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| Titel |
Triplicated P-wave measurements for waveform tomography of the mantle transition zone |
| VerfasserIn |
S. C. Stähler, K. Sigloch, T. Nissen-Meyer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 3, no. 2 ; Nr. 3, no. 2 (2012-11-07), S.339-354 |
| Datensatznummer |
250000992
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| Publikation (Nr.) |
 copernicus.org/se-3-339-2012.pdf |
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| Zusammenfassung |
| Triplicated body waves sample the mantle transition zone more extensively
than any other wave type, and interact strongly with the discontinuities at
410 km and 660 km. Since the seismograms bear a strong imprint of these
geodynamically interesting features, it is highly desirable to invert them
for structure of the transition zone. This has rarely been attempted, due to
a mismatch between the complex and band-limited data and the
(ray-theoretical) modelling methods. Here we present a data processing and
modelling strategy to harness such broadband seismograms for finite-frequency
tomography. We include triplicated P-waves (epicentral distance range between
14 and 30°) across their entire broadband frequency range, for both
deep and shallow sources. We show that is it possible to predict the complex
sequence of arrivals in these seismograms, but only after a careful effort to
estimate source time functions and other source parameters from data,
variables that strongly influence the waveforms. Modelled and observed
waveforms then yield decent cross-correlation fits, from which we measure
finite-frequency traveltime anomalies. We discuss two such data sets, for
North America and Europe, and conclude that their signal quality and
azimuthal coverage should be adequate for tomographic inversion. In order to
compute sensitivity kernels at the pertinent high body wave frequencies, we
use fully numerical forward modelling of the seismic wavefield through a
spherically symmetric Earth. |
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