Gelatin models for photoelastic analysis of gravity structures

Richards, Rowland; Märk, Robert

doi:10.1007/bf02327111

Cited by 32 publications

(11 citation statements)

References 5 publications

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“…These strength-related effects in experiments are remarkably similar to those reported in studies of mining-induced collapse (Reddish and Whittaker 1989), and have been observed at basaltic volcanoes (Rymer et al 1998;Carter et al 2006). Moreover, the experimental results support Anderson's (1936) postulate that high rock strength is required to develop the near-horizontal, opening-mode 'cross-fracture' that defines the upper cap of a complete subterranean 'ring dyke' (Clough et al 1909;Richey 1932) formed in the case of magma emplacement by cauldron subsidence.…”

Section: Effects Of Host-rocksupporting

confidence: 84%

Laboratory Modelling of Volcano Plumbing Systems: A Review

Galland

Holohan

Vries

et al. 2015

Advances in Volcanology

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We review the numerous experimental studies dedicated to unravelling the physics and dynamics of various parts of a volcanic plumbing system. Section 1 lists the model materials commonly used for model magmas or model rocks. We describe these materials' mechanical properties and discuss their suitability for modelling sub-volcanic processes. Section 2 examines the fundamental concepts of dimensional analysis and similarity in laboratory modelling. We provide a step-by-step explanation of how to apply dimensional analysis to laboratory models in order to identify fundamental physical laws that govern the modelled processes in dimensionless (i.e. scale independent) form. Section 3 summarises and discusses the past applications of laboratory models to understand numerous features of volcanic plumbing systems. These include: dykes, cone sheets, sills, laccoliths, caldera-related structures, ground deformation, magma/fault interactions, and explosive vents. We outline how laboratory models have yielded insights into the main geometric and mechanical controls on the development of each part of the volcanic

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Section: Effects Of Host-rocksupporting

confidence: 84%

Laboratory Modelling of Volcano Plumbing Systems: A Review

Galland

Holohan

Vries

et al. 2015

Advances in Volcanology

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“…g is the gravitational acceleration andn is the gelatin Poisson's ratio [n = 0.5; Crisp, 1952;Richards and Mark, 1966]. The fracture toughness (K c ) was then calculated using the relationship derived by Kavanagh et al [2013]:…”

Section: Methodsmentioning

confidence: 99%

“…Once set, the properties of the gelatin were measured as follows. The Young's modulus ( E ) was calculated by measuring the vertical deflection of the gelatin surface ( w ) induced by a cylindrical weight of known mass ( M ) and radius ( a ) [ Timoshenko and Goodier , ]:

E = \frac{Mg (1 - v^{2})}{2 a w}

g is the gravitational acceleration and ν is the gelatin Poisson's ratio [ ν = 0.5; Crisp , ; Richards and Mark , ]. The fracture toughness ( K c ) was then calculated using the relationship derived by Kavanagh et al .…”

Section: Analogue Modelingmentioning

confidence: 99%

Interaction of ascending magma with pre‐existing crustal fractures in monogenetic basaltic volcanism: an experimental approach

2013

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[1] Magma transport through dikes is a major component of the development of monogenetic volcanic fields. These volcanic fields are characterized by numerous volcanic centers, each typically resulting from a single eruption. Therefore, magma must be transported from source to surface at different places, which raises the question of the relative importance of (1) the self-propagation of magma through pristine rock and (2) the control exerted by pre-existing fractures. To address this issue, we have carried out a series of analogue experiments to constrain the interaction of a propagating dike through a medium with pre-existing fractures. The experiments involved the injection of air into an elastic gelatin solid, which was previously cut into its upper part to simulate pre-existing fractures. The volume of the dikes, their distance from the fractures, and the ambient stress field were systematically varied to assess their influence on potential dike-fracture interactions. The results show that distance and angle between dikes and fractures influence these interactions and the dike trajectory. Dike geometry and dynamics are also affected by both the presence of the fractures and the dike volume; dikes propagating in between fractures tend to decelerate. In nature, interactions are expected for dikes and fractures separated by less than about 200 m, and dikes with a volume less than about 10 À2 km 3 would experience a velocity decrease. These results highlight the influence of pre-existing fractures on the mechanics and dynamics of dikes. These heterogeneities must be considered when studying the transport of magmas within the crust.

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“…Its low rigidity allows the gravity to be significant in laboratory-scale models (Richards and Mark, 1966). We can easily make a fluid-filled crack in gelatin, and observe its three-dimensional behavior.…”

Section: Working Materialsmentioning

confidence: 99%

Analog experiments on magma-filled cracks: Competition between external stresses and internal pressure

et al. 2014

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We have performed two series of analog experiments using gelatin to study the propagation of liquid-filled cracks in stressed medium. The first series was designed to study the competition between the external stress and the liquid excess pressure in controlling the propagation direction. We systematically controlled the external stress and the liquid excess pressure by changing the surface load and the liquid volume. An ascending crack progressively deflected to be perpendicular to the maximum tensile direction of the external stress. The degree of deflection depends on the ratio of the shear stress on a crack plane to the average liquid excess pressure. More deflection was observed for a crack with a larger ratio. No significant deflection was observed for the ratio less than 0.2. The volcanic activity in a compressional stress field might be understood in the context of this competition. The first series also demonstrated the importance of the gradient of the crack normal stress as a driving force for propagation. The vertical gradient of the gravitational stress generated by a mountain load can control the emplacement depth of magmas, and it might lead to the evolution of eruption style during the lifetime of a volcano. The second series was designed to study the three-dimensional interaction of two parallel buoyancy-driven cracks. The deflection of the second crack takes place, when the ratio of the shear stress generated by the first one to the average excess pressure of the second crack is larger than 0.2. If the second crack reaches the first one, the interaction can lead to the coalescence of two cracks. It has directivity: the region of coalescence extends more in the direction perpendicular to the first crack than in the direction parallel to it. It reflects the stress field around the first crack. This directivity might cause a characteristic spatial variation of magma chemistry through magma mixing.

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Gelatin models for photoelastic analysis of gravity structures

Cited by 32 publications

References 5 publications

Laboratory Modelling of Volcano Plumbing Systems: A Review

Laboratory Modelling of Volcano Plumbing Systems: A Review

Interaction of ascending magma with pre‐existing crustal fractures in monogenetic basaltic volcanism: an experimental approach

Analog experiments on magma-filled cracks: Competition between external stresses and internal pressure

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