Temperature profiles in the earth of importance to deep electrical conductivity models

Deep in the Earth, the electrical conductivity of geological material is extremely dependent on temperature. The knowledge of temperature is thus essential for any interpretation of magnetotelluric data in projecting lithospheric structural models. The measured values of the terrestrial heat flow, radiogenic heat production and thermal conductivity of rocks allow the extrapolation of surface observations to a greater depth and the calculation of the temperature field within the lithosphere. Various methods of deep temperature calculations are presented and discussed. Characteristic geotherms are proposed for major tectonic provinces of Europe and it is shown that the existing temperatures on the crust-upper mantle boundary may vary in a broad interval of 350–1,000°C. The present work is completed with a survey of the temperature dependence of electrical conductivity for selected crustal and upper mantle rocks within the interval 200–1,000°C. It is shown how the knowledge of the temperature field can be used in the evaluation of the deep electrical conductivity pattern by converting the conductivity-versustemperature data into the conductivity-versus-depth data.     

Numerical modelling of time-harmonic seismic wave fields in simple structures by the gaussian beam method. part I

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To the infrared spectroscopy of natural uranyl phosphates

An interpretation based on site and factor symmetry analysis has been given of infrared spectra of the natural layered uranyl phosphates metaautunite, metatorbernite, metauranocircite I and II, saléeite and sabugalite, of the deuteroanalogues of metaautunite, metatorbernite and metauranocircite II and of the Raman spectrum of metatorbernite. The principal correlation relationships for the analysis of virbrational spectra G _M (symmetry of free ion) ? G _S (site symmetry) ? G _F (factor symmetry) have been described. The results have been correlated with data from X-ray structure analysis.     

Periodicity of annual precipitation in different climate regions of Croatia

Summary The periodicity of a 100-year series of annual precipitation over Croatia has been studied by means of power spectrum analysis at 3 stations representing the different climatic regions of Croatia. The annual precipitation variance spectra in the continental lowland (Osijek) and at the north East Adriatic coast (Crikvenica) can be fitted by Markov white noise continuum, but in the transitional region between the Dinaric Alps and the Pannonian lowland (Zagreb-Gri) a non-white noise continuum is necessary. Quasi-periodic oscillations appear in two spectra ranges: short (2.2 and 4.7 years) and medium (25.0 and 33.3 years). These results are compared with those of other authors for other parts of the Europe.With 2 Figures     

The transport system of Slovenia

The article presents the global and regional transport-geographic position of Slovenian territory, the role and importance of individual modes of transport, and degree of motorization and its spatial impact.     

Free-free opacity in strong magnetic fields

A way of computing the absorption cross-section for photons on electrons undergoing free-free transitions in magnetic plasma is described. Theoretical expressions for the free-free cross sections in magnetic plasma are given in a representation in which they can be easily compared with the classical results in the absence of the magnetic field. The results of numerical computations of these cross-sections are also presented and discussed. Finally the free-free cross-sections are averaged over the electron states in magnetic plasma in thermal equilibrium, yielding the opacity coefficient as a function of photons frequency. The results of numerical computations are given in graphical form.     

Magnetic arcades in stellar coronae I. Cylindrical geometry

X-ray spectroscopy performed by different astronomical spacecrafts has shown that many active late-type stars possess coronae. For such reason, the magnetic structure of stellar coronae has raised considerable interest and, by analogy with the Sun, it is generally assumed that stellar coronae are structured by magnetic fields having the shape of arcades. Most of those coronal magnetic field configurations assume translational symmetry and are based in planar source surfaces. However, as soon as either the length or the width of such source surfaces become non negligible as compared to the stellar radius, the application of the cylindrical geometry seems to be more appropriate. Then, one way of obtaining coronal magnetic configurations is to deal with source domains extended over a cylindrical surface. In this paper we generate potential coronal arcades based on cylindrical source surfaces with non negligible length or width compared to the stellar radius. The flux function, the magnetic field components, the shape of magnetic field lines and other characteristic magnitudes have been obtained and analyzed for both cases. This revised version was published online in July 2006 with corrections to the Cover Date.     

CONTRIBUTION TO THE TRACER KINETICS THEORY

Abstract

This paper presents a new integrated GIS modelling methodology for assessing groundwater contamination risk. Analytical and numerical tools within a GIS framework were used to define the raster maps of various factors interfering along the contaminant pathway from source to groundwater. In the proposed methodology, these factors were introduced into a unified GIS model for groundwater risk assessment that incorporates all the necessary information to improve the accuracy of the results. Fifteen factors were considered in order to estimate the spatial distribution of the groundwater contamination risk areas. Some of these factors, such as artificial drainage and seepage velocity, had not been used previously in GIS groundwater risk mapping. The study area, the island of Crete in Greece, was divided into five regions characterized by different degrees of groundwater risk ranging from very low to very high. A sensitivity analysis was performed and the developed methodology was validated for different contaminants that were detected in groundwater of the island of Crete.

Editor Z.W. Kundzewicz