Conclusions

Infragravity waves are generated in the nearshore region and are observed at KEBB only after they propagate from the shelf into deeper water and pass over KEBB. This agrees with the previous analysis of the MOBB data which also showed that the infragravity waves are generated in the nearshore region (Dolenc et al., 2005). It sheds some light on the generation of the earth's low frequency "hum" , confirming that coupling of infragravity waves with the solid earth occurs close to the shore (Rhie and Romanowicz, 2006). The long-period noise due to infragravity waves is unavoidable in shallow ocean bottom installations and postprocessing is needed to remove it from the seismic observations (Dolenc et al., 2007a).