiments of the crust and mantle along two transects across the Cascadia subduction zone. One crosses Vancouver Island and the Canadian margin, and the other crosses the margin of central Oregon. Both density models were constructed independently to a depth of approximately 50 km. We gathered all possible geologic, geophysical, and borehole data to constrain the density calculations. The final densities for the Oregon and Vancouver lithosphere models were obtained from gravity inversions.