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A partially molten buchite xenolith containing quartz, glass, mullite/sillimanite, corundum, Al-rich orthopyroxene, spinel, Mg-Al-bearing Fe-Ti oxides, ilmenite and rutile was found in the basaltic tuff of Szigliget (Balaton Highlands, Hungary). The pre-existing rock may have been a quartz-rich micaschist or phyllite from the wall of the magma vent. Minerals like mullite, Al-mullite and Al-rich orthopyroxene with Al2O3 between 7.62 to 11.54 wt% show ultrahigh-temperature (UHT) metamorphism of the xenolith with temperatures in excess of 1080 °C, which means that the temperature of metamorphism approached that of the enclosing alkaline basaltic melt. CO2 fluid inclusions with homogenization temperatures between +26.5 and +29.7 °C and mineral equilibria indicate pressure of buchitization between 310 and 390 MPa.  Glass compositions are similar to a peraluminous leucogranite which is in accordance with melting experiments when metagreywackes, pelites and orthogneisses are involved. The presence of glass suggests that the duration of the heating process was not long enough to extract the melt from the rock and admix it with the alkaline basaltic melt.  

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The uncertainty in the semivariogram has hardly been investigated in previous geostatistical studies. This paper presents an efficient methodology of uncertainty assessment based on the bootstrap. By applying this computer-intensive statistical method one can easily simulate the distribution of the empirical semivariogram estimate for each lag. The lag-wise standard errors and confidence intervals of a given level can then be easily calculated from the bootstrap replicates. These estimations are valid in any situation when classical statistics fail. The bootstrap also provides a mathematical-statistical tool to decide whether the semivariogram reaches its maximum at a given lag or not. It leads directly to a simple determination of the range of influence. Effects beyond the range, such as the hole effect, can be explored with the same approach. The empirical semivariogram, supplied by measures of uncertainty, adequately describes the true spatial behavior of the studied variable. This universal method renders the customary theoretical semivariogram models obsolete.

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An "unknown Ni-Al hydrosilicate" was found in the karstic nickel deposits in the localities Ba and Takovo in Serbia, and Aghios Ioannis in Greece. It occurs in fine-grained bluish-green and green aggregates with takovite and hydrated halloysite. It is an epigenetic product in the karstic nickel deposit. X-ray powder diffraction (XRPD) data are indexed with a monoclinic unit cell, a = 8.524 (4), b = 7.490 (3), c = 24.214 (6) Å, b = 104.55 (6)°, V = 1545.9 Å3. The thermal study has shown a characteristic dehydroxylation effect at 450 °C, which distinguishes this mineral from takovite and halloysite. The infra-red technique is very sensitive for the detection of the "unknown Ni-Al hydrosilicate": an absorption band between 1250 cm-1 and 1270 cm-1 is very characteristic for this mineral. From chemical analyses of the admixture of this mineral and hydrated halloysite in different proportions from the Aghios Ioannis deposit in Greece, after removal of impurities, the calculated formula is close to Ni2.00 Al2.00 (Si1.93 Al0.07) on the basis of 12 (O,OH).

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K-Ar age data from minerals (white mica, amphibole, biotite, and feldspar) in metamorphic rocks and pegmatite indicate Variscan metamorphic and magmatic events in the Zemplin Unit. The rocks hosting these minerals are amphibolite, gneiss, micaschist, and pegmatite. This is the first report on the occurrence of pegmatite from this unit, which indicates a Variscan age (≯ 307.9 ± 12.0 Ma) for igneous activity. Amphibolite facies metamorphism is dated based on K-Ar measurement of amphibole from amphibolite that gave age of 338 Ma. K-Ar ages of muscovite and of some amphiboles depend on the degree of mylonitization of the host micaschists and amphibolite, and range from 284.8 ± Ma to 211 ± 9 Ma. Ar/Ar spectrum on a white mica of 227 Ma K-Ar age yielded a ca. 300 Ma plateau-like age and indicates a younger, most likely Alpine overprint. Cretaceous ages of 105 ± 4.2 Ma and 126.6 ± 5.2 Ma were obtained from plagioclase and from white mica concentrate (< 2µm fraction) from strongly mylonitized amphibolite. This suggests that most K/Ar ages between the Variscan and Alpine orogenies (284-211 Ma) are geologically meaningless mixed values. The data support the interpretation of Variscan amphibolite facies metamorphism ≯ 338 Ma with subsequent magmatism ≯ 307.9 Ma) followed by Alpine overprint (126-105 Ma).

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A deterministic analytical procedure for ground motion modelling, combining both modal summation and mode coupling techniques has been implemented to obtain synthetic seismic signals at Russe, NE Bulgaria, due to  one of the strongest Vrancea intermediate-depth earthquakes, which occurred during the last century, May  30, 1990. The frequency content of the synthetic signals in different frequency ranges, up to 1 and 2 Hz, has been studied separately. The results of this study, i.e. time histories and related ground motions parameters, can be used for different earthquake engineering analyses, e.g. structural performance assessments.

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U/Pb data on single zircons from acidic volcanics are presented from the Kékkút-4 borehole, Balaton Highland, Transdanubian Central Range, Pelso Mega-Unit. Generally accepted as Lower Permian in age, they were also considered - due to some metamorphic features - to belong to the metamorphic, Lower Paleozoic basement. Clear, elongated crystals of these thick, acidic volcanics are regarded as co-genetic magmatic products, supplying a U/Pb age of 291.4±4.7 Ma (Lower Permian), representing the first radiometric magmatic age-dating of Upper Paleozoic acidic volcanism in this tectonic unit.

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At the northeastern part of Transdanubia, connected to the karst-water system of the Gerecse Mts, travertine pools were formed in several localities, at different times and at various altitudes. Quarrying of the travertine is documented since the Bronze Age. The hand-operated quarries are known to have also functioned during the Middle Ages. Several relics of architecture and sculpture from the Roman province of Pannonia and Medieval Hungary were made of this material, specifically from the quarries of the study area. Exploitation of the limestone opened the large, vertically-walled pools preserving the settlements of Paleolithic people in the loose sediments and the travertine cover: at Vértesszõlõs, remains of Homo erectus, and at Tata, habitations of Homo sapiens neanderthalensis were found in the travertine. Collaboration between geoscientists and archeologists could, apart from identifying the sources of worked travertine, also result in the discovery of new archeological sites.

