Understanding the link between circumferential dikes and eruptive fissures around calderas based on numerical and analog models

Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Acocella, Valerio

doi:10.1002/2016gl068721

Cited by 32 publications

(36 citation statements)

References 39 publications

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“…To summarize, a dike rising vertically beneath a rift or a caldera is deflected outside the topographic depression and its velocity is much lower than it would have been if it had risen vertically. This deflection together with the velocity decrease is consistent with experimental results obtained for a caldera context [Corbi et al, 2016].…”

Section: Surface Unloading: Caldera Formationsupporting

confidence: 92%

“…The deflection is oriented toward the center of the surface load, and its amplitude depends on the ratio between the applied load and the magma driving pressure (deflection increases for larger surface load) [ Watanabe et al , ; Muller et al , ; Watanabe et al , ]. More recently, the control exerted on dike trajectories by unloading due to mass wasting events or crustal thinning has also been evidenced [ Maccaferri et al , ; Corbi et al , , ]. Similarly, the effect of a compressive stress on the deflection of a vertically ascending dike into a horizontal sill depends on the ratio between the amplitude of the deviatoric stress over the buoyancy forces [ Menand et al , ].…”

Section: Introductionmentioning

confidence: 99%

“…Dike pathways and velocity depend on many factors, including (i) the location of the magma source, its geometry, and physical state; (ii) the physical properties of magma; (iii) the physical properties of country rocks; and (iv) the regional and local stress field. For example, numerical and analog models have shown that ascending dikes approaching a volcanic edifice become deflected on their pathway [Watanabe et al, 1999;Dahm, 2000a;Muller et al, 2001;Watanabe et al, 2002;Maccaferri et al, 2011;Corbi et al, 2016] and decelerate [Pinel and Jaupart, 2000;Watanabe et al, 2002;Maccaferri et al, 2016;Corbi et al, 2016]. The deflection is oriented toward the center of the surface load, and its amplitude depends on the ratio between the applied load and the magma driving pressure (deflection increases for larger surface load) [Watanabe et al, 1999;Muller et al, 2001;Watanabe et al, 2002].…”

Section: Introductionmentioning

confidence: 99%

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A two‐step model for dynamical dike propagation in two dimensions: Application to the July 2001 Etna eruption

et al. 2017

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We developed a hybrid numerical model of dike propagation in two dimensions solving both for the magma trajectory and velocity as a function of the source overpressure, the magma physical properties (density and viscosity), and the crustal density and stress field. This model is used to characterize the influence of surface load changes on magma migration toward the surface. We confirm that surface loading induced by volcanic edifice construction tends both to attract the magma and to reduce its velocity. In contrast, surface unloading, for instance, due to caldera formation, tends to divert the magma to the periphery‐retarding eruption. In both cases the deflected magma may remain trapped at depth. Amplitudes of dike deflection and magma velocity variation depend on the ratio between the magma driving pressure (source overpressure as well as buoyancy) and the stress field perturbation. Our model is then applied to the July 2001 eruption of Etna, where the final dike deflection had been previously interpreted as due to the topographic load. We show that the velocity decrease observed during the last stage of the propagation can also be attributed to the local stress field. We use the dike propagation duration to estimate the magma overpressure at the dike bottom to be less than 4 MPa. This approach can be potentially used to forecast if, where, and when propagating magma might reach the surface when having knowledge on the local stress field, magma physical properties, and reservoir overpressure.

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Section: Surface Unloading: Caldera Formationsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A two‐step model for dynamical dike propagation in two dimensions: Application to the July 2001 Etna eruption

et al. 2017

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“…Also, given a background stress model, the critical ratio for deflection represents an important reference value to validate forecast trajectories of magmatic intrusions (Corbi et al, ). Practically, the critical ratio for deflection has been used to identify two end member scenarios for the propagation paths of the intrusions (Pinel et al, ): (i) The total stress field is dominated by the background stress (the effect of the stress change due to the intrusion on its propagation path is negligible).…”

Section: Introductionmentioning

confidence: 99%

On the Propagation Path of Magma‐Filled Dikes and Hydrofractures: The Competition Between External Stress, Internal Pressure, and Crack Length

