COMPUTER PROCESSED LANDSAT LAND COVER MAPS OF HUNGARY

Two studies using LANDSAT imagery are summarized. The urban area study of the city of Budapest uses a statistical classifying method with ground truth to identify eleven land use categories resulting in a 60 to 80% reliability. The rural area study of Komarom County attempts to use LANDSAT to monitor the utilization of farms of agri-ecological research by identifying actual cropland patterns. Translated by the authors and submitted for publication in June, 1984.     

Estimation of an upper limit on prehistoric peak ground acceleration using the parameters of intact speleothems in Hungarian caves

The examination of speleothems in the Hajnóczy and Baradla caves (northeastern Hungary) allows estimating an upper limit for horizontal peak ground acceleration generated by paleoearthquakes. The density, the Young’s modulus and the tensile failure stress of the samples originating from a broken speleothem have been measured in a laboratory, whereas the natural frequency of intact speleothems was determined by in situ observations. The value of horizontal ground acceleration resulting in failure, the natural frequency and the inner friction coefficient of speleothems were assessed by theoretical calculations. The ages of the samples taken from a stalagmite 5.1 m in height (Baradla cave) have been determined by inductively coupled plasma mass spectrometry analysis and alpha spectrometry. The measured ages fall between 140,000 and 70,000 years; therefore, we assume the speleothem has not been changed since the end of this time interval. According to our modeling results, this speleothem has not been excited by a horizontal acceleration higher than 0.05 g during the last 70,000 years.     

Charcoal and pollen analyses and vegetation reconstruction of the Alpine foreland in West Hungary

In the area of archaeological excavations that were performed prior to the construction of Main Road No. 86 in Vas County (West Hungary) in the Alpine foreland new geoarchaeological analyses have been conducted. We used anthracology and pollen analyses to reconstruct the former vegetation cover at the study site. Charcoal data provide site-related information about the local woodland composition, management and human impact, while pollen data provide information on the arboreal and non-arboreal vegetation on a regional or local scale. Adequate samples for anthracological analyses derive from the Bronze Age, Iron Age, Imperial and Migration Periods and Middle-Ages archaeological objects. The core for pollen analyses originates from alluvial sediments of the Borzó Creek and covers the late Pleistocene and the Holocene until the Medieval Period. Charcoal analyses show the dominance of Quercus trees in the vicinity of the human settlements that might indicate a strong human selection, or the fragmentation of samples. Pollen analyses indicate thermophilous vegetation from the beginning of the Holocene, with increasing values of Fagus and Carpinus. Pollens of cereals indicate human activity, which is also demonstrated by the presence of pollen from Juglans and Vitis in the Iron Age sequence. Extensive forest clearance occurred in the Late Iron Age and the Imperial Period.     

Spot Modelling of ζ Andromedae

The photometric light modulation of ζ Andromedae originates from the distorted geometry of the primary, and additionally, from spots of which parameters (temperature, size, location) are variable in time. We present spot modelling results for six two-colour light curves which show that spots preferably appear on the stellar surface towards the companion star and opposite to it, where the distortion also causes dimming. Therefore, simple fitting of the measured data for the ellipticity effect does not yield correct result. Instead, ellipticity calculated from exact stellar parameters should be removed from the data to get reliable spotted light curves.     

Fluvial flood risk in Europe in present and future climates

In this work we evaluate the implications of climate change for future fluvial flood risk in Europe, considering climate developments under the SRES A2 (high emission) and B2 (low emission) scenario. We define flood risk as the product of flood probability (or hazard), exposure of capital and population, and vulnerability to the effect of flooding. From the European flood hazard simulations of Dankers and Feyen (J Geophys Res 114:D16108. doi:, 2009) discharges with return periods of 2, 5, 10, 20, 50, 100, 250 and 500 years were extracted and converted into flood inundation extents and depths using a planar approximation approach. Flood inundation extents and depths were transformed into direct monetary damage using country specific flood depth-damage functions and land use information. Population exposure was assessed by overlaying the flood inundation information with data on population density. By linearly interpolating damages and population exposed between the different return periods, we constructed damage and population exposure probability functions under present and future climate. From the latter expected annual damages (EAD) and expected annual population exposed (EAP) were calculated. To account for flood protection the damage and population exposure probability functions were truncated at design return periods based on the country GDP/capita. Results indicate that flood damages are projected to rise across much of Western Europe. Decreases in flood damage are consistently projected for north-eastern parts of Europe. For EU27 as a whole, current EAD of approximately €6.4 billion is projected to amount to €14–21.5 billion (in constant prices of 2006) by the end of this century, depending on the scenario. The number of people affected by flooding is projected to rise by approximately 250,000 to 400,000. Notwithstanding these numbers are subject to uncertainty, they provide an indication of potential future developments in flood risk in a changing climate.     

