323,297 research outputs found
Monitoring eruptive activity through web-cameras network and thermal mapping
No full textThermal imaging, especially in combination with geophysical and geochemical signals, have proved to be useful precursors of eruption
onsets. At many volcanoes, changes in temperatures at fumaroles, open-conduit vents, pre-existing fractures, groundwater, and
lava domes were followed by eruptions. In this paper I illustrate a few examples of results from thermal monitoring obtained during
recent effusive and explosive eruptions occurred at Etna and Stromboli Volcanoes.Published47-521.5. TTC - Sorveglianza dell'attività eruttiva dei vulcaniN/A or not JCRrestricte
Instabilities in the summit region of Mount Etna during the 1999 eruption
No full textDuring the 1999 eruption of Mount Etna,
Sicily, the summit of the volcano changed dramatically.
Lavas erupted from a fissure on the southern flank of SE
Cone formed a large compound flow field that buried a
substantial part of the northern wall of Valle del Bove
and the ground between there and SE Cone. Hot mass
flow deposits formed on the eastern and western flanks
of the Chasm following a period of intense Strombolian
activity. At the same time, a new vent opened on the
southern flank of SE Cone and there was a major rockfall
from its summit. Seven weeks later, part of the outer
western rim of Bocca Nuova crater collapsed during another
period of intense Strombolian activity, and lava
emerged at a high effusion rate through the breached crater
wall. Following a subsequent collapse of the Bocca
Nuova crater rim, a hot avalanche flowed a few hundred
metres on top of the previous lava flow field. Similar deposits
have been described on other volcanoes, but their
importance in the evolution of the summit of Etna has
not previously been recognised.grant from the commission of the European Communities underthe Fourth Framework Programme, Environment and Climate, Contract ENV4-CT97-0713Published526-5351.5. TTC - Sorveglianza dell'attività eruttiva dei vulcaniJCR Journalreserve
Instabilities in the summit region of Mount Etna during the 1999 eruption.
No full textDuring the 1999 eruption of Mount Etna, Sicily, the summit of the volcano changed dramatically. Lavas erupted from a fissure on the southern flank of SE Cone formed a large compound flow field that buried a substantial part of the northern wall of Valle del Bove and the ground between there and SE Cone. Hot mass flow deposits formed on the eastern and western flanks of the Chasm following a period of intense Strombolian activity. At the same time, a new vent opened on the southern flank of SE Cone and there was a major rockfall from its summit. Seven weeks later, part of the outer western rim of Bocca Nuova crater collapsed during another period of intense Strombolian activity, and lava emerged at a high effusion rate through the breached crater wall. Following a subsequent collapse of the Bocca Nuova crater rim, a hot avalanche flowed a few hundred metres on top of the previous lava flow field. Similar deposits have been described on other volcanoes, but their importance in the evolution of the summit of Etna has not previously been recognised
The Miocene Costa Giardini diatreme, Iblean Mountains, southern Italy: Model for maar-diatreme formation on a submerged carbonate platform
No full textIn this paper we present a model for the growth of a maar-diatreme complex in a shallow marine environment. The Miocene-age Costa Giardini diatreme near Sortino, in the region of the Iblei Mountains of southern Sicily, has an outer tuff ring formed by the accumulation of debris flows and surge deposits during hydromagmatic eruptions. Vesicular lava clasts, accretionary lapilli and bombs in the older ejecta indicate that initial eruptions were of gas-rich magma. Abundant xenoliths in the upper, late-deposited beds of the ring suggest rapid magma ascent, and deepening of the eruptive vent is shown by the change in slope of the country rock. The interior of the diatreme contains nonbedded breccia composed of both volcanic and country rock clasts of variable size and amount. The occurrence of bedded hyaloclastite breccia in an isolated outcrop in the middle-lower part of the diatreme suggests subaqueous effusion at a low rate following the end of explosive activity. Intrusions of nonvesicular magma, forming plugs and dikes, occur on the western side of the diatreme, and at the margins, close to the contact between breccia deposits and country rock; they indicate involvement of volatile-poor magma, possibly during late stages of activity. We propose that initial hydromagmatic explosive activity occurred in a shallow marine environment and the ejecta created a rampart that isolated for a short time the inner crater from the surrounding marine environment. This allowed explosive activity to draw down the water table in the vicinity of the vent and caused deepening of the explosive center. A subsequent decrease in the effusion rate and cessation of explosive eruptions allowed the crater to refill with water, at which time the hyaloclastite was deposited. Emplacement of dikes and plugs occurred nonexplosively while the breccia sediment was mostly still soft and unconsolidated, locally forming peperites. The sheltered, low-energy lagoon filled with marine limestones mixed with volcaniclastic material eroded from the surrounding ramparts. Ultimately, lagoonal sediments accumulated in the crater until subsidence or erosion of the tuff ring caused a return to normal shallow marine conditions.In press3.5. Geologia e storia dei vulcani ed evoluzione dei magmiJCR Journalope
Lava tube morphology on Etna and evidence for lava flow emplacement mechanisms
No full textLava tubes play a pivotal role in the formation of many lava flow fields. A detailed examination of several compound
‘a‘a lava flow fields on Etna confirmed that a complex network of tubes forms at successively higher levels within the flow
field, and that tubes generally advance by processes that include flow inflation and tube coalescence. Flow inflation is
commonly followed by the formation of major, first-order ephemeral vents which, in turn, form an arterial tube network.
