Multidisciplinary investigation on a lava fountain preceding a flank eruption: The 10 May 2008 Etna case

Abstract

A multidisciplinary approach integrating a wide data set ranging from bulk rock compositions of the erupted products to volcanic tremor, long‐period events, and tilt and gravity signals is used to investigate the source depth and magma dynamics of the 10 May 2008 lava fountain at Southeast crater (SEC) of Mount Etna. The investigation was undertaken in the framework of the previous 2007 explosive activity as well as the subsequent effusive eruption beginning 13 May 2008 and lasting up to July 2009. All the data concur in indicating that the 10 May lava fountain was generated by the fragmentation of a foam layer trapped at the top of a shallow reservoir, about 1500–1700 m below the summit of SEC. The shift from the episodic strombolian/lava fountain activity occurring in 2007 at SEC to the more powerful 10 May 2008 lava fountain is explained by the intrusion of a new more primitive magma into the shallow reservoir. Data also indicate that an attempted magma intrusion east of the summit area occurred during the 10 May fire fountain. This event caused the fracturing and weakening of the surrounding rocks and created a preferential pathway for the penetration of the magma that, only 3 days later, started to feed the 2008–2009 effusive eruption.

Continuous magma recharge at Mt. Etna during the 2011–2013 period controls the style of volcanic activity and compositions of erupted lavas

“…Various types of evidence suggest that the pulsating magma transfer from the intermediate (2-6 km b.s.l. ; Patané et al 2006;Bonforte et al 2008;Bonaccorso et al 2011) to the shallow (1-2 km a.s.l. ; Palano et al 2008;Patanè et al 2013;Viccaro et al 2014) portions of the plumbing system could be considered the triggering mechanism of the paroxysmal activity of the NSEC.…”

“…The pressure range has been fixed between 250 and 60 MPa, which simulates differentiation occurring from~8 up to Patané et al 2006;Bonforte et al 2008;Palano et al 2008;Bonaccorso et al 2011;Viccaro et al 2014). In this regard, all the models in literature provide evidence for an elongated storage volume ranging between 2 and 6 km below sea level (Bonforte et al 2008;Bonaccorso et al 2011), which constitutes the intermediate portions of the plumbing system, and a shallower source with variable geometry at 1-2 km above sea level Patanè et al 2013;Viccaro et al 2014). Oxygen fugacity was set at the QFM buffer, which is in agreement with redox conditions expected for trachybasaltic magmas at Mt.…”

Open-path FTIR spectroscopy of magma degassing processes during eight lava fountains on Mount Etna

“…Etna in Sicily (e.g. Alparone et al, 2003;Branca and Del Carlo, 2005;Allard et al, 2005), Piton de la Fournaise in Reunion island (Staudacher et al, 2009) Nyamuragira on the east-African rift (Hayashi et al, 1992), and Izu-Oshima in Japan (Endo et al, 1988). Two models have been proposed for their genesis: i) the homogeneous flow and effervescent disruption of fast-rising bubbly melt (Wilson and Head, 1981;Parfitt, 2004), or ii) the violent emptying of a bubble-melt foam layer previously accumulated at depth, on top of a reservoir or a sill-like conduit discontinuity Vergniolle, 1988, 1989;Vergniolle and Jaupart, 1990).…”

Pressurization and depressurization phases inside the plumbing system of Mount Etna volcano: Evidence from a multiparametric approach

“…For these reasons, during the last years the number of multidisciplinary studies on Mount Etna has been increasing. Some of these studies focus on a single lava fountain episode [e.g., Bonaccorso et al ., ]; others take into account longer time intervals [e.g., Patanè et al ., ].…”