MT-data analysis from a survey in the Mygdonia basin (N. Greece)

A magnetotelluric (MT) profile comprising eight measuring sites was conducted in the Mygdonia basin, a European Seismological Test Site. The MT-stations were deployed in a direction almost perpendicular to the major axis of the sedimentary basin to cover the area between the Lagada and Volvi lakes. The earth beneath the measuring points was considered to consist of a 2D-regional basement coupled with local, near surface, 3D-inhomogeneities. Impedance tensor decomposition analysis in conjunction with the magnetotelluric study of Mohr circles was implemented in the MT-data. From the electric field polarization diagrams and the interpretation of the Mohr circles results it is inferred that the local structure at all the sites polarizes the electric field in comparable directions ranging from N60°E to N80°E, except for the cases of the two stations located at the northern and southern borders of the basin, where the boundary conditions produce a deviation. Furthermore, the deeper structure seems to be two-dimensional. The strike-direction of the 2D-basement was found to be ~ N70°E. Although the regional geological strike in the area is NW-SE, the regional geoelectric strike is more compatible with the orientation of the faults in the area.