Fractal analysis of a Quaternary fault array in the central Apennines, Italy

The Monte Vettore fault array, in the central Apennines fold and thrust belt, is part of a major Quaternary fault system displaying the main features of a regional negative flower structure associated with a roughly N-S-trending left-lateral strike-slip fault zone. Fractal analysis of the fault trace pattern of the area has shown that the box-counting curve derived for the Monte Vettore array is defined by two straight line segments, each showing a characteristic slope value. The first segment, which refers to a spatial distribution extending over about one order of magnitude, is characterized by a fractal dimension of about 1.6, whereas the second one fits a Euclidean (i.e. a non-fractal) distribution. The box-counting analysis emphasizes that faults with variable sizes exhibit different scaling relations, hence suggesting that fault linkage played a major role in the development and evolution of the Monte Vettore fault array. The split point between the two segments falls at a value of log ls, corresponding to a box size of 635 m, hence suggesting that self-similarity among faults within the array breaks down below this value. Fractal analysis of the Monte Vettore array also provides statistically-based segmentation criteria for analysing a young immature fault structure capable of generating medium-size earthquakes in a continental geotectonic setting.