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| Titel |
Finite-difference modelling to evaluate seismic P-wave and shear-wave field data |
| VerfasserIn |
T. Burschil, T. Beilecke, C. M. Krawczyk |
| 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 ; 6, no. 1 ; Nr. 6, no. 1 (2015-01-13), S.33-47 |
| Datensatznummer |
250115385
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| Publikation (Nr.) |
 copernicus.org/se-6-33-2015.pdf |
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| Zusammenfassung |
High-resolution reflection seismic methods are an established non-destructive
tool for engineering tasks. In the near surface, shear-wave reflection
seismic measurements usually offer a higher spatial resolution in the same
effective signal frequency spectrum than P-wave data, but data quality varies
more strongly.
To discuss the causes of these differences, we investigated a P-wave and a SH-wave
seismic reflection profile measured at the same location on the island of
Föhr, Germany and applied seismic reflection processing to the field data as well
as finite-difference modelling of the seismic wave field. The simulations
calculated were adapted to the acquisition field geometry, comprising 2 m
receiver distance (1 m for SH wave) and 4 m shot distance along the 1.5 km
long P-wave and 800 m long SH-wave profiles. A Ricker wavelet and the use of
absorbing frames were first-order model parameters. The petrophysical
parameters to populate the structural models down to 400 m depth were taken
from borehole data, VSP (vertical
seismic profile) measurements and cross-plot relations.
The simulation of the P-wave wave-field was based on interpretation of the
P-wave depth section that included a priori information from boreholes and
airborne electromagnetics. Velocities for 14 layers in the model were derived
from the analysis of five nearby VSPs (vP
=1600–2300 m s-1). Synthetic shot data were compared with the
field data and seismic sections were created. Major features like direct wave
and reflections are imaged. We reproduce the mayor reflectors in the depth
section of the field data, e.g. a prominent till layer and several deep
reflectors. The SH-wave model was adapted accordingly but only led to minor
correlation with the field data and produced a higher signal-to-noise ratio.
Therefore, we suggest to consider for future simulations additional features
like intrinsic damping, thin layering, or a near-surface weathering layer.
These may lead to a better understanding of key parameters determining the
data quality of near-surface shear-wave seismic measurements. |
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