GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Fig. 1 - Map of the study area showing the main geologic units and structural elements, the seismic statons (black triangle), the seismic events with Mw 3.1 (black star), and 2.4 ML 3.0 (black circle). Beachballs represent the TDMT focal soluton of Mw 3.1 and show predominantly normal kinematcs with strike oriented in the N-NW/S-SE directon. The red beachballs correspond to the mainshocks (Mw5.20 and Mw4.28) of the seismic sequence nucleated on two diferent tectonic structures. Red lines represent known normal faults developed following the extensional tectonics during the Plio-Pleistocene. Two main fault systems are identfed. The frst includes main fault segments with a trend that varies southwards from N-S to WNW-ESE. The other two groups of faults have a NW-SE strike with SW dipping. The lithological basis is taken from the "Carta Geologica dell'area compresa tra Maratea, Castrovillari e Sangineto by A. Iannace; M. D'Errico; S. Vitale - (2004). Other Quaternary faults are present in the area whose contributon plays an important role on the seismicity of the area. In this region two carbonate platorms, the Apennines Platorm and the deeper Inner Apulian Platorm, are believed to be overlapped at about 5 km depth. Recent papers describe results obtained from diferent analyses that indicate the presence of high pressure fuids in the seismogenic volume where the seismic sequence occurred (De Mateis et al., 2021; Pastori et al., 2021; Napolitano et al., 2021, 2023). The fuid moving along the faults causes the lubrifcaton that facilitates the earthquake occurrence. A reducton of the dynamic strength due to high pressure fuid is expected to increase the seismic efciency ηsw. From our analysis we fnd the highest ηsw values along the two main faults, reaching their maximum values at the tps of these faults. The concentraton of elevated ηsw values at fault tps supports the observatons that fuid- related processes play a signifcant role in the seismic actvity within this partcular area. The ηsw variability in the target area could be elucidated by considering fuid involvement in controlling