Scholte wave velocity inversion for a near surface S‐velocity model and PS‐statics

Muyzert, Everhard

doi:10.1190/1.1815606

Cited by 26 publications

(27 citation statements)

References 5 publications

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“…The P-wave velocity at the ocean bottom is V P 0 (0) = 1.5 km/s, while the corresponding value for S-waves, V S0 (0) = 0.2 km/s, was obtained by Muyzert (2000) for underwater sediments. The P-and S-wave velocity gradients are selected in such a way that V P 0 and V S0 at the depth z = 2 km are close to the interval velocities for the horizon immediately above the top of the Balder formation.…”

Section: B1 Numerical Examplesmentioning

confidence: 99%

Seismology of Azimuthally Anisotropic Media and Seismic Fracture Characterization

Tsvankin¹,

Grechka²

2011

180

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Section: B1 Numerical Examplesmentioning

confidence: 99%

Seismology of Azimuthally Anisotropic Media and Seismic Fracture Characterization

Tsvankin¹,

Grechka²

2011

180

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“…Recently, the multichannel analysis of surface waves (MASW) has been employed in marine applications (Allnor et al, 1997;Muyzert, 2000;Park et al, 2000;Ritzwoller and Levshin, 2002;Bohlen et al, 2004;Klein et al, 2005). This enables an analysis of lateral variation along continuous profiles.…”

Section: Introductionmentioning

confidence: 99%

“…This enables an analysis of lateral variation along continuous profiles. Multichannel Scholte-wave data can be acquired with a moving source and a single ocean-bottom-seismometer (Allnor et al, 1997;Bohlen et al, 2004), a single source and a multichannel geophone-cable deployed on the sea floor Muyzert, 2000), or, in favorable environments, with a towed source and a deep-towed multichannel hydrophone-streamer (Klein et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Variability of Scholte-wave Dispersion in Shallow-water Marine Sediments

Kugler

Bohlen

Bussat

et al. 2005

JEEG

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Models of in situ shear-wave velocities of shallow-water marine sediments are of importance for geotechnical applications, sediment characterization, and seismic exploration studies. Here pseudo-2D shear-wave velocity models are inferred from the lateral variation of Scholte-wave dispersion at five different geological sites in the Baltic Sea (northern Germany). To explore Scholte-wave dispersion and the lateral variability of shear-wave velocities, Scholte waves were excited by air gun shots in the water layer and recorded by stationary ocean-bottom-seismometers or buried geophones. We analyze the recorded seismograms in a common-receiver-gather using offset-windowed, multichannel dispersion analysis.The observed local slowness-frequency spectra for the different study sites vary significantly with respect to excitation amplitudes and phase slownesses of different modes, as well as the excited frequency range. The excitation amplitudes are influenced by the local shear-wave velocity structure, absorption, length of Scholte-wave travel path, and the elevation of the source above the sea floor.The inverted shear-wave velocities range from 50 m/s to 600 m/s. Directly at the sea bottom, shear-wave velocities of 50 m/s for fine muddy sand and 300 m/s for glacial till were inferred. The maximum vertical gradient was 680% (mean 250 m/s) within a depth range of 40 m, and horizontally 633% (mean 350 m/s) within 300 m distance. The layer boundaries in the inverted shear-wave velocity models are in good agreement with high-frequency, zero-offset compressional-wave reflections. However, it was not possible to acquire the fundamental Scholte mode above very soft, unconsolidated sediment with shear-wave velocities smaller 50 m/s. The analysis of synthetic data shows that this is due to the elevation of the source and the receiver response function.

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“…(Stokoe et al, 1991;Luke & Stokoe, 1998) and investigations of the application of multi-channel analysis has started recently (Bohlen et al, 2003;Klein et al, 2000;Park et al, 2000;Muyzert, 2000;Bohlen et al, 1999;Xia et al, 1999;Park et al, 1999). While most authors use the enhanced seismic data to better resolve the disperison curve for inversion methods I will investigate the potential of including information from the amplitudes of the wavefield spectra.…”

Section: Introductionmentioning

confidence: 99%

Acquisition and Inversion of Dispersive Seismic Waves in Shallow Marine Environments

Klein

Bohlen²,

Theilen³

et al. 2005

Mar Geophys Res

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ZusammenfassungDie Kenntnis der elastischen Eigenschaften mariner Sedimente, insbesondere die Scherwellengeschwindigkeit, ist eine wichtige Information für die Untersuchung der Stabilität von Meeresböden. Dies ist insbesondere für geotechnische Anwendungen im flachmarinen Bereich von Bedeutung, aber auch für die Untersuchung von Hangstabilitäten der Kontinentalrän-der und für die Gashydratforschung von Interesse.Seismische Experimente in der Ostsee sowie die Analyse eines Datensatzes aus der Nordsibirischen Laptevsee konnten zeigen, dass dispersive seismische Wellenfelder mit Hilfe einer nahe der Meeresoberfläche geschleppten seismischen Quelle (Airgun) angeregt werden können. AbstractThe knowledge of the shear wave velocity structure of shallow marine sediments is an important information for the assessment of sediment stability. This is of interest for marine geotechnical applications as well as investigations of sea-floor stability of continental shelves and margins and in gashydrate research. The derivation of seismic velocities with special interest on the shear wave velocity from the analysis and inversion of dispersive seismic waves is investigated in this work.Dispersive waves are excited by surface towed airguns and the acquisition was achieved with two different configurations. Firstly, the stationary-receiver method comprises of an ocean bottom seismometer station (OBS) and excitation with a surface towed airgun. Secondly, a towed-acquisition system includes a streamer towed at ten meters above the sea bed and excitation with an airgun. Two different wave types could be observed with either of the two acquisition systems. Interface waves, namely of the Scholte wave type, propagating along the sea floor and guided waves in the water column, denoted as acoustic guided waves despite of their sediment interaction at the sea bed. The both wave types were observed in certain environments indicating the limitations in the acquisition of these wave types depending on the sediment properties. These limitations as well as the difference in dispersion sensitivity to variations of the seismic properties give rise for separate treatment of both wave types. While the dispersion sensitivity of Scholte waves as well as other interface waves is dominant for shear wave velocity variations, the variation of the dispersion of acoustic guided waves is affected by variations of compressional and shear wave velocity as well as density to a smaller extend. The difference in velocity and frequency range of interest for both wave types, i.e. the ranges of most variations in the dispersion characteristics, also affect the required acquisition configuration and parameters. While a long offset recording (exceeding 800 m) is required for acoustic guided waves, the fulfillment of the spatial sample criteria sometimes limits the feasibility to adequately acquire the dispersive wavefield. This is most dominant for the Scholte wave measurements in very soft marine sediments.The derivation of the shear wave velocity structure was inve...

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Scholte wave velocity inversion for a near surface S‐velocity model and PS‐statics

Cited by 26 publications

References 5 publications

Seismology of Azimuthally Anisotropic Media and Seismic Fracture Characterization

Seismology of Azimuthally Anisotropic Media and Seismic Fracture Characterization

Variability of Scholte-wave Dispersion in Shallow-water Marine Sediments

Acquisition and Inversion of Dispersive Seismic Waves in Shallow Marine Environments

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