Analytical expressions for Fresnel volumes and interface fresnel zones of seismic body waves. Part 2: Transmitted and converted waves. Head waves

1996 ◽  
Vol 40 (4) ◽  
pp. 381-397 ◽  
Author(s):  
Michal Kvasnička ◽  
Vlastislav Červený
Keyword(s):  
Body Waves ◽  
Head Waves ◽  
Converted Waves ◽  
Analytical Expressions ◽  
Fresnel Zones ◽  
Fresnel Volumes ◽  
Interface Fresnel Zones ◽  
Seismic Body Waves

CONVERTED WAVES IN REFRACTION SURVEYS OVER MARKERS WITH VARIABLE DEPTH

Geophysics ◽  
1964 ◽  
Vol 29 (5) ◽  
pp. 733-744 ◽  
Author(s):  
D. H. Hall
Keyword(s):  
Future Research ◽  
Single Shot ◽  
Lateral Variation ◽  
Wave Type ◽  
Single Wave ◽  
Recording Point ◽  
Head Waves ◽  
Layer Medium ◽  
Converted Waves

Converted head waves are observed sufficiently often in crustal and other refraction surveys to raise interesting questions as to their possibilities in interpretation. Some simple cases are examined in which sequences of P, S, and converted head waves are assumed to be observed over a two‐ and a three‐layer medium. Investigation is made of the theoretical requirements in terms of numbers of shot and recording points, and the number of members in the sequence, to allow calculation of layer velocities and thicknesses when there is low to moderate structure on the interfaces. It is found that as few as a single shot and a single recording point, and two, three, or four members of a sequence are sufficient to allow determination of some or all of the P and S velocities in the layers, and the depths to the layers below shot and recording point. How far these possibilities can be realized in practice is dependent on the development of techniques to produce and observe converted waves consistently in refraction surveys. To what extent this can be done is at present little known, and is a matter for future research. If converted waves can be used regularly in refraction work, some operational advantages might result as follows. Because of the decrease in the number of shot and recording points necessary to derive velocities and depths when sequences of head waves are observed, it is possible either to gather usable data with minimum effort, or, if a more elaborate array of points is used, to achieve greater detail regarding the lateral variation in velocity and depth over what would have been obtained from a single wave type.

Numerical computation of individual far‐field arrivals excited by an acoustic source in a borehole

Geophysics ◽  
1985 ◽  
Vol 50 (5) ◽  
pp. 852-866 ◽  
Author(s):  
Andrew L. Kurkjian
Keyword(s):  
Numerical Computation ◽  
The Body ◽  
Body Waves ◽  
Head Wave ◽  
Far Field ◽  
Trapped Mode ◽  
Full Waveform ◽  
Full Wave ◽  
Head Waves ◽  
Strong Shear

In this paper, I model the acoustic logging problem and numerically compute individual arrivals at far‐field receivers. The ability to compute individual arrivals is useful for examining the sensitivities of each arrival to various factors of interest, as opposed to examining the full waveform as a whole. While the numerical computation of the mode arrivals (Peterson, 1974) and the numerical computation of the first head waves (Tsang and Rader, 1979) have been previously reported, the numerical computation of the entire set of head‐wave arrivals is new and is the major contribution of this paper. Following Roever et al. (1974) and others, the full wave field is represented as a sum of contributions from both poles and branchcuts in the complex wavenumber plane. The pole contributions correspond to mode arrivals while the branch cuts are associated with the body waves (i.e., head waves). Both the pole and branch cut contributions are computed numerically and results are presented for the cases of a slow and a fast formation. The shear event in the slow formation is found to be relatively small, consistent with observations in measured data. Contrary to existing knowledge, the shear event in the fast formation is also relatively small. The apparent strong shear arrival in the full waveforms is due primarily to the trapped mode pole in the vicinity of cutoff.

Elementary seismograms of seismic body waves in dissipative media

1980 ◽  
Vol 24 (4) ◽  
pp. 365-372 ◽  
Author(s):  
Vlastislav Červený ◽  
Antoine B. Frangié ◽  
J. Vaněk
Keyword(s):  
Body Waves ◽  
Dissipative Media ◽  
Seismic Body Waves

Computation of ray amplitudes of seismic body waves in vertically inhomogeneous media

1977 ◽  
Vol 21 (3-4) ◽  
pp. 248-255 ◽  
Author(s):  
Vlastislav Červený ◽  
Věnceslava Pretlová ◽  
I. Pšenčik
Keyword(s):  
Inhomogeneous Media ◽  
Body Waves ◽  
Seismic Body Waves
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