Starspot modelling of the RS CVn binary HK lacertae

Investigating more than 270 nightly mean magnitudes of the long-period RS CVn binary HK Lac, we can draw some conclusions about the nature of its complicated light variations. The mean brightness, the apparent photometric period, and the shape of the light curve all show strong variations. Analysis with a starspot model, assuming two large spots and a general uniform spottedness, indicates two comparably large spots which appear to have maintained their separate identities for the last 15 yr and drifted in longitude separation from each other smoothly by only about 45°. The phase of the two spots indicates both are rotating very nearly synchronously with the orbital motion, one slightly (0.025%) faster and the other slightly (0.080%) slower. the latitudes of the two spots, one farther above the equator and one closer to the equator, are consistent with solar-type differential rotation and yield an estimate of 25±12° for the co-rotating latitude. A correlation between mean spot latitude and instantaneous photometric period yields another estimate of 31±2°, in agreement with the first.     

The statistical relationship between unconfined compressive strengths and the frequency distributions of slope gradients — A case study in northern Hungary

This paper focuses on the question of whether there is a deterministic connection between the slope gradient and unconfined compression strength (UCS) as a lithological factor and on describing the nature of this connection. Moreover, the authors determined the sensitive statistical parameters in the statistical surface analyses. The surface analyses were carried out in an area extending over 1500 km² in northern Hungary and containing parts of the uplifted Palaeozoic and Mesozoic basement and the semi-consolidated material of the Palaeogene and Neogene molasse sediments.The 67 geological formations of the area were grouped into 10 petrophysical categories characterised by unconfined compressive strength as a petrophysical parameter. The geological database was the digitalized geological map of North Hungarian Region (1 : 100 000). The digital topographic database was based on 10 m contour lines of 1 : 50 000 maps, the digital elevation model was generated by kriging interpolation. Three topographic models were created with resolutions of 25 × 25, 50 × 50 and 100 × 100 m per pixels.Evident correlation can be shown between the UCS and the relative frequency of the slope gradient. The adequate regression procedure is the power regression for low slope category values while logarithmic regression is applicable at high slope angles. Based on the characteristic of the relationship and the value of r², slope category intervals can be identified the relative frequency of which is proven to be determined by the UCS. These intervals are found to be between 4–10%, 10–16%, 16–22%, 22–44% and over 44%.Using the determination equations of slope gradient between 4–10% and over 44%, the UCS of the bedrock can be calculated approximately as the average value of the two calculated results. So the quotient of the frequency of these two category intervals can be regarded as an important morphometric index for a given bedrock.From the aspect of petrophysical characteristics, the rock with UCS between 6 and 86 MPa were proven to be deterministic for the slope development i.e. in the determination of the slope category frequencies. Applying the relative frequency of slope gradients a relative erosion resistance of the petrophysical categories can be calculated.Considering the determination coefficients, among the statistical parameters of the distribution of slope category values the standard deviation, mode, mean and median proved to be determined by the UCS of the bedrock.     

Retrograde alterations of phyllosilicates in low-grade metapelite: a case study from the Szendr? Paleozoic, NE-Hungary

