Urban development and migration processes in the urban region of Bratislava from the post-socialist transformation until the global economic crisis

This article contributes to understanding population migration in Central European urban regions and its connection with urban development. This topic has been addressed in other studies, focused mainly on large cities, particularly Prague, Budapest, and Warsaw. Bratislava, the capital of the Slovak Republic, is a relatively small city at the core of one of the most economically developed regions in Central Europe. The region has experienced a transformation of migration trends, from those determined by socialist urbanization to trends resembling those observed in Western Europe. Similar to those of other major Central European cities, recent patterns of migration to and from Bratislava are characterized by a rising intensity of concentration and decentralization, but also reflect several unique historical circumstances. Furthermore, the results indicate that the global economic crisis that erupted in 2007 has eased the intensity of the observed processes, although it has not changed their nature. This effect is similar to that of the economic decline in the 1990s.     

Estimation of velocity in the uppermost crust in a part of the western Gulf of Corinth,Greece, from the inversion of <Emphasis Type="Italic">P</Emphasis> and <Emphasis Type="Italic">S</Emphasis> arrival times using the neighbourhood algorithm

We determine the velocities in an upper crustal model, composed of three homogeneous layers, for one subregion of the western part of the Gulf of Corinth, NE of the town of Aigion, Greece. We have used local events that occurred there in the year 2001 and were recorded by the Corinth Rift Laboratory Network. Weighted P and S arrival time residuals are minimized using the Neighbourhood Algorithm of Sambridge (1999), combined with the grid search for source locations. The resolution of the inversion is tested by delete-one jackknifing. The model obtained is compared with some other models derived or applied to the subregion. A fast velocity increase between depths of 5 and 7 km is confirmed as the major structural element.     

Magnetic fabric variations in Mesozoic black shales, Northern Siberia, Russia: Possible paleomagnetic implications

A 28-m-long section situated on the coast of the Arctic Ocean, Russia (74°N, 113°E) was extensively sampled primarily for the purpose of magnetostratigraphic investigations across the Jurassic/Cretaceous boundary. The section consists predominantly of marine black shales with abundant siderite concretions and several distinct siderite cemented layers. Low-field magnetic susceptibility (k) ranges from 8 × 10^− 5 to 2 × 10^− 3 SI and is predominantly controlled by the paramagnetic minerals, i.e. iron-bearing chlorites, micas, and siderite. The siderite-bearing samples possess the highest magnetic susceptibility, usually one order of magnitude higher than the neighboring rock. The intensity of the natural remanent magnetization (M₀) varies between 1 × 10^− 5 and 6 × 10^− 3 A/m. Several samples possessing extremely high values of M₀ were found. There is no apparent correlation between the high k and high M₀ values; on the contrary, the samples with relatively high M₀ values possess average magnetic susceptibility and vice versa. According to the low-field anisotropy of magnetic susceptibility (AMS), three different groups of samples can be distinguished. In the siderite-bearing samples (i), an inverse magnetic fabric is observed, i.e., the maximum and minimum principal susceptibility directions are interchanged and the magnetic fabric has a distinctly prolate shape. Triaxial-fabric samples (ii), showing an intermediate magnetic fabric, are always characterized by high M₀ values. It seems probable that the magnetic fabric is controlled by the preferred orientation of paramagnetic phyllosilicates, e.g., chlorite and mica, and by some ferromagnetic mineral with anomalous orientation in relation to the bedding plane. Oblate-fabric samples (iii) are characterized by a bedding-controlled magnetic fabric, and by moderate magnetic susceptibility and M₀ values. The magnetic fabric is controlled by the preferred orientation of phyllosilicate minerals and, to a minor extent, by a ferrimagnetic fraction, most probably detrital magnetite. Considering the magnetic fabric together with paleomagnetic component analyses, the siderite-bearing, and the high-NRM samples (about 15% of samples) were excluded from further magnetostratigraphic research.     

FOREWORD

Foreword

FOREWORD     

Climate Change Projections Based on GCM-Simulated Daily Data

Three-dimensional general circulation models (GCMs) are 'state-of-the-art' tools for projecting possible changes in climate. Scenarios constructed for the Czech Republic are based on daily outputs of the ECHAM-GCM in the central European region. Essential findings, derived from validating, procedures are summarized and changes in variables between the control and perturbed experiments are examined. The resulting findings have been used in selecting the most proper methods of generating climate change projections for assessing possible hydrological and agricultural impacts of climate change in selected exposure units. The following weather variables have been studied: Daily extreme temperatures, daily mean temperature, daily sum of global solar radiation, and daily precipitation amounts. Due to some discrepancies revealed, the temperature series for changed climate conditions (2×CO ₂ ) have been created with the help of temperature differences between the control and perturbed runs, and the precipitation series have been derived from an incremental scenario based on an intercomparison of the GCMs' precipitation performance in the region. Solar radiation simulated by the ECHAM was not available and, therefore, it was generated using regression techniques relating monthly means of daily extreme temperatures and global radiation sums. The scenarios published in the paper consist of monthly means of all temperatures, their standard deviations, and monthly means of solar radiation and precipitation amounts. Daily weather series, the necessary input to impact models, are created (i) by the additive or multiplicative modification of observed weather daily series or (ii) by generating synthetic time series with the help of a weather generator whose parameters have been modified in accord with the suggested climate change scenarios.     

