Effects of mechanical layering of host rocks on dike growth and arrest

Geshi, Nobuo; Kusumoto, Shigekazu; Guðmundsson, Ágúst

doi:10.1016/j.jvolgeores.2012.02.004

Cited by 65 publications

(52 citation statements)

References 26 publications

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“…This is because elastic mismatch between layers is much more common, and generally much greater, in a stratovolcano than in a basaltic edifice. These theoretical conclusions are in good agreement with the results of a study of 165 dikes exposed in the uppermost 200 m of the caldera walls of the stratovolcano Miyakejima (Japan), the wall being the result of a caldera collapse in the year 2000 (Geshi et al, 2010(Geshi et al, , 2012. Even at such a shallow depth ( (a) A basaltic edifice is composed primarily of mechanically similar layers so that, once , landslide faults (or slip surfaces or failure planes), ring faults, and dikes have a atively high probability of reaching the surface, as indicated here by the many feeder b) A stratovolcano is composed of mechanically dissimilar layers so that faults and dikes mparatively low probability of reaching the surface, as indicated here by the many and deflected (into sills) dikes.…”

Section: Figsupporting

confidence: 88%

“…Some papers explicitly deal with the effects of overpressure-related variation in dike aperture and external loading on magma flow during eruptions (Costa et al, 2009(Costa et al, , 2011. Other recent papers on this and related topics include Canon-Tapia et al (2006), Menand et al (2010), Geshi et al (2010Geshi et al ( , 2012, Taisne et al (2011), and Maccaferri et al (2010, 2011. A detailed statistical summary of "failed eruptions" (mostly arrested dikes) is provided by Moran et al (2011).…”

Section: Discussionmentioning

confidence: 99%

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Strengths and strain energies of volcanic edifices: implications for eruptions, collapse calderas, and landslides

Guðmundsson

2012

Nat. Hazards Earth Syst. Sci.

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Abstract. Natural hazards associated with volcanic edifices depend partly on how fracture resistant the edifices are, i.e. on their strengths. Observations worldwide indicate that large fluid-driven extension fractures (dikes, inclined sheets), shear fractures (landslides), and mixed-mode fractures (ring dikes and ring faults) normally propagate more easily in a basaltic edifice (shield volcano) than in a stratovolcano. For example, dike-fed eruptions occur once every few years in many basaltic edifices but once every 10 2−3 yr in many stratovolcanoes. Large landslides and caldera collapses also appear to be more common in a typical basaltic edifice/shield volcano than in a typical stratovolcano. In contrast to a basaltic edifice, a stratovolcano is composed of mechanically dissimilar rock layers, i.e. layers with mismatching elastic properties (primarily Young's modulus). Elastic mismatch encourages fracture deflection and arrest at contacts and increases the amount of energy needed for a large-scale edifice failure. Fracture-related hazards depend on the potential energy available to propagate the fractures which, in turn, depends on the boundary conditions during fracture propagation. Here there are two possible scenarios: one in which the outer boundary of the volcanic edifice or rift zone does not move during the fracture propagation (constant displacement); the other in which the boundary moves (constant load). In the former, the total potential energy is the strain energy stored in the volcano before fracture formation; in the latter, the total potential energy is the strain energy plus the work done by the forces moving the boundary. Constantdisplacement boundary conditions favor small eruptions, landslides, and caldera collapses, whereas constant-load conditions favor comparatively large eruptions, landslides, and collapses. For a typical magma chamber (sill-like with a diameter of 8 km), the strain energy change due to magmachamber inflation is estimated at the order of 10 14 J (0.1 PJ).For comparison, the surface energy needed to form a typical feeder dike is of the same order of magnitude, or 10 14 J. There are several processes besides magma-chamber inflation that may increase the strain energy in a volcano before eruption. Thus, during a typical unrest period with magmachamber inflation, the added strain energy in the volcano is large enough for a typical feeder dike to form. An injected dike, however, only reaches the surface and becomes a feeder if it is able to propagate through the numerous layers and contacts that tend to deflect or arrest dikes. The strong elastic mismatch between layers that constitute stratovolcanoes not only encourages fracture arrest, but also the storage of more strain energy (than in a typical basaltic edifice/shield volcano) before fracture formation and failure. It is thus through producing materials of widely different mechanical properties that stratovolcanoes become strong and resilient.

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Section: Figsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Strengths and strain energies of volcanic edifices: implications for eruptions, collapse calderas, and landslides

Guðmundsson

2012

Nat. Hazards Earth Syst. Sci.

