Surface-wave tomography the Canadian upper mantle

Work done in collaboration with Drs. Michael Bostock and John Cassidy

Details of this project have been published in this paper.

Map of stations and tectonic provinces Map of source-receiver paths

Using the available archive of regional surface-wave data from the broadband instruments of the CNSN (circles) and IRIS (squares) arrays, Guust Nolet's partitioned waveform inversion technique was used to derive 1-D and 3-D S velocity models of the Canadian upper mantle.

Two sample waveform 

The resulting one-dimensional velocity models for shield regions (top) generally exhibit high mantle velocities, while cordilleran paths (bottom) generally display low mantle velocities.

Comparison to Grand's model

A 100-km section through the surface-wave velocity model (top) shows considerably more roughness than a comparable section through Steve Grand's model.

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Andrew Frederiksen /