Surface wave phase velocities between stations of the Canadian seismic network were combined with crustal refraction data to obtain crust and upper mantle models for a number of regions of Canada. Both Rayleigh and Love wave dispersion were used. After fixing model crustal thicknesses and Pn velocities from refraction measurements, the fit to surface wave phase velocities was obtained primarily by variation of the shear velocities and the thickness of the lithosphere.Striking differences are found in the depth to the upper mantle low velocity layer with a minimum lithospheric thickness in the Cordillera and the thickest in the central Shield area. In addition the low velocity contrast is most prominent in the Cordillera. The base of the low velocity layer is less well defined from the study, but may be deepest in shield areas.The results obtained indicate the potential of the methods for determining more detail about boundaries between different lithospheric units, and appear to be generally concordant with flexural rigidity studies of the lithosphere.

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