Dimensión fractal de la distribución espacial de fracturas en el área granítica de El Berrocal (Sistema Central): relación con el tensor de esfuerzos

Resum

A fractal analysis of fracture spatial patterns was carried out in the granitic massif of "El Berrocal" for three structural map scales (1:2.000, 1:10.000 and 1:500.000). At first, the total fracture map was analysed on each scale, and a second step, the dynamic fracture maps were built and analysed by filtering of active faults due to two stress fields. The technique used to obtain the fractal dimension was the "box-counting" 1-D and 2-D (one dimension and two dimension). The "box-counting 1-D" technique has been used to take values of the fractal dimension related to the orientation of the measurements. One fractal anisotropy was showed in dynamic fracture maps associated to palaeostress fields, as the maximum value of fractal dimension. A good relationship has been found between ϬHmax strike (maximum horizontal stress) and the orientation of the fracturing profiles for the maximum fractal dimension value. First results point to SHmax strike is perpendicular with the maximum complexity orientation. The larger value of fractal dimension in fracture dynamic map due to recent stress field (Alpine) is agree with the fact that, this stress field activates old faults and generates new faults, and it shows a more complex fracture pattern.