Wyniki wyszukiwania - Biblioteka Nauki

1

Sygnaly kataklizmu

100%

Ernst T.

Academia. Magazyn Polskiej Akademii Nauk

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2005

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nr 3

39-41

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q-analogues of general reduction formulas by Buschman and Srivastava and an important q-operator reminding of MacRobert

100%

Ernst T.

Demonstratio Mathematica

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2011

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tom Vol. 44, nr 2

285-296

EN

We find four q-analogues of general reduction formulas from Buschman and Srivastava together with some special cases, e.g. q-analogues of reduction formulas for Appell- and Kampé de Fériet functions. A proper q-analogue of the notation (…) by MacRobert, Meijer and Srivastava is given, and the definition of q-hypergeometric series is generalized accordingly.

3

Electrical conductivity inhomogeneities in Greece on the west margin of the Anatolian Fault

100%

Ernst T.

Acta Geophysica Polonica

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2005

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tom Vol. 53, nr 1

103-114

EN

Qualitative interpretation of the magnetotelluric results, based on the calculated polar diagrams and impedance tensors, is presented. The experimental data have been collected in Sterea Ellas region in Greece. Our interpretation allowed us to localize two conductive faults in the study area. One of them is probably a continuation of the west margin of the well-known Anatolian Fault.

4

Tectonic model of Egypt based on magnetic analysis

63%

Rabeh T. , Ernst T.

Acta Geophysica

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2009

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tom Vol. 57, no. 3

680-695

EN

The main target of this work was to study the dynamics of the Earth's crust for Egypt based on the magnetic survey. High-resolution land magnetic data were analyzed, combined with the results of GPS and seismic stress analyses. The constructed tectonic map shows that the N35°-N45°W trend of the structure (related to the Red Sea and Gulf of Suez tectonics) predominates along the Gulf of Suez, Red Sea, covering wide parts of the study area. The N45°-N65°E tectonic trend (related to the Syrian Arc tectonics), prevailing in the northern part of Egypt, is of the second rank. The Aqaba (N15°-25°E) and E-W trends prevail in the northern part and along the transition zone of stable/unstable shelves. The depth to the basement rocks ranges from the surface along the Red Sea and southern parts of Egypt to more than 4 km below sea level at the northern part of the study area. The results also show that the opening rate along the Red Sea was faster in the past than nowadays. Furthermore, a preliminary kinematics model is proposed.

5

A new magnetic index based on the external part of vertical geomagnetic variations

51%

Ernst T. , Jankowski J. , Nowożyński K.

Acta Geophysica

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2010

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tom Vol. 58, no. 6

963-972

EN

Variations of geomagnetic components X, Y, and Z recorded in 19 Intermagnet European observatories in 2004 were analysed. The original data from all observatories were preliminarily processed. In the first step, periods longer than three hours were filtered out. In the second step, variations of vertical geomagnetic component Z were separated into external and internal parts. We introduced a non-dimensional index η defined as the square root of a ratio of the energy of the external part of the vertical component to that of the horizontal components. Maps of the surface distribution of a new magnetic index η for the area of Europe at selected time periods were created, and their time changes are presented. The time changes of η for selected observatories are also shown. Moreover, we discuss a very interesting phenomenon we discovered, that has never been described in geophysical literature. Namely, in the recordings of all the observatories we noticed the presence of very regular variations, observed almost exclusively in the vertical component Z, which is quite unusual. These regular variations occur in the form of sinusoidal "wave packets". The amplitudes of these variations do not depend on the geomagnetic latitude and appear in the records of all the observatories we analyzed. They occur in quiet days, which suggests that their source is in the ionosphere.

6

Physical modeling of electromagnetic field of 3D anisotropic conductance inhomogeneity

51%

Kobzova V. , Ladanivsky B. , Ernst T.

Acta Geophysica Polonica

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2000

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tom Vol. 48, nr 3

395-410

EN

The physical modeling method is used to investigate the natural electromagnetic field of a geological medium with anisotropic conductance. A special laboratory installation is used. Scale 3D models of geoelectric sections are created in a 5 x 5 x 0.7 m electrolytic tank. Variations of natural electromagnetic field are simulated by a harmonic plane-homogeneous field. The process of creating anisotropic models of local or regional anisotropic zones of any size or form is developed. The results are presented of analogue modeling of uplift in the upper three-layer section characterized by conductance along lateral axes varying approximately 100 times. MT-sounding curves and the spatial structure of electromagnetic field components of anisotropic and isotropic 3D scale models are compared to estimate the influence of anisotropy.

