Natural moraines bounding glacial lakes can fail and cause floods called glacier lake outburst floods (GLOFs). Because of the volume of water released and the speed with which the outburst travels, GLOFs represent a serious hazard to downstream regions. Current ideas suggest the development and expansion of glacial lakes may be due to global warming, although this view is not universally accepted. In any event, people living downstream are exposed to significant hazard risk. For example, on October 7, 1994, the failure of the moraine at Lugge Lake in the Lunana region, Bhutan, caused a GLOF that killed more than 20 people. This paper presents a first attempt to understand the dynamics of GLOFs through numerical simulations, using a two phase model of fluid and granular material flows over natural terrain. These computations extend the TITAN2D simulation environment originally developed for volcanic hazard computations. By combining simulations and field studies, scientists can provide those charged with civil protection with better information with which to make preparations. (C) 2012 Published by Elsevier B.V.