Shear localisation, strain partitioning and frictional melting in a debris avalanche generated by volcanic flank collapse

Hughes, Amy; Kendrick, Jackie E.; Salas, Guido; Wallace, Paul A. W.; Legros, F.; Toro, Giulio Di; Lavallée, Yan

doi:10.1016/j.jsg.2020.104132

Cited by 12 publications

(5 citation statements)

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“…Following failure, the flow velocity and maximum distance obtained by a volcanic debris avalanche can depend on the frictional properties of volcanic rocks (e.g. Legros et al 2000;Hürlimann et al 2000;Brodsky et al 2003;Sosio et al 2012;Bernard and van Wyk de Vries 2017;Peruzzetto et al 2019;Hughes et al 2020). Laboratory-measured values of tensile strength can inform on the magma overpressures required for intrusion/ eruption (e.g.…”

Section: Introductionmentioning

confidence: 99%

The mechanical behaviour and failure modes of volcanic rocks: a review

2021

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The microstructure and mineralogy of volcanic rocks is varied and complex, and their mechanical behaviour is similarly varied and complex. This review summarises recent developments in our understanding of the mechanical behaviour and failure modes of volcanic rocks. Compiled data show that, although porosity exerts a first-order influence on the uniaxial compressive strength of volcanic rocks, parameters such as the partitioning of the void space (pores and microcracks), pore and crystal size and shape, and alteration also play a role. The presence of water, strain rate, and temperature can also influence uniaxial compressive strength. We also discuss the merits of micromechanical models in understanding the mechanical behaviour of volcanic rocks (which includes a review of the available fracture toughness data). Compiled data show that the effective pressure required for the onset of hydrostatic inelastic compaction in volcanic rocks decreases as a function of increasing porosity, and represents the pressure required for cataclastic pore collapse. Differences between brittle and ductile mechanical behaviour (stress-strain curves and the evolution of porosity and acoustic emission activity) from triaxial deformation experiments are outlined. Brittle behaviour is typically characterised by shear fracture formation, and an increase in porosity and permeability. Ductile deformation can either be distributed (cataclastic pore collapse) or localised (compaction bands) and is characterised by a decrease in porosity and permeability. The available data show that tuffs deform by delocalised cataclasis and extrusive volcanic rocks develop compaction bands (planes of collapsed pores connected by microcracks). Brittle failure envelopes and compactive yield caps for volcanic rocks are compared, highlighting that porosity exerts a first-order control on the stresses required for the brittle-ductile transition and shear-enhanced compaction. However, these data cannot be explained by porosity alone and other microstructural parameters, such as pore size, must also play a role. Compactive yield caps for tuffs are elliptical, similar to data for sedimentary rocks, but are linear for extrusive volcanic rocks. Linear yield caps are considered to be a result of a high pre-existing microcrack density and/or a heterogeneous distribution of porosity. However, it is still unclear, with the available data, why compaction bands develop in some volcanic rocks but not others, which microstructural attributes influence the stresses required for the brittle-ductile transition and shear-enhanced compaction, and why the compactive yield caps of extrusive volcanic rocks are linear. We also review the Young’s modulus, tensile strength, and frictional properties of volcanic rocks. Finally, we review how laboratory data have and can be used to improve our understanding of volcanic systems and highlight directions for future research. A deep understanding of the mechanical behaviour and failure modes of volcanic rock can help refine and develop tools to routinely monitor the hazards posed by active volcanoes.

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Section: Introductionmentioning

confidence: 99%

The mechanical behaviour and failure modes of volcanic rocks: a review

2021

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“…These events are controlled, especially in the early phases, by the initial wear and friction parameters, impacting the extent of initial collapse controlling the velocity of the mass movement (e.g., Legros, 2002) and the runout distance (often greater than predicted by simple friction models; e.g., Scheidegger, 1973). Such large displacement events often juxtapose lithologies of differing porosities, in which case predominant damage and wear of the more porous rocks contributes to cataclasis and material entrainment, potentially leading to a reduction in basal friction (Hughes et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…The frictional behaviour of rocks has been studied extensively using field observations (e.g., Sibson, 1994;Mitchell et al, 2016;Hughes et al, 2020), controlled laboratory experiments (e.g., Byerlee, 1978;Marone, 1998;Scholz, 1998;Hirose and Shimamoto, 2005a;Hirose and Shimamoto, 2005b;Di Toro et al, 2006;Di Toro et al, 2011;Kendrick et al, 2014;Hornby et al, 2015;Wallace et al, 2019a), and modelling (e.g., Nielsen et al, 2008;Weng and Yang, 2018). In an early attempt to reconcile laboratory data, Byerlee (1978) advanced that at low slip velocities and shallow crustal conditions (<200 MPa normal stress), the shear resistance (τ) of rocks during slip is proportional to the normal stress (σ n ), such that:…”

