Marsili Seamount (Marsili Volcano), Southern Tyrrhenian Sea, Tyrrhenian Sea, Italyi

Regional Level Types
Marsili Seamount (Marsili Volcano)	Seamount
Southern Tyrrhenian Sea	Sea
Tyrrhenian Sea	Sea
Italy	- not defined -

Marsili, located in the Tyrrhenian Sea about 175 kilometers south of Naples, is one of the largest volcanoes in Europe, with a length of 70 kilometres and a width of 30 kilometres. It is a NNE-SSW elongated volcanic complex of about 2100 km and rises from about 3200 m to 508 m b.s.l. It was discovered during the 1920s and named after Italian scholar Luigi Ferdinando Marsili (1658-1730). Extensive studies have been carried on only since the early 2000s.

The Marsili rocks have a medium to high K-calc-alkaline affinity and range in composition from basalts to trachytes with the less evolved basalts related to IAB and OIB-like mantle sources (Beccaluva et al., 1982; Trua et al., 2002, 2010; Iezzi et al., 2014; Tamburrino et al., 2015). Most of the Marsili products consist of 1.07 to 0.1 Ma old lava flows (Selli et al., 1977; Cocchi et al., 2009). Geochemical data indicate that the Marsili evolution is dominated by fractional crystallisation processes from a heterogeneous, enriched mantle source variously modified, according to geophysical data (Pontevivo & Panza, 2006; Chiarabba et al., 2015), by the addition of slab-derived fluids (Trua et al., 2002, 2010). At present, Marsili seamount is affected by intra-seamount seismicity due to volcanotectonic and hydrothermal-induced activity (D'Alessandro et al., 2009). The occurrence of such hydrothermal activity and active degassing is supported by the occurrence of primary sulfide-poor Fe-oxyhydroxides and by geochemical data on the water column, which detect He of mantle origin (Dekov & Savelli, 2004; Lupton et al., 2011). Results of a coupled magnetic and gravity survey (Caratori Tontini et al., 2010) suggest that Marsili is characterised by a shallow, magmatic reservoir whose top is located at about 2500 m b.s.l., i.e., 2000 m from the M seamount summit, and by a deeper reservoir located at about 10–12 km depth (Pontevivo & Panza, 2006). Both Caratori Tontini et al. (2010) and Ventura et al. (2013) also suggest that Marsili has a tsunami-related hazard related to possible sector collapses and/or sea floor sliding associated to a renewal of explosive activity and/or gravity instability related to pore pressure variations. On the basis of the above considerations, Marsili is on a list of the most dangerous submarine volcanoes of the Tyrrhenian Sea, along with Magnaghi, Vavilov, and Palinuro.

References

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