Teconics, hydrogeology and karstic morphogenesis: a new multidisciplinary approach to investigate active faults? from the example of the 1980 irpinia earthquake to the west marsica case stidy (Southern Latium region)

After the November 23, 1980 Irpinia earthquake (Mw 6.9), several seismically induced effects at surface have been identified. Among these, a strong variation of the Sanità spring flow rate (from 4.5 m3/sec, in the days preceding the quake, to 7.5 m3/sec, in December 1980) occurred. a multidisciplinary approach aiming at the identification of sectors of the central Apennines where carbonate reliefs (carbonate hydrostructures), affected by active normal faults, are characterised by springs related to permeability thresholds and by karst systems. In particular, we investigate the southern sector of the carbonate ridge that bounds the Marsica region to the West, where the Posta Fibreno springs (10 m3/sec) are located, acting as the present base level for karstic erosion. This sector is affected by a portion of the regional tectonic structure known in the literature as "Val Roveto-Atina Line", here represented by the Posta Fibreno fault, which places in contact the cretaceous-miocenic carbonate sequences with the miocenic flysch and with quaternary continental sequences hosted by the Posta Fibreno depression. Several epigeous and hypogeous karstic landforms (dolines, abandoned valleys and karstic conducts) developed in this area along tectonic features NW-SE trending; the not well developed hydrographic network is characterised by abandoned valley which originate from the rims of the main dolines (i.e. Fossa Maiura, Pozzo la Pescura). These landforms show evidence of different stationary phases of the karstic erosion probably due to hydrological base level of the Posta Fibreno springs.