ELECTROMAGNETIC MEASUREMENTS IN THE VICINITY OF THE KTB DRILL SITE .2. MAGNETOTELLURIC RESULTS

In addition to the magnetovariational measurements across an array in Western Bohemia, close to the KTB ultradeep borehole (Germany), discus sed in part I of this paper [1], magnetotelluric results from pivot so unding point Ostruvek within the array are presented here. Good qualit y of long-period magnetotelluric data (period range from 30 s to about 1 hour) allowed structural dimensionality of the medium to be analyse d in detail. The geoelectrical structure was identified as a slightly distorted two-dimensional regional substratum, with dominating E - W s trike, overlaid by a heterogeneous subsurface layer with extremely str ong and anisotropic galvanic distortion effect on the magnetotelluric data. Estimating the total static shift distortion tensor by fitting t he local magnetotelluric curve to the curve of the global magnetovaria tional soundings (for the European continent), the static distortions were identified as of generally multidirectional origin. The resulting telluric ellipse is, however, strongly anisotropic, indicating an app roximately SW - NE apparent local strike, which is in the approximate agreement with remote reference magnetovariational results. Finally, t he magnetotelluric results from the station Ostruvek are compared with long-period data from the immediate neighbourhood of the KTB borehole on the German territory.