The plot below shows the various long-period waves in Lyttelton Harbour over the last week, as measured by the tide gauge.
These waves have periods between 3 and 24 minutes.
They result from swell waves and moving low-pressure systems.
Oscillation of the harbour in its various resonant modes.
Details of the modes are presented in this report.
Oscillation of Pegasus Bay at its natural period of 3.4 h.