error relating to interface files

[aakash10gupta]

• For the anisotropic model case, I tried generating the mesh files both with and without the topography option. In both cases the Mesh_Par_file and the tomography_model.xyz were written out but the interface files were only written out when the paramater generate_topography was set to true.

• The filenames of interface files that were written out currently have the form layer_*.txt. Since the interface files do not contain information about the layer, but about the interfaces only, I think it is better to be consistent with the specfem3d convention of naming it in the style interface*.txt.

• The interface files that were written out seem to define non-planar interfaces for the non-topographic interfaces as well. Is this to compensate for the topography? Generally if the non-topographic interfaces are deep enough, we have previously used plane horizontal interfaces defined by a fixed depth assigned to 4 points.