This paper presents some of the implications of oceanic asperities in subduction zones, based on examples gathered during the world circumnavigation of R/V Jean Charcot . The study of these examples provides a new overview of active margin modelling in response to asperity subduction. It is concluded that both erosion and accretion may be governed by the oceanic plate even though frontal tectonic erosion is better documented because it is accessible to conventional surveys. Most of the time, erosion is due to the relaxation of the arc slope in the wake of asperity/subduction.