Models constraining models: Analogue modelling to assess theoretical uncertainties
Our research group is focused on understanding the movement of magma in the upper crust. Such movement is commonly in the form of a dyke, a sheet of magma that migrates through the crust by continually cracking the crust at the upper end.
A key force allowing dykes to propagate is the buoyancy of the magma, in which relatively-less-dense magma pushes up through the denser crust. More specifically, we are examining how a dike slows down and stops propagating (arrests) and how a dyke accelerates in the vicinity of the surface. This helps us to understand the conditions that can lead to the stalling of a dyke or the occurrence of a volcanic eruption.
Simple “quasi-static” experiments are to be performed, in which a dyke is subjected to a static load and allowed it to evolve into a new static state. Previous experiments have used gravity as the driving force. However, as gravity cannot be turned on and off (thankfully!), we will instead apply a compressive force to one end of the dyke, compressing it and causing it to propagate.
To remove gravity as a factor in propagation, neutrally buoyant liquids will be used to make the dyke. This can be done by introducing a density gradient to the host gelatin and allowing the dyke to propagate laterally at its preferred depth. In order to perform a lateral propagation, a new experimental apparatus will be set up allowing continual examination the conditions for dyke arrest and acceleration while simultaneously benchmarking numerical codes.
In one experiment, a tank is filled with gelatin, which acts similar to the Earth’s crust. Inside the gelatin, a crack filled with oil grows upward towards the surface, which represents magma moving through the crust. A camera in front of the tank tracks what happens inside. An array of cameras positioned above the tank is used to make a 3D model of the surface. As the crack moves up, it begins to affect the surface, which can be measured with these models.
- Earth Observatory of Singapore
Meetings & Abstracts:
Pansino, S, & Taisne, B., Can a dike “feel” a free surface?, Abstract V43B-3109 presented at 2015 Fall Meeting, AGU, San Francisco California 14-18 Dec.
Adel Emadzadeh, Asian School of the Environment, Nanyang Technological University
Lior Kamhaji, Institute of the Earth Sciences, Hebrew University of Jerusalem
Amotz Agnon, Institute of the Earth Sciences, Hebrew University of Jerusalem