Magnetotelluric applied to deep geothermal exploration: Canary Islands

Abstract

There is currently a growing interest in geothermal energy. Geothermal energy for electricity generation usually corresponds to deep reservoirs, located deeper than one kilometer. This will condition the geophysical methods to be used during the exploration of the geothermal system, being magnetotelluric (MT) the only electromagnetic method capable of reaching such depths. Commonly used in geothermal exploration, this method will provide information on the electrical resistivity distribution of the subsurface, and therefore will allow characterizing the main components of the system. This is the case of the seal of the reservoir, which will be easily detectable with MT since usually consists of a layer of clays resulting from hydrothermal alteration (the so-called clay cap). A reference for the application of this method to geothermal exploration can be found in the Canary Islands, where studies have been carried out on a regional scale for the last decade. The results obtained so far, with the generation of three-dimensional geoelectrical models in three of the seven islands (Tenerife, Gran Canaria and La Palma), show the great value of this type of studies that will be used (and are already being used) as a basis for new geothermal exploration projects to be carried out in the archipelago.