Ship generated tsunamis: linearity vs. nonlinearity

Very long waves running ahead of ships is a recent phenomenon in the Oslofjord in Norway. The waves are triggered when the new very large and relatively fast cruiseferries are running across significant depth changes in the shallow fjord. An asymptotic linear analysis expressing the upstream wave field in terms of a pressure impulse at the depth change is complemented by fully dispersive calculations of the upstream waves. At very shallow positions the local ship speed becomes critical where the effect of nonlinearity is analyzed. A wave length of 700 m, wave height at the shore of 1 m, average depth of the fjord of 35 m, depth change similar to the average depth, ship length of 200 m, moving at subcritical speed, are typical characteristics.Non UBCUnreviewedAuthor affiliation: University of OsloFacult