A Note on the Reflection of Seismic Pulses With Application to Second Event Refraction Shooting*

O'Brien, P. N. S.

doi:10.1111/j.1365-2478.1963.tb02025.x

Cited by 14 publications

(10 citation statements)

References 8 publications

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“…1 have similar shape and differ significantly only in amplitude. This is in agreement with wave theory results (Cerveny 1966;Cerveny & Ravindra 1971, p. 285) and experimentally determined phase shifts presented by O'Brien (1963).…”

Section: Near-critical Point Reflectionssupporting

confidence: 92%

Guide to the Interpretation of Crustal Refraction Profiles

Braile¹,

Smith²

1975

Geophysical Journal International

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Using the reflectivity method, synthetic, vertical-component seismograms have been computed for simple velocity transitions appropriate to crustal models. Record sections of the synthetic seismograms including refracted and reflected phases aid in elucidating the fine structure of the crust since they illustrate the effects of various velocity models. The computed record sections indicate the importance to interpretation of secondary arrivals such as near-vertical incidence and wide-angle reflections and illustrate the following: (1) an upper crustal low velocity layer (LVL) can best be recognized from reflections from the top of the LVL; (2) wide-angle reflections are nearly always of larger amplitude than head waves and have apparent velocities indicative of the layer velocities; (3) head wave amplitudes are greatly affected by velocity gradients within the refracting layer; (4) near-vertical incidence reflections are of significant amplitude principally for reflections from first-order velocity discontinuities; and (5) comp!ex wave patterns result from relatively simple upper crustal models which contain an LVL and serve to emphasize the need for detailed amplitude studies so that amplitudes of head waves and near-critical reflections may be considered. Synthetic seismograms which closely approximate observed seismograms for a detailed refraction line in the eastern Basin and Range province are used to infer fine structure of the crust. Synthetic record sections computed for a Basin and Range and an eastern United States crustal model illustrate different amplitude-timedistance features which are characteristic of observed seismic data from these regions.

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Section: Near-critical Point Reflectionssupporting

confidence: 92%

Guide to the Interpretation of Crustal Refraction Profiles

Braile¹,

Smith²

1975

Geophysical Journal International

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“…However, plane-wave reflection coefficients (PRCs) are not applicable near the critical angle (O'Brien, 1962;Macdonald et al, 1987;van der Baan and Smit, 2006). Point source reflection responses (spherical waves) modeled by the reflectivity method show excellent amplitude agreement with the laboratory experiments around the critical angle (Alhussain et al, 2008).…”

Section: Introductionmentioning

confidence: 79%

Phase variation with angle inversion using plane and spherical waves

Zhu¹,

McMechan²

2011

SEG Technical Program Expanded Abstracts 2011

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Seismic reflection data from near-to post-critical angles provide the potential of both velocity and density inversion. It is known that plane wave solutions are inapplicable near the critical angle. Spherical-wave solutions have recently been considered to study the amplitude variation with offset (AVO). However, amplitude is difficult to extract reliably due to transmission losses. To overcome this, we propose to use the phase variation with angle (PVA) information for elastic parameter inversion. The modeling is by spherical-wave reflection coefficients (SRCs). A linearized least-squares scheme is used to invert the modeled PVA for density and three velocities across the reflector. Numerical tests indicate that a correct solution can be reached only when the models are consistent for both observed and predicted phases. A spherical-wave model can produce a more accurate solution for real (spherical-wave) data than a plane-wave model can.

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“…II et 12) ne peut présenter d'augmentation de l'arrivée réfléchie dans la zone d'interfCrence entre PP et PPP.…”

Section: Modèle Laitow/acierunclassified