Vedecké časopisy a ročenky vydávané na pôde SAV
Volume 40, 2010, No. 2
- Grinč, M. - Bielik, M. - Mojzeš, A. - Hók, J.
Results of the gravity field interpretation in the Turčianska Kotlina Basin.
In Contributions to Geophysics and Geodesy. Vol. 40, no. 2 (2010), p. 103-120.
- Gaál, L. - Szolgay, J. - Kohnová, S. - Hlavčová, K. - Viglione, A.
Inclusion of historical information in flood frequency analysis using a Bayesian MCMC technique: a case study for the power dam Orlík, Czech Republic.
In Contributions to Geophysics and Geodesy. Vol. 40, no. 2 (2010), p. 121-147.
- Ondrášková, A. - Ševčík, S. - Kostecký, P. - Tóth, J. - Kysel, R.
On the relation between the red sprites and the transients in the ELF band.
In Contributions to Geophysics and Geodesy. Vol. 40, no. 2 (2010), p. 149-157.
- Orlický, O.
A realistic approach to explanation of the normal and reversed remanent magnetization of rocks: Application for submarine volcanics.
In Contributions to Geophysics and Geodesy. Vol. 40, no. 2 (2010), p. 159-172.
- Issawy, E. - Radwan, A. - Dahy, S. - Rayan, A.
Monitoring of recent crustal movements around Cairo by repeated gravity and geodetic observations.
In Contributions to Geophysics and Geodesy. Vol. 40, no. 2 (2010), p. 173-184.
Results of the gravity field interpretation in the Turčianska Kotlina Basin|
Michal Grinč 1), Miroslav Bielik 2), Andrej Mojzeš 3), Jozef Hók 4)
gravity, geophysics, geology, density modelling, interpretation, Turčianska Kotlina Basin
The paper deals with the quantitative interpretation of the gravity field in the Turčianska Kotlina Basin. The interpretation was done by means of the application of the 2D density modelling method using the GM-SYS software. Geophysical constraints of the density models are represented by the existing geophysical measurements and interpretations. The Turčianska Kotlina Basin in the picture of the regional gravity field is characterized by the local gravity low with amplitude of about 12 mGal. The source of this gravity low is low density Tertiary sediments, which fill the basin. From the Tertiary sediments the Neogene sediments play dominant role in observed gravity, because their gravity effects are considerably larger in comparison with the gravity effects of the Paleogene sediments. The contacts between the Malá Fatra and Veľká Fatra Mts., and the Turčianska Kotlina Basin are characterized by the significant gravity gradients. They reflect tectonic contact between the basin and crystalline core mountains. In the Turčianska gravity low we can see along the Profile TK-AL three local gravity lows. The highest local gravity low is explained by the largest thickness of the Tertiary sediments. Another two local gravity lows are also characterised by thicker layers of the Tertiary sediments. Density models assume that the eastern (western) part of the basin basement is built by the Mesozoic (crystalline) rocks. In the central part of the Profile TK-BL the thick Paleogene sedimentary filling (more than 1 km) compensates the deepest part of the Pretertiary basement. Density model along the Profile TK-BL does not suggest a presence of the Paleogene sediments in the basin filling. It is also indicated that the Mesozoic rocks underlie the Tertiary sediments. The Pretertiary basement was interpreted in the depths from 0 km up to the 2 km. Note that all geological structures (blocks) are sliding from the East to the West. The dipping of the Malá Fatra Mts. is steeper than in a case of the Veľká Fatra Mts. The anomalous bodies observed on the western part of the basin result from the alluvial and detrital cones. Their presence and gravity effect can be observed mainly on the eastern slope of the Malá Fatra Mts.
Contributions to Geophysics and Geodesy. Volume 40, 2010, No. 2: 103-120.
Inclusion of historical information in flood frequency analysis using a Bayesian MCMC technique: a case study for the power dam Orlík, Czech Republic|
Ladislav Gaál 1), Ján Szolgay 2), Silvia Kohnová 3), Kamila Hlavčová 4), Alberto Viglione 5)
flood frequency analysis, historical floods, Bayesian inference, Markov chain Monte Carlo simulations, likelihood function, confidence intervals
The paper deals with at-site flood frequency estimation in the case when also information on hydrological events from the past with extraordinary magnitude are available. For the joint frequency analysis of systematic observations and historical data, respectively, the Bayesian framework is chosen, which, through adequately defined likelihood functions, allows for incorporation of different sources of hydrological information, e.g., maximum annual flood peaks, historical events as well as measurement errors. The distribution of the parameters of the fitted distribution function and the confidence intervals of the flood quantiles are derived by means of the Markov chain Monte Carlo simulation (MCMC) technique.
