Method for numerical computing of wave fields of sources in nonuniform media

Summary An effective method of computing wave fields is proposed. It is applicable in regions intermediate to a slowly varying (geometrical optics) and strongly nonuniform medium (full-wave solution).

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¶rt;azam mu m¶rt; ama n, nuu nm am ¶rt; ¶rt; (zmua nmua) u u ¶rt;¶rt; ¶rt; (n u).

     

Seismic events with non-shear component: II. Rock bursts with implosive source component

The rock burst mechanism of an implosive character is introduced and discussed; it is based on the idea that the compressional component of the stress field around the loaded stress concentrator can participate in the rock burst event. For easier classification of the rock burst from this viewpoint, a set of P-wave radiation patterns of the rock burst with a varying portion of the implosive component and varying propagation velocity of the displacements is presented and discussed. To support the credibility of the rock burst mechanism of an implosive character the seismic signals of the rock bursts from the mid-Bohemian coal district with negative signs of the P-wave first onsets are presented.     

Die Alpiden und die Kimmeriden: die verdoppelte Geschichte der Tethys: Reply

Ohne Zusammenfassung     

Seismotectonic model of the upper part of the Earth's crust of Czechoslovakia

Summary A correlation of the earthquake occurrence on the territory of Czechoslovakia and in its close neighbourhood with the data on the neotectonic and geomorphological development of the respective area, the recent movements of the Earth's crust, the courses of photolineations and on the geophysical fields enabled the fundamental structural blocks in the upper part of the Earth's crust to be singled out. The contact zones established between the above blocks exhibit increased long-term movement tendencies particularly in the Neoid period. A seismotectonic model of the upper part of the Earth's crust of Czechoslovakia, compiled with the use of the data mentioned above, is described.

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u m uu mu a mumuu auu u mmu ¶rt;au n mmu,uu, ¶rt;uu , u nmu u uuuu n nua ¶rt;um mm u amu . a a ¶rt; muu au a¶rt;am amau ¶rt; ¶rt;uu, u¶rt; nu¶rt;. m n¶rt;aaa mmua ¶rt; amu aa a au¶rt;uauu n, nu¶rt;u a ua mumuu, u a u u n¶rt;uu au.

     

Heat flow in the upper-silesian coal basin: Re-evaluation of data with special attention to the lithology

Summary The area of the Upper Silesian Coal Basin was characterized by generally high heat flow ranging from 60 to 120 mWm^–2, mean 82±16 mWm^–2, which has been difficult to explain. Therefore all published data on the heat flow in this region (n=37) were summarized and re-evaluated. Special attention was paid to the detailed assessment of the lithological structure and the contribution of the individual rock types to the characteristic in-situ thermal conductivity. Also the thermal conductivity of the coal bearing layers was estimated and its effect on the temperature-depth distribution was investigated. The application of the data obtained for the representative thermal conductivity profiles of the whole drilled section considerably reduced the mean heat flow to 70±8 mWm^–2. The latter value is fully compatible with the tectonic structure of the northern part of the Carpathian Frontal Foredeep. Slightly increased geothermal activity compared with the heat flow field of the adjacent part of the Bohemian Massif corresponds to certain deep geological rejuvenation during the creation of the Western Carpathians.

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a -uu aa aamum nu uuau mn nma (m 60 ¶rt; 120 m.^–2 nu ¶rt; 82±16 m. ^–2), m ¶rt;a ¶rt u. m u u nm a nua ¶rt;a mn nma (n=37) ¶rt; ¶rt;a ua. ua ¶rt; ¶rt;ma aau umuu aa u u mnn¶rt;mu in situ ¶rt; a¶rt; muna n¶rt;. a a mnn¶rt;m m, a ma, a ma u¶rt;aa an¶rt;u mnam nu. nau n mam ¶rt; nuau mnn¶rt;mu m u amu aa nu am uum ¶rt;u mn nm ¶rt; 70±8 m.^–2. a uua n mam mmu u amu anam a nua. m uumu amumu n au mn n nuaa amu aua mmmmuuau amuuauu nu uauu um ana¶rdt; anam.

     

Photo-electric compensating tiltmeter

Summary A new instrument has been designed for recording the horizontal components of tidal variations of the Earth's field of gravity and of tidal and non-tidal tilts of the Earth's crust. After justifying the use of the individual constructional elements, the functional model of the photo-electric compensating tiltmeter, constructing in the Geophysical Institute of the CSAS and installed at the tidal station in the Anna mine, Píbram, is described. Special attention is devoted to the sensitivity and recording azimuth of the tiltmeter and to the practical determination of these quantities. A high and constant sensitivity, the invariance of the recording azimuth and the possibility of simple automation of the whole evaluating procedure are the main advantages of the proposed instrument. In the conclusion some of the experience gained from test operations is discussed.     

Efficient estimates of points in a net constructed in stages

auau¶rt;u mu uam nua u mau a¶rt; ¶rt;a a au. a¶rt;a n¶rt;amm mau u mau, m mumu mu, a¶rt;a u aua n mana, nuam a man uu ¶rt;unuu aua ¶rt;uam (ma mum). u m umam mamumuu ma u a nma u u n¶rt;¶rt;u man. am ma au n¶rt; na ma¶rt;am n auau.     

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.     

A hundred years of Hungarian geographical society

The first phase of geographical literature in Hungary covers the period from the end of the 12th century to the beginning of the 19th century. The language used by writers of various nationalities was Latin. The body of literature which emerged included works in which geography was not the only subject, but appeared in association with history, astronomy, cosmology, or cartography. The second phase covers the period prior to the foundation of the Hungarian Geographical Society and was for a considerable time influenced by the spirit of nationalism. The 100 year history of the Hungarian Geographical Society may be classified into the following four periods, which correspond to generations: 1. Period of explorations. 2. Investigation of the regions of the country and enquiry into general questions of geography prior to World War 1. 3. Chauvinistic attitude following World War 1. 4. The development of Marxist geography in Hungary. In the paper special attention is given to problems of fluvial morphology and river control.     

Amplitude of a reflected wave in a horizontally stratified medium

Zusammenfassung Den Gegenstand der Arbeit bildet die Berechnung der Amplitudenkurve einer Reflexionswelle für ein bestimmtes gegebenes Medium anhand der Ersetzung dieses Mediums durch ein horizontal geschichtetes Medium mit einem einfachen Geschwindigkeitsgang in den Schichten. Die Amplitude wird nach der Nulln?herung der Strahlen-Theorie berechnet.

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