| Thu May 15th 2008 13:30 | Seminar | Magma-rock-fault interactions for the Shimabara-Beppu Graben Onno Bokhove |
Details:Collaborators: Vijaya Ambati, Department of Applied Mathematics, Enschede, The Netherlands Chuck Connor Koji Kiyosugi, Department of Geology, University of South Florida, Tampa Bay, U.S.A.We present preliminary laboratory experiments and potentially numerical results on magma-rock interactions, with the aim to understand key physical processes in magma- dike-fault interactions in the Aso volcanic region, Kyushu, Japan. Two locations of volcanoes, Omine Volcano and Akai Volcano, about 10km and 25km from the central vent of Aso Volcano along the southern fault of the Shimabara-Beppu Graben, suggest fault involvement in the dike propagation processes from the magma source region under and around Aso Volcano. Geological and geophysical observations lead to the question of under what circumstances a magma dike encountering an inclined fault will continue to propagate vertically or follow the fault. We aim to investigate through a hierarchy of idealized laboratory and numerical experiments, using gelatine as proxy for rock and water(/glycerine) as a proxy for magma and three-dimensional finite element simulations. This hierarchy includes stationary eruption-states of plain vertical dikes without pre-existing faults, and dike-fault interactions; and, their dependence on overpressure, container size, and depth. Our methodology will be to use the idealized laboratory experiments to validate the numerical models by systematically measuring the dependence on the dike shape (along the major axis and in the vertical) and "magma" discharge in the steady state, as function of hydrostatic head ("overpressure") and fluid ("magma") viscosity. In addition we will determine the rheology of the gelatine, also as function of time, in compression and/or shear tests to fix parameters in linear elastic or nonlinear hyperelastic models. Subsequently, the numerical models can and will be extended with more confidence to realistic geological scales. | ||
