Seiches in Lützow-Holm Bay, Antarctica

Sea-level oscillations induced by Sumatran earthquakes on 26 December 2004 and 28 March 2005 were analyzed using tide gauge data recorded in Lützow-Holm Bay, Antarctica. The oscillations continued for more than 2 days, with principal periods of about 1 and 3 h. The 3-h component was repeatedly excited by the 1-h component, resulting in alternations of the dominant period of oscillation. The dynamical modes of sea-level oscillations were calculated based on topographic data for Lützow-Holm Bay. The predominant periods of the long-lived sea-level oscillations were found to be similar to those of the waves of topographically constrained modes. The alternations in the dominant period of the oscillations may be interpreted as disturbances that were initially localized in a shallow region of the basin and subsequently expanded to the entire basin.