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Crustal Structure of the Bohemian Massif Based on Seismic Refraction Data
Hrubcová, Pavla ; Vavryčuk, Václav (advisor) ; Plomerová, Jaroslava (referee) ; Švancara, Jan (referee)
The deep structure of the Bohemian Massif, the largest stable outcrop of the Variscan rocks in central Europe, was studied using the data of the international seismic refraction and wide- angle reflection experiments CELEBRATION 2000, ALP 2002 and SUDETES 2003. The data were interpreted by seismic tomographic inversion and by 2-D trial-and-error forward modelling of the P and S waves. Above, additional constraints on the crustal structure were imposed by reflectivity or gravity modelling, and by receiver function interpretation. Knowledge of the crustal velocity structure in the Bohemian Massif was complemented by its azimuthal variation. Though consolidated, the Bohemian Massif can be subdivided into several tectonic units separated by faults, shear zones, or thrusts reflecting varying influence of the crust forming processes. The resultant velocity models determined different types of the crust-mantle transition reflecting variable crustal thickness and delimiting contacts of these tectonic units at depth.
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Anisotropic tomography of the European upper mantle
Žlebčíková, Helena ; Plomerová, Jaroslava (advisor)
Title: Anisotropic tomography of the European upper mantle Author: Helena Žlebčíková Department: Department of Geophysics, Faculty of Mathematics and Physics, Charles University Training institution: Institute of Geophysics of the Czech Academy of Sciences (IG CAS) Supervisor: RNDr. Jaroslava Plomerová, DrSc., IG CAS Consultants: RNDr. Vladislav Babuška, DrSc., IG CAS RNDr. Luděk Vecsey, Ph.D., IG CAS Abstract: Large-scale seismic anisotropy of the continental mantle lithosphere derived from joint inversion/interpretation of directional variations of P-wave travel-time residuals and SKS-wave splitting calls for orientation of the symmetry axes to be treated generally in 3D. Nevertheless, most of the tomography studies neglect the anisotropy of the body waves completely or they are limited to either azimuthal or radial anisotropy. Therefore, we have developed a code called AniTomo for coupled anisotropic-isotropic travel-time tomography of the upper mantle. The novel code allows inversion of relative travel-time residuals of teleseismic P waves simultaneously for 3D distribution of P-wave isotropic- velocity perturbations and anisotropy of the upper mantle. We assume weak anisotropy of hexagonal symmetry with either the 'high-velocity' a axis or the 'low-velocity' b axis. The symmetry axis is allowed to be...
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Anisotropic tomography of the European upper mantle
Žlebčíková, Helena ; Plomerová, Jaroslava (advisor)
Title: Anisotropic tomography of the European upper mantle Author: Helena Žlebčíková Department: Department of Geophysics, Faculty of Mathematics and Physics, Charles University Training institution: Institute of Geophysics of the Czech Academy of Sciences (IG CAS) Supervisor: RNDr. Jaroslava Plomerová, DrSc., IG CAS Consultants: RNDr. Vladislav Babuška, DrSc., IG CAS RNDr. Luděk Vecsey, Ph.D., IG CAS Abstract: Large-scale seismic anisotropy of the continental mantle lithosphere derived from joint inversion/interpretation of directional variations of P-wave travel-time residuals and SKS-wave splitting calls for orientation of the symmetry axes to be treated generally in 3D. Nevertheless, most of the tomography studies neglect the anisotropy of the body waves completely or they are limited to either azimuthal or radial anisotropy. Therefore, we have developed a code called AniTomo for coupled anisotropic-isotropic travel-time tomography of the upper mantle. The novel code allows inversion of relative travel-time residuals of teleseismic P waves simultaneously for 3D distribution of P-wave isotropic- velocity perturbations and anisotropy of the upper mantle. We assume weak anisotropy of hexagonal symmetry with either the 'high-velocity' a axis or the 'low-velocity' b axis. The symmetry axis is allowed to be...
