Geodetic aspects of seismological phenomena     

Peter Varga  Carlo Denis 《Journal of Geodesy》2010,84(2):107-121

Seismology is related to many problems of geodesy. The energy production of our planet is rather close to energy consumption of the Earth so that the energy balance can be disturbed significantly by minor processes acting on global scale. From this point of view the effect of tidal triggering of earthquakes is discussed by the study of tidal stress tensor components expressed in spherical system of coordinates. Tidal friction influences through the despinning of the axial rotation the geometrical flattening. This flattening variation causes stresses along the longitude and this phenomenon is closely related to the seismic energy release. Until now there is no unambiguous success to relate changes of the Earth orientation parameters with seismicity. Present-day accuracy of the length of day variations is not sufficient yet to detect spin variation generated by the greatest earthquakes. The polar motion is probably more sensitive to earthquakes and then there is a chance to detect the polar displacements generated by seismic events. In the last section of the present contribution, the strain rates derived from the static seismic moments and from space geodetic observations are compared. Future geodetic strain rate data will be useful in earthquake prediction.  相似文献   

Variations of the geomagnetic dipole magnitude over the past 400 My     

A. A. Schreider  Al. A. Schreider  P. Varga  C. Denis 《Oceanology》2008,48(2):250-254

The international bank of the virtual dipole moment data supplemented by the values from more recent publications is used as the basis for an analysis of the behavior of the virtual dipole moment values over the last 400 My. The results obtained revealed a positive linear trend from 4.1 × 10²² to 5.7 × 10²² A m² during the last 400 My. Against the background of the linear increase, fluctuations with a periodicity of about 40 My were observed. In the Phanerozoic time, minimums within the intervals of 340–370, 290–300, 240–270, 190–210, 165-140 (chrons M17-M43), 130-120 (chrons M2-M10), 100–110 (chron 34), 75–85 (chron C33 and the beginning of chron C34), 70-60 (chrons C31-C27), and 40-15 (chrons C18-C5AD) My B.P. are found. The distribution of the virtual dipole moment is strictly related to the distribution of the ancient geomagnetic field and may be taken into consideration when modeling the magnetization of the inversive magnetic layer of the ocean.  相似文献   

Distribution of relict permafrost features in the Pannonian Basin,Hungary     

Szabolcs Ákos Fábián  János Kovács  Gábor Varga  György Sipos  Zoltán Horváth  Edit Thamó‐Bozsó  Gábor Tóth 《Boreas: An International Journal of Quaternary Research》2014,43(3):722-732

Wedge structures and involutions suggest that Late Pleistocene frozen ground, either permafrost or deep seasonal frost, extended at least as far south as latitude 47°N in central Europe (the Pannonian Basin). Optically stimulated luminescence dating of the sand infill from a number of wedges indicates that emplacement of the sand infill occurred during the Late Pleistocene (22.2–15.7 ka). This suggests that during this time the mean annual air temperature was depressed by at least ～15°C relative to the present. Either continuous or discontinuous permafrost was probably present in the north and NW of the Pannonian Basin. The subsequent thaw of frozen ground is indicated by the widespread occurrence of deformed sediments. The presence of soil (ground) wedges suggests conditions of deep seasonal frost probably existed during the period when climate ameliorated following the Last Permafrost Maximum (LPM).  相似文献   

Variations of the Earth’s magnetic field in the Phanerozoic     

A. A. Schreider  Al. A. Schreider  P. Varga  C. Denis 《Oceanology》2011,51(3):506-510

The global VDM database, which was later supplemented by new determinations published in the world literature (a total of 3194 determinations), is used as the basis for addressing the VDM behavior in the Phanerozoic (0–542 Ma) and up to 580 Ma. The results revealed a positive linear trend to higher VDM values from 3.5 × l0²² Am² to 5.7 × l0²² Am². Against this background, fluctuations of the mean VDMs occur with a periodicity of about 40 Myr. In the Phanerozoic, prominent minima of the intensity are found in the time intervals of 510–520, 420–460, 340–370, 290–300, 240–270, 190–210, 165–140 Ma (chrons M17–M43), 130–120 Ma (chrons M2–M10), 100–110 Ma (chron C34), 75–85 Ma (chrons C33 and the beginning of chron C34), 70–60 Ma (chrons C31–C27), and 40–15 Ma (chrons C18–C5AD). The distribution of the VDMs appears to reflect the paleomagnetic field behavior and may be taken into account in a magnetization model for the reversely magnetized oceanic crust.  相似文献   

Study on the Chemical Character of Water Soluble Organic Compounds in Fine Atmospheric Aerosol at the Jungfraujoch   总被引：1，自引：0，他引：1  

Zoltán Krivácsy  András Gelencsér  Gyula Kiss  Ernő Mészáros  Ágnes Molnár  András Hoffer  Tamás Mészáros  Zsolt Sárvári  Dóra Temesi  Bálint Varga  Urs Baltensperger  Stephan Nyeki  Ernest Weingartner 《Journal of Atmospheric Chemistry》2001,39(3):235-259

