The application of wave field continuation for seismic refraction |
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| Authors: | Lijun Wu Rui Feng and Zhiming Huang |
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| Institution: | (1) Institute of Geophysics, State Seismological Bureau, 100081 Beijing, China;(2) Institute of Oceanology, Academia Sinica, 510301 Guangzhou, China |
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| Abstract: | Based on wave equation a fundamental formula for plane wave propagaton is derived, the theoretical method of inverting wave
volocity structure of earth interior through the observational wave field is discussed in this paper. The observational wave
field can be decomposed into the surface plane wave field by using τ −p transform. The maximum amplitude curve in the plane wave field can show stably the change tendency of wave velocity with
depth in the Earth. This property can be used to restrict the solution space. By using the wave field continuation method
more useful information from the observational wave field can be extracted and the inverion solution not only can be obtained
simply and quickly, but also is stable and less influenced by the subjective factor. The wave field continuation is a fine
inversion method.
Theoretical analysis and numerical modelling are carried out in the study of wave field continuation. By applying homomorphic
decovolution the signal — to — noese ratio is improved.
Finaly a sonar refraction profile in the northern part of the South China Sea is interpreted and computed. It is found as
a result that there is a velocity interface from 1.76 km/s to 2.21 km/s at the depth of 1.4 km. The velocity gradients in
the upper and lower layers are 0.54 km · s−1/km and 0.63 km · s−1/km respectively. A discussion of the characteristics of shallow sea structure in the view of tectonic movements is geven.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13. 41–52, 1991. |
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| Keywords: | wave field continuation τ − p transform inversion homomorphic decovolution |
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