Cellular Automata represent a formal frame for dynamical systems which evolve on the base of local interactions. We here present first results of the CUDA parallelization of the SCIDDICA S3-hex Complex Cellular Automata model for simulating debris flows. In particular, a first strategy for the parallelization of the model is based on a straightforward one thread - one cell approach, where each cell in the cellular space is computed by a CUDA thread. A second approach concerns the adoption of a list of CA computational active cells which is handled step by step by an efficient stream compaction algorithm, in order to reduce the excessive use of computationally inactive threads. First results performed on different graphic processors have shown that, by adopting the different CUDA strategies, this kind of hardware can be effective for landslide risk mitigation.

This paper presents the release fv3 of the Complex Cellular Automata model Sciara for simulating lava flows. It is based on a Bingham-like rheology and both flow velocity and the physical time corresponding to a computational step have been made explicit. The model has been preliminary tested with satisfying results by considering the 2006 lava event at Mt Etna (Italy). A HTML5 based Web application with a WebGL 3D interactive visualization system has also been developed as user interface for Sciara-fv3. Eventually, the numerical code has been parallelised by the CUDA GPGPU paradigm, allowing for a considerable reduction of the execution time, despite the numerical code complexity.