Hidden Layer Problem in Seismic Refraction Work*

Banerjee, B.; Gupta, S. K.

doi:10.1111/j.1365-2478.1975.tb01550.x

Cited by 24 publications

(10 citation statements)

References 5 publications

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“…Most of the time, there is no direct evidence for the velocity inversion. Banerjee and Gupta (1975) suggested that this type of problem could be solved by recording converted waves (S, P, S,). Kaila, Tewari and Krishna (1981) presented an indirect approach to solving the velocity inversion problem.…”

Section: Introductionmentioning

confidence: 99%

Use of traveltime skips in refraction analysis to delineate velocity inversion¹

Tewari¹,

Dixit²,

Murty³

1995

Geophysical Prospecting

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Abst ractFirst arrival refraction data does not normally provide any indication of the velocity inversion problem. However, under certain favourable circumstances, when the low-velocity layer (LVL) is considerably thicker than the overlying higher-velocity layer (HVL), the velocity inversion can be seen in the form of a traveltime skip. Model Studies show that in such cases the length of the HVL traveltime branch can be used to determine the thickness of the HVL and the magnitude of the traveltime skip in order to determine the thickness of the LVL. This is also applicable in the case of field data.

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Section: Introductionmentioning

confidence: 99%

Use of traveltime skips in refraction analysis to delineate velocity inversion¹

Tewari¹,

Dixit²,

Murty³

1995

Geophysical Prospecting

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“…For example, Soske (1959) suggested making additional shots at a deeper depth so that the hidden layer is no longer hidden; Morgan (1967) proposed the use of a combined reflection and refraction approach. Other papers that review the hidden layer problem include Green (1962), Kaila and Narain (1970), Banerjee and Gupta (1975), Greenhalgh (1977), Raghava and Kumar (1979), Whiteley and Greenhalgh (1979), and Pant and Raghava (1987). Other papers that review the hidden layer problem include Green (1962), Kaila and Narain (1970), Banerjee and Gupta (1975), Greenhalgh (1977), Raghava and Kumar (1979), Whiteley and Greenhalgh (1979), and Pant and Raghava (1987).…”

Section: Hidden Layers Velocity Inversions and Blind Zonesmentioning

confidence: 99%

5. Refraction Surveys

Cox¹

1999

Static Corrections for Seismic Reflection Surveys

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Refraction SurveysDownloaded 10/09/15 to 129.78.139.28. Redistribution subject to SEG license or copyright; see Terms of Use at http://library.seg.org/ c c c c c or t z V x z V z V Downloaded 10/09/15 to 129.78.139.28. Redistribution subject to SEG license or copyright; see Terms of Use at http://library.seg.org/ Downloaded 10/09/15 to 129.78.139.28. Redistribution subject to SEG license or copyright; see Terms of Use at http://library.seg.org/ Downloaded 10/09/15 to 129.78.139.28. Redistribution subject to SEG license or copyright; see Terms of Use at http://library.seg.org/Fig. 5-20. Refraction arrival picking using a peak-trough ratio technique: (a) seismic data after removal of the refractor moveout or stepout; (b) display of all peaks and troughs, with the maximum ratio between successive events (the preferred pick) indicated by a thicker line (Chun and Jacewitz, 1981; preprint).

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“…Seismic reflection information has also been used in solving the VI problem in refraction work (Hunter & Hobson 1977). Banerjee & Gupta (1975) used SPS-type mode-converted waves to solve the VI problem. This type of wave is very difficult to recognize on a seismogram due to energy partitioning on mode conversion.…”

Section: Introductionmentioning

confidence: 99%

Ambiguity in the solution to the velocity inversion problem and a solution by joint inversion of seismic refraction and wide-angle reflection times

Sain

Kaila²

1996

Geophysical Journal International

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S U M M A R YIn a multilayered earth system no refraction signal will be generated from the top of a layer that has a seismic velocity less than that of the layer immediately above. The interpretation of refraction data in such a situation cannot provide any information about the low-speed layer (LSL), and its presence leads to the overestimation of depths to the bottom of the overlying or cap layer and all subsequent underlying layers. This is the velocity inversion (VI) problem of seismic refraction work. Other geological/geophysical information is required to solve the VI problem. In this respect, wide-angle reflections from the bottom of the LSL may constitute the most reliable information, since they are observed as very strong arrivals on the seismogram after first arrivals. This paper shows that, even if reflections from the bottom of the LSL are used, the solution (i.e. the thickness of the cap layer, and the thickness and velocity of the low-speed layer) to the VI problem is still ambiguous. However, use of the wideangle reflected phase limits the number of solutions. A method of joint inversion of traveltimes for refractions and wide-angle reflections from the bottom of the LSL is proposed to calculate the thickness of the cap layer and that of the LSL, the velocity of the LSL having been constrained from other information. The reliability of the method has been tested on synthetic data using various initial models. Application to field data demonstrates the practical feasibility of the method by comparing the result with the available solution for the region.

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Hidden Layer Problem in Seismic Refraction Work*

Cited by 24 publications

References 5 publications

Use of traveltime skips in refraction analysis to delineate velocity inversion¹

Use of traveltime skips in refraction analysis to delineate velocity inversion¹

5. Refraction Surveys

Ambiguity in the solution to the velocity inversion problem and a solution by joint inversion of seismic refraction and wide-angle reflection times

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Hidden Layer Problem in Seismic Refraction Work*

Cited by 24 publications

References 5 publications

Use of traveltime skips in refraction analysis to delineate velocity inversion1

Use of traveltime skips in refraction analysis to delineate velocity inversion1

5. Refraction Surveys

Ambiguity in the solution to the velocity inversion problem and a solution by joint inversion of seismic refraction and wide-angle reflection times

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Product

Resources

About

Use of traveltime skips in refraction analysis to delineate velocity inversion¹

Use of traveltime skips in refraction analysis to delineate velocity inversion¹