The teleseismic transmission of seismic surface waves from earthquakes results in a loss of the high frequencies needed to infer information about Earth’s crust and uppermost mantle. A recent innovation in seismic imaging based on using long time sequences of ambient seismic noise moves beyond some of the limitations imposed on earthquakebased methods to reveal high resolution information about...

[1] Cylindrical anisotropy in Earth’s inner core has been invoked to account for travel times of PKP core‐sensitive seismic waves, such as from the South Sandwich Islands (SSI) earthquakes observed in Alaska, which depart from predictions. Newly collected travel‐time residuals from seismic waves from the SSI region that sample only Earth’s mantle (PcP and P waves) have a comparable range to the...

Despite strong anisotropy seen in analysis of seismic data from the NoMelt experiment in 70 Ma Pacific seafloor, a previous analysis of coincident magnetotelluric (MT) data showed no evidence for anisotropy in the electrical conductivity structure of either lithosphere or asthenosphere. We revisit the MT data and use 1D anisotropic models of the lithosphere to demonstrate the limits of acceptab...

[1] The cause of seismic anisotropy exhibiting trench parallel fast directions in subduction systems has been the subject of significant recent research. We provide new constraints on the contributions of hydrous phases to seismic anisotropy from an unusually well-localized region of trench parallel fast directions in Rayleigh wave phase velocities near the Cascade arc at 45 to 66 s periods. We...

[1] Shear wave splitting measurements using teleseismic PKS, SKKS, and SKS phases recorded by station LSA on the southern part of the Lhasa Terrane of the Tibetan Plateau reveal significant azimuthal anisotropy with a splitting time of up to 1.5 s, a conclusion that is contradictory to previous studies which suggested isotropy or weak anisotropy. In addition, systematic variations of the splitt...

[1] Seismological observations have revealed patches of seismic anisotropy in regions related to mantle upwelling and paleosubduction within an otherwise isotropic lower mantle. A combination of numerical modeling and mineral physics is used to constrain the source of anisotropy in these regions in an effort to better understand lower mantle dynamics and mineral physics. Specifically, it is inv...

Aligned vertical fractures introduce velocity anisotropy which is directly related to parameters, such as fracture density, fracture shape and fracture contents. Effective medium models allow us to study qPand qS-wave velocity anisotropy in rocks with aligned vertical fractures, intersecting fracture sets and aligned fractures with smallscale porosity. Spatially varying fracture density distrib...

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...