Environmental Engineering Reference
In-Depth Information
50
1
2
3
4
5-1617-19
SEC paroxysmal episodes
Weak strombolian activit
Effusive activity
40
30
20
10
120 000
10 000 000
100 000
8 000 000
80 000
6 000 000
60 000
4 000 000
40 000
4500 t/d
2 000 000
20 000
Jan 2009
Jan 2010
Jan 2011
Jan 2012
Figure 6.5 Temporal evolution of CO
2
/SO
2
ratios (upper panel) and CO
2
uxes
(lower panel, solid thin line, right scale) at Etna during 2009
ed
from Patanè
et al
.,
2013
). Resumption of lava-fountaining activity (vertical grey
bars) at the new south-east crater in early 2011 was preceded by several months of
increasing CO
2
/SO
2
ratios and CO
2
-
2011 (modi
20 000
t/day, respectively. Four main distinct CO
2
degassing regimes are identi
fluxes, with peaks of
20 and
>
>
ed by
changes in the gradient of the cumulative CO
2
mass curve (lower panel, solid
thick curve, left scale), with the highest
fluxes being observed in the preparatory
phase of the eruptions (September to December 2010).
(Stoiber
et al
.,
1983
). The COSPEC was central to volcanology for more than
20 years, before it was replaced with ultraviolet (UV) spectrometers based on
charge-coupled device (CCD) detectors (Galle
et al
.,
2003
). A major advantage of
UV spectrometers is a high degree of automation, which opened the way for the
ux scanning systems (Edmonds
et al
.,
2003
; Galle
et al
.,
2010
). The higher time resolution of differential optical
absorption spectroscopy (DOAS) scanning networks represented a major advance
in the geochemical surveillance of active volcanoes (e.g. Burton
et al
.,
2009
).
Ultraviolet cameras with temporal resolutions up to
first networks of fully autonomous volcanic SO
2
-
~
1 Hz (Mori and Burton,
2006
) are now used to study rapid SO
2
flux variations associated with passive
degassing (Tamburello
et al
.,
2013
) and transient volcanic phenomena such as
Strombolian (Tamburello
et al
.,
2012
) and Vulcanian (Holland
et al
.,
2011
)
explosions.
SO
2
-
ux observations made over the last 40 years have greatly advanced several
central issues in volcanology. They have served as the basis for calculations of gas
and magma-degassing budgets for individual volcanic systems (e.g. Allard
et al
.,
