We calculated SKS splitting parameters for the California Integrated Seismic Network. In southern California, we also estimated splitting in the upper 100 km using azimuthal anisotropy determined from surface waves. The inferred splitting from surface waves in the mantle lithosphere is small (on average <0.2 sec) compared with SKS splitting (1.5 sec) and obtains a maximum value (0.5 sec) in the...

[1] In this study, we utilize data from broadband seismic stations of the Japanese F-net network to investigate anisotropic structure in the lowermost mantle beneath the northwestern Pacific. The comparison of shear wave splitting from phases that have similar paths in the upper mantle but different paths in the lowermost mantle, such as PcS/ScS or SKS/SKKS, can yield constraints on anisotropy ...

[1] The Pacific Northwest (PNW) has experienced voluminous intraplate volcanism over the past 17 Ma, beginning with the Steens/Columbia River flood basalts and continuing with the stillongoing volcanism in the High Lava Plains (HLP) and eastern Snake River Plain (SRP). Here we present two complementary datasets (SKS splitting and Rayleigh wave phase velocity anisotropy) that place constraints o...

Measurements of seismic anisotropy constitute a very important tool for examining patterns of flow and mineral properties in the Earth’s mantle. A popular strategy for gaining insight into upper mantle processes is to examine the splitting of SK(K)S phases and interpret them in terms of upper mantle anisotropy and deformation; in such studies, any contribution to splitting from anisotropy in th...

S U M M A R Y Upper-mantle seismic anisotropy has been observed using a variety of methods, including S and SKS splitting, P and Pn traveltimes, P polarization anomalies and P to S conversions, and surface waves. Care must be taken when comparing the results from different methods because of bias introduced by depth sensitivity, frequency dependence, and simplifying assumptions concerning the f...

[1] We constrain the anisotropy associated with a very low velocity province (VLVP) at the base of the Earth’s mantle using the SKS and SKKS waves sampling the region. Our selected high-quality data sets consist of 415 SKS and 111 SKKS waveforms for 127 deep earthquakes recorded at distances between 90 and 150 by the seismic stations in three temporary broadband PASSCAL seismic arrays: the Kaap...

Seismic anisotropy in the upper mantle beneath continental interiors is generally complicated, with contributions from both the lithosphere and the asthenosphere. Previous studies of SKS splitting beneath the eastern United States have yielded evidence for complex and laterally variable anisotropy, but until the recent arrival of the USArray Transportable Array (TA) the station coverage has bee...