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Phreatomagmatic eruption

About: Phreatomagmatic eruption is a research topic. Over the lifetime, 1281 publications have been published within this topic receiving 48612 citations.


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Journal ArticleDOI
26 May 1977-Nature
TL;DR: Injection of basic magma into acid magma causes superheating of the acid and vigorous convection as discussed by the authors, which can lead to an explosive acid eruption in volcanic edifices.
Abstract: Injection of basic magma into acid magma causes superheating of the acid magma and vigorous convection. Vesiculation induced by convection and increased magma pressure fractures the volcanic edifice triggering an explosive acid eruption. The 1875 plinian eruption of Askja, Iceland is an example of an explosive eruption triggered by magma mixing.

732 citations

Journal ArticleDOI
TL;DR: In this paper, the authors identified 205 eruptions in historical time by detailed mapping and dating of events along with extensive research on documentation of volcanic activity in historical chronicles and classified them into three categories: effusive, effusive and mixed.

571 citations

Journal ArticleDOI
TL;DR: In this article, the vesicularity of juvenile clasts in pyroclastic deposits is measured for the 16-32 mm size fraction by water immersion techniques and converted to vesicleities using measured dense-rock equivalent densities.
Abstract: The vesicularity of juvenile clasts in pyroclastic deposits gives information on the relative timing of vesiculation and fragmentation, and on the role of magmatic volatiles versus external water in driving explosive eruptions. The vesicularity index and range are defined as the arithmetic mean and total spread of vesicularity values, respectively. Clast densities are measured for the 16–32 mm size fraction by water immersion techniques and converted to vesicularities using measured dense-rock equivalent densities. The techniques used are applied to four case studies involving magmas of widely varying viscosities and discharge rates: Kilauea Iki 1959 (basalt), Eifel tuff rings (basanite), Mayor Island cone-forming deposits (peralkaline rhyolite) and Taupo 1800 B.P. (calc-alkaline rhyolite). Previous theoretical studies suggested that a spectrum of clast vesicularities should be seen, depending on the magma viscosity, eruption rate, and the presence and timing of magma: water interaction. The new data are consistent with these predictions. In magmatic “dry” eruptions the vesicularity index lies uniformly in the range 70%–80% regardless of magma viscosity. For high viscosities and eruption rates the vesicularity ranges are narrow (< 25%), but broaden to between 30% and 50% as the viscosity and eruption rates are lowered and the volatiles and magma can de-couple. In phreatomagmatic “wet” eruptions, widely varying clast vesicularities reflect complex variations in the relative timing of vesiculation and water-induced fragmentation. Magma:water interaction at an early stage greatly reduces the vesicularity indices (< 40%) and broadens the ranges (as high as 80%), whereas late-stage interaction has only a minor effect on the index and broadens the range to a limited extent. Clast vesicularity represents a useful third parameter in addition to dispersal and fragmentation to characterise pyroclastic deposits.

519 citations

Journal ArticleDOI
01 Mar 1988-Nature
TL;DR: The relationship Ω·−α Ω¨ − A = 0 describes the behavior of materials in terminal stages of failure, where Ω is an observable quantity such as strain, and A and α are empirical constants.
Abstract: The relationship Ω·–α Ω¨ – A = 0 describes the behaviour of materials in terminal stages of failure, where Ω is an observable quantity such as strain, and A and α are empirical constants. Drawing on analogies between failure mechanics and eruption processes at volcanoes, Ω is interpreted in terms of conventional geodetic, seismic or geochemical observations. Manipulation of Ω provides a consistent analytical basis for eruption prediction.

487 citations

Journal ArticleDOI
TL;DR: The Skaftar Fires eruption in southern Iceland lasted for eight months during 1783 to 1784, and produced one of the largest basaltic lava flows in historic times (14.7±1.0 km3).
Abstract: The Laki (Skaftar Fires) fissure eruption in southern Iceland lasted for eight months during 1783 to 1784, and produced one of the largest basaltic lava flows in historic times (14.7±1.0 km3). In addition, neighboring Grimsvotn central volcano was frequently active during the period from May 1783 to May 1785. The combined activity is interpreted as having been the result of a two-year-long volcano-tectonic episode on the Grimsvotn volcanic system. Contemporary descriptions of the explosive activity make it possible to relate the tephra stratigraphy to the progress of the eruption on a weekly basis and show that activity on the fissures propagated to the NE with time, towards Grimsvotn. The eruption at Laki began on 8 June with a brief explosive event on a short fissure, and lava rapidly began to flow into the Skafta river gorge. It reached the lowlands, 35 km away, four days later and continued to flow, with variable discharge, until 7 February 1784. Approximately 90% of the lava was emplaced in the first five months of activity. The 27-km-long vent complex is composed of tenen echelon fissures distributed on both sides of the much older Laki hyaloclastite mountain. The surface expression of each fissure is a continuous row of vents consisting of scoria cones, spatter cones, and tuff cones. Six tephra fall units are positively identified; two units are completely compsed of phreatomagmatic tephra derived from two tuff cones and the others are Strombolian deposits. The volume of tephra, including ash fall that extended to mainland Europe, is 0.4 km3 dense rock equivalent volume, or 2.6% of the total erupted volume. Interpretation of contemporary descriptions of tephra falls, combined with the preserved stratigraphy, allow the identification of ten eruptive episodes during the eight months of activity on the Laki fissures. These eruptive episodes are inferred to have resulted from the unsteady flow of magma in the feeder system. In addition, at least eight eruption episodes occurred at Grimsvotn in 1783 to 1785, five in 1783, two in 1784, and one in 1785. Each episode at Laki began with a seismic swarm of increasing intensity that led to the formation of a new fissure, the opening of which was followed by short-lived phreatomagmatic activity caused by the high water table around the eruption site. Activity usually changed to violent Strombolian or sub-Plinian, followed by Hawaiian fire fountaining and effusive activity as the availability of groundwater dwindled. Thus, the explosive activity associated with the opening of each fissure was largely controlled by external watermagma interactions. Maximum effusion rates, occurring in the first two episodes, are estimated to have been 8.5x103 and 8.7x103 m3 s-1 from fissures totaling 2.2 and 2.8 km in length, respectively, and, in general, discharge gradually decreased over time. The highest rates are equivalent to 5.6x103 and 4.5x103 kg s-1 per meter length of fissure, values that could conceivably be similar to those that produced some flood basalt lava flows. Maximum fire fountain heights are estimated to have varied from 800 m to 1400 m and convecting eruption columns above the vents rose to a maximum altitude of about 15 km. The release of sulfur gases during fountaining produced an acid haze (aerosol) which spread widely and had a considerable environmental, and possibly climatic, impact on the Northern Hemisphere.

424 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202320
202255
202130
202033
201945
201830