Magnitude 8.9 quake off the west coast of Northern Sumatra

A great earthquake occurred at 00:58:50 (UTC) on Sunday, December 26, 2004. The magnitude 8.9 event has been located off the west coast of Northern Sumatra. This event has been reviewed by a seismologist.

At least 2,200 people killed in Sri Lanka, 1,600 in India, 700 in Indonesia, 220 in Thailand, 29 in Malaysia and 2 in Bangladesh by tsunamis. Tsunamis also occurred on the coasts of Maldives, Cocos Island and Somalia. At least 200 people killed, buildings destroyed or damaged in the Banda Aceh area, Sumatra. Felt widely in Sumatra. Also felt in Bangladesh, India, Malaysia, Myanmar, Singapore and Thailand. This is the fifth largest earthquake in the world since 1900 and is the largest since the 1964 Prince William Sound, Alaska earthquake.

Today’s shallow, thrust-type earthquake occurred off the west coast of northern Sumatra at the interface between the India and Burma plates. In this region, the Burma plate is characterized by significant strain partitioning due to oblique convergence of the India and Australia plates to the west and the Sunda and Eurasian plates to the east. Off the west coast of northern Sumatra, the India plate is moving in a northeastward direction at about 5 cm per year relative to the Burma plate.

Preliminary locations of larger aftershocks following today’s earthquake show that approximately 1000 km of the plate boundary slipped as a result of the earthquake. Aftershocks are distributed along much of the shallow plate boundary between northern Sumatra (approximately 3 degrees north) to near Andaman Island (at about 14 degrees north).

From U.S. Geological Service

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