The paper presents a sensitivity analysis related to the choice of the most influential parameters of the statistical model, which are the length of the historical period h and the perception threshold X0. These are involved in the statistical model under the assumption that except for the events termed as 'historical' ones, none of the (unknown) peak discharges from the historical period h should have exceeded the threshold X0. Both higher values of h and lower values of X0 lead to narrower confidence intervals of the estimated flood quantiles; however, it is emphasized that one should be prudent of selecting those parameters, in order to avoid making inferences with wrong assumptions on the unknown hydrological events having occurred in the past.
The Bayesian MCMC methodology is presented on the example of the maximum discharges observed during the warm half year at the station Vltava-Kamýk (Czech Republic) in the period 18777–2002. Although the 2002 flood peak, which is related to the vast flooding that affected a large part of Central Europe at that time, occurred in the near past, in the analysis it is treated virtually as a 'historical' event in order to illustrate some crucial aspects of including information on extreme historical floods into at-site flood frequency analyses.
Contributions to Geophysics and Geodesy. Volume 40, 2010, No. 2: 121-147.
On the relation between the red sprites and the transients in the ELF band|
Adriena Ondrášková 1), Sebastián Ševčík 2), Pavel Kostecký 3), Juraj Tóth 4), Róbert Kysel 5)
electromagnetic field, ELF, lightning, sprites, Schumann resonances
Under favourable conditions sprites appear above large storms. Long continuing current in tens of ms in the parent +CG stroke radiates electromagnetic energy also in the Schumann resonance (SR) band. Optical and Extremely Low Frequency (ELF) observations at the Astronomical and Geophysical Observatory (AGO) near Modra are analyzed to find these two effects associated with +CG discharges. Since April 2007 dozens of sprites have been captured by automated all-sky TV system at AGO. A majority (77%) of the optical transient events are accompanied with the transients in the SR band. No ELF counterparts are found for 23% of the captured sprites. Our observations are compared with similar observations in Sopron and Nagycenk (NCK). Example of the optical frames, the associated ELF time plot and the Fourier as well as dynamic spectrum are presented for one of the events simultaneously observed at AGO and NCK.
Contributions to Geophysics and Geodesy. Volume 40, 2010, No. 2: 149-157.
A realistic approach to explanation of the normal and reversed remanent magnetization of rocks: Application for submarine volcanics|
Oto Orlický 1)
Ti-rich Ti-Mt and magnetite the carriers of normal RM, the low-temperature oxidized Ti-Mt and the ilmenite-hematites the carriers of reversed RM of rocks
The results of the magnetic measurements and mineralogic data of the submarine basalts and peridotites have been compared with the original model to explain the origin of the normal and the reversed remanent magnetization (RM) of volcanics. According to the author the Ti-rich titano-magnetite (Ti-Mt) bearing rocks (without the secondary magnetic phase) and the magnetite are always the carriers of only normal RM. The low-temperature oxidized Ti-Mt bearing rocks and those of the ilmenite-hematite bearing rocks of the deutheric oxidation origin (of the defined composition) are the carriers of dominantly reversed RM of the self-reversal origin. This idea have been approved by many results of submarine volcanics, mostly basalts.
Contributions to Geophysics and Geodesy. Volume 40, 2010, No. 2: 159-172.
Monitoring of recent crustal movements around Cairo by repeated gravity and geodetic observations|
Elsayed A. Issawy 1), Anwar H. A. Radwan 2), Sayed A. Dahy 3), Ali Rayan 4)
temporal gravity variations, earthquakes, geodynamics
The mass distribution and density inhomogeneities are one of the main factors affecting Earth's dynamics. The temporal gravity variations were used to understand the surface tectonics and geodynamic modeling after the occurrence of an earthquake of 1992. The gravity field changes have been used for monitoring recent crustal movements in the area around Cairo and Southern part of Delta, Egypt. More than five successive gravity measurement campaigns were performed in parallel with the geodetic technique (GPS).
The gravity changes were determined and correlated with seismic activity for all periods of observations. It was found that there is a certain relation shown by increasing of gravity values before the main seismic activity. As an example, a relatively considerable increase of gravity values was noticed for the network between the epochs of 2000 and 2004. Otherwise, the temporal gravity variations exhibited a considerable decrease in gravity values between the two campaigns of 2004 and 2007 for the same stations. This behavior could be explained by compressive deformation and strain buildup stage before the Southwestern Cairo earthquake (July 31, 2005 with magnitude of 4.3) and the stress release stage occurred after the main-shock. In addition, the results of geodetic measurements of the network around Cairo after five campaigns showed that the estimated horizontal velocities for almost of points are 5.5 mm/year in approximately NW direction.
Contributions to Geophysics and Geodesy. Volume 40, 2010, No. 2: 173-184.