Flood Events of Selected European Rivers in the Sixteenth Century

The severity and frequency of sixteenth-century floods of the Rhine, the Main, the middle and upper Elbe with its tributaries, rivers of northern and central Italy, the Garonne and rivers in Catalonia and Andalusia are analyzed using documentary evidence. The basic topographical and hydrological characteristics of the rivers investigated as well as the synoptic causes of their flooding during the instrumental period are presented. Different examples of modifications of the run-off process due to anthropogenic activity are discussed. Prevalence in flood occurrence during the second half of the sixteenth century in comparison to the first half is typical for central European and Andalusian rivers (mainly in the 1560s and 1590s) and agrees with the evolution of precipitation patterns. On the other hand, Italian and Catalonian rivers, in part, had a higher occurrence of floods during the first half of the century. Changes in the flooding seasons in both halves of the century are not unambiguous. Results of an analysis on a broader European scale show floods to be a random natural phenomena with limited areal extent defined by the spatial influence of forcing meteorological factors (continuous heavy rains, sudden melting of thick snow cover, etc.). Despite some limitations of documentary evidence, series of reconstructed historical floods are valuable sources of proxy data which can be utilized for the study of the flooding fluctuations in the pre-instrumental period.     

Un paleoplacer métamorphisé d'hématite — rutile uranifère et thorifère dans l'Atacorien (Précambrian supérieur) du Togo,Afrique occidentale

Résumé Dans l'Atacorien (Akwapimian) du Togo, qui représente probablement la partie la plus inférieure du Précambrien supérieur, on a trouvé en 1970 une minéralisation sédimentaire à hématite et rutile uranifère et thorifère. Cette minéralisation contient des minéraux radioactifs du groupe de brannérite — davidite, aussi bien que l'uranothorite et le pyrochlore. Elle a été deposée dans un paleoplacer qui fait part d'un niveau flyscheux et a été transformée sous l'action du métamorphisme régional. La minéralisation représente un nouveau type génétique des minérais titanifères en Togo, aussi bien qu'en Afrique occidentale. Cette découverte change le but de la prospection detaillée de certaines séries dédritiques du Précambrien de l'Afrique occidentale.

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In the Atacorian (Akwapimian) of Togo, which probably represents a lower part of Upper Precambrian, a sedimentary mineralization of Hematite and urano-thoriferous rutil was discovered in 1970. In this mineralization occur some radioactive minerals of the davidite-brannerite group, as well as uranothorite and pyrochlore. It is built up by paleoplacers, located in a flysch series of the Atacorien, which was exposed to a later metamorphosis. These mineralizations represent a new genetic type of titaniferious ores in Togo, as well as in West Africa. This discovery changes the scope of detailed prospection of certain detritic series of the Precambrian of West Africa.

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Institut géologique Dionýz túr.     

Frequency content of stress waves in the nearest zone of a spherical explosive source in gravel sandy soil

Zusammenfassung Bei Verfolgung der Entstehung und Formierung der durch eine explosive Kugelquelle erregten Druckwellen steht die Frage ihres Frequenzgehalts im Vordergrund. Der Frequenzgehalt dieser Wellen wurde durch die Abhängigkeit ausgedrückt (2), die die Änderungen der relativen Breite des Amplitudenspektrums (1) vom Gewicht und von der Entfernung der Quelle angibt. Aus(2) erfolgt, dass der Frequenzgehalt der Druckwellen mit wachsender Entfernung und Grösse der Ladung exponential sinkt, wobei die Steilheit dieses Abfalls für höhere Grössen der Ladung kleiner ist. Das Herabsetzen des Frequenzgehalts dieser Wellen verursacht, dass die maximate spektral Dichte in grösseren Entfernungen von der Quelle markanter wird.     

Modellseismische Untersuchungen an 2- und 3-dimensionalen Testmodellen,Teil 1

Summary Following the recommendation of the European Seismological Commission (Copenhagen 1966) to carry out comparative measurements on simple seismic models with a prescribed velocity-depth distribution (test models), an attempt was made to compare results obtained with different model techniques. In the present paper, model investigations with the first two proposed test models carried out by 2- and 3-dimensional model techniques are described. Seismogrammes, travel-time curves and amplitude-distance curves of the models investigated are given. A quantitative comparison of the results shows a satisfactory agreement.     

Les formes différentielles extérieures dans la géodésie II: Courbure moyenne

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