ELECTRICAL AND THERMAL ANOMALIES IN THE CENTRAL ANDEAN SUBDUCTION ZONE

An enhancement of the electrical conductivity in the upper layers in t he subduction zones of southern Peru and northern Argentina is found b y analyzing the solar quiet geomagnetic variations. This feature appea rs in a zone associated with large subduction angles. In this region h igh values of heat how have been measured, therefore a one-dimensional thermal model is proposed using regional characteristic parameters to reproduce these values. It is found that thermal convection necessari ly plays a contributing role. This effect may be produced by the ascen ding magma and fluids, which can explain the enhancement of the electr ical conductivity.