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71.
Long-term groundwater monitoring has been carried in the model locality of the landslide area at Třebenice, situated in the northern part of the Czech Republic in Cretaceous claystones to marlstones. Primarily, long-term fluctuation of the groundwater and piezometric levels has been monitored. Monitoring of groundwater flow was carried out in selected wells also by the photometry logging method using a dilution technique of a marked liquid. On the basis of these results, the pattern of the groundwater flow through the landslide area was determined in lithologically homogeneous Cretaceous claystones to marlstones. Interpretation of monitoring results indicated that water flows preferentially through the zone of near-surface loosening of the claystone rock massif, in general parallel to the slope inclination between 8 and 10-m depth below ground level. This zone exhibits a higher permeability given by 1–2 orders of hydraulic conductivity compared with overlying strata and underlying rock in which this zone is closed. This verified pattern of groundwater flow has a significant effect on the stability of the sliding slope and it is one of the main factors affecting the evolution of landslides on the slopes formed by these rocks.  相似文献   
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Natural Hazards - To investigate the propagation of meteorological droughts to agricultural and hydrological droughts, the relationship between droughts was analyzed using observed precipitation...  相似文献   
74.
Summary In order to obtain basic palaeomagnetic data on Upper Carboniferous, Permian and Triassic sediments collected from the NW Bulgaria, laboratory stability tests were extended from A.C. and thermal treatments to studies of mineral phase changes and to investigations of changes of magnetic anisotropy during laboratory procedures. Laboratory criteria were found which permitted to distinguish samples suitable for palaeomagnetic analyses from those representing rocks totally or almost totally chemically reworked during their history. Palaeomagnetic directions and pole positions derived from Stephanian, Lower Permian and Triassic rocks from the southern margin of the Moesian Platform are compatible with the values obtained for the tectonically stable North-European Platform.  相似文献   
75.
Zusammenfassung Die saxonische Tektonik beeinflußte nach dem Abschluß der variszischen Gebirgsbildung wesentlich die tektonische Entwicklung der Böhmischen Masse, die zu einem konsolidierten Block von Hebungstendenz wurde. Die saxonische Tektogenese der Böhmischen Masse stellt vor allem ein Abbild der tektonischen Entwicklung der alpinkarpatischen Geosynklinale im Meso- und Känozoikum dar. Orogenetische Bewegungen der alpin-karpatischen Geosynklinale beeinflußten unmittelbar die Tektonik in der Böhmischen Masse.Das Mesozoikum stellte in der Böhmischen Masse eine Zeitperiode lediglich mit Bruchtektonik, ohne Vulkanismus dar. Die mesozoischen tektonischen Strukturen der Böhmischen Masse werden durch tektonische Elemente von nordwest-südöstlicher Streichrichtung charakterisiert. Im Känozoikum kommen in der Böhmischen Masse zum Unterschied vom Mesozoikum richtungsmäßig unterschiedliche Strukturen zum Vorschein, nämlich Brüche von südwest-nordöstlicher Streichrichtung, die für das untere Miozän charakteristisch sind und dem jüngeren Strukturplan des Westabschnittes der tschechoslowakischen äußeren Karpaten entsprechen. Ferner Brüche, die von NW nach SO und NNW nach SSO streichen und für das Pliozän charakteristisch sind. Für das Känozoikum sind auch drei Phasen des basischen Vulkanismus in der Zeitperiode vom Anfang zum Ende des Neogens bedeutsam. Die heutzutage auf der Erdoberfläche bemerkbaren Brüche stellen meistens Äußerungen der Bewegungen einzelner Schollen im Neogen und Quartär dar. Die Sprunghöhe der Bewegungen erreicht mehr als 1000 m.
