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Moment tensor inversion and waveform clustering for 10 years of seismicity at the Campi Flegrei volcanic complex, Italy

Giacomo Rapagnani1,2, Gilberto Saccorotti 1, Simone Cesca3, Gesa Petersen3, Torsten Dahm3,4, Francesca Bianco5, Francesco Grigoli1,2

  • Affiliations: 1 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Italy 2 Dipartimento di Scienze della Terra - Università di Pisa, Italy 3 GFZ, Helmholtz Centre for Geosciences, Germany  4 Institute of Geosciences, University of Potsdam,Potsdam, Germany 5 Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Italy

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 218

  • Programme No: 3.10.17

  • Theme 3 > Session 10

Abstract

Campi Flegrei (CF) is a volcanic system located in a densely populated area west of Naples, Southern Italy. With a long history of eruptions, CF is the largest active caldera system in Europe. The most prominent feature of CF activity is ground deformation (so-called 'bradyseism'), which consists of rapid uplift usually accompanied by seismicity, followed by slow subsidence aseismic phases. The most recent awakening episode started almost 20 years ago, climaxing by mid 2024 with more than 1500 events / month,  and largest magnitude Md = 4.4. In this work we analyze the seismic catalogue from the INGV-Osservatorio Vesuviano, from 2014 to 2024. For a selected  subset of ~100 events with Md > 2.5, we perform time-domain, full-waveform Moment Tensor (MT) inversion using data recorded by up to 20 stations within 50 km epicentral range. The inversion is conducted using a probabilistic approach. Different velocity models and frequency bands are adopted for stations located within two distinct distance intervals. We obtain full, deviatoric and double-couple MT solutions for more than 80 events. From waveform similarity we identify 7 earthquake clusters, each characterized by similar locations and focal mechanisms. Most mechanisms indicate normal faulting; offshore events have locations and fault plane orientations which resemble the geometry of the caldera rim, while those in the most active Solfatara region mostly strike WSW-ENE. These results reveal with unprecedented detail the geometry and kinematics of the active fault structures in the Campi Flegrei region, and their relationships with volcano-tectonic lineaments.