Caracterización sísmica del entorno de Mina Ratones en el granito de Albalá

Abstract

A detailed characterization o f the physical properties of a granitic pluton, as well as a three dimensional reconstruction of the fractures network and its surrounding are obtained by high resolution seismic tomography. The input travel times were picked from offset and azimuth variable seismic profile (OVSP) acquired in a 500 m deep vertical borehole. The three-component seismic data sets recorded allowed to test the methodology for P- and S-waves and to compare the velocity models derived from the first arrivals tomographic inversion of the two different kind of seismic waves. Furthermore, the combination of the two velocity models (P- and S-waves) provides a 3D Poisson's ratio diagram of the rock massif. This coefficient allows o differentiate volumes of fractured and altered granite from fresh rock. Poisson's ratios close to 0.3 mean fractured areas and correlate with fracture index (FI) and sonic logs, otherwise Poisson's ratio close to 0.25 is related to unaltered and unfractured rock.