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In Hungary there are borehole tiltmeters used for monitoring tectonic movements and landslides. These investigations need long time continuous measurements. The Model 722A tiltmeters of Applied Geomechanics Inc. are fastened to the ground by tamped sand in the borehole.  In some cases the boreholes become untight  and it was thought that in this case the ground water seeping into the borehole could loosen the tamped sand causing a bad coupling between the tiltmeter and the ground. It was proved by laboratory test that the ground water and the variation of its level does not change the coupling of the instrument to the ground. In this paper the description of the test made at the Geodetic and Geophysical Research Institute of the Hungarian Academy of Sciences and the results of the measurements are given.

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Authors: K. I. Kis, P. T. Taylor, G. Wittmann, H. R. Kim, B. Toronyi and T. Mayer-Gürr

To solve a geophysical inverse problem means applying measurements to determine the parameters of the selected model. The inverse problem is formulated as the Bayesian inference. The Gaussian probability density functions are applied in the Bayes's equation. The CHAMP satellite gravity data are determined at the altitude of 400 km altitude over the South part of the Pannonian Basin. The model of interpretation is the right vertical cylinder. The parameters of the model are obtained from the minimum problem solved by the Simplex method.

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W Schröder ed.: The Einstein Century of Physics - The First Quarter (Collected papers by Hans-Jürgen Treder), Beitr. Gesch. Physik u. kosm. Physik, Science Ed., Bremen, Vol.\ 5, 2001, 52 pp; W Schröder ed.: Solar Variability and Geomagnetism. Beitr. Gesch. Geophysik u. kosm. Physik, Science Edition, Bremen/Potsdam, Vol. 3, No. 2, (and IAGA IDCH Newsletter, No. 44) 2002, 300 pp; W. Schröder ed.: Alte und neue Probleme der Physik und Geophysik. Beitr. Gesch. Geophysik u. kosm. Physik, Science Edition, Bremen/Potsdam, Vol. 4, No.1, (and IAGA IDCH Newsletter, No. 46), 2003, 160 pp; W. Schröder ed.: Leuchtende Nachtwolken/Noctilucent clouds. Beitr. Gesch. Geophysik u. kosm. Physik, Arbeitskreis Gesch. Geoph. u. kosm. Physik, Science Edition, Vol. 4, No. 2, 2003, 182 pp; W. Schröder ed.: Das Polarlicht (Hermann Fritz und die Polarlichtforschung)/The Aurora Borealis (Hermann Fritz and the Foundation of Auroral Research). Beitr. Gesch. Geophysik u. kosm. Physik,  Arbeitskreis Gesch. Geoph. u. kosm. Physik, Science Edition, Vol. 5, No. 1, 2004, 60 pp;

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Authors: L. Bányai and J. Verő

B. Hofmann-Wellenhof, K. Legat, M. Wieser: Navigation. Principles of Positioning and Guidance. Springer-Verlag, Wien, New York, 2003, 427 pages, 99 figs; W. Schröder ed.: Zur Entstehung der solar-terrestrischen Physik/Some aspects of the earlier history of solar-terrestrial physics. Beitrage zur Geschichte der Geophysik und kosmischen Physik, Vol. 5, No. 3., Science Edition, 2004, pp. 150

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In this paper, results of a bulk-rock geochemical study of silty and albitic claystone samples selected from the Upper Permian Boda Siltstone Formation (BSF) in the western part of the Mecsek Mountains (Tisza Mega-unit, Hungary) are presented. The high Na2O and P2O5 contents, relative to the post-Archean Australian average shale (PAAS) and the average Russian Paleozoic shale compositions, are the most striking features of the geochemistry of the Boda sediments. The samples studied are depleted in SiO2, TiO2 and Al2O3, and they are enriched in Fe2O3, MgO, CaO and K2O relative to the PAAS. The major element relations clearly show that the geochemistry of the BSF is strongly affected by post-depositional modification, corresponding to large-scale dispersal or addition of components. On the other hand, relatively high La content, low concentrations of V, Cr, Cu and Ni, and the result of the TiO2 versus Ni plot reflect a relatively felsic provenance of the BSF. By comparison with detrital mineralogy of the heteropic Cserdi alluvial fan system deposits, the authors assume that the Boda playa lake deposits had a similar immature primary composition consisting of quartz, plagioclase, K-feldspar, muscovite, biotite, chlorite and clay minerals. During weathering and transport in a semi-arid to arid climate, detrital mafic minerals were altered to yield chlorite and clay minerals plus Fe and Mg, and trace metals in solution. Mg was built into the structure of chlorite and of secondary carbonates such as dolomite and Mg-rich calcite. Based on previous geochemical studies, the BSF contains particularly sodic sedimentary rocks (up to 8 wt%) which may represent an addition of sodium in authigenic silicates from alkaline brine and/or evaporites in the playa deposits. In claystone, after albite formed, Na-depleted, Ca, K-enriched waters reacted with the clay minerals such as smectite and kaolinite to yield K-rich illitic sediments, Ca precipitated in calcite cement. P2O5 is enriched in some samples due to phosphorus mobilization during diagenesis.

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In the paper a combined inversion algorithm solving the nonlinear geophysical well-logging inverse problem is presented. We apply a successive combination of a float-encoded Genetic Algorithm as a global optimization method and the well-known linearized Marquardt algorithm forming a fast inversion procedure. The technique is able to decrease the CPU run time at least one order of magnitude compared to the Genetic Algorithm and gives the parameter estimation errors having a few linearized optimization steps at the end of the iteration process. We use depth-dependent tool response equations to invert all the data of a greater depth-interval jointly in order to determine petrophysical parameters of homogeneous or inhomogeneous layers in one inversion procedure. The so-called interval inversion method gives more accurate and reliable estimation for the petrophysical model parameters than the conventional point by point inversion methods. It also enables us to determine the layer-thicknesses that can not be extracted from the data set by means of conventional inversion techniques. We test the combined interval inversion method on synthetic data, and employ it to the interpretation of well logs measured in a Hungarian hydrocarbon exploratory borehole.

