Fracture characterization in granites has been an important subject of study during these last years, by
means of geological-structural cartography, hydrogeology and geochemical analysis. These works have
been carried out to investigate the hydromechanics and permeability in low-permeability rocks. In this
study we apply a surface geophysical method in order to characterize the permeability of the fault zones
affecting «El Berrocal» granite (Central System, Spain). The low-induction electromagnetic method (EM)
gives us the apparent resistivity (ρa) values of the rocks at a maximum depth. As the ρa depends on the
granite alteration and/or the water content, this parameter allows estimating the relative permeability of
different fracture zones. The obtained results show that the high-permeability fractures are those that are
larger ones which were active during Alpine deformation (Eocene-present)