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Abstract:
The Mt.Pollino area is the largest seismic gap in Italy, with faults capable of M6.5-7 but no historical and instrumental M6 events recorded. Between 2010 and 2014 this area has been affected by a seismic sequence of more than 10,000 small magnitude earthquakes and two moderate main events occurred late in the sequence (ML 4.3 and ML 5.0).
The goal of this work is to provide 3D scattering and absorption images of this area using the peak delay time and the coda-Q methods, respectively. Scattering anomalies suggest that the area involved in the sequence is highly fractured, with the strongest scattering contrast interpreted as the Pollino Fault. This large structure acted as a barrier, bounding migration of the seismicity southward, as suggested in recent structural geological works. Declustered high-absorption anomalies mark the area affected by the sequence, suggesting that fluids have played a key role in its development. This result is in good agreement with high VP/VS and high pore pressure anomalies highlighted by recent works on the area.
This work was supported by the PRIN-2017 MATISSE project (no. 20177EPPN2), funded by the Italian Ministry of Education and Research.
