The surface flow evolution over 6 years of a glacier surge in Svalbard is revealed by satellite radar interferometry from ERS-1 and ERS-2. Eleven surface velocity maps, generated by combining multi-temporal, differential interferograms utilising 36 ascending and descending-pass images, give an unprecedented overview of the spatio-temporal development of the surge. The surge is characterised by gradual initiation and termination phases, and flow restrictions appear to remain spatially consistent despite the relatively large changes in surface velocity. Results from this type of study are expected to help constrain physically-based models of surge behaviour.