Indonesia Earthquake

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Posting Date: November 12, 2004, 9:00:00 AM

On Thursday, November 11, 2004, a strong earthquake struck the remote Indonesian island of Alor at 5:26 a.m. local time (21:26 UTC). The U.S. Geological Survey has estimated the moment magnitude at 7.3 and the focal depth at 37.8 km. A magnitude 6.4 aftershock followed about an hour after the mainshock. The quake was felt in Dili, the capital of East Timor, which lies 100 km west-northwest of the epicenter, though no major damage has been reported there. In Kalabahi, the main town on Alor Island, at least 600 houses are reported to have been damaged, along with several schools and churches. Sixteen people are reported killed, most by the collapse of their homes, and there are indications that this figure may rise as rescue workers make their way across the island’s mountainous terrain to some of the more remote villages. Alor’s airport was forced to close as a result of damage. The Indonesia region is one of the most seismically active areas in the world. It is a typical island-arc structure with deep oceanic trenches and surrounded by four tectonic plates--the Sunda and Philippine Sea plates to the north, the Pacific plate to the west, and Australian plate to the south—making this of one of the most tectonically complex regions on Earth. Yesterday’s earthquake occurred near the boundary of two “micro-plates” that are sandwiched between the four larger plates. In July 1991, a magnitude 6.9 earthquake occurred just 20 km to the west of the current one, killing 23 people and injuring 181. Because of the remoteness of the location and the sparse population in the epicentral region, AIR expects insured losses to be minimal.

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Posting Date: November 12, 2004, 9:00:00 AM