Electrical Resistivity Tomography as a guideline for detecting altered volcanic ash deposits

In this paper we propose the application of Electrical Resistivity Tomography (ERT) as a guideline to localize and characterize altered volcanic ash deposits quickly and reliable. The geophysical method was tested on an altered epiclastic layer, identified within a composite Oligo-Miocene volcanic succession in central Sardinia (Italy). The equipment employed in continuous current mode (DC) was a Terrameter SAS 1000 (ABEM, Inc.) based on the use of metal electrodes for galvanic coupling. The high resistivity contrast between the epiclastite and the overlying ignimbrite, allowed the ERT method to provide valuable indications about the locations, lateral continuity and thickness of the deposit.