In this study the chemical nature of the bulk of water soluble organic compounds in fine atmospheric aerosol collected during summer 1998 at the Jungfraujoch, Switzerland (3580 m asl) is characterised. The mass concentration of water soluble organic substances was similar to those of major inorganic ions, and the water soluble organic matter was found to be composed of two main fractions: (i) highly polyconjugated, acidic compounds with a varying degree of hydrophobicity and (ii) slightly polyconjugated, neutral and very hydrophilic compounds. The contribution of both fractions to the total water soluble organic carbon was about 50%. Separation into individual components was impossible either by HPLC or capillary electrophoresis which indicates the presence of a high number of chemically similar but not identical species. Results obtained by ultrafiltration and HPLC-MS have shown that the molecular weights are of the order of several hundreds. Most of the protonation constants for the acidic compounds determined by capillary electrophoresis were in the range 10⁴–10⁷.  相似文献   

Distortions of the electromagnetic field by shallow basins and by resistive outcrops     

A.   d  m  G. Varga 《Physics of the Earth and Planetary Interiors》1990,60(1-4):80-88

The interpretation of magnetotelluric (MT) measurements carried out on shallow (several hundred metres deep) basins and on the surrounding highly resistive rock outcrops can be difficult due to different forms of distortion, mainly 3D effects. A good example for study of this problem is the Mór Graben, which is the transition zone between the Bakony and Vértes Mountains (W-Hungary), where more than 20 MT soundings have been made with stations spaced about 2 km apart to determine the structure of a conductivity anomaly at a depth of about 3–4 km.

The statistical treatment of the different distortions due to varying sediment cover (the S-effect or static shift) and to the steep wall of the resistive basement outcrops (edge effect), etc., enabled the estimation of the actual parameters of the conductive formation. The interpretation of the field data is supported by numerical modelling.  相似文献   

Despinning of the earth rotation in the geological past and geomagnetic paleointensities     

C. Denis  A. A. Schreider  P. Varga  J. Zvoti 《Journal of Geodynamics》2002,34(5)

Length of day (l.o.d.) values deduced from fossils and tidal deposits suggest that the despinning rate was, on the average, about 5 times smaller during the Proterozoic than during the Phanerozoic and, moreover, that between 250 and 100 million years ago, there was a slight non-linear variation super-imposed on the overall linear trend of the Earth's rotation rate. To explain these observational facts, it has recently been argued that formation of the inner structure of the Earth (mass redistribution within the mantle and/or core formation) had not been fully completed before the Proterozoic, and that the decrease of the inertia moment associated with the evolving terrestrial interior compensated to some extent the rotational effects of tidal friction. There is an another plausible explanation to account for the difference of despinning rates during the Proterozoic and Phanerozoic, namely: the distribution of the continents had been significantly different during these epochs and the world ocean had been much shallower in the Proterozoic than in the Phanerozoic. We used published data for the Phanerozoic, Proterozoic and Archean in order to check whether there had been significant long-term changes of geomagnetic intensity. Our results are based on robust statistical analysis; they indicate that during a time interval coinciding roughly with the Mesozoic, the geomagnetic dipole moment underwent a minimum in a quite similar way as the l.o.d. data. For the Proterozoic (2500–570 million years ago) and the late Archean (3000–2500 million years ago), it is very difficult to draw a conclusion concerning the variation in time of the intensity of the geomagnetic field: the data set we used is incomplete and the statistical scatter is larger than the derived mean value. Nevertheless, we tentatively conclude that the values of the average geomagnetic moment were approximately the same in the Phanerozoic and in the Proterozoic+late Archean, and that there is no significant long-term change in the geomagnetic intensity detectable before the Phanerozoic.  相似文献   

Virtual dipole moment variations through the Proterozoic-Phanerozoic eons     

A. A. Schreider  Al. A. Schreider  P. Varga  C. Denis 《Oceanology》2012,52(4):545-549

The international bank of virtual dipole moment (VDM) data, combined with materials from recent publications (3384 values in total), served as a basis for the analysis of the VDM??s distribution through the Proterozoic and Phanerozoic eons (0?C2.6 Ga). The VDM distribution obtained by the method of a moving average exhibits a positive linear trend from 3.7 × 10²² Am² 2.6 Ga ago to 5.8 × 10²² Am² at present. Against the background of this linear growth, fluctuations with a periodicity of approximately 390 Ma are defined. The obtained data substantially specify the available data on the behavior of the magnetic field during the Proterozoic and Phanerozoic eons and should be taken into consideration for modeling the physical processes in the development of the Earth in the geological past and predicting its ecological and energetic evolution in the future.  相似文献   

A spatio-temporal Poisson hurdle point process to model wildfires   总被引：1，自引：1，他引：0  

Laura Serra  Marc Saez  Pablo Juan  Diego Varga  Jorge Mateu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(7):1671-1684

Wildfires have been studied in many ways, for instance as a spatial point pattern or through modeling the size of fires or the relative risk of big fires. Lately a large variety of complex statistical models can be fitted routinely to complex data sets, in particular wildfires, as a result of widely accessible high-level statistical software, such as R. The objective in this paper is to model the occurrence of big wildfires (greater than a given extension of hectares) using an adapted two-part econometric model, specifically a hurdle model. The methodology used in this paper is useful to determine those factors that help any fire to become a big wildfire. Our proposal and methodology can be routinely used to contribute to the management of big wildfires.  相似文献   

Evolution of the Virtual Dipole Moment in Earth’s Geological History     

Schreider  A. A.  Sazhneva  A. E.  Varga  P.  Denis  C. 《Oceanology》2019,59(5):771-776

Oceanology - Data of the International Bank of Digital Information on the time distribution of the virtual dipole moment (VDM), supplemented by data of more recent studies (a total of 5645 values),...  相似文献