Lava effusion — A slow fuse for paroxysms at Stromboli volcano?

Calvari, Sonia; Spampinato, Letizia; Bonaccorso, Alessandro; Oppenheimer, Clive; Rivalta, Eleonora; Boschi, E.

doi:10.1016/j.epsl.2010.11.015

Cited by 53 publications

(83 citation statements)

References 46 publications

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“…The effusion rate, Q U (t) ¼ pa 2 u(t), decays in time depending on the exit velocity, u(t), of the lava flow from the vent with radius a (1.5 m in our case 20 ). Modelling the effusion rate means modelling changes in the exit velocity with time.…”

Section: Resultsmentioning

confidence: 98%

“…The lava discharge mechanism is thus responsible for the gas exsolution in deeper portions of the conduit, promoting the gradual upward rise in the gas-rich magma column 20,23 . This process is considered to be the cause of the decompression of the deep (7-10 km) 21,33,34 magma reservoir, which in turn triggered the rapid, buoyant rise of the crystal-poor, volatile-rich batch of magma during the 15 March violent 'paroxysmal' explosion 20,23 .…”

Section: Discussionmentioning

confidence: 99%

“…This process is considered to be the cause of the decompression of the deep (7-10 km) 21,33,34 magma reservoir, which in turn triggered the rapid, buoyant rise of the crystal-poor, volatile-rich batch of magma during the 15 March violent 'paroxysmal' explosion 20,23 .…”

Section: Discussionmentioning

confidence: 99%

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Volcano seismicity and ground deformation unveil the gravity-driven magma discharge dynamics of a volcanic eruption

et al. 2015

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Effusive eruptions are explained as the mechanism by which volcanoes restore the equilibrium perturbed by magma rising in a chamber deep in the crust. Seismic, ground deformation and topographic measurements are compared with effusion rate during the 2007 Stromboli eruption, drawing an eruptive scenario that shifts our attention from the interior of the crust to the surface. The eruption is modelled as a gravity-driven drainage of magma stored in the volcanic edifice with a minor contribution of magma supplied at a steady rate from a deep reservoir. Here we show that the discharge rate can be predicted by the contraction of the volcano edifice and that the very-long-period seismicity migrates downwards, tracking the residual volume of magma in the shallow reservoir. Gravity-driven magma discharge dynamics explain the initially high discharge rates observed during eruptive crises and greatly influence our ability to predict the evolution of effusive eruptions.

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Section: Resultsmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

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Volcano seismicity and ground deformation unveil the gravity-driven magma discharge dynamics of a volcanic eruption

et al. 2015

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“…As for the paroxysms, their mechanism, in our opinion, has a different origin, although supporters of the "bubbles" theories explain such eruptions by non-standard sizes of bubble-slug (Del Bello et al, 2012). The nontrivial fact characteristic for paroxysms was found by Calvari et al, 2011: it is the existence of a "cumulative" amount of lava, which must be erupted before paroxysmal events. Critical volume of lava was equal to 4 .…”

Section: Eruptive Cycles and Paroxysmsmentioning

confidence: 85%

“…10 6 m 3 . It was found for two paroxysms occurred April 5, 2003 andMarch 15, 2007 during the corresponding effusive eruptions (Calvari et al, 2011).…”

Section: Eruptive Cycles and Paroxysmsmentioning

confidence: 93%

Magma, Crust and Fluid: Critical Conditions of their Interaction and Types of Volcanic Eruptions

