Seismic anisotropy beneath east Greenland revealed by shear wave splitting

Abstract

Seismic anisotropy was investigated by measuring shear wave splitting at 7 broadband stations in eastern Greenland. Splitting parameters (fast polarization and time delay) were determined for SKS and SKKS phases. Fast polarizations are oriented roughly parallel to the east Greenland coast at 5 stations, while for two they are nearly perpendicular to the coast. The anisotropy at 5 is unrelated to the spreading direction of the North Atlantic or absolute plate motion. The fast polarization direction can be related to tectonic fabric in the Caledonides in the north, suggesting that anisotropy is frozen in the lithosphere, deformed coherently with depth. Another explanation of the coast parallel fast polarization is asthenospheric flow along the Mid‐Atlantic Ridge at the time of opening of the ocean inducing fabric in the thickened lithosphere. The time delays (0.5–1.3 s) do, however, require that fabric to be strong or distributed over a substantial depth range.