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| Titel |
Scholte-wave Inversion for shallow 2D shear-wave velocity models at different locations in North- and Baltic sea using a hybrid particle swarm optimization scheme |
| VerfasserIn |
Dennis Wilken, Wolfgang Rabbel |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250039970
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| Zusammenfassung |
| In the years 2006 to 2008 we performed Airgun profiles to excite Scholte-waves at different
locations in the North and Baltic sea. Scholte-wave energy was recorded using a
specially developed Ocean-Bottom-Seismometer. The system is able to sample
signals up to 11kHz and can thus be localised at seafloor with an accuracy of a few
meters using traveltimes of high frequent seismic signals that are excited in the
watercolumn.
Scholte-wave recordings are added to common-receiver-gathers which are then inverted for
shear-wave velocity structure by fitting modelled phase-slowness frequency dispersion
spectra to spectra of the wavefield. By extracting local wavefields from the profile-gathers,
multiple 1D Inversions of these fields at different offset-points lead to a 2D shear-wave
velocity model of the profile.
A new spectral misfit calculation was developed, working without the requirement of
identification of the Scholte-wave dispersed modes in the spectra. For minimization of the
misfit we implemented a new hybrid method using a combination of particle swarm
optimization and a local downhill-simplex resulting in a resolution of global misfit minimum
of about 7%. The method was used for shear-wave velocity inversion at four different
locations in North and Baltic sea. Resulting models show very good coherence along each
Profile and especially a very good correlation to high resolution reflection seismic sections of
the same profiles. |
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