Morphotectonic signature of the Campo Imperatore intermontane basin (Central Apennines): implications for the seismotectonics of Central Italy

This research aims at highlighting the small- and medium-scale morphotectonic framework of an intermontane basin emplaced within an area with a multi-phased tectonic history and currently characterized by an unclear seismic regime.

The land-sculpting processes acting upon the Campo Imperatore area (Abruzzi Apennines, Central Italy) are strongly influenced by the structural imprint of the Apennine thrust-belt and the subsequent extensional pattern. An E-W trending branch of a major normal fault system downthrows the back-limb of the chain, thus acting as the northern boundary between the Quaternary floodplain and its surrounding uplands. Prospective conjugate faulting is detected only in restricted areas and away from the influence of two basin thresholds, which triggered terrace deposition and their intermittent dissection. These thresholds, in turn, may well represent the linkage between the two segments of the E-W fault system.

Adjacent intermontane basins, all of comparable timing and tectonic scenario with the investigated geomorphological domain, record prominent and well-defined seismic histories. Within these areas, seismogenic normal faults with apparently long recurrence intervals have been recognised. Conversely, at Campo Imperatore, no such record is to be found despite its geodynamic environs. Furthermore, while evidence of Late Quaternary normal faulting was recognised in the recent fluvio-glacial sedimentary infill, they notwithstanding yield low-magnitude/high-frequency morphological features.

While brittle tectonics is either scarce or of difficult identification, active drainage system and landscape evolution provide a fresh insight into the subtle dynamics of this basin. Furthermore, new geophysical data, complemented by modeling of coseismic displacement, contributed to demonstrating that Campo Imperatore underwent very recent deformation capable of lowering its S margin. This led to the creation of proper accommodation space, towards which high-energy deposits from present-day alluvial fan systems are being conveyed by a shift in tilting of the basin floor.

Active geomorphic evolution indicates a prospectively ongoing deformation, possibly at its inception stage, as suggested by the recently superposed landscapes.