Mechanical behaviour and failure modes in the Whakaari (White Island volcano) hydrothermal system, New Zealand

Heap, Michael; Kennedy, Ben; Pernin, Noémie; Jacquemard, Laura; Baud, Patrick; Farquharson, Jamie; Scheu, Bettina; Lavallée, Yan; Gilg, H. Albert; Letham-Brake, Mark; Mayer, Klaus; Jolly, Arthur D.; Reuschlé, Thierry; Dingwell, Donald B.

doi:10.1016/j.jvolgeores.2015.02.012

Cited by 100 publications

(107 citation statements)

References 81 publications

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“…the confining pressure) in any given region of the edifice (e.g. Heap et al, 2015a). It is generally understood that all volcanoes deform under their own weight to some extent (Shteynberg and Solov'yev, 1976;Dieterich, 1988;van Wyk de Vries and Borgia, 1996), driven largely by gravitational spreading and substratum flexure (van Wyk de Vries and Matela, 1998), which indicates that the local and far-field stresses operating in a volcanic edifice will evolve over time.…”

Section: Introductionmentioning

confidence: 99%

“…In Yakuno basalt, Shimada et al (1989) showed that ductile deformation was associated with distributed microcracking, granulation, and pore occlusion. The underlying physical mechanism -cataclastic pore collapse -is described in detail by Zhu et al (2010) and has since been interpreted in triaxially deformed tuff (Zhu et al, 2011;Alam et al, 2014;Heap et al, 2015b), basalt (Adelinet et al, 2013;Zhu et al, 2016), andesite (Heap et al, 2015a, trachyandesite (Loaiza et al, 2012), and dacite . This micromechanism can be distributed (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…This micromechanism can be distributed (e.g. Zhu et al, 2011;Heap et al, 2015b) or localised (e.g. Loaiza et al, 2012;Adelinet et al, 2013;Heap et al, 2015a) in the form of bands of compacted pores.…”

Section: Introductionmentioning

confidence: 99%

“…Zhu et al, 2011;Heap et al, 2015b) or localised (e.g. Loaiza et al, 2012;Adelinet et al, 2013;Heap et al, 2015a) in the form of bands of compacted pores. The predisposition for strain localisation in volcanic rock has been suggested as a function of stress nucleation around equant porosity (Adelinet et al, 2013), due to preferential alignment of pores (Loaiza et al, 2012), or along pre-existing planes of weakness, such as zones of amoeboid pores (pores that are rounded but highly irregular in shape) or microfractures (Heap et al, 2015a).…”

Section: Introductionmentioning

confidence: 99%

“…Shimada et al, 1989;Heap et al, 2015a;Zhu et al, 2016), as well as being heavily reliant on its initial porosity (Heap et al, 2015a;Zhu et al, 2016) and other factors such as temperature (Violay et al, 2012(Violay et al, , 2015Heap et al, 2017) and alteration (Siratovich et al, 2016). In detail, high effective pressures and/or high initial porosity promote ductile behaviour, whereas dilatant brittle failure is favoured in low-porosity volcanic rock deformed under a range of effective pressures.…”

Section: Introductionmentioning

confidence: 99%

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Inelastic compaction and permeability evolution in volcanic rock

2017

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Abstract. Active volcanoes are mechanically dynamic environments, and edifice-forming material may often be subjected to significant amounts of stress and strain. It is understood that porous volcanic rock can compact inelastically under a wide range of in situ conditions. In this contribution, we explore the evolution of porosity and permeability -critical properties influencing the style and magnitude of volcanic activity -as a function of inelastic compaction of porous andesite under triaxial conditions. Progressive axial strain accumulation is associated with progressive porosity loss. The efficiency of compaction was found to be related to the effective confining pressure under which deformation occurred: at higher effective pressure, more porosity was lost for any given amount of axial strain. Permeability evolution is more complex, with small amounts of stress-induced compaction ( < 0.05, i.e. less than 5 % reduction in sample length) yielding an increase in permeability under all effective pressures tested, occasionally by almost 1 order of magnitude. This phenomenon is considered here to be the result of improved connectivity of formerly isolated porosity during triaxial loading. This effect is then overshadowed by a decrease in permeability with further inelastic strain accumulation, especially notable at high axial strains (> 0.20) where samples may undergo a reduction in permeability by 2 orders of magnitude relative to their initial values. A physical limit to compaction is discussed, which we suggest is echoed in a limit to the potential for permeability reduction in compacting volcanic rock. Compiled literature data illustrate that at high axial strain (both in the brittle and ductile regimes), porosity φ and permeability k tend to converge towards intermediate values (i.e. 0.10 ≤ φ ≤ 0.20; 10 −14 ≤ k ≤10 −13 m 2 ). These results are discussed in light of their potential ramifications for impacting edifice outgassing -and in turn, eruptive activity -in active volcanoes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inelastic compaction and permeability evolution in volcanic rock

2017

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Direct Associations Between Potassic Igneous Rocks and Gold-Copper Deposits in Volcanic Arcs

Müller¹,

Groves

2018

Potassic Igneous Rocks and Associated Gold-Copper Mineralization

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Fracture and compaction of andesite in a volcanic edifice

et al. 2015

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The failure mode of lava—dilatant or compactant—depends on the physical attributes of the lava, primarily the porosity and pore size, and the conditions under which it deforms. The failure mode for edifice host rock has attendant implications for the structural stability of the edifice and the efficiency of the sidewall outgassing of the volcanic conduit. In this contribution, we present a systematic experimental study on the failure mode of edifice-forming andesitic rocks (porosity from 7 to 25 %) from Volcán de Colima, Mexico. The experiments show that, at shallow depths (<1 km), both low- and high-porosity lavas dilate and fail by shear fracturing. However, deeper in the edifice (>1 km), while low-porosity (<10 %) lava remains dilatant, the failure of high-porosity lava is compactant and driven by cataclastic pore collapse. Although inelastic compaction is typically characterised by the absence of strain localisation, we observe compactive localisation features in our porous andesite lavas manifest as subplanar surfaces of collapsed pores. In terms of volcano stability, faulting in the upper edifice could destabilise the volcano, leading to an increased risk of flank or large-scale dome collapse, while compactant deformation deeper in the edifice may emerge as a viable mechanism driving volcano subsidence, spreading and destabilisation. The failure mode influences the evolution of rock physical properties: permeability measurements demonstrate that a throughgoing tensile fracture increases sample permeability (i.e. equivalent permeability) by about a factor of two, and that inelastic compaction to an axial strain of 4.5 % reduces sample permeability by an order of magnitude. The implication of these data is that sidewall outgassing may therefore be efficient in the shallow edifice, where rock can fracture, but may be impeded deeper in the edifice due to compaction. The explosive potential of a volcano may therefore be subject to increase over time if the progressive compaction and permeability reduction in the lower edifice cannot be offset by the formation of permeable fracture pathways in the upper edifice. The mode of failure of the edifice host rock is therefore likely to be an important factor controlling lateral outgassing and thus eruption style (effusive versus explosive) at stratovolcanoes.

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Mechanical behaviour and failure modes in the Whakaari (White Island volcano) hydrothermal system, New Zealand

Abstract: International audienc

Cited by 100 publications

References 81 publications

Inelastic compaction and permeability evolution in volcanic rock

Inelastic compaction and permeability evolution in volcanic rock

Direct Associations Between Potassic Igneous Rocks and Gold-Copper Deposits in Volcanic Arcs

Fracture and compaction of andesite in a volcanic edifice

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