Travel-time tomography of the northern Canadian cordillera

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

For details of this project, see this article. An interpretation of mantle xenoliths in light of these results is found here.

Using a small array of permanent (black) and portable (red) seismographs, we recorded teleseismic (distant) earthquakes from July, 1995 through July, 1996. P-wave arrival times were determined using multi-channel cross-correlation.

Azimuthal variations in station residuals indicate substantial variations in upper-mantle velocity structure. We inverted the travel-time residuals using a 3-D tomography code developed by John VanDecar.

A checkerboard resolution test revealed the limitations of the model's resolution.

In addition to the high-velocity edge of the Alaskan slab (blue), the model reveals a substantial low-velocity model beneath the northern Cordillera (red), which we interpret as a mantle upwelling driven by the opening of a slab window and the retreat of the slab edge.

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