7

Comparison of two techniques for magnetotelluric data processing using synthetic data sets

51%

Ernst T. , Sokolova E. , Varentsov I. , Golubev N.

Acta Geophysica Polonica

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2001

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tom Vol. 49, nr 2

213-243

EN

The mathematical backgrounds and the computer program for the generation of synthetic magnetotelluric (MT) data sets are presented in the first part of this paper. The imitation approach provides the possibility to calculate MT time series with the a priori assigned signal properties similar to the properties of natural MT fields and realistic (but controlled) structure of the noise added to the signal. The transfer operator (impedance) connecting MT fields is known; thus, the processing of these data sets gives a possibility of direct comparison of estimated and "true" impedance elements and provides the objective study of the efficiency of MT processing techniques at the quantitative level. In the second part of the paper, first results of such a study of two MT processing codes with different mathematical formulation are discussed. The PRC system is based on the generalized harmonic analysis and frequency domain selective weighting and robust estimators, while the essence of the code of Wielądek and Ernst is the solution of the time domain integral equation. These two techniques are jointly checked on the basis of two seven-day long synthetic MT time series designed in the frames of the COMDAT processing software comparison project. The first test contains pure MT signal, and in the second one the same signal is disturbed with significant additive noise of different nature. The surprisingly good convergence of the estimates of both codes to the "true" impedance responses is reported.

8

Effect of thin near-surface layer on the geomagnetic induction arrows: an example from the East European Platform

51%

Jankowski J. , Ernst T. , Jóźwiak W.

Acta Geophysica Polonica

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2004

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tom Vol. 52, nr 3

349-361

EN

Nineteen deep geomagnetic soundings were made in NE Poland which belongs to the East European Platform. The calculated transfer functions show that the induction vectors are quite large, achieving 0.8. The maximum length of the vectors is at the period of about 300 s. Comparing the directions of the induction vectors with the map of the thickness of sedimentary cover we found a striking correlation with the crystalline basement depth isolines. An auxiliary 2D modelling and a thin-sheet model support the statement that substantial part of the vectors is due to induction in the sedimentary cover.

9

A new method for presentation of induction vector distribution in Europe

45%

Wybraniec S. , Jankowski J. , Ernst T. , Pecova J. , Praus O.

Acta Geophysica Polonica

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1999

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tom Vol. 47, nr 3

323-334

EN

A new method of presentation of the vector fields on a plane is described. The method is used to create a map of Wiese vectors in Europe. The map is based on the results of 1800 measurement points collected mainly from the literature. The colour graphics is used for the presentation. It seems that all characteristic features are more clearly visible as compared to classical picture. Additionally, the data were transformed using 2-D Hilbert transform. The maps after transformation contain the same information as the original ones, but the pattern of anomalies is more clear.

10

Physical modeling of the induction vectors above the structures including 3d blocks in the crust

45%

Ladanivsky B. , Jankowski J. , Ernst T. , Kobzova V. , Rusiniak L.

Acta Geophysica Polonica

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2002

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tom Vol. 50, nr 4

575-582

EN

Space and frequency distributions of the induction vectors induced by the 2D subsurface conductive anomaly have been studied using the physical modeling in relation to the deeper 3D crust and 1D mantle structures. It was established that the influence of the 3D block structures of the crust on these vectors is less than the influence of conductivity of the deep mantle structures and than the contrast of resistivities between the sediments and the crust.

11

Geoelectrical model along a profile across the Tornquist-Teisseyre zone in southeastern Poland

45%

Ernst T. , Jankowski J. , Jóźwiak W. , Lefeld J. , Logvinov I.

Acta Geophysica Polonica

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2002

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tom Vol. 50, nr 4

505-515

EN

We present results from the Polish part of a long international profile, ranging from the Ukraine to Hungary (PREPAN 95) and traversing the T-T zone in southeastern Poland, extended by data from two new geomagnetic soundings made in 1997. The new data allowed us to create a more detailed and realistic model. The 2-D interpretation was carried out on the basis of the complex induction vectors obtained from six points, supplemented by information derived from deep magnetotelluric soundings in Pawłówka. The results have shown that to the north of the well-known Carpathian anomaly, there are two deep and conductive faults within T-T zone. The joint interpretation of the deep magnetotelluric sounding comprising the results from Pawłówka and magnetovariation data from the Lvov Magnetic Observatory suggests the existence of a conductive zone at depths of about 100-200 km.

