Add to ORKGabove the astronomical tide) have been observed on the western cliff, exposed to large swell from the North Atlantic. The analy-sis of hydrodynamic measurements collected during the storm of February 10, 2009 shows unusually high (over 2 m) infragravity wave run-up events. A comparison of run-up observations to mea-surements in approximately 7-m of water, and numerical simula-tions with a simplified nonlinear model allow two distinct infra-gravity bands to be identified: an 80-s infragravity wave, produced by nonlinear shoaling of the storm swell, and a 300-s wave, trapped on the intertidal platform of the island and generating intermittent, low-frequency inundation. Our analysis shows that the 300-s waves are a key component of the extreme...