9:30 AM - 9:45 AM
[SIT26-03] Fluid migration in poro-viscoelastic slab
Keywords:fluid migration, poro-viscoelasticity, subduction zones
We use numerical approach based on a theory of two-phase flow, which allows us to simultaneously consider the movement of matrix and fluid phases. We consider 2D model domain inside the slab. A thin layer of fluid source is assumed. Bulk modulus and bulk viscosity which characterize elastic and viscous deformation with volumetric change, respectively, are assumed to be constants. We fix bulk modulus to be 130 GPa and change only bulk viscosity to see its effects on fluid behavior.
Preliminary results show that when the viscosity is lower than ~10^22 Pa.s, viscous deformation is dominant in the slab and almost all the fluids go up vertically soon after its generation, producing porosity waves. When we use bulk viscosity of 10^24 Pa.s, the slab behaves as an elastic medium and a large part of fluids is trapped in the slab. Considering that the slab has a high shear viscosity due to its low temperature and that bulk viscosity is at least as high as shear viscosity, bulk viscosity in the slab is likely to be very high. Therefore the slab may deform as an elastic medium in response to fluid migration and a large part of fluids will remain in the slab.