3D fault model building and seismic potential in the Pollino area (Calabria–Basilicata, southern Italy)

We reconstructed the 3D geometries and kinematics of the interconnected fault pattern responsible for the moderate-magnitude earthquakes, which were recently affected by the 2010-2014 seismic activity of the Pollino area (Calabrian-Lucanian boundary). The 3D Faults Model of the Pollino area was reconstructed by integrating the structural-geological and seismological data. We constrained the model at the surface with fault-slip data and by using selected relocated hypocenters’ distributions at depth. Geological and seismological data allowed us to highlight an asymmetric active extensional fault system characterized by an E to NNE-dipping low-angle detachment with high-angle synthetic splays and SW- to WSW-dipping, high-angle antithetic faults. Hypocenters and the time-space evolution of the events suggest that two main sub-parallel WSW-dipping seismogenic sources, the Rotonda-Campotenese and Morano-Piano di Ruggio faults, are responsible for the strongest events of the 2010-2014 seismic activity (Brozzetti et al., 2017; Ercoli et al., 2021; Cirillo et al., 2022). We calculated the area of the seismogenic patches obtained by projecting the hypocenters of the early aftershocks on the 3D fault planes is consistent with the observed magnitude of the strongest events of October 2012 and May 2012 (Mw=5.2 and Mw=4.3). Since earthquake-scaling relationships provide maximum expected magnitudes of Mw=6.4 for the RotondaCampotenese and Mw=6.2 for the Morano-Piano di Ruggio faults, we may suppose that during the 2010-2014 seismic activity, the two structures did not release their seismic potential entirely. The reconstructed 3D faults model also points out the relationships between the activated fault system and the western segment of the Pollino Fault. This latter was not involved in the recent seismic activity but could have acted as a barrier to the southern propagation of the seismogenic faults, limiting their dimensions and the magnitude of the generated earthquakes.