Information from wikipedia is very poor. Something about experiments done in 1862, then "Telluric currents in fiction". Not worth researching into it seems.A telluric current (from Latin tellūs, "earth"), or Earth current,[1] is an electric current which moves underground or through the sea. Telluric currents result from both natural causes and human activity, and the discrete currents interact in a complex pattern. The currents are extremely low frequency and travel over large areas at or near the surface of the Earth.
I am thinking - if the magma inside the Earth moves, does it generate electricity by friction? Can this be a cause of telluric currents (and other electromagnetic phenomena) ?