Section: Introductionmentioning

confidence: 99%

“…In the brittle regime in near surface shear zones, gouge and cataclasite layers and zones are preserved (Engelder, 1974;Sibson, 1977;Wallace et al, 2019b). At greater pressures, ductile mylonites are formed (Sibson, 1977) and in cases of extreme heating during slip, pseudotachylytes, solidified frictional melts, occur (Sibson, 1977;Di Toro et al, 2011;Kendrick et al, 2012;Mitchell et al, 2016) and are often used as evidence for the occurrence of coseismic slip (Sibson, 1975;Cowan, 1999), though they have also been recorded in mass movements (e.g., Masch et al, 1985;Grunewald et al, 2000;Hacker et al, 2014;Hughes et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Frictional Behaviour, Wear and Comminution of Synthetic Porous Geomaterials

et al. 2020

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During shearing in geological environments, frictional processes, including the wear of sliding rock surfaces, control the nature of the slip events. Multiple studies focusing on natural samples have investigated the frictional behaviour of a large suite of geological materials. However, due to the varied and heterogeneous nature of geomaterials, the individual controls of material properties on friction and wear remain unconstrained. Here, we use variably porous synthetic glass samples (8, 19 and 30% porosity) to explore the frictional behaviour and development of wear in geomaterials at low normal stresses (≤1 MPa). We propose that porosity provides an inherent roughness to material which wear and abrasion cannot smooth, allowing material at the pore margins to interact with the slip surface. This results in an increase in measured friction coefficient from <0.4 for 8% porosity, to <0.55 for 19% porosity and 0.6–0.8 for 30% porosity for the slip rates evaluated. For a given porosity, wear rate reduces with slip rate due to less asperity interaction time. At higher slip rates, samples also exhibit slip weakening behaviour, either due to evolution of the slipping zone or by the activation of temperature-dependent microphysical processes. However, heating rate and peak temperature may be reduced by rapid wear rates as frictional heating and wear compete. The higher wear rates and reduced heating rates of porous rocks during slip may delay the onset of thermally triggered dynamic weakening mechanisms such as flash heating, frictional melting and thermal pressurisation. Hence porosity, and the resultant friction coefficient, work, heating rate and wear rate, of materials can influence the dynamics of slip during such events as shallow crustal faulting or mass movements.

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“…The similarity of mechanisms operating in terrestrial long runout landslides and high‐slip‐rate seismic faulting has been suggested in the light of the role of frictional heating in triggering a series of physical and chemical reactions responsible for friction weakening mechanisms (e.g., Goren & Aharonov, 2007; Vardoulakis, 2002; Voight & Faust, 1982). Examples of frictional heating‐triggered weakening mechanisms that have been suggested to explain the hypermobility of some long runout landslides are gas overpressurization (e.g., the Heart Mountain landslide (Goren et al., 2010; Mitchell et al., 2015) and the Vajont landslide (Ibañez & Hatzor, 2018; Pinyol & Alonso, 2010; Veveakis et al., 2007)), melt production (e.g., the Köfels landslide: T. Erismann et al., 1977); the Arequipa volcanic landslide (Hughes et al., 2020; Legros et al., 2000); and flash heating (on Iapetus: Singer et al., 2012; on Charon: Beddingfield et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Friction Experiments on Lunar Analog Gouges and Implications for the Mechanism of the Apollo 17 Long Runout Landslide

et al. 2023

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The Light Mantle landslide is a hypermobile landslide on the Moon. Apollo 17 astronauts collected a core sample of the top 60 cm of the Light Mantle deposit, which is currently being analyzed as part of the NASA's Apollo Next Generation Sample Analysis program. The origin of its hypermobility remains undetermined, as the proposed mechanisms are difficult to prove because of the lack of theoretical and experimental support and the scarcity of field data related to the internal structures of its deposit. Regardless of the emplacement mechanisms, it has been proposed that localized dynamic frictional weakening is responsible for the early stage instability that leads to catastrophic failure. Here, we conduct friction experiments under vacuum to investigate the viability of dynamic friction weakening in lunar analog anorthosite‐bearing gouges (i.e., rock powders). Our results show that localized dynamic friction weakening does not occur in these gouges at loading conditions where, instead, weakening is observed in other materials on Earth. Therefore, possibly other fluidization‐related mechanisms contributed to the initiation of the hypermobile Light Mantle landslide. Finally, we describe the microstructures formed in the experiments, including the presence of clast cortex aggregates. Preliminary investigation of the Light Mantle core samples (73001/73002) shows the presence of similar microstructures. Therefore, our microstructural observations will help the analysis and interpretation of the Apollo 17 core samples, as keys to insights about internal processes occurring during the emplacement of the landslide.

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Shear localisation, strain partitioning and frictional melting in a debris avalanche generated by volcanic flank collapse

Cited by 12 publications

References 81 publications

The mechanical behaviour and failure modes of volcanic rocks: a review

The mechanical behaviour and failure modes of volcanic rocks: a review

Frictional Behaviour, Wear and Comminution of Synthetic Porous Geomaterials

Friction Experiments on Lunar Analog Gouges and Implications for the Mechanism of the Apollo 17 Long Runout Landslide

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