Basic Role of Extrusion Processes in the Late Cenozoic Evolution of the Western and Central Mediterranean Belts

Tectonic activity in the Mediterranean area (involving migrations of old orogenic belts, formation of basins and building of orogenic systems) has been determined by the convergence of the confining plates (Nubia, Arabia and Eurasia). Such convergence has been mainly accommodated by the consumption of oceanic and thinned continental domains, triggered by the lateral escapes of orogenic wedges. Here, we argue that the implications of the above basic concepts can allow plausible explanations for the very complex time-space distribution of tectonic processes in the study area, with particular regard to the development of Trench-Arc-Back Arc systems. In the late Oligocene and lower–middle Miocene, the consumption of the eastern Alpine Tethys oceanic domain was caused by the eastward to SE ward migration/bending of the Alpine–Iberian belt, driven by the Nubia–Eurasia convergence. The crustal stretching that developed in the wake of that migrating Arc led to formation of the Balearic basin, whereas accretionary activity along the trench zone formed the Apennine belt. Since the collision of the Anatolian–Aegean–Pelagonian system (extruding westward in response to the indentation of the Arabian promontory) with the Nubia-Adriatic continental domain, around the late Miocene–early Pliocene, the tectonic setting in the central Mediterranean area underwent a major reorganization, aimed at activating a less resisted shortening pattern, which led to the consumption of the remnant oceanic and thinned continental domains in the central Mediterranean area.

Generalized statistical mechanics approaches to earthquakes and tectonics

Despite the extreme complexity that characterizes the mechanism of the earthquake generation process, simple empirical scaling relations apply to the collective properties of earthquakes and faults in a variety of tectonic environments and scales. The physical characterization of those properties and the scaling relations that describe them attract a wide scientific interest and are incorporated in the probabilistic forecasting of seismicity in local, regional and planetary scales. Considerable progress has been made in the analysis of the statistical mechanics of earthquakes, which, based on the principle of entropy, can provide a physical rationale to the macroscopic properties frequently observed. The scale-invariant properties, the (multi) fractal structures and the long-range interactions that have been found to characterize fault and earthquake populations have recently led to the consideration of non-extensive statistical mechanics (NESM) as a consistent statistical mechanics framework for the description of seismicity. The consistency between NESM and observations has been demonstrated in a series of publications on seismicity, faulting, rock physics and other fields of geosciences. The aim of this review is to present in a concise manner the fundamental macroscopic properties of earthquakes and faulting and how these can be derived by using the notions of statistical mechanics and NESM, providing further insights into earthquake physics and fault growth processes.

Flow in multiscale fractal fracture networks

The paper aims at defining the flow models, including equivalent permeability, that are appropriate for multiscale fracture networks. As a prerequisite of the flow analysis, we define the scaling nature of fracture networks that is likely quantified by power-law length distributions whose exponent fixes the contribution of large fractures versus small ones. Despite the absence of any characteristic length scale of the power-law model, the flow structure appears to contain three length scales at the very maximum: the connecting scale, the channelling scale, and the homogenization scale, above which the equivalent permeability tends to a constant value. These scales, including their existence, depend on the fracture length distribution and on the transmissivity distribution per fracture. They are basic in defining the flow properties of fracture networks.