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Current density pseudosections derived by filtering and probability tomography from calculated VLF vertical magnetic profiles over synthetic 2D targets with geometrical shape are examined critically. It was found that the position and shape of  target only in the case of single inhomogeneities with very limited cross-sectional area and simple shape can be revealed reliably by them. The locations of sharp cross-sectional boundaries can only be guessed. Fictitious, misleading current-density indications occur in the case of laterally extended, or multiple targets at too wide filter windows. Both procedures suppose that the measured values originate in the superposition of the magnetic fields of individual stationary current-lines inside the target. It is shown that in the quasistationary range the shape and position of the target can be outlined sharply using this simplified form of the forward problem solution and performing an inversion with respect of the vertices of the polygon approximating the cross-sectional contour of the target. Several kinds of inversionprocedures  were tested.

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The multiquadratic interpolation method by Hardy originally was created for the construction of surfaces from scattered data. The method, however, can also be used to advantage for the interpolation of two-dimensional curves, especially of closed ones.

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Three Internal Dinaridic tectonostratigraphic units are included in the PANCARDI domain; 1) the Bosnian Flysch, composed of the Liassic to Berriasian Vranduk Subgroup and the Albian to Maastrichtian Ugar Subgroup, originating on the passive Tethyan margin, 2) the Dinaride Ophiolite Zone, made up of the Radiolarite Formation, ophiolite included within the Jurassic olistostrome mélange, and a Cretaceous overstep sequence, partly with Urgon-type(?) signatures, and 3) the Sava-Vardar Zone, composed of Cretaceous-Early Paleogene flysch, locally with subduction-related basalt-rhyolites, a Paleogene, very low to medium-grade metamorphic sequence originating from the Cretaceous-Paleogene flysch, Paleogene tectonized ophiolite mélange, Eocene syncollisional granitoid occurrences and Oligocene postcollisional ones, accompanied by coeval shoshonite and andesite. All these formations occur as allochthonous blocks within two segments of the southern and western Pannonian Basin. 1) In the adjoining Tisia-Dinarides segment, the Sava-Vardar Zone lithologies occur both at the surface and in the subsurface of the Pannonian Basin, as the result of postorogenic Dinarides-Tisia interaction. Those located in the basement were uplifted during the Oligocene wrench faulting, which controlled the initial development of the Sava and Drava depressions. Those found at the surface were emplaced during the Pliocene phase of strike-slip faulting. 2) More common are Internal Dinaridic fragments sandwiched within the Alps-Dinarides-Tisia (e.g. Carpathians) triple junction area, e.g. the Zagorje-Bükk-Meliata Zone. In its southwestern Sava Subzone occur fragments of the Bosnian Flysch Zone and Sava-Vardar Zone, represented by a Paleogene tectonized ophiolite mélange, Cretaceous-Paleogene flysch and postcollisional andesite-shoshonite. The northeastern Bükk-Meliata Subzone is composed of a Jurassic ophiolite mélange correlative to the Dinaride Ophiolite Zone, which in its Slovakian part is thrust by Triassic, mainly carbonate formations. The accompanying Mónosbél Flysch can be correlated with the Vranduk Subgroup of the Bosnian Flysch. The displacement of the Internal Dinaridic formations can only partly be explained by Tertiary escape (extrusion) tectonics.

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Three shallowing upward and one deepening upward depositional cycles were described from the Upper Julian to Lower Tuvalian (Carnian) Sándorhegy Limestone Formation from the Balatonhenye – Barnag area. Lithological and microfacies characteristics of the depositional cycles suggest contemporaneous platform and basin sedimentation. Coarsening upward feature is certainly characteristic for Cycle I, yet progradation is doubtful. Cycle II represents platform sedimentation consisting of calcareous peritidal unit that progrades into the adjacent basin. Coeval deeper water sediments were mixed showing a coarsening upward trend from terrigenous mudstones to calcareous wacke-packstones (slope sediments) and grainstones (shoals). These cycles are asymmetric and were driven only by eustatic sea-level changes. Cycle IIIa, developed only in the basin, shows a gradual deepening upward trend. The laterally equivalent cycle on the platform is confined to an erosional hiatus. Tectonic subsidence along with eustatic sea-level rise may controlled the deposition of IIIa. We propose that tectonism may have been one of the plausible causes for the cessation and the following erosion of the Ederics Platform. Consequently, recolonization couldn't take place during the subsequent eustatic sea-level rise thus the source of IIIb prograding carbonate unit shifted to the Sédvölgy Platform.

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The aim of the present work is to deduce the tectonic structure of the area and to show the role of the separation methods in the resolution of the multisource of magnetic and gravity implications. The aeromagnetic total intensity map was transformed to the reduced pole aeromagnetic map (RTP). This step was followed by linear wavelength filtering of the RTP aeromagnetic map, and of the Bouguer anomaly map, in order to isolate shallower residual components using different grid intervals. A comparative analysis was carried out for the different filtered RTP aeromagnetic and gravity maps. Statistical trend analysis was applied for the magnetic and gravity data. The study revealed that the area has been affected by three significant tectonic trends, namely: NE-SW, NW-SE and E-W. The RTP aeromagnetic map and Bouguer anomaly maps provided detailed data for 2D modeling of the source. The magnetic and gravity cross section indicates possible sources of the observed anomalies. Only depth of the anomaly sources (mostly in the basement) were determined from magnetic and gravity data to reveal a tectonic zone and structure which leads to a fluid migration. The result of depth estimation to the basement complex revealed that the depth of the basement ranges between 3.2 km and 4.3 km.

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In the 20th century more than 60000 torsion balance measurements were made in Hungary. At present efforts are made to rescue the historical torsion balance data; today 24544 torsion balance measurements are available for further processing in computer database. Previously only the horizontal gradients of gravity were used by geophysicists, but there is a good possibility in geodesy to interpolate deflections of the vertical, and to compute geoid heights from curvature gradients of gravity. First the theory of the interpolation method is discussed, than results of test computations are presented. We have selected a test area where all kinds of torsion balance measurements are available at 249 points. There were 3 astrogeodetic points providing initial data for the interpolation, and 10 checkpoints for controlling the results. The size of our test area is about 750 km2 and the average site distance of torsion balance data is 1.5-2 km. The standard deviations of geoid height and deflection of the vertical differences at checkpoints were about ±1-3 cm, and ± 0.6'' respectively; which confirm that torsion balance measurements give possibility to compute very precise deflections of the vertical and local geoid heights at least for flat areas.

