We investigate a large geodetic data set of interferometric synthetic aperture radar (InSAR) and GPS measurements to determine the source parameters for the three main shocks of the 2016 Central Italy earthquake sequence on 24 August and 26 and 30 October (Mw 6.1, 5.9, and 6.5, respectively). Our preferred model is consistent with the activation of four main coseismic asperities belonging to the SW dipping normal fault system associated with the Mount Gorzano‐Mount Vettore‐Mount Bove alignment. Additional slip, equivalent to a Mw ~ 6.1–6.2 earthquake, on a secondary (1) NE dipping antithetic fault and/or (2) on a WNW dipping low‐angle fault in the hanging wall of the main system is required to better reproduce the complex deformation pattern associated with the greatest seismic event (the Mw 6.5 earthquake). The recognition of ancillary faults involved in the sequence suggests a complex interaction in the activated crustal volume between the main normal faults and the secondary structures and a partitioning of strain release.
Campi Flegrei caldera (Italy) was affected by a new unrest phase during 2011–2013. We exploit two COSMO‐SkyMed data sets to map the deformation field, obtaining displacement rates reaching 9 cm/yr in 2012 in the caldera center. The resulting data set is fitted in a geophysical inversion framework using finite element forward models to account for the 3‐D heterogeneous medium. The best fit model is a north dipping mixed‐mode dislocation source lying at ~5 km depth. The driving mechanism is ascribable to magma input into the source of the large 1982–1984 unrest (since similar source characteristics were inferred) that generates initial inflation followed by additional shear slip accompanying the extension of crack tips. The history and the current state of the system indicate that Campi Flegrei is able to erupt again, and the advanced techniques adopted provide useful information for short‐term forecasting.
We measured ground displacements before and after the 2009 L’Aquila earthquake using multi-temporal InSAR techniques to identify seismic precursor signals. We estimated the ground deformation and its temporal evolution by exploiting a large dataset of SAR imagery that spans seventy-two months before and sixteen months after the mainshock. These satellite data show that up to 15 mm of subsidence occurred beginning three years before the mainshock. This deformation occurred within two Quaternary basins that are located close to the epicentral area and are filled with sediments hosting multi-layer aquifers. After the earthquake, the same basins experienced up to 12 mm of uplift over approximately nine months. Before the earthquake, the rocks at depth dilated, and fractures opened. Consequently, fluids migrated into the dilated volume, thereby lowering the groundwater table in the carbonate hydrostructures and in the hydrologically connected multi-layer aquifers within the basins. This process caused the elastic consolidation of the fine-grained sediments within the basins, resulting in the detected subsidence. After the earthquake, the fractures closed, and the deep fluids were squeezed out. The pre-seismic ground displacements were then recovered because the groundwater table rose and natural recharge of the shallow multi-layer aquifers occurred, which caused the observed uplift.
1 April 2021 in International Journal of Disaster Risk Reduction
We present new 40Ar/39Ar data which allow us to refine the recurrence time for the most recent eruptive activity occurred at Colli Albani Volcanic District (CAVD) and constrain its geographic area. Time elapsed since the last eruption (36 kyr) overruns the recurrence time (31 kyr) in the last 100 kyr. New interferometric synthetic aperture radar data, covering the years 1993–2010, reveal ongoing inflation with maximum uplift rates (>2 mm/yr) in the area hosting the most recent (<200 ka) vents, suggesting that the observed uplift might be caused by magma injection within the youngest plumbing system. Finally, we frame the present deformation within the structural pattern of the area of Rome, characterized by 50 m of regional uplift since 200 ka and by geologic evidence for a recent (<2000 years) switch of the local stress‐field, highlighting that the precursors of a new phase of volcanic activity are likely occurring at the CAVD.
13 September 2024 in Communications Earth & Environment
Understanding and managing unrest at a volcano include i) ascertaining the magmatic distribution and migration, and ii) tracking the evolution of the shallow plumbing system. Here we use multi-technique geodetic data, mechanical models, and petrological simulations to define both aspects for the ongoing (2005-present) unrest at Campi Flegrei caldera, Italy. Results show a deformation source exhibiting progressive widening and shallowing, from 5.9 to 3.9 kilometres. Concurrently, a deeper tabular source at 8 km depth experiences limited but constant deflation. Petrological calculations explain inflation of the shallower source resulting from the rise of 0.06 to 0.22 cubic kilometres of magma from depth ≥8 kilometres. Our analysis provides strong evidence that magma ascent to depths shallower than 8 kilometres is the ultimate driver behind the ongoing unrest. This merging of geodetic and petrological approaches to track the evolution of a plumbing system better constrains magma ascent at volcanoes experiencing unrest.