Volcanic hotspots and mid-ocean ridge spreading centers are the surface expressions of upwelling in Earth's mantle convection system, and their interaction provides unique information on upwelling dynamics. I investigated the influence of the Iceland hotspot on the adjacent mid-Atlantic spreading center using phase-delay times of seismic surface waves, which show anomalous polarization anisotro...

[1] We report measurements of long-period P wave polarization (Ppol) in Australia and Tahiti made by combining modeling of the polarization deviation and harmonic analysis. The analysis of the deviation of the horizontal polarization of the P wave as a function of event back azimuth may be used to obtain information about (1) sensor misorientation, (2) dipping discontinuities, (3) seismic aniso...

Withinoceanic lithospherea fossilized fabric is oftenpreserved originating from the time of plate formation. Such fabric is thought to form at the mid-ocean ridge when olivine crystals align with the direction of plate spreading1,2. It is unclear, however, whether this fossil fabric is preserved within slabs during subduction or overprinted by subduction-induced deformation. The alignment of ol...

We apply seismic interferometry to strong-motion records to detect the change in anisotropy caused by the MW 9.0 Tohoku-Oki earthquake on 11 March 2011. It is known that large earthquakes change fluid condition in cracks, and thereby the polarization-anisotropy condition. The Tohoku-Oki earthquake increased the difference between fast and slow shear-wave velocities arising from shearwave splitt...

Oil and gas production from tight, fractured reservoirs (sandstone, carbonates and shale) has increased significantly over the last decade. These hard rock targets are often characterized by vertically aligned fractures (i.e. HTI) embedded in a layered sequence (i.e. VTI). In this geologic setting, seismic velocities and η can vary with azimuth and depth. This is orthorhombic anisotropy and can...

Many volcanic arcs display fast seismic shear-wave velocities parallel to the strike of the trench. This pattern of anisotropy is inconsistent with simple models of corner flow in the mantle wedge. Although several models, including slab rollback, oblique subduction, and deformation of water-rich olivine, have been proposed to explain trench-parallel anisotropy, none of these mechanisms are con...

An absolute plate motion (APM) model is required to address issues such as the thermochemical evolution of Earth’s mantle. All APM models have to rely on indirect inferences, including those based on hot spots and seismic anisotropy, each with their own set of uncertainties. Here, we explore a seafloor spreading-aligned reference frame. We show that this reference frame fits azimuthal seismic a...

We investigate long-period surface waves (T> 100 s) propagating across the Tibetan Plateau, based on the seismic records from a PASSCAL portable array and nearby Chinese Digital Seismic Network (CDSN) stations. Significant quasi-Love waveform anomalies, associated with fundamental Rayleigh-Love coupling, are consistently observed, suggesting that strong lateral gradients in azimuthal anisotropy...

Anisotropy parameters are obtained by anisotropic velocity analysis performed on Blackfoot P-wave reflection-seismic data, in combination with sonic-log data. First, the line was processed with ProMAX seismic data-processing software using a sequence of conventional algorithms without taking anisotropy into account, in order to choose proper analysis points and horizons with confidence. Then, a...

The full elastic tensors of the sheet silicates muscovite, illite-smectite, kaolinite, dickite, and nacrite have been derived with first-principles calculations based on density functional theory. For muscovite, there is excellent agreement between calculated properties and experimental results. The influence of cation disorder was investigated and found to be minimal. On the other hand, stacki...