THE INDIAN OCEAN TSUNAMI OF 26 DECEMBER 2004 Analysis of Seismic Source Mechanism

Based on the keyboard model of tsunamigenic earthquakes, an analysis was performed of the physical aspects of the 26 December 2004 earthquake off Sumatra and of the seismic source of the great tsunami generated in the Indian Ocean. A simplified keyboard model with vertical displacements of keyboard blocks was used for the numerical simulation in defining the tsunami’s generation source and, based on known bathymetry, its subsequent propagation across the Indian Ocean basin. The numerical simulation of the seismic source took into account the oblique character of subduction zone, which was characteristic for this particular earthquake. Furthermore, the analysis evaluated the different scenarios of keyboard blocks motions - corresponding to real seismic and hydro acoustic studies of the earthquake process - as reported in the literature. Adequateness of the calculations performed was verified by comparison of real altimetry records of satellite “Yason-1” with virtual altimetric record, obtained by us for each calculation. The computational analysis helped explain the complex character of the tsunami and of its propagation and energy flux distribution in the Indian Ocean basin.