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The Brovar's condition of minimizing the Earth's anomalous gravity field focused to the determination of the parameters of the Earth's mean ellipsoid has been discussed and applied in two modified and simplified versions. The condition ?dS 0 S 0 T2 = minimum has been applied over the world ocean area S0 with the use of TOPEX/POSEIDON altimetry and mean sea surface topography height data. The semimajor axis of the Earth's mean ellipsoid has been  determined as a = (6 378 135.1 ± 1.5)m.

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From a letter by Leonhard Euler some speculations on the height of auroas in the atmosphere can be derived.

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The seismicity and seismic hazard of the Carpathian Basin are studied in this paper based on a recent comprehensive database cataloging over 20 thousands earthquakes between 456 and 1995. The epicentre distributions of these events indicate the geographical positions of the most active tectonic processes in the region. Among them the south-eastern bend of the Carpathians (Háromszék-Vrancea zone, Romania) and the area of south-eastern Alps have the highest seismic activity. The former source area is very specific by its strong seismicity from the intermediate depth domain (70-170 km). The intermediate-depth sources are deepening nearly vertically but in somewhat SW direction and the separation of the crustal earthquakes from the events connected to the lithospheric plate subsiding into the astenosphere is well observed at about 50 km, which is the depth of the Mohorovičić discontinuity (MOHO) in this region. The lithospheric plate subsiding to the depth of 150-200 km is supposed to be disconnected around 50 km. Some weakness of this slab can also be assumable based on the lower seismic activity observed between 100-120 km.

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Based on a complete dataset of the average magnitude M, the recurrence curve predicts an earthquake of magnitude M = 5 every one year, an earthquake of magnitude M = 6  every ten years, and an earthquake of magnitude M = 7 every one hundred years in the Carpathian Basin on average. The curve of elastic energy release of earthquakes does not indicate any noticeable periodicity in the Carpathian Basin based on the observations of nearly 500 years (1500- 1995). The average yearly energy release is 6.1E+13 joule in the whole Basin and the contribution of the Háromszék-Vrancea region to this amount is 4.8E+13 joule/year, while 1.3E+13 joule/year is the product of the remaining large part of the studied area. That is the vast portion of seismic energy is released in an area of only about 6% of the whole Carpathian Basin. According to the results of probabilistic seismic hazard estimations the highest hazard is expected in the region of Háromszék-Vrancea (Romania), where the expected peak horizontal ground accelerations 0.30g, 0.38g and 0.48g respectively will not be exceeded with 75% probability during 50, 100 and 250 years using s=0.5 value in the attenuation.

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The tendency of the relative effectiveness of the surplus error method is decreasing with decreasing N number of the applied surplus error sets but the value of diminishing is little for interval of small N-s: even if N = 9 is used the median of the relative increase of the accuracy amounts 39% in the investigated example.

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A Global Positioning System (GPS) permanent station has been established as a reference point at the Department of Civil Engineering of Indian Institute of Technology Bombay (IITB), by the IITB GPS group, and is continuously operating since January 2002. The station is being operated under a research project funded by the Department of Science and Technology (DST), Government of India, under the “National GPS Programme for Earthquake Studies”. A brief description of the station set up, the strategy used in determining its precise position, and some sample results are presented in this paper.

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New formulae based on the Sech-squared, Exponential and Chapman layers are introduced for a TEC-based electron density reconstruction technique using ionosonde and upper  ion transition level data. These analytical ionospheric models are implemented and tested as reconstruction tools with the help of satellite in-situ measurements of the ion  and electron densities. Particular attention is drawn to the calculation quality of the scale height in the upper ionosphere, from h mF2 up to the O+-H+ transition height.

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Two swarms of small earthquakes occurred on 22-24 October, 1995 and 13-18 September, 1996 about 15 km to the West-South-West (WSW) of the 1991 Uttarkashi earthquake (mb = 6.6) in Himalayas. The later swarm has migrated 5 km to the WSW of the former. Analyses of their seismicity rates, width of apertures and migration rates show that these swarms are triggered by a disturbance caused by the occurrence of the Uttarkashi earthquake thus triggered by this event. The disturbance, having slow propagation, rate represents evidence of creep of the earth material transferring stresses to the WSW direction. Occurrence  of creep (stable-slip) motion is supported by the inferred south-west (SW) orientation of compressive stresses in  Uttarkashi earthquake and presence of the north-west (NW) trending shear zones in the region. Ongoing convergence between India and Tibet would have provided the necessary tectonic forces transverse to the NW-SE trend of the Garhwal Himalayas indicating the future seismic activity of the region.

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The Pleistocene travertine of Buda Vár-hegy (Castle Hill) has been studied in subsurface galleries and cellars. Lithological variations, sedimentary features of the travertine and the underlying friable chalky carbonates and calcareous clays were described in the field. Four lithotypes and several microfacies types of travertine have been identified. The stratal pattern of travertine, distribution of lithotypes, the macrofauna, and the presence of microbial sediments suggests that the travertine was deposited in a shallow lake environment. The lake was fed by lukewarm springs from the central part (probably from Szentháromság-tér [Szentháromság Square] area), where the thickest travertine deposits are found. Direct evidence of cascade deposits or terraced tetarata deposits have not been found in the studied sections. The intense cementation and recrystallisation appear in the form of at least four, mostly phreatic, cement generations, including micrite envelopes, thin fibrous rims, thick radiaxial spars and pore occluding mosaics.

