Depth variations of P-wave azimuthal anisotropy beneath Mainland China

Depth variations of P-wave azimuthal anisotropy beneath Mainland China

A high-resolution model of P-wave anisotropic tomography beneath Mainland China and surrounding regions is determined using a large number of arrival-time data recorded by the China seismic network, the International Seismological Centre (ISC) and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducted Indian plate and mantle dynam...

Azimuthal anisotropy in the D00 layer beneath the Caribbean

[1] The lowermost mantle beneath Central America has anisotropic seismic velocity structure manifested in shear wave splitting of signals from South American earthquakes recorded at North American broadband recording stations. Prior studies of deep mantle anisotropy in this region have characterized the structure as having vertical transverse isotropy (VTI), which is sufficient to explain a gen...

Depth dependent azimuthal anisotropy in the western US upper mantle

Measurements of Shear-wave Azimuthal Anisotropy with Cross-dipole Logs

Three methods for analyzing azimuthal anisotropy from cross-dipole logs are applied to data from the Powder River Basin in Wyoming. These techniques are based on the phenomena of flexural wave splitting in anisotropic materials and are analogous to the techniques used for VSP data processing. The four-component cross-dipole logging data obtained with a Schumberger tool from a vertically-fractur...

Variations of P wave speeds in the mantle transition zone beneath the northern Philippine Sea

Using waveforms and travel times from deep earthquakes, weconstructed 16 seismic profiles, each of which constrains theradial variation i Vp over a small area beneath e northern Philippine Sea. Taken together, the azimuthal coverage of these profiles also places tight bounds on the lateral extent of a region of anomalously high Vp (up to 3% faster than average Earth models) originally suggested...