Tomasz Ernst

Electromagnetic images of the deep structure of the Trans-European Suture Zone beneath Polish Pomerania

A large-scale international electromagnetic experiment has been carried out in northwest Poland and northeast Germany. The main goal was to study the deep conductivity structure across the Trans-European Suture Zone, which is the most prominent tectonic structure of Phanerozoic age in Europe. Electromagnetic measurements were carried out mainly along seismic profiles P2, LT-7, and LT-2 crossing the suture zone and running in the northeastern direction. Strike and dimensionality analyses indicate that a geoelectrical strike of N60 degrees W common to both profiles LT-7 and P2 can be estimated. This strike direction was used to project and rotate all transfer functions and both profiles were subjected to 2D inversion using three different approaches. The results show the presence of highly conductive Cenozoic-Mesozoic sedimentary cover reaching depths up to 3 km. A significant conductivity anomaly beneath the central part of the TESZ, called the Central Polish Anticlinorium, has been well resolved at midcrustal depths. The upper mantle of the Precambrian East European Craton is more resistive than, adjacent to the West, the younger Paleozoic Platform.

Probing electrical conductivity of the Trans-European Suture Zone

The Trans-European Suture Zone (TESZ) is the largest tectonic boundary in Europe, crossing northwest-southeast through central Europe from the North Sea to the Black Sea. More than 2000 kilometers long, it constitutes a complex transition between the thick and cold East European Craton (EEQ/Baltic Shield, created more than 650 million years ago (Ma) during the Precambrian, and the warmer, younger Paleozoic (650 to 250 Ma) central European mobile belts.

Analysis of the electromagnetic field recorded in the Friuli seismic zone, northeast Italy

Abstract Some examples of unusual telluric activity were found during the Italian-Polish magnetotelluric measurement campaign in the Friuli seismic zone, 1987–1988. The standard procedure for the elimination of the induction component from the telluric recordings and the calculation of the transfer functions were first applied. However, due to a high noise level in the observed telluric fields in the northern Alpine region, it appeared indispensable to develop new methods for the detection of any tectonically related component of the telluric field. The common function, defined as the average curve derived from two telluric stations and multiplied by the correlation coefficients (moving window procedure), allowed an increase in the telluric activity (time changes of variances) to be traced before and during seismic events in September, 1987, and February, 1988. Another approach was based on the time-frequency isoline calculations of the Poynting vector of electromagnetic field. Positive isoline values (opposite to the usual downward direction of this flux), were discovered and correlated with a course of seismic activity; some good results were found for the time intervals studied. Some considerations on a mechanism for the generation of an electric current in a zone of seismic preparation are discussed. An accumulation of stress leads to an oriented motion of the charged (charge-bearing) dislocations. The mechanism consists of the formation of a kind of polarization current induced by the motion of these dislocations.

Electromagnetic Induction Profile (PREPAN95) from the East European Platform (EEP) to the Pannonian Basin

Complex electromagnetic measurements along a profile crossing different great tectonic units in East-Central Europe (East European Platform, Paleozoic Europe and Carpatho-Pannonian region) were carried out by Hungarian, Polish, Slovak and Ukrainian institutes. Beside recent MT sounding curves, geomagnetic induction vectors, polar diagrams, apparent resistivity and phase pseudosections, a short description of earlier magnetotelluric (MT) and magnetovariational (MV) experiments is also given. For interpretation of these data 1D and 2D inversions were used after separation of the quasi E and B polarized curves. The Carpathian conductor clearly appears in the magnetovariational profile. MT soundings indicate that the mantle conductive basement — presumabely the asthenosphere — steeply deepens from the Neogene Pannonian Basin characterized by high heat flow towards the much colder EEP through the Paleozoic area.

Magneto-telluric recordings from the Friuli seismic zone, northeast Italy

Abstract Magneto-telluric measurements were undertaken in the Friuli seismic area of north-east Italy. The purpose was to find possible correlations between magneto-telluric signals and seismic activity. Two stations were operational between July 1987 and June 1988. Apparent resistivity curves were found for September 1987 and January 1988 data, and a magneto-telluric inversion problem was solved. Artificial noise and natural disturbances of the electromagnetic field, especially those related to tectonic processes, are discussed.

New tool forecasting sporadic E layer appearance on the basis on magnetic eta index

We present new tool developed in SRC PAS used for forecasting sporadic E layer appearance. In the previous work we had shown the correlation between the ionospheric characteristics and magnetic eta index proposed by Ernst & Jankowski (2005). Our previous results show the increase of eta value emerges 1–2 hours before the sporadic E layer appearance. The outcome of this conclusion is the possibility of forecasting of sporadic E layer appearance on the basis on real-time magnetic data, especially nontransparent sporadic E layer. (See for example: Dziak-Jankowska B., Stanislawska I., Ernst T., Tomasik L., Advances in Space Research 48, 2011, 850–856)

Natural Variations of the Geomagnetic Field: Observations and Application to Study of the Earth’s Interior and Ionosphere

The magnetic investigations carried out incessantly from the very moment the Institute of Geophysics was established in 1953 are outlined. Since that time, continuous observations of the natural magnetic field of the Earth, also called “magnetic service”, have been carried out. The research methods are discussed, which cover a wide scope of problems relating to the use of natural electromagnetic field variations, including the recognition of the Earth’s crust and upper mantle, search for electromagnetic earthquake precursors, and the ionosphere state monitoring via surface-based observations of the magnetic field. The reported investigations are of methodological nature, relating to recording and processing of data, as well as geophysical and geological modeling and interpretation. The major results obtained during 60-year activity, referring to the structure of the Earth’s crust and mantle in central Europe, are summarized.