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Authors: János Haas, Kinga Hips, Pál Pelikán, Norbert Zajzon, Annette E. Götz and Edit Tardi-Filácz

The Permian/Triassic boundary was recognized in continuous marine successions in several outcrops in the Bükk Mts, North Hungary and in a few core sections in the northeastern part of the Transdanubian Range. In the Bükk Mts, of four studied boundary sections only two proved to be complete. They represent an outer ramp setting. In these sections the topmost Permian is made up of dark gray limestone, rich in fragments of crinoids, calcareous algae, mollusks, brachiopods, ostracods, and foraminifera. There is a dramatic decrease in the amount of the bioclasts in the last two limestone layers, which are overlain by a 1 m-thick shale bed. The lower two-thirds of this bed still contain Permian fauna but its upper part is almost free of bioclasts. The overlying platy limestone contains a pauperized fossil assemblage indicating stress conditions. The two core sections studied in the Transdanubian Range represent an inner ramp setting. The uppermost Permian is made up of lagoonal-sabkha cycles. It is overlain by subtidal packstone-grainstone, rich in Late Permian fossils. Oolitic facies characterizes the boundary interval. Onset of ooid formation was probably the consequence of biotic decline leading to cessation of skeletal carbonate production. Along with oolite beds, stromatolites, micrite with "microspheres" and fine siliciclastic microlayers characterize the basal Triassic succession, reflecting overall stress conditions and the changing energy of the depositional environment.

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As the variance (the square of the minimum L 2-norm, i.e., the square of the scatter) is one of the basic characteristics of the conventional statistics, it is of practical importance to know the errors of its determination for different parent distribution types. This statement is outstandingly valid for the geostatistics because the (h) variogram (called also as semi-variogram) is defined as the half variance of some quantity-difference (e.g. difference of ore concentrations) in function of the h dis- tance of the measuring points and this g (h)-curve plays a basic role in the classical geostatistics. If the scatter (s VAR) is chosen to characterize the determination uncertainties of the variance (denoted the latter by VAR), this can be easily calculate as the quotient A VAR= Ön (if the number n of the elements in the sample is large enough); for the so-called asymptotic scatter A VAR is known a simple formula (containing the fourth moment). The present paper shows that the AVAR has finite value unfortunately only for about a quarter of distribution types occurring in the earth sciences, it must be especially accentuate that A VAR has infinite value for that distribution type which most frequent occurs in the geostatistics. It is proven by the present paper that the law of large numbers is always fulfilled (i.e., the error always decreases if n increases) for the error-determinations if the semi-intersextile range is accepted (instead of the scatter); the single (quite natural) condition is the existence of the theoretical variance for the parent distribution. __

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In the Republic of Croatia there is a long tradition going on in carrying out systematic levelling works. These works have resulted, in the period of about 120 years, with the establishment of three fundamental levelling networks of geometric levelling. These are precise levelling network of the Austro-Hungarian Monarchy, I. levelling network of high accuracy and II. levelling network of high accuracy of former Yugoslavia. These networks are the basis of height system of the Republic of Croatia, and accompanied by adequate definitions of height datums they are used even today for solving fundamental and applied geodetic tasks and scientific researches.

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In Central Europe, Early Cretaceous alkaline igneous rocks (lamprophyres, basanites, phonolites) occur in the Moravian-Silesian Beskidy area (northern Czech Republic and southern Poland) and in the Mecsek-Alföld Zone (southern Hungary). Presently they are located at about 400 km distance of each other. These alkaline igneous rocks show close similarities in their mineral, chemical, and bulk rock compositional data, implying similar petrogenesis and suggesting that these two regions could have been much closer during the Early Cretaceous; they could belong to the same rift zone in the European continental margin. Their trace element distribution and Sr and Nd isotopic ratios suggest that the parental magmas derived from an enriched, HIMU OIB-like asthenospheric mantle by different degrees (3-6%) of partial melting at the depth of spinel-garnet transitional and garnet stabilization zone (about 60-80 km depth). This mantle source appears to be akin to that thought to have supplied the Tertiary to Quaternary alkaline mafic magmas in Europe (EAR=European Asthenospheric Reservoir). This may imply that this EAR-type mantle reservoir could have been present beneath Europe at least since the Early Cretaceous. It could reside at the base of the upper mantle (670 km discontinuity) supplying upwelling hot mantle fingers, or it may represent a long-lasting, polluted (HIMU+depleted MORB mantle) upper mantle at shallow depth beneath Europe.

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Distribution and partition of heavy metals (Cr, Co, Cu, Ni, Pb and Zn) in four forest soil profiles characterized by different parent materials and similar pedogenic processes were studied to distinguish the inherited characteristics from those caused by pedogenic processes in soils at natural background level of these metals. Distributions of total heavy metal amounts are determined mostly by the parent material, while the repartition of heavy metals among the soil components is regulated mainly by pedogenic effects. Heavy metals bound to residual phases are almost solely inherited from the parent material. Combined effects are the clay illuviation with different clay mineralogy due to the differences in parent material, as well as the calcareous subsoil resulting from inheritance and secondary carbonate precipitation. In the studied samples the organic matter plays the most decisive role in binding heavy metals. A significant proportion of lead is bound to it, but it also has an effect on copper and nickel repartition. Cobalt exhibits high affinity to Fe and Mn oxides, which is also characteristic of lead and zinc. The slight accumulation of zinc in the B horizon of soils suggests its relation to clay minerals.

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The Jakabhegy Sandstone Formation, known for a long time at surface in the western part of the Mecsek Mts, SE Transdanubia, was encountered by several boreholes in the second half of the 20th century in a large part of SE Transdanubia, during exploration for uranium ore in the Upper Permian formations in its subcrop. The formation is made up of five informal lithologic units, from the base upward the "main conglomerate", the "gravelly sandstone", the "pale sandstone" with "conglomerate 2" at its base, then the "red-brown siltstone and sandstone" and at the top the "variegated sandstone" (units "a, b, c, d, e"). Grain size becomes finer upsection, the grains are medium-rounded, and sorting generally improves upward. Planar cross-bedding of varying size is characteristic. The Jakabhegy Sandstone Formation occurs in two types of development. In the case of complete development, all the lithologic units are present, but the lower two ("a+b") do not overlap the Late Permian-Early Triassic Kővágószőlős Sandstone Formation. The case in which the formation is only built up of units "c+d+e" is called incomplete development. In both cases erosional unconformity and hiatus occur between the formation and its underlying unit, while showing continuous transition toward its cover, the Patacs Siltstone Formation. On the basis of the sedimentological features the main conglomerate and the gravelly sandstone ("a+b") were deposited in fluvial facies, "c" in wave-dominated, and "d" and "e" in tide-dominated delta facies. In the clast composition of the Jakabhegy Sandstone, the quartz predominates, the amount of K-feldspars is much smaller and plagioclase is almost completely absent. The rock debris is derived from metamorphic, acidic volcanic and plutonic rocks. According to the quartz/feldspar ratio, the most mature sandstone layers can be found in the central beds of unit "c" and appear in incomplete development at the base of the sequence, locally in quartz arenite quality. The fossil content of the Jakabhegy Sandstone consists almost exclusively of microflora found in the gray layers of the two upper units ("d+e"). According to the palynological investigation, unit "d" and the lower part of unit "e" represent the Spathian substage of the Olenekian stage, while the upper part of "e" already belongs to the Lower Anisian. Downsection, microflora-free red sediments are encountered down to the layers below the upper member of the underlying formation. In the microflora found in these lowest levels, Lower Triassic spores appear with dramatic suddenness and in remarkable quantity, alongside decrease in the amount of Upper Permian pollen.