Frequently, at temperatures lower than the metamorphic peak conditions, slates undergo mineral transformations, usually mediated by fluids. We have studied core material of an epizonal slate series (Szendr? Mountains, NE-Hungary) to reconstruct the post-metamorphic lower-T hydrothermal alterations using petrographic, X-ray diffraction, electron microprobe methods, and transmission electron microscopy. The borehole crosscuts an upper part of the ca. 600?C800?m Lower-Carboniferous flysch-like Szendr? Phyllite Formation. The samples were metamorphosed reaching epizonal conditions with a mineral assemblage characterized by quartz, muscovite, chlorite and albite. Even in the freshest samples, break-up and loosening of the regional metamorphic structure was observed, with cracks parallel to or crossing the cleavage. In the upper part, chlorite and albite are almost absent, while the presence of paragonite, mixed Na?CK mica, and mixed-layered minerals with smectitic component are characteristic. Goethite, halloysite, and subordinate kaolinite are present in the most altered sample (13.0?m in the profile) which may indicate the position of the fissures in which the circulation of the post-metamorphic fluids was the most intense. Muscovite is the only mica from the lower part of the profile and chlorite becomes a significant constituent, whereas paragonite, halloysite, and kaolinite are missing. Discrete smectite is present in all the samples in spite of being incompatible with the prograde evolution of the sequence. The interleaved smectite layers in chlorite and muscovite/chlorite mixed-layers show at the lattice level textural characteristics indicative of a later alteration process. After the metamorphic peak at epizonal conditions, the introduction of hot fluids through the fractures gave rise to the crystallization of Na?CK white micas and muscovite/chlorite under anchizonal conditions. In a final stage of the hydrothermal process, the cooling of the circulating fluids favored the formation of halloysite and kaolinite in the areas near to the fissures, smectites in the samples far away from the fractures, and locally, goethite. The Fe₂O₃ content increasing upwards indicates oxidizing conditions in the late stage of hydrothermal activity and/or eventually, an influence of a younger near-surface weathering.     

Geochemistry, Petrogenesis and Geodynamic Relationships of Miocene Calc-alkaline Volcanic Rocks in the Western Carpathian Arc, Eastern Central Europe

We report major and trace element abundances and Sr, Nd andPb isotopic data for Miocene (16·5–11 Ma) calc-alkalinevolcanic rocks from the western segment of the Carpathian arc.This volcanic suite consists mostly of andesites and dacites;basalts and basaltic andesites as well as rhyolites are rareand occur only at a late stage. Amphibole fractionation bothat high and low pressure played a significant role in magmaticdifferentiation, accompanied by high-pressure garnet fractionationduring the early stages. Sr–Nd–Pb isotopic dataindicate a major role for crustal materials in the petrogenesisof the magmas. The parental mafic magmas could have been generatedfrom an enriched mid-ocean ridge basalt (E-MORB)-type mantlesource, previously metasomatized by fluids derived from subductedsediment. Initially, the mafic magmas ponded beneath the thickcontinental crust and initiated melting in the lower crust.Mixing of mafic magmas with silicic melts from metasedimentarylower crust resulted in relatively Al-rich hybrid dacitic magmas,from which almandine could crystallize at high pressure. Theamount of crustal involvement in the petrogenesis of the magmasdecreased with time as the continental crust thinned. A strikingchange of mantle source occurred at about 13 Ma. The basalticmagmas generated during the later stages of the calc-alkalinemagmatism were derived from a more enriched mantle source, akinto FOZO. An upwelling mantle plume is unlikely to be presentin this area; therefore this mantle component probably residesin the heterogeneous upper mantle. Following the calc-alkalinemagmatism, alkaline mafic magmas erupted that were also generatedfrom an enriched asthenospheric source. We propose that bothtypes of magmatism were related in some way to lithosphericextension of the Pannonian Basin and that subduction playedonly an indirect role in generation of the calc-alkaline magmatism.The calc-alkaline magmas were formed during the peak phase ofextension by melting of metasomatized, enriched lithosphericmantle and were contaminated by various crustal materials, whereasthe alkaline mafic magmas were generated during the post-extensionalstage by low-degree melting of the shallow asthenosphere. Thewestern Carpathian volcanic areas provide an example of long-lastingmagmatism in which magma compositions changed continuously inresponse to changing geodynamic setting. KEY WORDS: Carpathian–Pannonian region; calc-alkaline magmatism; Sr, Nd and Pb isotopes; subduction; lithospheric extension     

Active Longitudes in Close Binaries

We obtain a class of transformations between Brans–Dicke (BD) scalar field conformal factor of the metric and the Klein–Gordon (KG) wave (its amplitude and phase), such that the BD action described by conformaly flat (CF) metrics is reduced to the KG action. We then present a modified theory as a causal Bohmian quantum gravity by using the quantum potential back reaction effects on the Minkowski background spacetime. We also derive Hamilton–Jacobi equations of the modified theory which is useful for obtaining its de Broglie pilot wave.