ABSTRACT
During the Indian Ocean Tsunami of 26 December 2004, high water levels persisted in certain harbors (for example in the state of Kerala in India) in the Indian Ocean, even after the main tsunami was dissipated. For a detailed analysis of various aspects of this tsunami, see Murty et al. (2005a-c), Murty et al. (2006a-c), Nirupama et al. (2005) and Nirupama et al. (2006). The reason for this persistence is the so-called Helmholtz mode of resonance, in which the long gravity wave energy of the tsunami enters a wide harbor through a narrow entrance channel. The energy, once entered the harbor cannot easily get out of the harbor because each successive reflection from the harbor walls only leak out a small amount of energy.
