3-D density structure and geological evolution of Stromboli volcano (Aeolian Islands, Italy) inferred from land-based and sea-surface gravity data

Abstract

International audienceWe present the first density model of Stromboli volcano (Aeolian Islands, Italy) obtained by simultaneously inverting land-based (543) and sea-surface (327) relative gravity data. Modern positioning technology, a 1 × 1 m digital elevation model, and a 15 × 15 m bathymetric model made it possible to obtain a detailed 3-D density model through an iteratively reweighted smoothness-constrained least-squares inversion that explained the land-based gravity data to 0.09 mGal and the sea-surface data to 5 mGal. Our inverse formulation avoids introducing any assumptions about density magnitudes. At 125 m depth from the land surface, the inferred mean density of the island is 2380 kg m^−3, with corresponding 2.5 and 97.5 percentiles of 2200 and 2530 kg m^−3. This density range covers the rock densities of new and previously published samples of Paleostromboli I, Vancori, Neostromboli and San Bartolo lava flows. High-density anomalies in the central and southern part of the island can be related to two main degassing faults crossing the island (N41 and N64) that are interpreted as preferential regions of dyke intrusions. In addition, two low-density anomalies are found in the northeastern part and in the summit area of the island. These anomalies seem to be geographically related with past paroxysmal explosive phreato-magmatic events that have played important roles in the evolution of Stromboli Island by forming the Scari caldera and the Neostromboli crater, respectively

Two‐dimensional seismic attenuation images of Stromboli Island using active data

“…The maximum opening of the high scattering attenuation in the center of the island coincides with the same zone of high intrinsic attenuation. Interestingly, the observed SW-NE trend is in concordance with the trend of the tectonic structures in the area, showing almost the same pattern [Bosman et al, 2009;Okuma et al, 2009;Aiello et al, 2014;Linde et al, 2014].…”

Three‐dimensional density structure of La Soufrière de Guadeloupe lava dome from simultaneous muon radiographies and gravity data

“…In the presence of strong topography variations, relative gravity data can be used to retrieve an absolute density model [e.g., Linde et al, 2014]. Simple synthetic tests with anomalies like the one shown in Figure 2 suggest that the altitude differences of ∼150 m between the dome's summit and base are sufficient to retrieve absolute density values.…”

Susceptibility of intrusion-related landslides at volcanic islands: the Stromboli case study

“…& the structural elements related to this volcanism such as faults identified by previous geological studies (Tibaldi 2001;Tibaldi et al 2009), monitoring data (Bonaccorso 1998;Falsaperla et al 1999) and geophysical and geochemical surveys (Finizola et al 2002(Finizola et al , 2003Linde et al 2014). …”

“…The other area showing moderate susceptibility to intrusion-related landslides is the Rina Grande-Le Schicciole depression. This composite landslide scar was generated by one or more collapse that occurred between 34-26 and 2 ka (Linde et al 2014), producing rock/debris avalanches (Romagnoli et al 2009). The moderate susceptibility in the Rina Grande-Le Schicciole depression is mainly related to the presence of destabilizing factors, mainly slope and the presence of Breccia and Pyroclastic deposit units (Apuani et al 2005b).…”