Maccaferri

Smittarello

Pinel

et al. 2019

Geochem Geophys Geosyst

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Mixed‐mode fluid‐filled cracks represent a common means of fluid transport within the Earth's crust. They often show complex propagation paths which may be due to interaction with crustal heterogeneities or heterogeneous crustal stress. Previous experimental and numerical studies focus on the interplay between fluid overpressure and external stress but neglect the effect of other crack parameters. In this study, we address the role of crack length on the propagation paths in the presence of an external heterogeneous stress field. We make use of numerical simulations of magmatic dike and hydrofracture propagation, carried out using a two‐dimensional boundary element model, and analogue experiments of air‐filled crack propagation into a transparent gelatin block. We use a 3‐D finite element model to compute the stress field acting within the gelatin block and perform a quantitative comparison between 2‐D numerical simulations and experiments. We show that, given the same ratio between external stress and fluid pressure, longer fluid‐filled cracks are less sensitive to the background stress, and we quantify this effect on fluid‐filled crack paths. Combining the magnitude of the external stress, the fluid pressure, and the crack length, we define a new parameter, which characterizes two end member scenarios for the propagation path of a fluid‐filled fracture. Our results have important implications for volcanological studies which aim to address the problem of complex trajectories of magmatic dikes (i.e., to forecast scenarios of new vents opening at volcanoes) but also have implications for studies that address the growth and propagation of natural and induced hydrofractures.

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“…Topographic reliefs provide a driving pressure for propagation by inducing lateral stress gradients (Acocella & Neri, ; Fialko & Rubin, ; Fiske & Jackson, ; Kervyn et al, ; Maccaferri et al, ; Muller et al, ; Pinel et al, ; Pinel & Jaupart, ; Rubin & Pollard, ), also inducing an increasingly intense compression at the tips of ascending dikes or approaching a relief, favoring dike arrest (Kervyn et al, ; Maccaferri et al, , ; Urbani et al, ; Watanabe et al, ). Additionally, reliefs modify dike trajectories by inducing rotations of the principal stress axes that may lead a dike to change propagation direction, for example, from vertical to horizontal or vice versa (Bagnardi et al, ; Corbi et al, , ; Dahm, ; Maccaferri et al, ; Watanabe et al, ). Preexisting discontinuities in the host rock may channelize the dikes, causing their arrest or deviation (Ito & Martel, ; Le Corvec et al, ; Maccaferri et al, ; Watanabe et al, ; Ziv et al, ).…”

Section: Introductionmentioning

confidence: 99%

What Drives the Lateral Versus Vertical Propagation of Dikes? Insights From Analogue Models

2018

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Volcanic eruptions are usually fed by dikes. Understanding how crustal inhomogeneities and topographic loads control the direction (lateral/vertical) and extent (propagation/arrest) of dikes is crucial to forecast the opening of a vent. Many factors, including buoyancy, crustal layering, and topography, may control the vertical or lateral propagation of a dike. To define a hierarchy between these factors, we have conducted analogue models, injecting water (magma analogue) within gelatin (crust analogue). We investigate the effect of crustal layering (both rigidity and density layering), topography, magma inflow rate, and the density ratio between host rock and magma. Based on the experimental observations and scaling considerations, we suggest that rigidity layering (a stiffer layer overlying a weaker one) and topographic gradient favor predominantly lateral dike propagation; inflow rate, density layering, and density ratio play a subordinate role. Conversely, a softer layer overlying a stiffer one favors vertical propagation. Our results highlight the higher efficiency of a stiff layer in driving lateral dike propagation and/or inhibiting vertical propagation with respect to the Level of Neutral Buoyancy proposed by previous studies.

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Understanding the link between circumferential dikes and eruptive fissures around calderas based on numerical and analog models

Cited by 32 publications

References 39 publications

A two‐step model for dynamical dike propagation in two dimensions: Application to the July 2001 Etna eruption

A two‐step model for dynamical dike propagation in two dimensions: Application to the July 2001 Etna eruption

On the Propagation Path of Magma‐Filled Dikes and Hydrofractures: The Competition Between External Stress, Internal Pressure, and Crack Length

What Drives the Lateral Versus Vertical Propagation of Dikes? Insights From Analogue Models

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