Publication Date:
2017-04-04
Description:
Volcanism at Mount Etna (Italy) has been observed for millennia and inspired ancient mythologies as well as scientific thought
through countless generations.Yetmuch of our understanding of the way this volcano works stems fromstudies of the past 20 years, and
in particular from strengthened monitoring since the late 1980s. In addition, the eruptive activity of Etna has undergone significant
changes during the past 13 years, and these have led to an improved understanding of the relationship between the plumbing system of
the volcano and instability of its eastern to southern f lanks. Following the end of the 1991–1993 eruption, a new eruptive cycle began,
which so far has produced about 0.23 km3 of lavas and pyroclastics (dense-rock equivalent). The cycle evolved frominitial recharging of
the plumbing system and inf lation, followed by powerful summit eruptions and slow spreading of the eastern to southern f lanks, to a
sequence of f lank eruptions accompanied by accelerated f lank displacement. Structurally, the volcanic system has become increasingly
unstable during this period. Volcanological, geophysical and geochemical data allow the cause–effect and feedback relationships
between magma accumulation below the volcano, f lank instability, and the shift from continuous summit activity to episodic f lank
eruptions to be investigated. In this scenario, the growth of magma storage areas at a depth of 3–5 km below sea level exerts pressure
against those f lank sectors prone to displacement, causing them to detach from the stable portions of the volcanic edifice. Geochemical
data indicate that magma remains stored belowthe volcano, even during phases of intense eruptive activity, thus causing a net volumetric
increase that is accommodated by f lank displacement. Instability can be enhanced by the forceful uprise ofmagma through the f lanks, as
in 2001, when the f irst f lank eruption of the current eruptive cycle took place. Subsequent f lank eruptions in 2002–2003 and 2004–
2004, on the other hand, were, at least in part, facilitated by the opening of fractures at the head of moving f lank sector, although the
eruptions were significantly dissimilar from one another. Renewed inflation of the volcano after the 2004–2005 eruption, continued
displacement of the unstable f lank sector, and gradual resumption of summit activity in late-2005, demonstrate that the same feedback
mechanisms continue to be active, and the Etna system remains highly unstable. The evolution of earlier eruptive cycles shows that a
return to a state of relative stability is only possible once a voluminous f lank eruption effectively drains the magmatic plumbing system.
Description:
Published
Description:
85–114
Description:
reserved
Keywords:
Mount Etna
;
eruptive cycle
;
volcano monitoring
;
seismicity
;
deformation
;
geochemistry
;
structural geology
;
magma storage
;
03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
;
04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes
;
04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
2522562 bytes
Format:
application/pdf
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