Surface‐Wave Tomography of the Northern Canadian Cordillera Using Earthquake Rayleigh Wave Group Velocities

• Published in: Journal of geophysical research. Solid earth 2021-08, Vol.126 (8), p.n/a
• Main Authors: Estève, C., Gosselin, J. M., Audet, P., Schaeffer, A. J., Schutt, D. L., Aster, R. C.
• Format: Article
• Language: English
• Subjects: Anisotropy; Asthenosphere; Bayesian analysis; Cratons; crust; Deformation; Depth; Dipping; Dispersion; Dispersion curve analysis; Earth mantle; Earthquakes; Eocene; Geophysics; Group velocity; Isotopes; Lithosphere; northern Canadian Cordillera; Ocean circulation; P-waves; Plates; Probability theory; Rayleigh waves; Segments; Seismic activity; seismic anisotropy; Seismic velocities; Seismic wave velocities; Seismic waves; surface‐wave tomography; Tectonics; Tomography; Upper mantle; uppermost mantle; Upwelling; Velocity; Volcanic activity; Volcanic fields; Volcanism; Wave dispersion; Wave groups; Wave velocity
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2021JB021960

We measure fundamental‐mode Rayleigh wave group velocity dispersion from regional earthquakes and employ transdimensional Bayesian tomography to invert for azimuthally anisotropic group velocity maps at 10–60 s periods. Seismic azimuthal anisotropy within the crust and uppermost mantle shows fast‐axis alignment with principal northern Canadian Cordillera (NCC) tectonic structures suggesting large‐scale and coherent deformation across the crust and upper mantle. We extract group velocity dispersion curves at each grid point of the isotropic group velocity maps and invert them independently for VS as a function of depth in a probabilistic framework. At mid‐to‐lower crustal depths, our pseudo 3‐D VS model reveals an anomalously low VS structure (