ABSTRACT
Active tectonics along the Northeast moving Indian plate, which is subducting under the Burmese micro-plate with the Sunda trench as undersea surface expression, resulted in this century’s fourth largest earthquake of magnitude (Mw) 9.0 in Banda-Aceh, Sumatra on 26 December 2004 at 00:58 h (UTC). The earthquake originated at a shallow depth of about 30 km with the epicenter located at 3.32◦N latitude and 95.85◦E longitude (Figure 19.1). The tremors of the earthquake was felt at Banda-Aceh with intensity IX, at Meulaboh with intensity of VIII and at Medan, intensity IV, Sumatra and in parts of Bangladesh, India, Malaysia, Maldives, Myanmar, Singapore, Sri Lanka and Thailand with III-V intensity (https://neic.usgs.gov/neis/eq_depot/2004/eq_041226/). This mega-thrust earthquake generated a totally unexpected tsunami in the Indian Ocean and Bay of Bengal whose fury left more than 283,100 people dead, 14,100 missing and more than 1,120,000 displaced in numerous countries; the effects of which were felt as far as East Africa. The Indian Ocean and the Bay of Bengal has rare records of tsunamis in the past. This Tsunami is the direct consequence of about 1300 km long thrust faulting, which ruptured undersea displacing huge volumes of water in the Indian Ocean and the Bay of Bengal. Numerous aftershocks ranging in magnitude (Mw) from 3 to less than 7 rocked the region from Simeulue Island (Sumatra, Indonesia) in the south to near Landfall Island (north Andaman, India) in the north. Twenty-five aftershocks were of magnitude (Mw) 6.0 or greater, the strongest one being of magnitude 7.1 that occurred on 26 December 2004 at 04:21 h (UTC) (Figure 19.1).