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Earlier investigations of the inuence of geomagnetic activity on radio wave absorption were based on storm selection criterion: SKp ³ 30. This criterion lumped together weak, moderate, and strong storms, and favouring weak and moderate storms made it impossible for the investigations to detect any change in equatorial radio wave absorption following geomagnetic storms. Presently, the effect of geomagnetic storms on equatorial radio wave absorption has been investigated using severe storms (Ap ? 54) and HF absorption data obtained at 4.87 MHz at 1000 hours LT at Lagos (3. 40oE, 6. 55oN). The absorption data were measured using radio waves reected from the F region, and the transmitter (Radio Cotonou) is located at Cotonou (2.43oE, 6.35oN). The present results obtained using the superposed epoch method show that HF absorption in the equatorial ionosphere increases after severe geomagnetic activity.

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Authors: W. Schröder and K.-H. Wiederkehr

The development of geomagnetic research in the 19th century is discussed in detail. Beginning with the Göttingen Magnetic Society (Gauss-Weber), scientific activity developed under von Humboldt's influence and reached a peak during the First International Polar Year (1882--1883). This was a broad international co-operation,  for which new instruments were constructed and new aspects of the geomagnetic studies were opened, including solar-terrestrial physics (Sun -- aurora -- Earth's atmosphere).

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Authors: S. M. Stankov, I. S. Kutiev, N. Jakowski and A. Wehrenpfennig

The GPS-derived TEC has proved to be a robust characteristic representing well the state of the Earth's ionosphere-plasmasphere system during both quiet and disturbed geomagnetic conditions. Successfully forecasting the TEC value can prove invaluable when trying to improve the communications, navigation, and surveying practices. Presented is a new forecasting method based on  auto-correlation analysis and consisting of two major parts - first, extrapolation of the TEC monthly medians using Fourier series approximation, and second, geomagnetically-correlated forecast of the TEC relative deviations of from its median value. Preliminary tests show a good agreement between measured and predicted median values. Presented are also important investigations related to the short-term forecast.

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Loránd Eötvös' torsion balance yields the local structure of the earth's gravity field with very high precision, still comparable to present days standards. The recently launched NASA satellite mission GRACE and the approved ESA mission GOCE (launch in 2005) apply the same measurement principle in space. It counteracts the natural attenuation  with growing distance from the earth's surface of the gravitational attraction. As a consequence, even from space the global gravity field will be mapped with unprecedented resolution and accuracy. Also temporal variations due to mass changes in the atmosphere, oceans, ice covers, groundwater tables and inside the earth are expected to be discernible. Geodesy, solid earth physics, oceanography and sea level research will greatly benefit from the detailed knowledge of the earth's gravity field.

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Sequence of neural networks has been applied to high accuracy regression in 3D as data representation in form  z = f(x,y). The first term of this series of networks estimates the values of the dependent variable as it is usual, while the second term estimates the error of the first network, the third term estimates the error of the second network and so on. Assuming that the relative error of every network in this sequence is less than 100 %, the sum of the estimated values converges to the values to be estimated, therefore the estimation error can be reduced very significantly and effectively. To illustrate this method the geoid of Hungary was estimated via RBF type network. The computations were carried out with the symbolic - numeric integrated system Mathematica.

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Inversions of measurements of twelve Engineering Geophysical Penetration holes were done by the Weighted Least Squares method. The soil model was supposed consisting of sand, clay, water and air. The input error variances and the zone parameters were fixed by the feedback optimization method. The logs of the estimates of soil model parameters and their covariance matrix were determined. There are good correlations among the result logs along the profile. Paleo-soil layers can be recognized on the result logs.

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Every geophysical exploration method has non-uniqueness/ambiguity due to which interpretation is often misleading. If two or more data sets that deal with different physical properties are interpreted jointly then the combined study reduces the ambiguities in either method significantly. For layered structures magnetotelluric and seismic method provide information about the conductivities, velocities and thicknesses of the layers, where the thicknesses are the common parameters of seismic and magnetotelluric models. Assuming that the conductivity and velocity discontinuities are identical, the joint inversion of the two methods can improve the reliability of the estimation of thicknesses. In this paper on synthetic data will be shown, that the joint inversion yields better layer parameters, than the individual magnetotelluric or seismic inversions. The joint inversion decrease the effect of the equivalence, which at the magnetotelluric inversion often leads to misconclusion.  As inversion technique the simulated annealing and the linearized inversion will be used. In the present work, attempt is made to study the seismic refraction and magnetotelluric data to delineate reliable subsurface information.

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Auroras observed visually during the July 1959 series of events are studied in this paper. Detailed investigation shows that the aurora of July 15/16 1959 was observed in the Northern hemisphere down to a latitude of 33\degree N and in the Southern hemisphere to 28°S. Morphologically nearly all auroral forms were observed, even at mid-latitudes. The July events including the auroral displays, can be attributed to extraordinary solar eruptions (class 3+).

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In autumn of 1997 two borehole tiltmeters, type AppliedGeomechanics, A722 were installed for monitoring recentmovements of the Mecsekalja fault in Southwest Hungary. Beside the continuous tilt measurements a geodetic network for GPS and electronic distance measurements (EDM) and a levelling line crossing the fault were established. The borehole tiltmeters are continuously recording and the geodetic measurements (GPS, EDM, precision levelling) are repeated twice in a year, in spring and in autumn. This paper presents experiences and results of the tiltmeter measurements and analyses the disturbing effects e.g. earth tide, tilt caused by ground water level variations, precipitation of the surrounding vegetation, etc.  superposed to the tilt signal. The paper shows some of these effects which can use to prove the goodness of the coupling between the instrument and the ground.