The Saxonic block-fault tectonics influenced substantially the tectonic development of the Bohemian Massif after the end of the Variscan orogeny, when the Bohemian Massif has become a consolidated block with a rising tendency. The Saxonic blockfault tectogenesis of the Bohemian Massif is mainly a reflexion of the tectonic development of the Alpine-Carpathian geosyncline in the Mesozoic and Cenozoic. Orogenic movements of individual orogenic phases in the Alpine-Carpathian geosyncline directly influenced tectonic movements in the Bohemian Massif. The Mesozoic was for the Bohemian Massif (after the preceding Variscan orogeny) a period with only fault tectonics, without any volcanic activity. Mesozoic tectonic structures of the Bohemian Massif are characterized by tectonic elements of NW-SE direction. Structures differing in direction from those in the Mesozoic apply in the Bohemian Massif in the Cenozoic. They are faults of the SW-NE direction characteristical for the Lower Miocene, which correspond to the younger structural plan of the Czechoslovak Inner Carpathians western section, and further faults of the NW-SE and NNW-SSE direction characteristical for the Pliocene. For the Cenozoic also three phases of basic volcanism in the period from the beginning to the end of Neogene are significant. Faults visible at present on the surface are mostly a consequence of movements of individual blocks during the Neogene and the Quaternary. The magnitude of movements reaches more than 1000 m.

Résumé La tectonique saxonienne a influencé essentiellement le développement tectonique du Massif de Bohême après la fin de l'orogenèse varisque qui le consolida en un bloc à tendance ascendante. La tectogenèse saxonienne du Massif de Bohême est avant tout le reflet du développement tectonique du géosynclinal alpino-carpatique au cours du Mésozoïque et du Cénozoïque, dont les mouvements orogéniques l'ont directement influencé. Le Mésozoïque représente seulement une ère de tectonique de failles sans activité volcanique, avec des structures tectoniques caractérisées par une direction NW-SE. Au Cénozoïque, par contre, des structures de directions différentes apparaissent, principalement des structures SW-NE qui sont caractéristique pour le Miocène inférieur, correspondant au plan structural de la partie occidentale des Carpates tchécoslovaques externes. D'autres failles, de direction NW-SE et NNW-SSE, sont caractéristiques pour le Pliocène. Sont également significatifs pour le Cénozoïque trois phases de volcanisme basique durant la période s'étendant du commencement à la fin du Néogène. Les failles aujourd'hui observables sont généralement l'expression de mouvements individuels de blocs au Néogène et au Quaternaire. L'ampleur des rejets liés à ces mouvements atteint plus de mille mètres.

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76.
Summary The present paper deals with the derivation of the intensity of the geomagnetic field in the Plio-Pleistocene, Central Europe. The intensity was derived from the thermo-remanence of porcellanites and palaeo-slags. These rocks represent a common product of intense thermal alteration of loams due to spontaneous combustion of coal seams. Porcellanites and palaeo-slags show outstanding palaeomagnetic properties, their remanent magnetization is of thermo-remanent origin and they were mineralogically stabilized under natural conditions in the geological past, during the coal combustion. It was found, that the intensity of the geomagnetic field during the Plio-Pleistocene oscillated about the value of the present-day intensity.  相似文献   
77.
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79.
Summary Statistical evaluation of palaeomagnetic data from the Early Carboniferous to the Middle Triassic rocks in Europe, north of the Alpine tectonic belt, confirmed previously defined palaeotectonic stability of the whole European Plate since the Early Permian. The Trans-European Suture Zone represents a plate boundary, SW of which the Early Variscan and pre-Variscan formations show different degrees of palaeotectonic rotations, predominantly rotations of clockwise sense. A theoretical model simulating the translation and rotation movements was proposed showing that the West European Variscides underwent Hercynian palaeotectonic rotations comparable with the rotations derived for the Alpine tectonic belt.  相似文献   
80.
Summary The aim of this article is the evaluating of the radiation flux changes connected with the changes of atmosphere structure after a volcanic eruption. A situation similar to the after the eruption of volcano El Chichon in 1982 is analyzed. The comparison of the calculated characteristics with measured radiation fluxes indicates good agreement. It is shown that the most important changes in the radiation fluxes are observed in the spectral range of 500–600 nm. The particles in dust layers contribute to increasing the albedo of the Earth-atmosphere system especially in the near infrared part of the spectrum. A shift of the energy maximum in the radiation spectrum of the dust layer in the volcanic atmosphere is also observed.on leave from the Astronomical Institute, Slovak Academy of Sciences  相似文献   
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