December 26, 2004 Earthquake: Off West Coast, Aceh, Sumatra, Indonesia

This is the third largest earthquake in the world since 1900 and is the largest since the 1964 Prince William Sound, Alaska earthquake. The earthquake caused severe damage and casualties in northern Sumatra, Indonesia and in the Nicobar Islands, India.

Reference #3969:

The assessments after the tsunami estimated losses and damage at just under $10 billion. 227,898 dead or missing. No separate death toll is available for the earthquake as the tsunamis followed within 20 minutes. However, the relatively light damage from the earthquake suggests that the death toll was probably no worse than for the earthquake of 28 March 2005 - that is, fewer than 1,000.

Reference #1610:

At least 170,000 dead, 100,000 missing, and more than 1,000,000 homeless by the earthquake and subsequent tsunami in 13 countries in South Asia and East Africa. According to provisional estimates (February 2005), the material losses caused by the catastrophe come to approximately US$ 10bn.

Reference #13456 (accessed June 2023) lists magnitude 9.1 Mw. Reference #13546 lists magnitude 9.2 Mw.

Reference #10476 (v.10) lists magnitude 9.31 Mw

Reference #1053:

Earthquake intensities were observed at the following selected localities:

Indonesia: IX: Banda Aceh, VIII: Meulaboh, IV: Medan, Sampali, III: Bukittinggi, Parapat, Payakumbuh, Felt: Jakarta

India: VII: Port Blair, Andaman Is., IV: Madras, III: Bengaluru, Vishakhapatnam, Felt: Bangalore, Bhubaneshwar, Calcutta, Kochi

Malaysia: V: Gelugor Estate, IV: Sungai Ara, III: Alor Setar, George Town, Kampong Tanjong Bunga, Kuala Lumpur, Kulim

Thailand: V: Hat Yai, IV: Bangkok, III: Chiang Mai, Phuket

Myanmar: IV: Mandalay, III: Rangoon

Singapore: II: Singapore

Bangladesh: III: Dhaka, Felt Chittagong

Sri Lanka:II: Kandy and other parts of Sri Lanka

Maldives:IV: Male (nearly 2500 km from the epicenter)

Guam:Felt by people in a high rise building at Hagatna (more than 5400 km from the epicenter)

Tectonic Summary

The devastating earthquake of 26 December 2004 occurred as thrust-faulting on the interface of the India plate and the Burma plate. In a period of minutes, the faulting released elastic strains that had accumulated for centuries from ongoing subduction of the India plate beneath the overriding Burma plate.

In a broad sense, the India and Australian plates move toward the north- northeast with respect to the interior of the Eurasia plate with velocities of about 60 mm/y in the region of the earthquake. In the region of northern Sumatra and the Nicobar Islands, most of the relative motion of India/Australia and the Eurasia plate is accommodated at the Sunda trench and within several hundred kilometers to the east of the Sunda trench, on the boundaries of the Burma plate. The direction in which India/Australia converges toward Eurasia is oblique to the trend of the Sunda trench. The oblique motion is partitioned into thrust-faulting and strike-slip faulting. The thrust faulting occurs on the interface between the India plate and the western margin of the Burma plate and involves slip directed at a large angle to the orientation of the trench. The strike-slip faulting occurs on the eastern boundary of the Burma plate and involves slip directed approximately parallel to the trench. The 26 December main shock occurred as the result of thrust faulting on the western Burma-plate boundary, but many strike-slip faulting aftershocks occurred on the eastern plate boundary.