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There is a good possibility tointerpolate a dense net of de ections of the vertical from Wgravity gradients measured by torsion balance and applying astronomical levelling to compute geoid heights. A new practical computation of astronomical levelling is suggested.

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Firstly the authors give an overview on the geological, geophysical and tectonical features of the Diósjenő  dislocation belt (or zone, according to some authors) around the river Ipoly near the Hungarian-Slovak border among great structural units: Vepor, Gemericum and formations of the Mid Hungarian Mts. The longest magnetic anomaly of the Pannonian Basin lies in this belt. It is assumed that it is due to ultrabasic magmatite of greenschist facies. The near-surface geoelectric soundings did not find any conductivity increase near Diósjenő  (western part of the zone), but there are graphitic micaschists in the boreholes around Szécsény. There is some earthquake activitiy in the region with hypothetical depth of 7-8 km. Two deep magnetotelluric (MT) profiles cross the dislocation zone. The resistivity distribution from the surface to the conductive asthenosphere along these profiles was obtained by using instruments, operating in two different period ranges. After processing the measured data by 1D/2D inversion, it became obvious that the dislocation zone includes electrically conducting roots at a depth of 7-11 km. This result hints at the presence of fluid in the broken rocks having increased porosity in the dislocation zone. Another component that can increase the conductivity could be the graphite (carbon) originating from the Paleozoic crystalline rocks of the Gemericum (or Vepor). The ductile phase (fluid/graphite) observed by high conductivity in the centre of the dislocation zone can play an important role in the generation of the earthquakes according to the most recent statements of the international literature.

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Kovács and Papšová (1986) described a Pelsonian conodont fauna from the base of the Misina Hill key geologic section (Mecsek Mts, South Hungary), extracted from the host-rock of a Schreyerites? binodosus specimen published by Detre (1973). In the present paper the conodont fauna of the entire key section is described on the basis of 26 samples (from No. Bh-1 to Bh-26). A detailed taxonomic review of Gondolella bulgarica, G. hanbulogi and G. bifurcata is given, which are distinguished at species level (following the detailed morphotaxonomic study by Germani 2000), although all morphological transitions between the three taxa are present. They are united into the "G. bulgarica Group". Correlated with the Pelsonian type sections in the Balaton Highland (Aszófo, Felsoörs), the entire exposed sections of the Bertalanhegy and Dömörkapu Limestone Members belong to the upper part of the Pelsonian, e.g. to the Binodosus Zone. The Illyrian evaporitic "Middle Muschelkalk" event appears to be represented by a hiatus in the Mecsek "Muschelkalk" succession.

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The conodont fauna published by Bóna (1976) from the Triassic of Villány Hills has been revised. It contains an association of Gondolella bifurcata, G. bulgarica and G. hanbulogi, the same as from coeval basinal deposits of the adjacent Mecsek Hills (Kovács and Rálisch-Felgenhauer, this volume), thus the Upper Pelsonian age assignment by Bóna (1976) is confirmed.

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Authors: Bernadett Bajnóczi, Ferenc Molnár, Katsuhiko Maeda and Et al.

Alunites from the low sulfidation-type epithermal systems of the Tokaj and the high sulfidation-type epithermal systems of the Velence Mountains were compared in terms of mineralogical and genetic aspects Na-enriched (1.14 to 2.35% Na2O) tabular alunites from the advanced argillic alteration zones of the Velence Mountains appear in the cavities formed from leached phenocrysts of andesitic rocks. These magmatic-hydrothermal alunites display compositional zoning due to variation in Na and K content and contain Ca-rich phosphate-sulfates with REE elements in their cores (i.e., woodhouseite series). The source of P is probably magmatic apatite that dissolved during intensive leaching of the host rock by acidic magmatic-hydrothermal fluids. Alunites in the steam-heated alteration zones of the Tokaj Mountains appear in the cavities formed from leached pumice fragments of rhyolite tuff units or in fractures in altered rhyolite domes. Rhombohedral and platy alunites have minor Na content (0.02 to 0.61%Na2O) and display compositional zoning due to the variation in Ba content. However, comb alunites contain more Na (1.55 to 1.82% Na2O) and compositional zoning can be attributed to variation of Na and K content. Alunites from the Velence Mountains have much higher d34S values (24.2 to 25.3‰) compared to alunites from the Tokaj Mountains (4.7 to 8.6‰). The d18O values for the sulfate site in the alunite structure are between 10.6 and 13.6‰ in both areas. High d34S values can be attributed to S isotope fractionation during the high temperature magmatic-hydrothermal formation of alunite from the Velence Mountains, which did not occur during formation of low-temperature steam-heated alunites from the Tokaj Mountains.

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The occurrence of Quaternary thrusting in Himalayas and its geodynamics constraints in Southern Tibet is modelled using stress simulation analysis. 2D non-linear elastic and homogeneous wedge models, representing cross-sections of the Himalayas and Tibet are used. Simulated stresses for a set of boundary conditions, representing building up of Himalayas and Southern Tibet, reveals the region of thrust failure gradually recedes away from the wedge towards the base (lower boundary) with a decrease in the strength of the base. Thus, the result favours the preposition that a strong and a weak basal (Main Himalayan Thrust; MHT) respectively, below Himalayas and Southern Tibet is responsible for presence and restricting the extension of Quaternary thrusting in these regions. A decrease in strength of MHT from the Himalayas to Tibet is also supported by observational evidence and thermal modelling, imply partial melting along MHT.

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Lake Balaton is the largest shallow-water lake in Central Europe. The main objective of the research on its Quaternary lacustrine sediments was to reconstruct the evolution of Lake Balaton from its formation until today. One of the key parameters in answering this question is to retrace lake-level changes. There is a lot of evidence, such as sedimentological, mineralogical, geochemical, archaeological, etc. to reveal these changes. Each type is of different reliability depending upon the sensitivity of the lake to level change and to preservation of the traces of those changes as a result of geologic, climatologic or human factors. The average thickness of Quaternary sediments accumulated in Lake Balaton is 5 m. From the lake bottom toward the surface lacustrine sediments are constituted by clastic deposits, peat and calcareous mud with upward-increasing carbonate content (calcite, dolomite, Mg-calcite, protodolomite and aragonite). Towards the end of Pleistocene, approximately 15,000-17,000 years BP, several shallow ponds with clean and cold water formed in the site of the present Lake Balaton. Inundation followed progressively from west to east. A warming climate and increasing precipitation brought about the rise of the water level. Moreover, abrasion progressively destroyed the dams separating the ponds and a uniform lake was formed. Later, as a function of changing climate the water level of the lake varied approximately between 103.0 and 108.0 m aASl. (above Adriatic Sea level). The average rate of total lacustrine sediment accumulation is 0.38 mm/year.

