Pressure, gas content and eruption periodicity of a shallow, crystallising magma chamber

Tait, S.; Jaupart, Claude; Vergniolle, S.

doi:10.1016/0012-821x(89)90025-3

Cited by 446 publications

(324 citation statements)

References 36 publications

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“…To estimate this stress change, we argue that the magma system might possibly have been overpressured relative to the roof rocks just prior to the channel eruption but not by an amount exceeding twice the tensile strength of the rocks [Tait et al, 1989] because there is no evidence that summit eruptions were occuring at that time; the system then had to become underpressured by an amount exceeding twice the compresive strength of the roof rocks so that roof failure and subsidence could occur. Assuming strengths of-5 MPa in tension and ~ 10 MPa in compression for the reservoir walls [Tait et al, 1989], we arrive at a required internal pressure change of at most 30 MPa. We estimate the volume of the reservoir to be of the order of 1400 km 3.…”

Section: Discussionmentioning

confidence: 99%

Estimation of volcanic eruption conditions for a large flank event on Elysium Mons, Mars

Wilson¹,

Mouginis-Mark²

2001

J. Geophys. Res.

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Section: Discussionmentioning

confidence: 99%

Estimation of volcanic eruption conditions for a large flank event on Elysium Mons, Mars

Wilson¹,

Mouginis-Mark²

2001

J. Geophys. Res.

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“…The overpressures driving magmatic ascent are typically 20 to 50 MPa, [Tait et al, 1989;Barmin et al, 2002;Stasiuk et al, 1993] which gives overpressure gradients of ∼ 10 4 Pa.m −1 .…”

Section: Low-slope Domes On the Moonmentioning

confidence: 99%

Dynamics of magmatic intrusions in the upper crust: Theory and applications to laccoliths on Earth and the Moon

Michaut

2011

J. Geophys. Res.

136

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[1] To understand the dynamics of shallow magmatic intrusions, I propose a theoretical model of magma spreading laterally below an elastic crust. Nondimensionalization of the flow equation leads to the identification of characteristic scales for the intrusion: while the characteristic intrusion length is controlled by the elastic response of the crust, its characteristic thickness primarily depends on magma properties and injection rate. Three spreading regimes are identified and characterized by different morphologies as well as by scaling laws for thickness versus length and thickness versus time. The first spreading regime is controlled by the elastic response of the crust and the shape of the flow is self-similar. When the time, length, and thickness become larger than an elastic time, length, and thickness scale, the edges of the flow become steeper and the system transitions to a gravity current regime. When the intrusion is thick enough to accommodate the pressure head, the flow enters a regime of lateral propagation and keeps a constant thickness. The intrusion shape in the elastic regime fits the observed shape of terrestrial laccoliths. The elastic scaling law for intrusion thickness versus length fits observations of laccoliths at Elba Island, Italy, and provides for a physical explanation for the observed relationship between length and thickness on terrestrial laccoliths. Laccoliths are predicted to form over short time scales, depending on magma viscosity, that vary between approximately a month to several years for felsic magmas on Earth. On the Moon, several elongated low-slope domes have recently been identified as possibly formed by laccolith intrusions at depth, although they are much larger than terrestrial laccoliths. Because the Moon has a smaller gravity than on the Earth, a deeper magma source, and a more mafic magma composition than for terrestrial laccoliths (implying smaller pressure gradient and dike width), lunar intrusions have a larger characteristic length and a smaller characteristic thickness. After nondimensionalization, the morphologies (length versus thickness) of terrestrial and inferred lunar laccoliths follow the same curve and are well fitted by the elastic scaling law. This model thus explains the size discrepancy between terrestrial laccoliths and lunar low-slope domes. Therefore, low-slope domes identified on the Moon are good candidates for laccolith-type intrusions at depth.

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“…The pressure change is normalized by the pressure change in incompressible magma. The shaded area is for the range of values characteristic of a 'dry magma' (K /E between 0.2 and 1.6; Tait et al 1989).…”

Section: Influence On Shallow Magma Chambers (A) Pressure Changes Witmentioning

confidence: 99%

Climate effects on volcanism: influence on magmatic systems of loading and unloading from ice mass variations, with examples from Iceland

Sigmundsson

Pinel

Lund

et al. 2010

Phil. Trans. R. Soc. A.

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Pressure influences both magma production and the failure of magma chambers. Changes in pressure interact with the local tectonic settings and can affect magmatic activity. Present-day reduction in ice load on subglacial volcanoes due to global warming is modifying pressure conditions in magmatic systems. The large pulse in volcanic production at the end of the last glaciation in Iceland suggests a link between unloading and volcanism, and models of that process can help to evaluate future scenarios. A viscoelastic model of glacio-isostatic adjustment that considers melt generation demonstrates how surface unloading may lead to a pulse in magmatic activity. Iceland's ice caps have been thinning since 1890 and glacial rebound at rates exceeding 20 mm yr −1 is ongoing. Modelling predicts a significant amount of 'additional' magma generation under Iceland due to ice retreat. The unloading also influences stress conditions in shallow magma chambers, modifying their failure conditions in a manner that depends critically on ice retreat, the shape and depth of magma chambers as well as the compressibility of the magma. An annual cycle of land elevation in Iceland, due to seasonal variation of ice mass, indicates an annual modulation of failure conditions in subglacial magma chambers.

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Pressure, gas content and eruption periodicity of a shallow, crystallising magma chamber

Cited by 446 publications

References 36 publications

Estimation of volcanic eruption conditions for a large flank event on Elysium Mons, Mars

Estimation of volcanic eruption conditions for a large flank event on Elysium Mons, Mars

Dynamics of magmatic intrusions in the upper crust: Theory and applications to laccoliths on Earth and the Moon

Climate effects on volcanism: influence on magmatic systems of loading and unloading from ice mass variations, with examples from Iceland

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