EGU23-1018, updated on 22 Feb 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Role of crustal fluids and thermo-mechanical structure for lower crustal seismicity: the Gargano Promontory (southern Italy)

Andrea Tallarico1, Alessio Lavecchia2, Marilena Filippucci1, Giulio Selvaggi2, Gianpaolo Cecere2, and Sierd Cloetingh3
Andrea Tallarico et al.
  • 1Dipartimento di Scienze della Terra e Geoambientali, Università di Bari - Aldo Moro, Italy
  • 2Istituto Nazionale Geofisica e Vulcanologia, Rome, Italy
  • 3Department of Earth Sciences, Utrecht University, The Netherlands

Several regions around the globe are characterized by a seismically active lower crust, at depths where lithological, thermal and rheological conditions suggest stress release by ductile flow. The Gargano Promontory (GP, southern Italy) is an example where a recently installed seismic network has recorded an intense seismic activity at depths between 20 and 30 km, i.e. in the lower crust. We analyze a possible mechanism controlling the distribution of seismicity in the GP to identify the factors that make the lower crust seismically active. To this aim, we construct a thermo-rheological model of a layered continental crust, calibrated on the basis of geometrical, lithological and thermal constraints. The model takes into account a multiphase crustal lithology, the presence of fluids in the crystalline basement, lateral variations of geotherm and stress field.

The numerical simulations show that the presence of fluids is a key factor controlling the cluster of seismicity in the lower crust. Moreover, the presence of water in the upper crystalline basement and sedimentary cover provides a plausible explanation for upper crustal seismicity in a zone of very high heat flow SW of the GP. The distribution of the seismicity is probably affected by the composition of the crystalline basement, with mafic bodies injected into the crust during the Paleocene magmatic phase that affected the Mediterranean region. Our findings suggest that the presence of hydrous diapiric upwelling(s) in the upper mantle can feed a deep fluid circulation system, inducing lower crustal seismicity.

How to cite: Tallarico, A., Lavecchia, A., Filippucci, M., Selvaggi, G., Cecere, G., and Cloetingh, S.: Role of crustal fluids and thermo-mechanical structure for lower crustal seismicity: the Gargano Promontory (southern Italy), EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1018,, 2023.