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Anisotropic tomography of the European upper mantle
Žlebčíková, Helena ; Plomerová, Jaroslava (advisor) ; Agostinetti Piana, Nicola (referee) ; Achauer, Ulrich (referee)
Title: Anisotropic tomography of the European upper mantle Author: Helena Žlebčíková Department: Department of Geophysics, Faculty of Mathematics and Physics, Charles University Training institution: Institute of Geophysics of the Czech Academy of Sciences (IG CAS) Supervisor: RNDr. Jaroslava Plomerová, DrSc., IG CAS Consultants: RNDr. Vladislav Babuška, DrSc., IG CAS RNDr. Luděk Vecsey, Ph.D., IG CAS Abstract: Large-scale seismic anisotropy of the continental mantle lithosphere derived from joint inversion/interpretation of directional variations of P-wave travel-time residuals and SKS-wave splitting calls for orientation of the symmetry axes to be treated generally in 3D. Nevertheless, most of the tomography studies neglect the anisotropy of the body waves completely or they are limited to either azimuthal or radial anisotropy. Therefore, we have developed a code called AniTomo for coupled anisotropic-isotropic travel-time tomography of the upper mantle. The novel code allows inversion of relative travel-time residuals of teleseismic P waves simultaneously for 3D distribution of P-wave isotropic- velocity perturbations and anisotropy of the upper mantle. We assume weak anisotropy of hexagonal symmetry with either the 'high-velocity' a axis or the 'low-velocity' b axis. The symmetry axis is allowed to be...
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Teleseismic Tomography of the Upper Mantle beneath the Bohemian Massif
Karousová, Hana ; Plomerová, Jaroslava (advisor) ; Růžek, Bohuslav (referee) ; Zahradník, Jiří (referee)
Passive seismic experiments, MOSAIC, BOHEMA I-III, EgerRift, or, PASSEQ, carried out in the region of the Bohemian Massif (BM), allowed a detailed study of velocity structure of the upper mantle. We present results of tomography studies of the upper mantle beneath the north-eastern and southern parts of the BM based on the data from the BOHEMA II and BOHEMA III experiments (2004-2006). Despite the fact that regions with the highest resolution of velocity perturbations differ in the models, tomography images are similar in overlapping parts. Models of the upper mantle show mostly low- velocity perturbations relatively to radially symmetric velocity model of the Earth beneath the BM. Limited high-velocity heterogeneity beneath the Moldanubian unit, extended in the NE-SW direction, reflects thickening of the lithosphere due to a collision of the BM with the Brunovistulian micro-plate during the Variscan orogeny. The tomography based on the data from the BOHEMA III experiment revealed significant high-velocity heterogeneity in the southern margin of the model with a subduction of the lithosphere beneath the Eastern Alps. Tomographic tests showed that effects of uncorrected velocity heterogeneities within the crust can appear as deep as 100 km and, therefore, they could lead to erroneous interpretation of...
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Crustal Structure of the Bohemian Massif Based on Seismic Refraction Data
Hrubcová, Pavla ; Vavryčuk, Václav (advisor) ; Plomerová, Jaroslava (referee) ; Švancara, Jan (referee)
The deep structure of the Bohemian Massif, the largest stable outcrop of the Variscan rocks in central Europe, was studied using the data of the international seismic refraction and wide- angle reflection experiments CELEBRATION 2000, ALP 2002 and SUDETES 2003. The data were interpreted by seismic tomographic inversion and by 2-D trial-and-error forward modelling of the P and S waves. Above, additional constraints on the crustal structure were imposed by reflectivity or gravity modelling, and by receiver function interpretation. Knowledge of the crustal velocity structure in the Bohemian Massif was complemented by its azimuthal variation. Though consolidated, the Bohemian Massif can be subdivided into several tectonic units separated by faults, shear zones, or thrusts reflecting varying influence of the crust forming processes. The resultant velocity models determined different types of the crust-mantle transition reflecting variable crustal thickness and delimiting contacts of these tectonic units at depth.
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