"Landslides and debris flows are serious geo-hazards common to countries with mountainous terrains. The high speed and the enormity of debris mass make debris flows one of the most dangerous natural hazards. Debris flows are often triggered by landslides partially or completely mobilizing into debris flows. Globally, landslides cause billions of dollars in damage and thousands of deaths and injuries each year. The numerous devastating events worldwide have made us aware of the complexity of landslides and debris flows and our insufficient knowledge to make reliable predictions. Traditional tools for prediction and design are based on limit equilibrium analysis for landslides and shallow water model with Finite Difference solver for debris flows. Usually soil and debris are modelled as single phase materials with constant material properties. That the simple models are unable to account for the complex behaviour of landslides and debris flows, which can be best described as multiphase and multiscale, is well known to researchers and stakeholders. Obviously there is an urgent need for better understanding of the triggering mechanisms, for reliable prediction of runout dynamics, deposition pattern and impact forces and for rational design of stabilization and protection structures. The last decade saw rapid developments in advanced constitutive models, experimental techniques in laboratory and in-situ, mechanics of multiphase media, localized deformation analysis, Discrete Element Method (DEM), advanced Finite Element Method (FEM) and Computational Fluid Dynamics (CFD). Training in these subjects has been rather sporadic and scattered in various disciplines. By integrating these advances into a coherent research network we expect to achieve the breakthrough in the research on landslides and debris flows, i.e. a consistent physical model with robust numerical scheme to provide reliable prediction and rational design of protection measures for landslides and debris flows."