Abstract
The structure of an active volcano is highly dependent on the interplay between the geodynamic context, the tectonic assessment as well as the magmatic processes in the plumbing system. This complex scenario, widely explored at Etna during the last 40 years, is nevertheless incomplete for the recent historical activity. In 1763 two eruptions occurred along the west flank of the volcano. There, an eruption started on 6th February and formed the scoria cone of Mt. Nuovo and a roughly 4-km-long lava flow field. Another small scoria cone, known as Mt. Mezza Luna, is not dated in historical sources. It is located just 1 km eastward of Mt. Nuovo and produced a 700 m long flow field. We focused on the activity of Mts. Nuovo and Mezza Luna for several reasons. First, the old geological maps and volcanological catalogues indicate that Mt. Mezza Luna and Mt. Nuovo cones were formed during the same eruption, while historical sources described Mt. Nuovo’s activity as producing a single scoria cone and do not give information about the formation of Mt. Mezza Luna. Second, petrologic studies highlight that the products of Mt. Mezza Luna are similar to the sub-aphyric Etna basalts; they preserve a composition relatively close to Etna primitive magma which were also erupted in 1763, during La Montagnola flank eruption, which took place along the South Rift of the volcano. Third, the two scoria cones built up along the so-called West Rift of Etna, which represents one of the main magma-ascent zones of the volcano. We applied a multidisciplinary approach that could prove useful for other volcanoes whose past activity is still to be reconstructed. Critical reviews of historical records, new field surveys, petrochemical analyses and petrologic modelling of the Mts. Nuovo and Mezza Luna eruptions have been integrated with literature data. The results allowed improving the stratigraphic record of historical eruptions reported in the Mount Etna Geological map, modelling the sub-volcanic magmatic processes responsible for magma differentiation, and evidencing recurrent mechanisms of magma transfer at Etna. Indeed, the intrusion of a deep primitive magma along the South Rift is often associated with the activation of other rift zones that erupt residual magma stored in the shallow plumbing system.
Highlights
The structure of Etna is closely determined by the interplay of processes involving magma dynamics as well as the geodynamic and volcano-tectonic setting of the area, which together influence the distribution of magma storage zones, the geometry of ascending magma paths and the eruptive style of volcanic activity (Condomines et al, 1995; Corsaro and Pompilio, 2004; Tanguy et al, 1997; Branca and Ferrara, 2013; Barreca et al, 2018, 2020)
Even if numerous accounts are available for the volcanic activity of Etna during the last 400 years (Branca and Del Carlo 2005; Tanguy et al, 2007), some eruptions are still not cited in the historical sources (Branca and Vigliotti, 2015)
Following the destructive 1669 eruption and 1693 tectonic earthquakes (Tanguy, 1981; Branca and Del Carlo, 2005; Branca et al, 2015b), a “pre-scientific” era began in the 18th century with a detailed description of all the observed phenomena, mainly thanks to Recupero
Summary
The structure of Etna is closely determined by the interplay of processes involving magma dynamics as well as the geodynamic and volcano-tectonic setting of the area, which together influence the distribution of magma storage zones, the geometry of ascending magma paths and the eruptive style of volcanic activity (Condomines et al, 1995; Corsaro and Pompilio, 2004; Tanguy et al, 1997; Branca and Ferrara, 2013; Barreca et al, 2018, 2020) This complex scenario has been widely explored from the 1980s onwards, as the development of Etna’s instrumental monitoring networks has led to an exponential increase of data available to study and better understand the recent eruptions. The investigations of eruptive activity in recent historical times are rare and unsystematic (Tanguy, 1981), in particular since the 17th century
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