Shear wave splitting at the Hawaiian hot spot from the PLUME land and ocean bottom seismometer deployments
MetadataShow full item record
We examine upper mantle anisotropy across the Hawaiian Swell by analyzing shear wave splitting of teleseismic SKS waves recorded by the PLUME broadband land and ocean bottom seismometer deployments. Mantle anisotropy beneath the oceans is often attributed to flow-induced lattice-preferred orientation of olivine. Splitting observations may reflect a combination of both fossil lithospheric anisotropy and anisotropy due to present-day asthenospheric flow, and here we address the question whether splitting provides diagnostic information on possible asthenospheric plume flow at Hawaii. We find that the splitting fast directions are coherent and predominantly parallel to the fossil spreading direction, suggesting that shear wave splitting dominantly reflects fossil lithospheric anisotropy. The signature of anisotropy from asthenospheric flow is more subtle, although it could add some perturbation to lithospheric splitting. The measured delay times are typically 1 s or less, although a few stations display larger splitting delays of 1–2 s. The variability in the delay times across the different stations indicates differences in the degree of anisotropy or in the thickness of the anisotropic layer or in the effect of multilayer anisotropy. Regions with smaller splitting times may have experienced processes that modified the lithosphere and partially erased the fossil anisotropy; alternatively, asthenospheric splitting may either constructively add to or destructively subtract from lithospheric splitting to produce the observed variability in delay times.
Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 13 (2012): Q02007, doi:10.1029/2011GC003881.
Showing items related by title, author, creator and subject.
Lin, Ying-Tsong; Duda, Timothy F. (Acoustical Society of America, 2012-07-03)A three-dimensional Cartesian parabolic-equation model with a higher-order approximation to the square-root Helmholtz operator is presented for simulating underwater sound propagation in ocean waveguides. The higher-order ...
A three-dimensional parabolic equation model of sound propagation using higher-order operator splitting and Padé approximants Lin, Ying-Tsong; Collis, Jon M.; Duda, Timothy F. (Acoustical Society of America, 2012-10-08)An alternating direction implicit (ADI) three-dimensional fluid parabolic equation solution method with enhanced accuracy is presented. The method uses a square-root Helmholtz operator splitting algorithm that retains ...
Foote, Kenneth G.; Aglen, Asgeir; Nakken, Odd (Acoustical Society of America, 1986-08)Data derived with a 38‐kHz split‐beam echo sounder have been analyzed to yield target strengths suitable for use with echo integrators. This has required compensation for both thresholding and saturation, since these ...