|
The 2004 Indian Ocean earthquake occurred at 00:58:53 UTC on 26 December with an epicentre off the west coast of Sumatra, Indonesia. The event is known by the scientific community as the ''Sumatra–Andaman earthquake.''〔Lay, T., Kanamori, H., Ammon, C., Nettles, M., Ward, S., Aster, R., Beck, S., Bilek, S., Brudzinski, M., Butler, R., DeShon, H., Ekström, G., Satake, K., Sipkin, S., The Great Sumatra-Andaman Earthquake of 26 December 2004, ''Science'', 308, 1127–1133, , 2005〕〔(【引用サイトリンク】title=Tsunamis and Earthquakes: Tsunami Generation from the 2004 Sumatra Earthquake — USGS Western Coastal and Marine Geology )〕 The resulting tsunami was given various names, including the ''2004 Indian Ocean tsunami'', ''South Asian tsunami'', ''Indonesian tsunami'', the ''Christmas tsunami'' and the Boxing Day tsunami. The undersea megathrust earthquake was caused when the Indian Plate was subducted by the Burma Plate and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing 230,000 people in 14 countries, and inundating coastal communities with waves up to high.〔 It was one of the deadliest natural disasters in recorded history. Indonesia was the hardest-hit country, followed by Sri Lanka, India, and Thailand. With a magnitude of Mw 9.1–9.3, it is the third-largest earthquake ever recorded on a seismograph. The earthquake had the longest duration of faulting ever observed, between 8.3 and 10 minutes.〔(NSF: "Analysis of the Sumatra-Andaman Earthquake Reveals Longest Fault Rupture Ever" )〕 It caused the entire planet to vibrate as much as 〔Walton, Marsha. "(Scientists: Sumatra quake longest ever recorded )." ''CNN.'' 20 May 2005〕 and triggered other earthquakes as far away as Alaska.〔West, Michael; Sanches, John J.; McNutt, Stephen R. "(Periodically Triggered Seismicity at Mount Wrangell, Alaska, After the Sumatra Earthquake )." ''Science''. Vol. 308, No. 5725, 1144–1146. 20 May 2005.〕 Its epicentre was between Simeulue and mainland Indonesia.〔Nalbant, S., Steacy, S., Sieh, K., Natawidjaja, D., and McCloskey, J. "(Seismology: Earthquake risk on the Sunda trench )." ''Nature''. Vol. 435, No. 7043, 756–757. 9 June 2005. Retrieved 16 May 2009. (Archived ) 18 May 2009.〕 The plight of the affected people and countries prompted a worldwide humanitarian response. In all, the worldwide community donated more than US$14 billion (2004) in humanitarian aid.〔Jayasuriya, Sisira and Peter McCawley, ("The Asian Tsunami: Aid and Reconstruction after a Disaster" ). Cheltenham UK and Northampton MA USA: Edward Elgar, 2010.〕 ==Earthquake characteristics== The earthquake was initially documented as moment magnitude 8.8. In February 2005 scientists revised the estimate of the magnitude to 9.0.〔McKee, Maggie. "(Power of tsunami earthquake heavily underestimated )." ''New Scientist''. 9 February 2005.〕 Although the Pacific Tsunami Warning Center has accepted these new numbers, the United States Geological Survey has so far not changed its estimate of 9.1. The most recent studies in 2006 have obtained a magnitude of Mw 9.1–9.3. Dr. Hiroo Kanamori of the California Institute of Technology believes that Mw 9.2 is a good representative value for the size of this great earthquake.〔EERI Publication 2006–06, page 14.〕 The hypocentre of the main earthquake was approximately off the western coast of northern Sumatra, in the Indian Ocean just north of Simeulue island at a depth of below mean sea level (initially reported as ). The northern section of the Sunda megathrust ruptured over a length of .〔 The earthquake (followed by the tsunami) was felt simultaneously in Bangladesh, India, Malaysia, Myanmar, Thailand, Singapore and the Maldives.〔Lovholt, F., Bungum, H., Harbitz, C.B., Glimsal, S., Lindholm, C.D., and Pedersen, G. "(Earthquake related tsunami hazard along the western coast of Thailand )." ''Natural Hazards and Earth System Sciences''. Vol. 6, No. 6, 979–997. 30 November 2006. Retrieved 16 May 2009. (Archived ) 18 May 2009.〕 Splay faults, or secondary "pop up faults", caused long, narrow parts of the sea floor to pop up in seconds. This quickly elevated the height and increased the speed of waves, causing the complete destruction of the nearby Indonesian town of Lhoknga.〔Sibuet, J-C., Rangin, C., Le Pichon, X., Singh, S., Cattaneo, A., Graindorge, D., Klingelhoefer, F., Lin, J-Y., Malod, J., Maury, T., Schneider, J-L., Sultan, N., Umber, M., Yamaguchi, H., and the "Sumatra aftershocks" team, "(26 December 2004 great Sumatra–Andaman earthquake: Co-seismic and post-seismic motions in northern Sumatra )." ''Earth and Planetary Science Letters''. Vol. 263, Issues. 1–2, 88–103. 15 November 2007. Retrieved 16 May 2009. (Archived ) 18 May 2009.〕 Indonesia lies between the Pacific Ring of Fire along the north-eastern islands adjacent to New Guinea, and the Alpide belt that runs along the south and west from Sumatra, Java, Bali, Flores to Timor. Great earthquakes such as the Sumatra-Andaman event, which are invariably associated with megathrust events in subduction zones, have seismic moments that can account for a significant fraction of the global earthquake moment across century-scale time periods. Of all the seismic moment released by earthquakes in the 100 years from 1906 through 2005, roughly one-eighth was due to the Sumatra-Andaman event. This quake, together with the Good Friday earthquake (Alaska, 1964) and the Great Chilean earthquake (1960), account for almost half of the total moment. The much smaller but still catastrophic 1906 San Francisco earthquake is included in the diagram below for perspective. Mw denotes the magnitude of an earthquake on the moment magnitude scale. Since 1900 the only earthquakes recorded with a greater magnitude were the 1960 Great Chilean earthquake (magnitude 9.5) and the 1964 Good Friday earthquake in Prince William Sound (9.2). The only other recorded earthquakes of magnitude 9.0 or greater were off Kamchatka, Russia, on 4 November 1952 (magnitude 9.0)〔"(Kamchatka Earthquake, 4 November 1952 )." United States Geological Survey.〕 and Tōhoku, Japan (magnitude 9.0) in March 2011. Each of these megathrust earthquakes also spawned tsunamis in the Pacific Ocean. However, the death toll from these was significantly lower, primarily because of the lower population density along the coasts near affected areas and the much greater distances to more populated coasts and also due to the superior infrastructure and warning systems in MEDCs (More Economically Developed Countries) such as Japan. Other very large megathrust earthquakes occurred in 1868 (Peru, Nazca Plate and South American Plate); 1827 (Colombia, Nazca Plate and South American Plate); 1812 (Venezuela, Caribbean Plate and South American Plate) and 1700 (western North America, Juan de Fuca Plate and North American Plate). All of them are believed to be greater than magnitude 9, but no accurate measurements were available at the time. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「2004 Indian Ocean earthquake and tsunami」の詳細全文を読む スポンサード リンク
|