Spatially resolved SO2 flux emissions from Mt Etna
Roberto D’AleoMarcello BitettoDario Delle DonneGiancarlo TamburelloAngélo BattagliaM. ColtelliDomenico PatanèMichele PrestifilippoMariangela SciottoAlessandro Aiuppa
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Abstract We report on a systematic record of SO 2 flux emissions from individual vents of Etna volcano (Sicily), which we obtained using a permanent UV camera network. Observations were carried out in summer 2014, a period encompassing two eruptive episodes of the New South East Crater (NSEC) and a fissure‐fed eruption in the upper Valle del Bove. We demonstrate that our vent‐resolved SO 2 flux time series allow capturing shifts in activity from one vent to another and contribute to our understanding of Etna's shallow plumbing system structure. We find that the fissure eruption contributed ~50,000 t of SO 2 or ~30% of the SO 2 emitted by the volcano during the 5 July to 10 August eruptive interval. Activity from this eruptive vent gradually vanished on 10 August, marking a switch of degassing toward the NSEC. Onset of degassing at the NSEC was a precursory to explosive paroxysmal activity on 11–15 August.Some of detailed petrologic studies on rock samples of middle to large sized explosive pyroclastic eruptions recently revealed that the eruptions were caused by simultaneous eruption of multiple distinct magma chambers beneath the volcanoes (e.g., Nakagawa et al. 2003: Shane et al. 2007). It is very important to examine the genetic relationships among the magmas to understand the magma feeding system which caused such explosive eruptions. The explosive pyroclastic eruption stage in Shirataka volcano, NE Japan (Fig. 1) is one of potential candidates for such kind of researches. The aim of this study is to reveal the magma feeding system beneath Shirataka volcano in the explosive pyroclastic eruption stage and examine the genetic relationships among magmas involved in the explosive eruption.
Peléan eruption
Vulcanian eruption
Pyroclastic fall
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Abstract We apply dynamical models to estimate the rheological properties of magma and lava during the 2021–22 eruption of La Soufrière Volcano, St Vincent. Analysis of the emplacement of a lava coulée gives viscosities in the range 0.94 × 10 10 Pa s to 5.97 × 10 10 Pa s. A static Bingham model gives a yield strength of 4.1 × 10 5 Pa. A dynamical model of conduit flow during the explosive phase of the eruption gives a viscosity range from 1.2 × 10 7 to 2.3 × 10 9 Pa s. A petrological model of magma viscosity in the source region falls in the range 10 2 to 10 3 Pa s. The very high viscosity of the lava is attributed to the presence of a remnant degassed and partially crystallized magma from previous eruptions that occupied the shallow conduit–vent system prior to onset of the 2021 explosive eruptions. Gas-rich magma pushed this degassed remnant magma out over a three-month period at a steady rate of about 1.2 m 3 s −1 and the explosive phase began when volatile-rich and much lower viscosity magma reached the surface.
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Abstract Magma ascent rate can control the hazard potential of an eruption, but it is difficult to directly determine. Here we investigate the variations in timescales of magma ascent and rates of magma ascent for the three most recent explosive and effusive eruptions of Kelud volcano in Indonesia (1990, 2007, and 2014) using the zoning of volatile elements (OH, Cl, F) in apatite. We found that crystals from the 2007 dome show chemical gradients and increasing concentrations (reverse zoning) in chlorine and/or fluorine towards the crystals’ rims whereas those of the 1990 and 2014 explosive eruptions are unzoned. Diffusion modelling of the volatile elements in zoned apatite of the 2007 dome rocks give magma ascent times of up to 3 months, although 71% of them are ≤ 60 days. In contrast, the maximum magma ascent timescales inferred from apatite of the 1990 and 2014 explosive eruptions are about 7–8 hours. Using the pre-eruptive magma storage depths obtained from petrological and phase equilibria studies, we calculate ascent rates of about > 0.4 × 10 − 3 m s − 1 for the 2007 dome, and > 2.6 × 10 − 1 m s − 1 for the 1990 and 2014 eruptions. We also calculated the magma viscosities for each eruption, which when combined with the magma ascent rates and magma mass discharge rates correspond well with the expected eruptive styles. Our study illustrates the robustness of modelling apatite zoning in volatile elements to constrain timescales and magma ascent dynamics, and highlights the important role of magma ascent on eruptive styles.
Magma chamber
Dome (geology)
Peléan eruption
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The long‐lived 222 Rn decay products 210 Pb, 210 Bi and 210 Po have been monitored in the plumes of several vents at Mount Etna (Sicily) from May to October 1986. The results show that the four main craters of this volcano emit gases whose compositions are different from each other. The 210 Bi/ 210 Pb ratios for the plumes have similar mean values, (close to 25), which correspond to a degassing time of 1.5 to 2.7 days, according to the model of Lambert et al. (1985/86). In contrast, 210 Po/ 210 Pb ratios have very different mean values in each plume: 35 at the Voragine crater, 20 at the Bocca Nuova crater, and 14 at the South East crater. These figures enable us to calculate proportions of deep magma of 50%, 29% and 19% in the degassing cells of these craters respectively. Moreover, the SE crater appears to be a secondary degassing vent, not directly related to the main magma reservoir. The evolution of these ratios has been related to variations in volcanic activity.
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Lunar pyroclastic beads are interpreted to represent primitive magmas derived from great depths and rapidly erupted to the surface in explosive events. However, a detailed mechanism for gas generation at great depth and rapid magma transport to the surface has not yet been described. Furthermore, the pyroclastic beads are not petrogenetically related to basalts erupted near the sampling sites. We propose a model in which these conundrums are resolved through gas build‐up in a low‐pressure micro‐environment near the tip of a magma‐filled crack (dike) propagating rapidly from the magma source depth to the surface. The gas rich region consists of a free gas cavity overlying a foam extending vertically for ∼20 km. Eruption of the foam results in the widespread emplacement of unfractionated pyroclastic beads. Subsequent ascent of the underlying gas‐free picritic magma is unlikely to occur, perhaps accounting for the lack of sampled eruptive equivalents.
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Interim results of thermal and structural modeling of volcanism on Io were presented. The final results of the modeling are summarized. The basic analysis is an evaluation of the magma trigger mechanism for initiating and maintaining eruptions. Secondary aspects include models of the mechanical mode of magma emplacement, interactions with a sulphur-rich upper crust, and more speculative implications for Io's volcanism.
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