For recent trans-Pacific tsunamis, such as the 2010
Chile tsunami or the 2011 Tohoku tsunami, discrepancies
(a few percent) in the travel time between the observed
waveforms recorded at DART stations and the computed
waveforms based on linear shallow water have been reported.
A small reduction of the tsunami phase velocity at
very long period (>1000 seconds), caused by the coupling
of seawater and self-gravitating elastic Earth, is considered
to be responsible for these delays.