Effect of earthquake locations on Rayleigh wave azimuthal anisotropy models

Abstract

Various factors need to be considered when inverting for surface wave azimuthal anisotropic structure. This paper focuses on the 2φ terms for Rayleigh wave azimuthal anisotropy and shows that the uncertainties of earthquake locations also have significant impacts on the resulting anisotropic structure. We use the global Rayleigh wave phase velocity data set collected in a previous study to demonstrate this effect. The differences between azimuthal anisotropic patterns with and without source relocations are greatest near plate boundaries. Large differences around the South American plate are also identified. Although most of the earthquakes are shifted by less than 15 km from the CMT locations, earthquakes near the Andes can be systematically shifted by more than 30 km. Our final epicentres for earthquakes on ridge-transform fault systems better match the plate boundaries.