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[1] The 2004 -05 eruption of Etna was characterised by outpouring of degassed lava from two vents within Valle del Bove. After three months of eruption lava volumes were estimated to be between 18.5 and 32 Â 10 6 m 3 , with eruption rate between 2.3 and 4.1 m 3 /s. Petrological analyses show that magma is resident in the shallow plumbing system, emplaced during the last South-East Crater activity. SO 2 flux data show no increase at the onset of the eruption and SO 2 /HCl ratios in gas emitted from the eruptive fissure are consistent with a degassed magma. No seismic activity was recorded prior to eruption, unlike eruptions observed since the 1980's. The purely effusive nature of this eruption, fed by a degassed, resident magma and the fracture dynamics suggest that magmatic overpressure played a limited role in this eruption. Rather, lateral spreading of Etna's eastern flank combined with general inflation of the edifice triggered a geodynamicallycontrolled eruption.

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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.