The morphostructural setting of Mount Etna sedimentary basement (Italy): Implications for the geometry and volume of the volcano and its flank instability

Branca, Stefano; Ferrara, Vincenzo

doi:10.1016/j.tecto.2012.11.011

Cited by 65 publications

(75 citation statements)

References 49 publications

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“…The geometry of the eastern Etna non-magnetic basement is fully consistent with that of huge, east facing landslide depression pre-existing the construction of the volcano7. This latter conclusion is supported by the occurrence of 220 to 130 ka old, 10 to 30° west-dipping lava successions along the Ionian coast821.…”

Section: Discussionsupporting

confidence: 68%

Volcanic conduit migration over a basement landslide at Mount Etna (Italy)

Nicolosi

Caracciolo

Branca

et al. 2014

Sci Rep

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The flanks of volcanoes may slide in response to the loading of the edifice on a weak basement, magma push, and/or to tectonic stress. However, examples of stratovolcanoes emplaced on active landslides are lacking and the possible effects on the volcano dynamics unknown. Here, we use aeromagnetic data to construct a three-dimensional model of the clay-rich basement of Etna volcano (Italy). We provide evidence for a large stratovolcano growing on a pre-existing basement landslide and show that the eastern Etna flank, which slides toward the sea irrespective of volcanic activity, moves coherently with the underlying landslide. The filling of the landslide depression by lava flows through time allows the formation of a stiffness barrier, which is responsible for the long-term migration of the magma pathways from the coast to the present-day Etna summit. These unexpected results provide a new interpretation clue on the causes of the volcanic instability processes and of the mechanisms of deflection and migration of volcanic conduits.

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Section: Discussionsupporting

confidence: 68%

Volcanic conduit migration over a basement landslide at Mount Etna (Italy)

Nicolosi

Caracciolo

Branca

et al. 2014

Sci Rep

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“…This dramatic and sudden drop in the level of the magma would have brought the magma into contact with the main groundwater contained in the volcanic body, which is located just above the contact surface between the volcanic pile and its impermeable (clay-rich) basement. In the central zone of the NE Rift, the impermeable basement is at ∼1200-1300 m asl (Branca and Ferrara, 2012;Siniscalchi et al, 2012). Therefore we assume the level of magma fragmentation may have interacted with the aquifer when the vents shifted from ∼2400 to 1450-1325 m asl, generating phreatomagmatic (Surtseyan) activity along the higher portion of Fissure 3 (see Figure 12B).…”

Section: Drain-back In the Later Stage Of The Eruptive Fissures Propamentioning

confidence: 99%

Dynamic feeder dyke systems in basaltic volcanoes: the exceptional example of the 1809 Etna eruption (Italy)

Geshi

Neri

2014

Front. Earth Sci.

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The detection and understanding of the movement of magma at very shallow levels remains one of the most fascinating challenges of modern volcanology, because such information allows us to identify and circumscribe the most probable location where future eruptive vents will open. Unfortunately, it is rarely possible to observe any detail of the internal structure of the feeder system of recent eruptions; in only very few cases, geological observations in dissected volcanoes can help us imagine how magma moved and evolved inside the feeder system. In this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical and rare case in which it is possible to closely observe the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analyzed well-exposed cross sections of the uppermost 15-20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose a dynamic model of the magma behavior inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. This is therefore an exceptional case to understand how basaltic magmas move during the propagation of an eruptive fissure, which furnishes fundamental elements for the modeling of superficial intrusive processes. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas.

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“…Etna (stations locations are shown in the inset map of Fig. 7a), the stratigraphic sequence and local velocity model were made by integrating literature information and geological observations (Azzaro et al, 2010;Branca et al, 2011;Branca and Ferrara, 2013;Panzera et al, 2011Panzera et al, , 2015Priolo, 1999). The soil models consist of a number of viscoelastic layers, stacked over a half-space, each of them being defined by the thickness (h), the velocity of the body waves (V p and V s ), the density (ρ) and the Q factor, which controls the inelastic properties.…”

Section: Accounting For Site-specific Responsementioning

confidence: 99%

When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy – Part 2: Computational implementation and first results

Peruzza

Azzaro

Gee

et al. 2017

Nat. Hazards Earth Syst. Sci.

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Abstract. This paper describes the model implementation and presents results of a probabilistic seismic hazard assessment (PSHA) for the Mt. Etna volcanic region in Sicily, Italy, considering local volcano-tectonic earthquakes. Working in a volcanic region presents new challenges not typically faced in standard PSHA, which are broadly due to the nature of the local volcano-tectonic earthquakes, the cone shape of the volcano and the attenuation properties of seismic waves in the volcanic region. These have been accounted for through the development of a seismic source model that integrates data from different disciplines (historical and instrumental earthquake datasets, tectonic data, etc.; presented in Part 1, by Azzaro et al., 2017) and through the development and software implementation of original tools for the computation, such as a new ground-motion prediction equation and magnitude-scaling relationship specifically derived for this volcanic area, and the capability to account for the surficial topography in the hazard calculation, which influences source-to-site distances. Hazard calculations have been carried out after updating the most recent releases of two widely used PSHA software packages (CRISIS, as in Ordaz et al., 2013; the OpenQuake engine, as in Pagani et al., 2014). Results are computed for short-to mid-term exposure times (10% probability of exceedance in 5 and 30 years, Poisson and time dependent) and spectral amplitudes of engineering interest. A preliminary exploration of the impact of sitespecific response is also presented for the densely inhabited Etna's eastern flank, and the change in expected ground motion is finally commented on. These results do not account for M > 6 regional seismogenic sources which control the hazard at long return periods. However, by focusing on the impact of M < 6 local volcano-tectonic earthquakes, which dominate the hazard at the short-to mid-term exposure times considered in this study, we present a different viewpoint that, in our opinion, is relevant for retrofitting the existing buildings and for driving impending interventions of risk reduction.

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The morphostructural setting of Mount Etna sedimentary basement (Italy): Implications for the geometry and volume of the volcano and its flank instability

Cited by 65 publications

References 49 publications

Volcanic conduit migration over a basement landslide at Mount Etna (Italy)

Volcanic conduit migration over a basement landslide at Mount Etna (Italy)

Dynamic feeder dyke systems in basaltic volcanoes: the exceptional example of the 1809 Etna eruption (Italy)

When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy – Part 2: Computational implementation and first results

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