Plate tectonics after the 26 December 2004 Great Sumatra earthquake resulted in major topological changes in the Andaman and Nicobar islands. Aerial and land reconnaissance surveys of those islands after the earthquake provide evidence of spectacular plate tectonics that took place during the earthquake. Initial submergence of the built environment and the subsequent inundation upon arrival of the tsunami wave, as well as emergence of the new beaches along the islands-particularly on the western rims of the islands and in the northern islands-are the major signatures of this Mw=9.3 event. © 2006, Earthquake Engineering Research Institute.