Understanding the electrical conductivity of earth materials is important to decipher structures and processes in Earth’s deep interior. Electromagnetic deep sounding methods are used to unravel structures at depths from a few tens of meters to tens of kilometres. The Geo-Electromagnetic Group of GFZ is interested in all aspects of this research field: sensor and instrument development, novel algorithms for signal processing and data inversion, conductivity measurements on rock samples and application of
the method to basic and applied research topics. We present examples from the San Andreas Fault, California, South Africa and the North German Basin.