Lava fountains during the episodic eruption of South-East Crater (Mt. Etna), 2000: insights into magma-gas dynamics within the shallow volcano plumbing system

Mt. Etna, in Sicily (Italy) is well known for
frequent effusive and explosive eruptions from both its
summit and flanks. South-East Crater (SE Crater), one of
the four summit craters, has been the most active in the last
20 years and often produces episodic lava fountains over
periods lasting from a few weeks to months. The most
striking of such eruptive phases was in 2000. Sixty four
lava fountains, separated by quiescent intervals and
sometimes associated with lava overflows, occurred that
year between January and June, a time period during which
we consider the volcano to have been in episodic eruption.
This paper presents mainly results of petrochemical inves-
tigations carried out on both tephra and lavas collected during
a number of the lava fountain episodes in 2000. The new data
have been integrated with volcanological and seismic infor-
mation in order to correlate the features of the eruptive activity
with magma-gas dynamics in the plumbing system of SE
Crater. The main findings allow us to characterise the 2000
episodic eruption in the framework of the recent SE Crater
activity. In particular, we infer that the onset of the 2000
eruption was triggered by the ascent of new, more primitive
and volatile-rich magma that progressively intruded into the
SE Crater reservoir, where it mixed with the resident, more
evolved magma. Furthermore, we argue that the 2000 SE
Crater lava fountains largely resulted from the instability of a
foam layer accumulated at the top of the underlying reservoir
and rebuilt prior to each episode, in agreement with the
collapsing foam model for lava fountains.