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A new quantitative paleobotanical method for the description of Quaternary organic sediments is presented. The Peat Component System, with the paleobotanical description of macroscopic organic material, allowed us to reconstruct the hydroseral succession. The modified "semi-quantitative quadrate and leaf-count macrofossil analysis technique" (QLCMA) was used to quantify the peat components. This quantitative plant macrofossil technique, together with pollen, mollusk, and radiocarbon analyses, was used to reconstruct the postglacial mire development of an eutrophic peat bog in S Hungary. The analysis of the Holocene peat sequence was used to reconstruct the development of a filling-up spillstream of the river Danube. Multiple cores made it possible to reconstruct vegetation development in space and time.

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Mid latitude spread-F has extensively studied recently as  compared to the earlier periods. In the course of these  investigations two concepts have appeared in the literature concerning the origin of the mid-latitude spread-F. The first concept based on radar measurements attributes the development of spread-F to plasma instabilities (Fukao et al.\ 1988), while according to the other concept based on the vertical incidence sounding of the ionosphere the occurrence of mid-latitude spread-F is related to travelling ionospheric disturbances (Bowman 1981). Therefore, it seemed worthy to study mid-latitude spread-F from the point of view of its origin. This study has been carried out by analysing the connection between  the occurrence of spread-F and the occurrence of sporadic E layers, keeping in mind that the development of sporadic E layers at mid-latitude is due to atmospheric gravity waves, which initiate plasma instabilities. On the other hand, the relation of the occurrence of spread-F to enhancements of the auroral electrojet index (AE) has been studied indicating the occurrence of large scale travelling ionospheric disturbances.

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This article reviews the development of the study of relationship between the earth's rotation and the spatio-temporal distribution of global seismicity by stationary model of seismicity rates and annual seismic energy released. Observed variations of seismic energy release in shallow, intermediate and deep focus earthquakes and their frequency distribution confirms this correlation. The peaks of these parameters are controlled by the earth rotation. There exists a phase relationship among earth's rotation rate minima and maxima with the maxima (peaks) of the above parameters as well as Thrust (T) and the strike slip (S) dominating periods of global seismicity. In order to compare our results with observations, the space-time dependence of the frequency of earthquakes and annual energy release has been established. The results are in very good agreement with previous studies and further enhance our knowledge for global seismicity distribution.

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Extracts from Otto Jesse's papers relating to twilight studies, noctilucent clouds and atmospheric movements are presented here to illustrate his contribution to the subject during the years 1884-1901. The most important result of his activity was the establishment of the Berlin “Atmospheric Programme” which included regular monitoring of noctilucent clouds by visual and photographic means. Furthermore, Jesse studied problems of dynamic processes in noctilucent clouds and in the corresponding upper atmospheric layers.

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Taking into consideration the Alps/Dinarides connection, the western part of the Zagorje-Mid-Transdanubian (or Sava) Zone (ZMTZ) in Slovenia, which is located between the Eastern and Southern Alps, includes disconnected outcrops of the northwesternmost Internal Dinaridic units. The northern part of the ZMTZ in Slovenia, which is close to the Periadriatic Lineament, is mainly composed of an Albian-Cenomanian to Late Cretaceous flysch sequence, underlain by Jurassic basinal sediments, which can be correlated to the Sava-Vardar Flysch. The outcrops are located in frontal parts of the Julian-Savinja Nappe. The southern part of the ZMTZ in Slovenia includes the Sava Nappe (or the Slovenian Trough), which is thrust upon the northern margin of the Adriatic-Dinaridic carbonate platform, e.g. the External Dinarides and Southern Alps, respectively. It is composed of Aptian to Cenomanian clastics and carbonates, disconformably overlain by Late Cretaceous carbonate flysch. It can be correlated to the Bosnian Fysch in the Central Dinarides. Both the Northern and Southern Zones can be followed westward up to Italian frontier. All presented data indicate a spatial connection between the northwesternmost Dinarides and the easternmost Alps during Alpine geodynamic evolution. Their apparent lack of connection in the present structure of the Dinarides and Alps is the result of the postorogenic indenting of Adria or of the African promontory, and related strike-slip faulting.

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Comments to papers on historical data and studies related to activity ingeomag-netism and aeronomy, collected over Croatian territory are presented. This way a general overview of historical development of these scientific branches in Croatia is obtained.

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At the Permian/Triassic boundary, terrestrial as well as marine life was seriously decimated. The drastic reduction was possibly due to a global event. In order to demonstrate this, sections at great distance from one another need to be correlated, which is a difficult task, especially between marine and land sections. One of the methods, which is independent of the environment, is magnetostratigraphic correlation. It was intended to apply this method for precise dating to Permian/Triassic boundary sections from the Bükk Mts, which include strata with high concentrations of magnetospherules. Since the Paleozoic-Mesozoic rocks of the Bükk Mts are anchimetamorphosed and intensively tectonized, it was decided to carry out a pilot paleomagnetic study on samples from two sections with different dips, before collecting a large number of samples for the intended magnetostratigraphy survey. The results of this study can be summarized as follows. The rocks of the sections possess remanences of pre-tilting age, and the magnetic fabric does not show any evidence of strong deformation. Nonetheless, the magnetization can not be primary since the measured inclinations are far too steep for the Permian/Triassic boundary. The estimated age of the acquisition of the paleomagnetic signal is Late Cretaceous. Although the results are negative in terms of magnetostratigraphy, they deserve attention from a tectonic point of view. The observations suggest that either the studied localities or the entire range of the Bükk Mts was involved in a post-Cretaceous (but pre-Miocene) counterclockwise rotation of about 40°

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