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“…Theoretical studies suggest that, on approaching the surface, feeder dykes should normally become thicker and shorter (Gudmundsson, 1986;Maaloe, 1998;Gudmundsson et al, 2008;Keating et al, 2008). This is supported by field observations of many feeders (e.g., Gudmundsson et al, 2008;Keating et al, 2008;Geshi et al, 2010Geshi et al, , 2012. Some feeder dykes have been studied to depths of a few hundred metres below the surface (e.g., Gudmundsson et al, 2008;Keating et al, 2008;Geshi et al, 2010Geshi et al, , 2012, but few feeders have been studied in great detail as regards changes in their geometry, internal structure, and texture on approaching the surface.…”

Section: Introductionmentioning

confidence: 91%

“…While arrested dykes are commonly observed in eroded parts of volcanic edifices, observed feeder dykes are rare 3684 I. Galindo and A. Gudmundsson: Basaltic feeder dykes in rift zones (Gudmundsson, 1986(Gudmundsson, , 2002Marinoni and Gudmundsson, 2000;Geshi et al, 2010Geshi et al, , 2012. Some feeder dykes have been reported from Iceland, Italy, USA, Japan and the Canary Islands (Saemundsson, 1967;Jonsson, 1978;Atkinson and Lambert, 1990;Gudmundsson, 1986Gudmundsson, , 2002Goto et al, 1990;Galindo, 2005;Gudmundsson et al, 2008;Keating et al, 2008;Geshi et al, 2010Geshi et al, , 2012.…”

Section: Introductionmentioning

confidence: 99%

“…Some feeder dykes have been reported from Iceland, Italy, USA, Japan and the Canary Islands (Saemundsson, 1967;Jonsson, 1978;Atkinson and Lambert, 1990;Gudmundsson, 1986Gudmundsson, , 2002Goto et al, 1990;Galindo, 2005;Gudmundsson et al, 2008;Keating et al, 2008;Geshi et al, 2010Geshi et al, , 2012. Theoretical studies suggest that, on approaching the surface, feeder dykes should normally become thicker and shorter (Gudmundsson, 1986;Maaloe, 1998;Gudmundsson et al, 2008;Keating et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Basaltic feeder dykes in rift zones: geometry, emplacement, and effusion rates

Galindo

Guðmundsson

2012

Nat. Hazards Earth Syst. Sci.

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Abstract. Most volcanic hazards depend on an injected dyke reaching the surface to form a feeder. Assessing the volcanic hazard in an area is thus related to understanding the condition for the formation of a feeder dyke in that area. For this latter, we need good field data on feeder dykes, their geometries, internal structures, and other characteristics that distinguish them from non-feeders. Unfortunately, feeder dykes are rarely observed, partly because they are commonly covered by their own products. For this reason, outcrops are scarce and usually restricted to cliffs, ravines, and man-made outcrops. Here we report the results of a study of feeder dykes in Tenerife (Canary Islands, Spain) and Iceland, focusing on their field characteristics and how their propagation is affected by existing structures. Although Holocene fissure eruptions have been common in both islands, only eleven basaltic feeder dykes have been identified: eight in Tenerife and three in Iceland. They are all well preserved and the relation with the eruptive fissure and/or the deposits is well exposed. While the eruptive fissures are generally longer in Iceland than in Tenerife, their feeders show many similarities, the main ones being that the feeder dykes (1) are generally sheet-shaped; (2) are segmented (as are the associated volcanic fissures); (3) normally contain elongated (prolate ellipsoidal) cavities in their central, topmost parts, that is, 2-3 m below the surface (with solidified magma drops on the cavity walls); (4) contain vesicles which increase in size and number close to the surface; (5) sometimes inject oblique dyke fingers into the planes of existing faults that cross the dyke paths; and (6) may reactivate, that is, trigger slip on existing faults. We analyse theoretically the feeder dyke of the 1991 Hekla eruption in Iceland. Our results indicate that during the initial peak in the effusion rate the opening (aperture) of the feeder dyke was as wide as 0.77 m, but quickly decreased to about 0.56 m. During the subsequent decline in the effusion rate to a minimum, the aperture decreased to about 0.19 m. At a later abrupt increase in the effusion rate, the feeder-dyke opening may have increased to about 0.34 m, and then decreased again as the effusion rate gradually declined during the end stages of the eruption. These thickness estimates fit well with those of many feeders in Iceland and Tenerife, and with the general dyke thickness within fossil central volcanoes in Iceland.

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Dike propagation energy balance from deformation modeling and seismic release

Bonaccorso

Aoki

Rivalta

2017

Geophysical Research Letters

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Magma is transported in the crust mainly by dike intrusions. In volcanic areas, dikes can ascend toward the free surface and also move by lateral propagation, eventually feeding flank eruptions. Understanding dike mechanics is a key to forecasting the expected propagation and associated hazard. Several studies have been conducted on dike mechanisms and propagation; however, a less in‐depth investigated aspect is the relation between measured dike‐induced deformation and the seismicity released during its propagation. We individuated a simple x that can be used as a proxy of the expected mechanical energy released by a propagating dike and is related to its average thickness. For several intrusions around the world (Afar, Japan, and Mount Etna), we correlate such mechanical energy to the seismic moment released by the induced earthquakes. We obtain an empirical law that quantifies the expected seismic energy released before arrest. The proposed approach may be helpful to predict the total seismic moment that will be released by an intrusion and thus to control the energy status during its propagation and the time of dike arrest.

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Effects of mechanical layering of host rocks on dike growth and arrest

Cited by 65 publications

References 26 publications

Strengths and strain energies of volcanic edifices: implications for eruptions, collapse calderas, and landslides

Strengths and strain energies of volcanic edifices: implications for eruptions, collapse calderas, and landslides

Basaltic feeder dykes in rift zones: geometry, emplacement, and effusion rates

Dike propagation energy balance from deformation modeling and seismic release

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