9218923 O'Connell The research is to study flow in the mantle where large viscosity variations are present. This includes the rise of plumes through the mantle, and the sinking of strong lithosphere as subducted slabs. The aim is to understand how the dynamics of the ascent of plumes is related to the rheological and thermal properties of the mantle, and how they interact with the core- mantle boundary, the transition zone and the Earth's surface. Another aim is to understand the deformation of sinking slabs, and to relate their seismicity and shape to the structure and dynamics of the mantle, and to determine how slabs interact with rheological and thermodynamic boundaries in the transition zone. The analysis of the problems will use the boundary integral method, which allows internal boundaries to be followed through large displacements and deformations, and makes the treatment of some three-dimensional subduction and plume problems feasible. The method will be extended to treat a phase boundary. ***
