Acta Geodaetica, Geophysica et Montanistica 12. (1977)

1–3. szám - I. Induction studies in selected continental areas - Europe - Ritter, E.: Frequency dependence of geomagnetic induction arrows

Acta Geodaet., Geophys. et Montanist. Acad. Sei. Hung. Tomus 12 (13), pp. 123 129 (1977) FREQUENCY DEPENDENCE OF GEOMAGNETIC INDUCTION ARROWS* E. RITTER CENTRAL EARTH PHYSICS INSTITUTE, GEOMAGNETIC OBSERVATORY NIEMEGK, GDR The frequency dependence of induction arrows in some regions of Europe was studied. In the Slovakian part of ÍSSR Wiese arrows, complex induction arrows and magnetic polar diagrams reveal a direction change of arrows with decreasing period from south to east-west. Basing on the frequency dependence of the arrows in the northwestern part of the GDR a conductivity model was developed recently confirmed by model computing. Introduction For the first evaluation of geomagnetic deep soundings carried out in Europe the method of induction arrows has been used very often. Therefore the map of Europe is covered by a very narrow net of arrows (Fig. 1). Pre­dominant are the North German-Polish conductivity anomaly (NPCA), the Rhine-Leine rift valley, the anomaly of the Carpathians and others. Usually the frequency dependence seems to be unimportant. But there are some areas with a considerable influence, for instance near Göttingen (FRG). Winter [8] reported a maximum of a frequency dependent spreading of arrows in the period range of 40 — 50 min. Measurements in the Carpathians Since Wiese made his first pilot studies on geomagnetic deep soundings in Czechoslovakia, Hungary and Rumania during IGY and IGC and detected the conductivity anomaly of the Carpathians which later on was studied by other authors in detail, we are very interested to get informations about this anomaly because of its model-size character. So we were very glad to be able to take part in a project of simultaneous registrations of geomagnetic variations on the deep seismic soundings (DSS) profile Y crossing the Carpathians from north to south. In the frame of this program 5 stations were operated in Poland, 5 in Czechoslovakia and 1 in Hungary. The research group of the Central Earth Physics Institute of the Academy of Sciences of the GDR equipped and served * Contribution No. 618 Acta Geodaelica, Geophysica el Montanistica Acad. Sei. Hung. 12, 1977

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