Nechayev¹

2015

APR

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The mechanism of Gas-Liquid Imbalance (GLI-mechanism) is applied to the theoretical description of the behavior of the magmatic system for different types of volcanic eruptions. It is shown that physical interaction of contacting volumes of magma and gaseous fluid under certain critical conditions can lead to the formation of stratovolcano and caldera. With unified theoretical positions the development of Strombolian, Plinian, Hawaiian, areal and highexplosive volcanic eruption is discussed.Keywords: Magma system, stratovolcano, caldera forming, eruption mechanism, fluid layer, monogenetic cone Mechanisms of Volcanic EruptionModern scientific ideas about the structure of the Globe are based on the fact that the Earth's crust was formed due to cooling of juvenile magmatic melt which is still now at depths of several tens of kilometers and from time to time is erupting to the surface as a result of volcano activity. There are many theories of volcanism (Parfitt & Wilson, 2008) but they do not satisfy fully the scientific community. A variety of types of volcanoes creates space for scientific thought, but the need for a simple, clear and physically "universal" mechanism of volcanic eruption is not diminished. Perhaps the knowledge of such a mechanism (if it really exists) could give scientific basis for real predictions of eruptions with disastrous consequences.There are two most popular models of basaltic volcanism: the Rise Speed Dependence (RSD)-model, where the acceleration and eruption occur due to magma defragmentation and expansion of gas bubbles; the Collapse Foam (CF)-model, where gas bubbles accumulated inside plumbing system attain some critical volume, rise with magma and erupt out from volcano (Parfitt, 2004). RSD-model allows extensive physical and mathematical treatment, since the formation of bubbles, reducing density and viscosity of magma melt, can be adequately considered in the thermo-and hydrodynamics of the process. In the CF-model similar approach is missing. However, in Del Bello et al., 2012 the possibility of bubble instability depending on its linear dimensions is demonstrated. It is important that for RSD-model you need a primary upward movement of magma to bring at lower pressures new portions of gas-saturated melt. Further acceleration of magma (up to supersonic speeds) is explained by its defragmentation and decreasing of average density and viscosity due to gas bubbles. But where does this driving force of the primary magma ascent come from? This question usually remains unanswered. Bottle effect of "Coca-Cola" which supporters of RSD-model like to refer occurs only when you are opening a bottle sharply, that is when you quickly drop the pressure inside the liquid saturated with gas. Real magma rises to the surface slowly, its decompression occurs gradually (this, of course, not talking about explosive eruptions when lava vent is clogged by plug). As for the CF-model, it is unclear how a large volume gas bubble can push out magma column. It can float in the magma as a buoyant...

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Reactivation of Stromboli's summit craters at the end of the 2007 effusive eruption detected by thermal surveys and seismicity

et al. 2015

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This work arises from the field observations made during the civil protection emergency period connected to the 2007 Stromboli eruption. We observed changes in the shallow feeding system of the volcano to which we give a volcanological interpretation and the relative implications. Here we describe the processes that occurred in the upper feeding system from the end of the 2007 effusive eruption on 3 April to the renewal of the strombolian explosive activity at the summit craters (30 June), interpreted using multidisciplinary data. We used thermal camera data collected both from helicopter and from a fixed station at 400 m to retrieve the evolving summit crater activity. These data, compared with seismic signals and published geochemical records, allowed us to detail the shifting of the degassing activity within the crater terrace from NE to SW, occurred between 15 and 25 April 2007 prior to the resumption of the strombolian activity. In particular, from mid‐April, a gradual SW displacement in the maximum apparent temperatures was recorded at the vents within the summit craters, together with a change in the very long period location and confirmed by variations in geochemical indicators (CO2/SO2 plume ratios and CO2 fluxes) from literature. The shallow feeding system experienced a major readjustment after the end of the effusive activity, determining variations in the pressure leakage of the source, slowly deepening and shifting toward SW. All these data, together with the framework supplied by previous structural surveys, allowed us to propose that the compaction of debris accumulated in the uppermost conduit by inward crater collapses, occurred in early March, produced the observed anomalies. At Stromboli, major morphology changes, taking place in the following years, were anticipated by these small and apparently minor processes occurred in the upper feeding system. Other studies are relating similar changes to modifications of the eruptive activity also at other open‐conduit volcanoes, so we believe that it may be important to have a constant monitoring of these phenomena in order to better understand their shallow feeding systems.

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Lava effusion — A slow fuse for paroxysms at Stromboli volcano?

Cited by 53 publications

References 46 publications

Volcano seismicity and ground deformation unveil the gravity-driven magma discharge dynamics of a volcanic eruption

Volcano seismicity and ground deformation unveil the gravity-driven magma discharge dynamics of a volcanic eruption

Magma, Crust and Fluid: Critical Conditions of their Interaction and Types of Volcanic Eruptions

Reactivation of Stromboli's summit craters at the end of the 2007 effusive eruption detected by thermal surveys and seismicity

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