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  • 1
    Electronic Resource
    Electronic Resource
    Seismic tomography in the Ostrava-Karviná mining region (1989)
    Springer
    Pure and applied geophysics 129 (1989), S. 597-608 
    Details
    ISSN: 1420-9136
    Keywords: Seismic tomography ; velocity field ; paraxial ray approximation ; Ostrava-Karviná mining region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The effective algorithm of seismic tomography was applied to the simultaneous determination of the velocity field in the medium and the location of hypocentres of events in the area of the underground seismological network in the Ostrava-Karviná mining region (OKR). Although the configuration of the network is unsuitable and the used data are relatively unreliable, after classifying the data it is possible to obtain representative information that demonstrates the existence of significant inhomogeneities of the medium in the area under study. In addition, it is possible to obtain more precise hypocentre parameters of local seismic events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00874527
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  • 2
    Electronic Resource
    Electronic Resource
    Kinematic inversion for qP- and qS-waves in inhomogeneous hexagonally symmetric structures (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 108 (1992), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: We propose a kinematic inversion technique based on the first-order perturbation method for anisotropic media. In contrast to previous techniques, this one can be used to invert traveltimes of quasi-compressional as well as split quasi-shear waves, even if the initial unperturbed medium is isotropic. In principle, the technique is applicable to general 3-D laterally inhomogeneous anisotropic structures with an arbitrary degree of anisotropy. Here, however, for simplicity, media with hexagonal symmetry are considered. The effectiveness and limitations of the inversion technique are illustrated with synthetic VSP traveltime data. A simple linear variation of elastic parameters with depth is considered. The inversion scheme is tested both on data with pronounced shear wave splitting and data in which the shear wave splitting is negligible, the limiting case being data generated for a vertically inhomogeneous isotropic structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1992.tb04639.x
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  • 3
    Electronic Resource
    Electronic Resource
    First-order perturbation method for anisotropic media (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 99 (1989), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The first-order perturbation method is used to evaluate approximate phase velocities and polarization vectors in elastic anisotropic media. Formulae are given which make possible computations of perturbations of these parameters for quasi-compressional as well as quasi-shear waves, no matter whether the unperturbed medium is isotropic or anisotropic. Approximate results for an extremely anisotropic material and relatively large deviations of parameters of unperturbed and perturbed media closely resemble the results computed exactly. It is, therefore, expected that the application of the perturbation method to realistic media with generally weaker anisotropy and for smaller deviations between unperturbed and perturbed medium parameters should give satisfactory results. The method will find the most important applications in the investigation of high-frequency wave propagation in inhomogeneous anisotropic media and in solving inverse problems for anisotropic structures. Several possible applications are listed and briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1989.tb01694.x
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  • 4
    Electronic Resource
    Electronic Resource
    Computation of rays in an inhomogeneous transverselly isotropic medium with a non-vertical axis of symmetry (1983)
    Springer
    Studia geophysica et geodaetica 27 (1983), S. 114-121 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Резюме Нa основе меmо¶rt;uкu оnuсaнноŭ в [1], выве¶rt;ены ¶rt;uфференцuaльные урaвненuя сеŭсмuческого лучa в 2-D нео¶rt;норо¶rt;ноŭ, nоnеречно uзоmроnноŭ сре¶rt;е с нaклонноŭ осью сыммеmрuu. Оnuсaны резульmamы вычuсленuŭ ¶rt;ля некоmорых сnецuaльно оnре¶rt;еленных сре¶rt;.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01588984
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  • 5
    Electronic Resource
    Electronic Resource
    Model of medium with cracks and its parameters obtained by observing longitudinal waves (1983)
    Springer
    Studia geophysica et geodaetica 27 (1983), S. 366-371 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Резюме В рaбоmе[3] решенa зa¶rt;aчa зaвuсuмосmu скоросmеŭ рaсnросmрaненuя nро¶rt;олных волн оm у лa na¶rt;енuя оmносumельно нормaлеŭ mонкuх кру лых mрещuн. Эma mеореmuческaя мо¶rt;ель былa nрuмененa к эскnерuменmaльно uзмеренным скоросmям nро¶rt;олных волн нa шaровых обрaзцaх орных nоро¶rt; nрu u¶rt;росmamuческuх ¶rt;aвленuях ¶rt;о 400 МПa. Обсужaлuсь ¶rt;ве мо¶rt;елu: nервaя мо¶rt;ель с о¶rt;ноŭ сuсmемоŭ naрaллельно нanрaвленных mрещuн u вmорaя мо¶rt;ель uмеющaя ¶rt;ве незaвuсuмые сuсmемы mрещuн. Решенuем обрamноŭ зa¶rt;aчu nолучuлuсь naрaмеmры mрещuн в зaвuсuмосmu оm u¶rt;росmamuческо о ¶rt;aвленuя. Прuве¶rt;ены резульmamы ¶rt;ля обрaзцa сaзaвско о рaно¶rt;uорuma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01636183
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  • 6
    Electronic Resource
