Shear wave splitting at the Hawaiian hot spot from the PLUME land and ocean bottom seismometer deployments Journal Article


Authors: Collins, John A.; Wolfe, Cecily J.; Laske, Gabi
Article Title: Shear wave splitting at the Hawaiian hot spot from the PLUME land and ocean bottom seismometer deployments
Abstract: 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.
Keywords: PACIFIC; Hawaii; SEISMIC ANISOTROPY; SEA-FLOOR; AZIMUTHAL ANISOTROPY; STRUCTURE BENEATH; NETWORK PILOT EXPERIMENT; FLOW BENEATH; splittting; MANTLE DEFORMATION MODELS; SEAMOUNT CHAIN; SWELL-EVIDENCE
Journal Title: Geochemistry Geophysics Geosystems
Volume: 13
ISSN: 1525-2027
Publisher: American Geophysical Union  
Publication Place: WASHINGTON; 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA
Date Published: 2012
Start Page: Q02007
End Page: Q02007
DOI/URL:
Notes: PT: J; TC: 0; J9: GEOCHEM GEOPHY GEOSY; UT: WOS:000300819900002