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Deep Earth Dynamics Finite element models designed to study deformation in a specific subduction zone must include an accurate and smooth representation of structures such as the subducting plate and plate boundary. The locations of these features are often well-constrained at the surface, but must be interpolated from sparse data sets in the subsurface (e.g. earthquake locations). While there are existing tools for surface fitting from earthquake location, (e.g., splines in tension), these methods often generate artifacts due to the inhomogeneous distribution of data or inappropriate weighting of outliers. In addition, once the location of the slab surface is known, this information needs to be used to construct the input model data on a finite element grid. For example, the input temperature and viscosity field for a subduction model are attributes that need to be assigned to the finite element mesh in such a way as to create a smoothly varying field without effects of aliasing on the grid. Algorithms for surface generation, geometric manipulations and interpolations on variable grids are routinely used in the field of data visualization and can be adapted to the problem of input model generation for finite element calculations. Geology graduate student Margarete Jadamec and Computer Science Post-Doc Oliver Kreylos are currently working together to design a simple and efficient method for generating slab surfaces from earthquake data and using such a surface to assign attributes to a 3D grid. We plan to release the source code for two C-programs, which allow these algorithms to be applied to any point-set defining a surface and/or any surface used to generate attributes on a 3D grid. As new data become available, these programs will allow researchers focused on specific regions to generate an accurate representation of the slab surface shape or other structure instead of depending on previously available data sets that may be out-dated or incomplete.
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