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| Titel |
Modeling Anomalous Rayleigh-wave Azimuthal Anisotropy near Hawaii |
| VerfasserIn |
Gabi Laske, Lennart Ramme |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140465
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| Publikation (Nr.) |
 EGU/EGU2017-3861.pdf |
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| Zusammenfassung |
| The 2005-2007 Hawaiian PLUME (Plume-Lithosphere Undersea Melt Experiment)
deployment yielded continuous seismic data at ten land stations and nearly 70 ocean bottom
sites. Both the usage broad-band seismometers as well as the central location of Hawaii with
good azimuthal seismicity coverage has allowed us to conduct a comprehensive analysis of
surface wave azimuthal anisotropy at periods between 20 and 100 s. We use a sub-array
approach to obtain ’in-situ’ estimates of azimuthal variations in the attempt to minimize
imaging trade-offs and cross-mapping with lateral heterogeneity. We apply the
standard Smith-and-Dahlen trigonometric expansion to express azimuthal variations. A
systematic comparison between results obtained for different truncation levels in the
trigonometric expansion allows us to assess stability of the results and assign error
bars.
At long periods, azimuthal anisotropy is increasingly disturbed away from the pattern
expected for a cooling Pacific plate where ambient plate motion is ’frozen’ to the bottom of
the thickening plate. We present results from grid-search modeling for best-fitting
several-layer models that contain anisotropic mantle material with hexagonal symmetry.
Finding the optimal orientation of the symmetry axis and the corresponding thickness of
anisotropic layers are some of the focus aspects in the grid search. Results suggest that
ascending mantle plume material penetrates the asthenosphere to the southwest of Hawaii but
does not reach into the upper lithosphere. Part of this work was conducted through a
DAAD-sponsored (Deutscher Akademischer AustauschDienst) undergraduate RISE
fellowship. |
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