EGU21-1076
https://doi.org/10.5194/egusphere-egu21-1076
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Deciphering the source parameters and genesis of the 2017, Mw 4 Montesano earthquake close to the Val d’Agri Oilfield (Italy)

José Ángel López-Comino1,2,3, Thomas Braun4, Torsten Dahm3,5, Simone Cesca5, and Stefania Danesi6
José Ángel López-Comino et al.
  • 1Instituto Andaluz de Geofísica, Universidad de Granada, Granada, Spain.
  • 2Departamento de Física Teórica y del Cosmos, Universidad de Granada, Granada, Spain.
  • 3Institute of Geosciences, University of Potsdam, Potsdam-Golm, Germany.
  • 4Istituto Nazionale di Geofisica e Vulcanologia, Arezzo, Italy.
  • 5GFZ German Research Centre for Geosciences, Potsdam, Germany
  • 6Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy.

On October 27th, 2017, a Mw 4 earthquake occurred close to the municipality of Montesano sulla Marcellana, less than 10 km external to the concession of the largest European on-shore hydrocarbon reservoir - the Val d’Agri oilfield (Southern Italy). Being a weak event located outside the extended monitoring domain of the industrial concession, the relevance of this earthquake and possible links with the hydrocarbon exploitation were not deepened. The study of weak to moderate earthquakes can improve the characterization of the potentially destructive seismic hazard of this particular area, already struck by M>6.5 episodes in the past. Taking advantage of a wide coverage of seismic stations deployed in the VA region, we analyze the source parameters of this Mw 4 earthquake applying advanced seismological techniques to estimate the uncertainties derived from the moment tensor inversion and identify plausible directivity effects. The moment tensor is dominated by a NW-SE oriented normal faulting with a centroid depth of 14 km. A single ML 2.1 aftershock was recorded and used as empirical Green function to calculate the apparent source time function for the mainshock. Apparent durations (in the range 0.11 - 0.21 s, obtained from S-waves) define an azimuthal pattern which reveals an asymmetric bilateral rupture with the 70% of the rupture propagation in the N310°W direction, suggesting a rupture plane dipping to the SW. Our results conclude that the Montesano earthquake activated a deeper fault segment associated to the Eastern Agri Fault System close to the basement. The relative low trigger potential below 10% based on depletion-induced stress changes discards an induced or triggered event due to the long-term hydrocarbon extraction in the Val d’Agri oilfield, and it rather suggests a natural cause due to the local tectonic stress.

How to cite: López-Comino, J. Á., Braun, T., Dahm, T., Cesca, S., and Danesi, S.: Deciphering the source parameters and genesis of the 2017, Mw 4 Montesano earthquake close to the Val d’Agri Oilfield (Italy), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1076, https://doi.org/10.5194/egusphere-egu21-1076, 2021.

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