Distribution of crack density parameter in Central Betic Cordillera (Southern Spain)

Abstract

SUMMARY In this study we have used high-resolution P- and S-wave velocity results to estimate crack density (ε, epsilon) and saturation ratio (ξ, xi) at a depth of 2km in an intramountain basin and surrounding regions. Detailed observations of gravity, seismic profile and geological data reveal high ε consistent with large sedimentary thickness and minimum ε coinciding with elevations arising from the basement of the basin. From the distribution of seismic measurements of ξ it is possible to identify the presence of aquifers in detrital sediments, sandstone and dolostone. However, ξ does not show significant changes for the aquifers in geological formations made up also of schists and marbles. A low ξ anomaly in the western part could be associated with Triassic evaporite and clay rocks, and high values of ξ in the southwestern part near thermal springs may be imaging the intricate system of fractures which connect at depth with aquifer rocks.