What Drives the Lateral Versus Vertical Propagation of Dikes? Insights From Analogue Models. Issue 5 (30th May 2018)

• Record Type: Journal Article
• Authors: Urbani, S.; Acocella, V.; Rivalta, E.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 5(2018)
• Page Start: 3680
• Page End: 3697
• Publication Date: 2018-05-30
• Subjects: dike -- lateral propagation -- vertical propagation -- analogue modeling -- layering -- rigidity; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2017JB015376
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: 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. Key Points: Understanding what drives the propagation direction of dikes is a crucial step for eruption forecasting Analogue models show that rigidity layering (stiff layer above a soft layer) and topography dominantly favor lateral dike propagation A stiff layer promotes lateral propagation more efficiently than the Level of Neutral Buoyancy (LNB) by inhibiting its vertical ascent