Seismic Attenuation and Earth Structure

Shear velocity of olivineData from Kumazawa & Anderson [1969]Seismic Anisotropy1Anisotropy of Polycrystaline RocksTwin Sisters Dunite

Babuska, 19722Velocity Anisotropy - Twin Sisters DuniteBabuska, 1972

B - axesC - axesA - axesP velocities3

Lattice Preferred Orientation - Relationship of anisotropy and strainMainprice & Silver [1993]4Different Slip Systems

Jung et al., 20065Radial Anisotropy (Transverse Isotropy)Hexagonal symmetry with a vertical axisVertical and horizontal propagating waves have different velocitiesSame velocity for all horizontal directionsStudied using difference between Love (SH) and Rayleigh (SV) waves

Ekstrom & Dziewonski, 1998Azimuthal Anisotropy: Pn anisotropy in oceanic lithosphere

7Shear Wave Splitting

Smith et al., [2001] Seismic and Geochemical Evidence for Mantle Flow - Lau

Helium isotope anomaliesShear wave splittingMantle flow diagramAfter Turner and Hawkesworth, 19989 Mariana Arc Shear Wave SplittingRose Diagrams - plotted at station for sources in upper 250 kmSpatial Averaging - for paths in the upper 250 kmPozgay et al. [2007]

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