Tube coalescence occurs when lava breaks through the roof or wall of an older lava tube; this can result in the unexpected
appearance of vents several kilometers downstream. A close examination of underground features allowed us to distinguish
between ephemeral vent formation and tube coalescence, both of which are responsible for abrupt changes in level or flow
direction of lava within tubes on Etna. Ephemeral vent formation on the surface is frequently recorded underground by a
marked increase in size of the tube immediately upstream of these vents. When the lining of an inflated tube has collapsed,
‘a‘a clinker is commonly seen in the roof and walls of the tube, and this is used to infer that inflation has taken place in the
distal part of an ‘a‘a lava flow. Tube coalescence is recognised either from the compound shape of tube sections, or from
breached levees, lava falls, inclined grooves or other structures on the walls and roof. Our observations confirm the
importance of lava tubes in the evolution of extensive pahoehoe and ‘a‘a flow fields on Etna.grant from the commission of the European Communities under the Fourth Framework Programme, Environment and Climate, Contract ENV4-CT97-0713.Published263-2801.5. TTC - Sorveglianza dell'attività eruttiva dei vulcaniJCR Journalreserve
Erratum to: Lava discharge during Etna’s January 2011 fire fountain tracked using MSG-SEVIRI
No full textIn the paper by Gouhier, M., Harris, A., Calvari, S., Labazuy,
P., Guéhenneux, Y., Donnadieu, F., Valade, S, entitled “Lava
discharge during Etna’s January 2011 fire fountain tracked
using MSG-SEVIRI” (Bull Volcanol (2012) 74:787–793,
DOI 10.1007/s00445-011-0572-y), we present data from a
Doppler radar (VOLDORAD 2B). This ground-based Lband
radar has been monitoring the eruptive activity of the
summit craters of Mt. Etna in real-time since July 2009 from a
site about 3.5 km SSE of the craters. Examples of applications
of this type of radar are reviewed by Donnadieu (2012)
and shown on the VOLDORAD website (http://wwwobs.
univbpclermont.fr/SO/televolc/voldorad/).
Although designed and owned by the Observatoire de
Physique du Globe in Clermont-Ferrand (OPGC), France,
VOLDORAD 2B is operated jointly with the INGV-Catania
(Italy) in the framework of a technical and scientific collaboration
agreement between the INGV of Catania, the French
CNRS and the OPGC-Université Blaise Pascal in Clermont-
Ferrand. The system also utilizes a dedicated micropatch
antenna designed at the University of Calabria (Boccia et al.
2010) and owned by INGV. The objective of the joint acquisition
of the radar data by INGV-Catania and the OPGC is
twofold: (1) to mitigate volcanic risks at Etna by better assessing
the hazards arising from ash plumes and (2) to allow detailed
study of volcanic activity and its environmental impact.
In the paper by Gouhier et al. (2012), we failed to
highlight this important collaboration between the INGV
Catania and the OPGC; a cooperation essential for the past,
current and future generation of such valuable data sets.
Specifically we wish to acknowledge the roles of Mauro
Coltelli, Michele Prestifilippo and Simona Scollo for their
important input into this project, and pivotal role in setting
up, and maintaining, this collaborative deployment.Published12611.5. TTC - Sorveglianza dell'attività eruttiva dei vulcaniJCR Journalrestricte
Magmatic Gas Leakage at Mount Etna (Sicily, Italy): Relationships With the Volcano-Tectonic Structures, the Hydrological Pattern and the Eruptive Activity
No full textLava tube morphology on Etna and evidence for lava flow emplacement mechanisms.
No full textLava tubes play a pivotal role in the formation of many lava flow fields. A detailed examination of several compound ‘a‘a lava flow fields on Etna confirmed that a complex network of tubes forms at successively higher levels within the flow field, and that tubes generally advance by processes that include flow inflation and tube coalescence. Flow inflation is commonly followed by the formation of major, first-order ephemeral vents which, in turn, form an arterial tube network. Tube coalescence occurs when lava breaks through the roof or wall of an older lava tube; this can result in the unexpected appearance of vents several kilometers downstream. A close examination of underground features allowed us to distinguish between ephemeral vent formation and tube coalescence, both of which are responsible for abrupt changes in level or flow direction of lava within tubes on Etna. Ephemeral vent formation on the surface is frequently recorded underground by a marked increase in size of the tube immediately upstream of these vents. When the lining of an inflated tube has collapsed, ‘a‘a clinker is commonly seen in the roof and walls of the tube, and this is used to infer that inflation has taken place in the distal part of an ‘a‘a lava flow. Tube coalescence is recognised either from the compound shape of tube sections, or from breached levees, lava falls, inclined grooves or other structures on the walls and roof. Our observations confirm the importance of lava tubes in the evolution of extensive pahoehoe and ‘a‘a flow fields on Etna
Major effusive eruptions and recent lava fountains: Balance between expected and erupted magma volumes at Etna volcano
No full textOver the last four decades Etna has shown a high output rate through numerous eruptions. The volcano has displayed two eruptive behaviors. The first is characterized by effusive eruptions that efficiently drained the storage system and emitted large volumes of magma, the second behavior is related to lava fountains, erupting small magma batches, which are normally with high frequency and have been considered as precursors of major effusive eruptions. In this paper, we present an updated estimation of emitted volumes from Etna eruptions, which include the 38 lava fountain episodes that occurred from January 2011 to April 2013. These recent explosive episodes have been frequent, discharging significant magma volumes. Observing the steady trend of magma output over time, we present insights on expected erupted volumes. We highlight that the January 2011 –April 2013 lava fountains, efficiently drained the intermediate-shallow storage system and favored a balance between the incoming and outgoing magma.Published6069–60731.5. TTC - Sorveglianza dell'attività eruttiva dei vulcaniJCR Journalope
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