Publication Date:
2017-04-04
Description:
Seismic activity, ground deformation, and soil and
fumarole temperatures acquired during 2004–2007 at Vulcano
(Aeolian Islands) are analysed and the time relations among the
different time series are discussed. Changes in temperature of
fumarolic gases took place during four ‘‘anomalous’’ periods
(November 2004–March 2005; October 2005–February 2006;
August–October 2006; July–December 2007) at the same time as
an increasing number of volcano-seismic events. In particular, the
temperatures at high temperature vents and at steam heated soil
ranged in time from 180 to 440 C and from 20 to 90 C, respectively.
The maximum daily number of volcano-seismic events was
57, reached during the second anomalous period. This seismicity,
characterised by focal depth generally lower than 1 km below sea
level (b.s.l.) and composed of different kinds of events associated
to both resonance and shear failure processes, is related to the
shallow dynamics of the hydrothermal system. During the analysed
period, very few volcano-tectonic earthquakes took place and tilt
recordings showed no sharp or important changes. In light of such
observations, the increases in both temperature and volcano-seismic
events number were associated to increases in the release of
gas from a deep and stable magma body, without magma intrusions
within the shallow hydrothermal system. Indeed, a greater release
of gas from depth leads to increased fluid circulation, that can
promote increases in volcano-seismic events number by both
fracturing processes and resonance and vibration in cracks and
conduits. The different trends observed in the measured geochemical
and geophysical series during the anomalous periods can
be due to either time changes in the medium permeability or a
changing speed of gas release from a deep magma body. Finally, all
the observed variations, together with the changing temporal distribution
of the different seismic event kinds, suggest that the
hydrothermal system at Vulcano can be considered unsteady and
dynamic.
Description:
Published
Description:
167–182
Description:
1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
Description:
JCR Journal
Description:
reserved
Keywords:
Volcano seismolog
;
soil and fumarole temperatures
;
tilt data
;
hydrothermal system
;
Vulcano Island
;
volcanic unrest
;
04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
;
04. Solid Earth::04.08. Volcanology::04.08.01. Gases
;
04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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