Estimating the potential runout distance of a landslide and it associated impacted area is an important component of landslide hazard and risk analysis. Back analysis of previous landslides is traditionally used to predict the runout behaviour of potential future landslides. This can be done using empirical – statistical relationships (typically adopted for regional scale studies), or through numerical modelling of landslide run-out (typically used for more detailed, site-specific analysis).

This presentation will outline and discuss current techniques for, and research into modelling landslide runout using back -analysis of the landslides generated during the 2016 Kaikōura Earthquake. This back-analysis allows for calibration and validation of landslide runout models, quantification of the uncertainty of the model outputs, as well as analysis of controls on landslide runout. This presentation will provide an overview of the use a national and international empirical database used to assess landslide runout for different landslide types including : i) earthquake-triggered debris avalanches, ii) rainfall-triggered debris avalanches, iii) rainfall-triggered debris flows, alongside a numerical modelling approach, using RAMMS debris flow software, for earthquake-induced landslides as well as rainfall-induced landslides triggered along the Kaikōura coast during the ex-tropical cyclone Gita rain event. The presentation will finish with a discussion of how these runout models link to landslide sources, mechanisms and susceptibility and how they can be used for planning and decision-making.