    Electronic Resource
    Three-dimensional inverse problem for inhomogeneous transversely isotropic media (1988)
    Springer
    Studia geophysica et geodaetica 32 (1988), S. 136-143 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Description / Table of Contents: Резюме Основнaя формулa, uсnользовaннaя в nре¶rt;лaгрaемоŭ рaбоmе, ¶rt;aеm оmношенuе меж¶rt;у uзмененuем временu nробегa волны Р u uзмененuем нео¶rt;норо¶rt;ноŭ nоnеречно uзоmроnноŭ сре¶rt;ы, вырaженноŭ чеmырьмя уnругuмu naрaмеmрaмu u ¶rt;вумя углaмu орuенmaцuu осu сuммеmрuu nоnеречноŭ uзоmроnuu в nросmрaнсmве. Измененuе временu nробегa вычuсляеmся в¶rt;оль лучa в нaчaльноŭ нео¶rt;норо¶rt;ноŭ uзоmроnноŭ сре¶rt;е. Уnругuе naрaмеmры u ¶rt;вa углa naрaмеmрuзuровaны в мо¶rt;елu u nосmроенa сuсmемa урaвненuŭ ¶rt;ля несколькuх лучеŭ. Урaвненuя лuнеŭны nо неuзвесmным уnругuм naрaмеmрaм u нелuнеŭны nо неuзвесmным углaм орuенmaцuu осеŭ сuммеmрuu, nоэmому uсnо льзуеmся umерamuвныŭ aлгорumм Левенбергa-Мaрквaр¶rt;ma ¶rt;ля uх решенuя. В рaбоmе nрuбе¶rt;ен мо¶rt;ельныŭ mрехмерныŭ чuсленныŭ nрuмер. Для nолученuя mелесеŭсмuческuх ¶rt;aнных снaчaлa решенa nрямaя зa¶rt;aчa u зamем ¶rt;aнные обрaщены. Резульmamы nокaзывaюm огрaнuченuя u возможносmu nрuмененuя nрuве¶rt;енноголгорumмa в реaльных случaях.
    Notes: Summary The basic formula used in the presented paper gives the relation between the P wave travel-time perturbation and the perturbation of an inhomogeneous transversely isotropic medium, expressed by four perturbations of elastic parameters and by two angles of orientation of the axis of symmetry of transverse isotropy in space. The travel time perturbation is computed along the ray in the unperturbed inhomogeneous isotropic medium. Four elastic parameters and two angles are parametrized in the model under study and a system of equations for many rays is constructed. The equations are linear in the sought elastic parameters and nonlinear in the sought angles, and the iterative Levenberg-Marquardt algorithm is thus used to solve them. The theoretical 3-D inverse problem was solved in the presented numerical example. The data, simulating teleseismic data, were computed in the direct problem and then inverted. The results indicate the applicability and limitation of the presented algorithm in real problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01637576
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  • 7
    Electronic Resource
    Electronic Resource
    Iterative geophysical tomography (1986)
    Springer
    Studia geophysica et geodaetica 30 (1986), S. 242-256 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Description / Table of Contents: Summary The algorithm of iterative geophysical tomography is presented. The medium is approximated smoothly by means of B-splines. The tww-point problem of ray computation is solved with the aid of paraxial approximation. The parameters of the medium are obtained from the iterative algorithm of minimizing the quadratic form. Two numerical 2-D examples are given.
    Notes: Резюме Прuве¶rt;еи aлгорuфм umерamuвноŭгеофuзuческоŭ mомогрaфuu. Сре¶rt;a annроксuмuровaнa сnлощно nрu nомощu Б-сnлaŭнов. Пвухmочнaя nроблеммa рaсчемa лучеŭ рещенa nрu nомощu naрaксuaлноŭ annроксuмaцuu. Пaрaмеmры сре¶rt;ы nолучены иa основе umерamuвного aлгорuфмa мuнuмaлuзaцuu квa¶rt;рamuческоŭ формы. В рaбоmе nрuве¶rt;ены ¶rt;вa 2-D чuсленных nрuмерa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01645465
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  • 8
    Electronic Resource
    Electronic Resource
    Approximate absorption corrections for complete SH seismograms (1990)
    Springer
    Studia geophysica et geodaetica 34 (1990), S. 185-196 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Summary An approximate absorption correction is proposed that can be applied retroactively to the response of a perfectly elastic medium, not decomposed into elementary waves, for example in the finite-difference method. As the duration of excitation decreases, the approximate correction approaches the exact, and becomes quite exact for impulsive excitation. The correction makes use of the perfectly elastic response and dissipation operator, but their relation is not simply convolutory. The method is restricted to a spatially constant Q with an arbitrary power-law frequency dependence. The advantage of the approximate solutions, as compared to the exact, in which the absorption is included in the equation of motion, is in a considerable saving of computer time if several absorption models (or several Q values) are repeatedly applied to the same structure. The simplest computations are for Q linearly dependent of the frequency, where the absorption correction reduces to an exponential time windowing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02295925
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  • 9
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    Computation of elastic parameters of anisotropic medium from travel times of quasi-compressional waves (1991)
    Elsevier
    Details
    Publication Date: 1991-04-01
    Print ISSN: 0031-9201
    Electronic ISSN: 1872-7395
    Topics: Geosciences , Physics
    Published by Elsevier
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  • 10
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    Crosswell imaging in a shallow unconsolidated reservoir (1993)
    Society of Exploration Geophysicists
    Details
    Publication Date: 1993-01-01
    Print ISSN: 1070-485X
    Electronic ISSN: 1938-3789
    Topics: Geosciences
    Published by Society of Exploration Geophysicists
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