A discussion of the mechanisms of explosive basaltic eruptions

Parfitt, E. A.

doi:10.1016/j.jvolgeores.2004.01.002

Cited by 282 publications

(210 citation statements)

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“…Parfitt andWilson, 1995, 1999;Cashman, 2004;Parfitt, 2004). This study presents the first independent quantitative observational constraints on magma decompression rates, and thereby indirectly ascent rates, during explosive basaltic eruptions.…”

Section: Resultsmentioning

confidence: 91%

“…The style of basaltic explosive eruptions is thought to be predominantly dependent on the magma ascent velocity, which asserts a strong control on the movement and spatial distribution of the magmatic vapor (e.g. Wilson and Head, 1981;Parfitt et al, 1995;Parfitt, 2004;Goepfert and Gardner, 2010), and in turn affects the fluid dynamics and fragmentation of the erupting magma (Vergniolle and Jaupart, 1986;Parfitt, 2004;Houghton and Gonnermann, 2008;Namiki and Manga, 2006;Gonnermann, 2015). The presence of pre-existing exsolved volatiles (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

et al. 2016

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The decompression rate of magma as it ascends during volcanic eruptions is an important but poorly constrained parameter that controls many of the processes that influence eruptive behaviour. In this study we quantify decompression rates for basaltic magmas using volatile diffusion in olivine-hosted melt tubes (embayments) for three contrasting eruptions of Kīlauea volcano, Hawai'i. Incomplete exsolution of H 2 O, CO 2 and S from the embayment melts during eruptive ascent creates diffusion profiles that can be measured using microanalytical techniques, and then modelled to infer the average decompression rate. We obtain average rates of ~0.05-0.45 MPa s -1 for eruptions ranging from Hawaiian style fountains to basaltic subplinian, with the more intense eruptions having higher rates. The ascent timescales for these magmas vary from around ~5 to ~36 minutes from depths of ~2 to ~4 km respectively. Decompression-exsolution models based on the embayment data also allow for an estimate of the mass fraction of pre-existing exsolved volatiles within the magma body. In the eruptions studied this varies from 0.1-3.2 wt%, but does not appear to be the key control on eruptive intensity. Our results do not support a direct link between the concentration of pre-eruptive volatiles and eruptive intensity; rather they suggest that for these eruptions decompression rates are proportional to independent estimates of mass discharge rate. Although the intensity of eruptions is defined by the discharge rate, based on the currently available dataset of embayment analyses it does not appear to scale linearly with average decompression rate. This study demonstrates the utility of the embayment method for providing quantitative constraints on magma ascent during explosive basaltic eruptions.

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Section: Resultsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

et al. 2016

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“…Houghton and Gonnermann 2008;Cashman and Sparks 2013;Taddeucci et al 2015). Eruptions result from the arrival and burst of overpressured gas pockets (slugs) at the free-surface Blackburn et al 1976;Parfitt 2004;Houghton and Gonnermann 2008). This widely accepted scenario is supported by a large body of literature focused on understanding the mechanism behind explosions at Stromboli volcano (Aeolian Islands, Italy) via, for example, interpretation of seismic and infrasonic data (e.g.…”

Section: Introductionmentioning

confidence: 99%

Recycled ejecta modulating Strombolian explosions

et al. 2016

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Two main end-members of eruptive regimes are identified from analyses of high-speed videos collected at Stromboli volcano (Italy), based on vent conditions: one where the vent is completely clogged by debris, and a second where the vent is open, without any cover. By detailing the vent processes for each regime, we provide the first account of how the presence of a cover affects eruptive dynamics compared to open-vent explosions. For clogged vents, explosion dynamics are controlled by the amount and grain size of the debris. Fine-grained covers are entirely removed by explosions, favouring the generation of fine ash plumes, while coarse-grained covers are only partially removed by the explosions, involving minor amounts of ash. In both fine-and coarse-grained cases, in-vent ground deformation of the debris reflect variations in the volumetric expansion of gas in the conduit, with rates of change of the deformation comparable to ground inflation related to pre-burst conduit pressurization. Eruptions involve the ejection of relatively slow and cold bombs and lapilli, and debris is observed to both fall back into the vent after each explosion and to gravitationally accumulate between explosions by rolling down the inner crater flanks to produce the cover itself. Part of this material may also contribute to the formation of a more degassed, crystallized and viscous magma layer at the top of the conduit. Conversely, open-vent explosions erupt with hotter pyroclasts, with higher exit velocity and with minor or no ash phase involved.

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“…Two models were proposed to explain Strombolian explosions (summary in Parfitt, 2004): a collapsing foam model and a rise-rate-dependent model. In the collapsing foam model (CF), magma is stored within the area, like a magma chamber or a dike system, at a depth (3 km) where gas bubbles can exsolve from magma.…”

Section: Causes Of Strombolian Activitymentioning

confidence: 99%

“…In the rise-rate-dependent model (RSD), the Strombolian eruptions are assumed to be the result of bubbles segregation and coalescence process (summary in Parfitt, 2004). If the rise speed of magma is relatively low (below 0.01 m/s; Parfitt, Wilson, 1995; Fig.…”

Section: Causes Of Strombolian Activitymentioning

confidence: 99%

Stromboli – the best place to actively learn and understand the behavior of an active volcano and its processes

Bąk¹,

Bąk²,

Szubert³

2016

geotour

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Basaltic volcanism, a dominant mode of volcanic activity on Earth, occurs as explosive eruptions, resulting from the exsolution of magmatic gases and is exhibited by IntroductionActive volcanoes can become major tourist destinations visited by people for a variety of reasons. Some people would like to experience scenic beauty close to nature, while others have the ambition to climb a volcano, take photos, or learn about the surrounding geodiversity. Most of the tourists would like to explore various volcanic features such as eruptions, lava flows, fumaroles, geysers, boiling mud, and hot springs.A large impact on volcanic tourism is related to volcanic eruptions. An example is the eruption of Eyjafjallajökull (2010) in Iceland, when during a one month period, tourists watched both the fiery fissures and vast ash clouds from a close proximity. From the tourist's point of view, the best forms of volcanic activity are long-lived eruptions, when people can observe the activity from immediate vicinity and in relative safety. Such examples are displayed in the Hawaiian and Strombolian eruptions.In this paper, we present one of the most popular active volcanos in the world, the Stromboli Volcano (Fig. 1), that has been almost continuously active for 1300 yrs (Rosi et al., 2000). Anyone who sailed to Stromboli would be able to see the explosions at any time, because the ejection of bombs, black scoria, lapilli and ash occur every 10-20 min, accompanied by continuous degassing (Barberi et al., 1993). Location and accessStromboli is the northernmost island of the Aeolian Arc, located in the Southern Tyrrhenian Sea in the central Mediterranean. The distance to the mainland is 54 km, while it is 240 km to Naples (Napoli) and 55 km to Sicily. The nearest of the other Aeolian Islands is Panarea Island (Fig. 2), 18 km to the Southwest. Stromboli -the best place to actively learn and understand the behavior of an active volcano and its processesStromboli -najlepsze miejsce do poznania aktywnego wulkanu i zrozumienia procesów wulkanicznych

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A discussion of the mechanisms of explosive basaltic eruptions

Cited by 282 publications

References 73 publications

Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

Recycled ejecta modulating Strombolian explosions

Stromboli – the best place to actively learn and understand the behavior of an active volcano and its processes

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