EGU22-2202
https://doi.org/10.5194/egusphere-egu22-2202
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Unraveling the complexity of the Pollino (Italy) seismic gap fault system.

Ferdinando Napolitano1, Ortensia Amoroso1, Mario La Rocca2, Luca De Siena3, Danilo Galluzzo4, Vincenzo Convertito4, Raffaella De Matteis5, Toshiko Terakawa6, and Paolo Capuano1
Ferdinando Napolitano et al.
  • 1Università degli Studi di Salerno, Dipartimento di Fisica "E.R. Caianiello", Fisciano, Italy (fnapolitano@unisa.it)
  • 2Università della Calabria, Dipartimento di Biologia, Ecologia e Scienze della Terra, Rende, Italy
  • 3Johannes Gutenberg University, Mainz, Germany
  • 4Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy
  • 5Università degli Studi del Sannio, Dipartimento di Sciente e Tecnologie, Benevento, Italy
  • 6Earthquake and Volcano Research Center, Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan

The Mt. Pollino area has been affected by a 4-year long seismic sequence, occurred between 2010 and 2014 and characterized by low-to-moderate seismicity and two moderate events (ML 4.3 and ML 5.0). The sequence developed as a combination of swarm-like and aftershocks. The two main earthquakes occurred late in the sequence, with a slow-slip event starting 3-4 months before the largest earthquake and lasting for a year. Despite the lack of historical and instrumental recordings of strong earthquakes (M>6), paleo-seismological investigations confirm the occurrence in the last 10,000 years of at least two M 6.5-7 earthquakes on the Pollino and Castrovillari faults, located in the SE sector of the Mt. Pollino area. Thus, the area has been marked as the widest high seismic hazard gap in Italy.

In this study we present the most recent advancements in the comprehension of the main peculiarities of the last seismic sequence and of its space and time evolution.   

New local 3D P- and S-wave tomographic images offered a detailed picture of the main lithological units involved in the sequence and more reliable earthquake hypocenter locations. The inferred velocity contrasts have been compared with 2D scattering and absorption maps computed for the area, along with total direct wave attenuation. Clusters of events of similar waveforms (cross-correlation higher than 0.8) have been selected and located applying the master-slave relative location technique. New fault mechanisms have been computed. These mechanisms allowed modeling the local stress field and performing a Focal Mechanism Tomography. Its result was an evaluation of the excess of pore fluid pressure in the volume interested by the sequence. A 1D diffusivity analysis suggests a pore fluid pressure diffusion which, in addition to the Coulomb static stress transfer, can explain the delayed triggering of the two larger events.

This work has been supported by the CORE (“sCience and human factor for Resilient sociEty”) project, funded from the European Union’s Horizon 2020 - research and innovation program under grant agreement No 101021746 and by PRIN-MATISSE (20177EPPN2) project funded by Italian Ministry of Education and Research.

How to cite: Napolitano, F., Amoroso, O., La Rocca, M., De Siena, L., Galluzzo, D., Convertito, V., De Matteis, R., Terakawa, T., and Capuano, P.: Unraveling the complexity of the Pollino (Italy) seismic gap fault system., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2202, https://doi.org/10.5194/egusphere-egu22-2202, 2022.