Seismogenic fault characterization in the Pollino area (Southern Italy)

One of the most intense periods of the 2010-2014 Pollino swarm (Southern Italy), namely from November 2011 to April 2012, has been analyzed with the aim of a precise relocation of the hypocenters in order to image the seismogenetic structure(s) responsible for this swarm. Using recordings of temporary and permanent stations installed in the area during the sequence, we identified 18 clusters of earthquakes characterized by extremely similar waveforms, selected through a cross-correlation analysis. We performed a relative location of each event of each cluster. For each cluster the spatial distribution of hypocenters was fitted by a plane to infer the fault plane orientation. We compared the results with the focal mechanism of individual earthquakes of the same cluster. For an overall view of the relative position of each reference event of all analyzed clusters, we performed the relative location of all these master events adjusted to take into account the different shapes of the waveforms. The results show that different clusters are likely patches of the same fault plane, mostly parallel among them and with similar focal mechanisms, with a strike angle in the NW-SE direction and dip around 35-45 degrees, deepening SW toward the Tyrrhenian sea. The absolute location gives a depth distribution between 4.5 and 6 km b.s.l