Acceleration of 2.5D Elastic Anisotropic Modelling

3D modelling can be simplified if the medium properties are fixed along some direction. Such type models are called 2.5D ones. One source line computed in 2.5D model can be replicated to produce full 3D survey. 2.5D elastic anisotropic method of finite-difference forward modelling can generate realistic 3D synthetic seismograms for geometrically simplified but detailed models with arbitrary 3D TTI anisotropy and fracturing. The method is based on space frequency decomposition along the direction of fixed parameters. Despite its computational complexity is almost the same as in 3D case GPUs accelerate 2.5D modelling much better than full 3D. Efficient memory decomposition which reduces 2.5D problem to a set of independent quasi-2D problems is a key to the GPU efficiency. 2.5D method runs GPU calculations in the most favourable mode: without data reload, using single floating point precision and local calculations only. Both high level and low level GPUs provide high performance for 2.5D. Additional 3-4 times acceleration of 2.5D over full 3D can be obtained for simple models by random undersampling with spectrum interpolation (for the cost of about 1% noise). 2.5D complements 3D ray tracing in investigation of benefits from multi-component surveys, quasi-anisotropy effects, processing resolution, etc.