Models of downdip frictional coupling for the Cascadia megathrust

We have developed models of downdip frictional coupling along two transects across the Cascadia subduction zone in northern Washington and central Ore gon. The models involve complicated downdip coupling profiles. Although not unique, our models closely predict available GPS shortening rates and vert ical uplift data. We are able to explain relatively low horizontal shorteni ng rates along the Washington coast and small vertical uplift rates in cent ral Oregon. Our models depart from previous models by inclusion of a deeply coupled region assumed to be related to mafic rocks in both the upper and lower plates of the thrust.