Electrical crust of Portugal mainland

Abstract:

One of the major space weather hazards at the planetary level that is being investigated and better understood in recent decades is the Geomagnetic Induced Currents (GICs). In the last decades, it was realized that large GICs can flow in power systems and become problematic and even severe enough to cause a complete system shutdown. Two major factors determine GICs: (1) the strength and orientation of the electric field in the power system, which depends on the ionospheric and magnetospheric currents as well as on the earth´s conductivity; and (2) the electric power network characteristics. The earth´s conductivity can be obtained based on geophysical measurements that give the distribution of the conductivity in depth and laterally. A realistic model of conductivity can be built based on the interpretation of magnetotelluric (MT) soundings. This geophysical method allows to estimate the conductivity distribution from a dozen of meters to some kilometers in depth.

The main goal of this work is to build a model of the crustal electrical conductivity of Portugal mainland to contribute to a full understanding of GICs events. A first crustal model based on 40 broadband MT soundings, carried out in Portugal mainland, is presented. Its correlation with main geological structures in the country and importance for GICs studies is discussed.