12

Observations of electromagnetic radiation in the Central Apennines seismic region

45%

Ernst T. , Jankowski J. , Teisseyre R. , Meloni A. , Palangio P.

Acta Geophysica Polonica

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2001

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tom Vol. 49, nr 1

43-53

EN

In recent years, continuous radio-noise recording is in use at many geophysical observatories, in order to detect possible earthquake precursors and/or coseismic signals. The recordings obtained indicate that electromagnetic radiation (e.g., in the range of 10-40 kH) can indeed be treated as seismic precursor. We present here the examples of successful prediction observation, which we have obtained in the Central Apennines region at the l'Aquila Observatory (Polish-Italian cooperation). A short discussion on relation between the evolution of stresses (dislocation dynamics) and electromagnetic emission supplements this paper.

13

Pre-seismic Geomagnetic and Ionosphere Signatures Related to the Mw5.7 Earthquake Occurred in Vrancea Zone on September 24, 2016

38%

Stanica D. A. , Stanica D. , Błęcki J. , Ernst T. , Jóźwiak W. , Słomiński J.

Acta Geophysica

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2018

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tom Vol. 66, no. 2

167--177

EN

To emphasize the relationship between the pre-seismic geomagnetic signals and Vrancea seismicity, in this work it is hypothesized that before an earthquake initiation, the high stress reached into seismogenic volume generates dehydration of the rocks and fracturing processes followed by release of electric charges along the faulting systems, which lead to resistivity changes. These changes were explored on September 2016 by the normalized function Bzn obtained from the geomagnetic data recorded in ULF range (0.001-0.0083 Hz). A statistical analysis was also performed to discriminate on the new Bzn* time series a pre-seismic signature related to the Mw5.7 earthquake. Significant anomalous behavior of Bzn* was identified on September 21, with 3 days prior to the onset of the seismic event. Similar information is provided by registrations of the magnetic and electron concentration variations in the ionosphere over the Vrancea zone, by Swarm satellites, 4 days and 1 day before the earthquake.

14

Electromagnetic soundings across the Holy Cross Mountains, Poland

38%

Semenov V. Y. , Jankowski J. , Ernst T. , Jóźwiak W. , Pawliszyn J. , Lewandowski M.

Acta Geophysica Polonica

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1998

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tom Vol. 46, nr 2

171-185

EN

Ten deep electromagnetic soundings were performed along the 150 km profile across the southern part of the Tornquist-Teisseyre zone (TTZ) in SE Poland. Five electromagnetic components have been recorded in the period range from few seconds to several hours. The real induction vectors were estimated at all 10 sets, but data from 6 stations only were good enough for magnetotelluric soundings. The magnetovariation data have shown the presence of a high-conductivity, deeply rooted narrow fractive zone of resistivity of about 5 Ohmm, situated in the northern part of Łysogóry unit of the Holy Cross Mountains (HCM). This zone separates two blocks with different geoelectrical properties, particularly well expressed in their upper part. Juxtaposed together with the earlier magnetotelluric (MT) soundings performed east of that profile, the results ofthis study suggest an existence of the easterly extension of the high resistivity zone of the Łysogóry unit far beyond the HCM. If our interpretation accounts for the Carpathian conductive anomaly, a conductive layer within TTZ at the depth of the crust-mantle boundary can be inferred. The mantle conductivity structure for the 2-D modelling was assumed in accordance with results obtained from the Polish geomagnetic observatories Belsk and Hel together with MT deep sounding from Wola Kanigowska.

15

Reconnaissance electromagnetic soundings on Bornholm

38%

Jankowski J. , Ernst T. , Jóźwiak W. , Lewandowski M. , Abrahamsen N. , Semenov V.

Acta Geophysica Polonica

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2001

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tom Vol. 49, nr 3

361-372

EN

Two electromagnetic (magnetotelluric and geomagnetic) soundings have been made in the region of Bornholm Island (Denmark). The results of analysis suggest a very complicated, locally three-dimensional character of the conductivity distribution; however, we interpret the outcome of the soundings in terms of a two-dimensional model, additionally using other published results from the region under study. From the interpretation it follows that Bornholm belongs to the East European Platform, whereas from the south and from the west an influence of large sedimentary basins appears. The depth of the sedimentary basin adjoining the island to the south is probably much deeper than estimated so far. Also, geological structures at greater depth in this region of the Baltic Sea may be much more complicated than it could be assumed from a simple extrapolation of data obtained from the surface geology.