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Which forces drive North America?
G. H. R. Bokelmann, Department of Geophysics, Stanford University, Stanford, California 94305-2215, USA. Pages 1027-1030
Everybody (or almost everybody) agrees that the plates under our feet move. But why do they move, or in other words, which forces drive them? There are two main views on this question: that the plates are driven by forces acting from the side, that is, pulled by subducting slabs and pushed by ridge-oceanic ridges; or that the plates are riding (passively) on mantle convection cells, and thus are driven from below. Unfortunately it has been very difficult to distinguish these two sets of driving forces. This paper addresses the question based on the pattern of deformation within the plates, specifically the North American plate. Seismic anisotropy is a tool that allows us to do so. The orientation of anisotropy we find is indicative of forces acting from below being important. Thus it appears that the North American plate is driven largely by mantle convection, which dr
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