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Abstract

We discuss five useful equations related to high-frequency surface-wave techniques and<br>their implications in practice. These equations are theoretical results from published literature<br>regarding source selection, data-acquisition parameters, resolution of a dispersion curve image in<br>the frequency-velocity domain, and the cut-off frequency of high modes. The first equation<br>suggests Rayleigh waves appear in the shortest offset when a source is located on the ground<br>surface, which supports our observations that surface impact sources are the best source for<br>surface-wave techniques. The second and third equations, based on the layered earth model,<br>reveal a relationship between the optimal nearest offset in Rayleigh-wave data acquisition and<br>seismic setting—the observed maximum and minimum phase velocities, and the maximum<br>wavelength. Comparison among data acquired with different offsets at one test site confirms the<br>better data were acquired with the suggested optimal nearest offset. The fourth equation<br>illustrates that resolution of a dispersion curve image at a given frequency is directly proportional<br>to the product of a length of a geophone array and the frequency. We used real-world data to<br>verify the fourth equation. The last equation shows that the cut-off frequency of high modes of<br>Love waves for a two-layer model is determined by shear-wave velocities and the thickness of<br>the top layer. We applied this equation to Rayleigh waves and multi-layer models with the<br>average velocity and obtained encouraging results. This equation not only endows with a<br>criterion to distinguish high modes from numerical artifacts but also provides a straightforward<br>means to resolve the depth to the half space of a layered earth model.

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/content/papers/10.3997/2214-4609-pdb.183.1089-1104
2005-04-03
2024-03-29
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609-pdb.183.1089-1104
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