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The Armero tragedy ( (:tɾaˈxeðja ðe arˈmeɾo)) was one of the major consequences of the eruption of the Nevado del Ruiz stratovolcano in Tolima, Colombia, on November 13, 1985. After 69 years of dormancy, the volcano's eruption caught nearby towns unaware, even though the government had received warnings from multiple volcanological organizations to evacuate the area when volcanic activity had been detected in September 1985. As pyroclastic flows erupted from the volcano's crater, they melted the mountain's glaciers, sending four enormous lahars (volcanically induced mudslides, landslides, and debris flows) down its slopes at . The lahars picked up speed in gullies and coursed into the six major rivers at the base of the volcano; they engulfed the town of Armero, killing more than 20,000 of its almost 29,000 inhabitants.〔Schuster, Robert L. and Highland, Lynn M. (2001). (Socioeconomic and Environmental Impacts of Landslides in the Western Hemisphere ), U.S. Geological Survey Open-File Report 01-0276. Also previously published in the Proceedings of the Third Panamerican Symposium on Landslides, July 29 to August 3, 2001, Cartagena, Colombia. Castaneda Martinez, Jorge E., and Olarte Montero, Juan, eds. Retrieved June 11, 2010.〕 Casualties in other towns, particularly Chinchiná, brought the overall death toll to 23,000. Footage and photographs of Omayra Sánchez, a young victim of the tragedy, were published around the world. Other photographs of the lahars and the impact of the disaster captured attention worldwide and led to controversy over the degree to which the Colombian government was responsible for the disaster. A banner at a mass funeral in Ibagué read, "The volcano didn't kill 22,000 people. The government killed them." The relief efforts were hindered by the composition of the mud, which made it nearly impossible to move through without becoming stuck. By the time relief workers reached Armero twelve hours after the eruption, many of the victims with serious injuries were dead. The relief workers were horrified by the landscape of fallen trees, disfigured human bodies, and piles of debris from entire houses. This was the second-deadliest volcanic disaster of the 20th century, surpassed only by the 1902 eruption of Mount Pelée, and is the fourth-deadliest volcanic event recorded since 1500 AD. The event was a foreseeable catastrophe exacerbated by the populace's unawareness of the volcano's destructive history; geologists and other experts had warned authorities and media outlets about the danger over the weeks and days leading up to the eruption. Hazard maps for the vicinity were prepared, but poorly distributed. On the day of the eruption, several evacuation attempts were made, but a severe storm restricted communications. Many victims stayed in their houses as they had been instructed, believing that the eruption had ended. The noise from the storm may have prevented many from hearing the sounds from Ruiz until it was too late. Nevado del Ruiz has erupted several times since the disaster, and continues to threaten up to 500,000 people living along the Combeima, Chinchina, Coello-Toche, and Guali river valleys. A lahar (or group of lahars) similar in size to the 1985 event could potentially travel as far as from the volcano, and could be triggered by a small eruption. To counter this threat, the Colombian government established a specialized office which promotes awareness of natural threats. The United States Geological Survey also created the Volcano Disaster Assistance Program and the Volcano Crisis Assistance Team, which evacuated roughly 75,000 people from the area around Mount Pinatubo before its 1991 eruption. In 1988, three years after the eruption, Dr. Stanley Williams of Louisiana State University stated that, "With the possible exception of Mount St. Helens in the state of Washington, no other volcano in the Western Hemisphere is being watched so elaborately" as Nevado del Ruiz. Additionally, many of Colombia's cities have programs to raise awareness of natural disaster planning programs which have helped save lives in natural disasters. Near Nevado del Ruiz in particular, locals have become wary of volcanic activity: when the volcano erupted in 1989, more than 2,300 people living around it were evacuated. ==Background== Armero, located from the Nevado del Ruiz volcano and from Colombia's capital of Bogotá, was the third largest town in Tolima Department, after Ibagué and Espinal. A prominent farming town before the eruption, it was responsible for roughly one-fifth of Colombia's rice production, and for a large share of the cotton, sorghum, and coffee crops. Much of this success can be attributed to Nevado del Ruiz, as the fertile volcanic soil had stimulated agricultural growth. Built on top of an alluvial fan〔 that had been host to historic lahars, the town was previously destroyed by a volcanic eruption in 1595 and by mudflows in 1845. In the 1595 eruption, three distinct Plinian eruptions〔Mileti et. al, 1991, p. 9.〕 produced lahars that claimed the lives of 636 people.〔 During the 1845 event, 1,000 people were killed by earthquake-generated mudflows near the Magdalena River.〔Mileti et. al, 1991, p. 10.〕 Nevado del Ruiz has undergone three distinct eruptive periods, the first beginning 1.8 million years ago. During the present period (beginning 11,000 years ago), it has erupted at least twelve times, producing ashfalls, pyroclastic flows, and lahars. The historically recorded eruptions have primarily involved a central vent eruption (in the caldera) followed by an explosive eruption, then the formation of lahars. Ruiz's earliest identified Holocene eruption was in about 6660 BC, and further eruptions occurred around 1245, 850, 200 BC and in about 350, 675, in 1350, 1541 (perhaps), 1570, 1595, 1623, 1805, 1826, 1828 (perhaps), 1829, 1831, 1833 (perhaps), 1845, 1916, December 1984 through March 1985, 1987 through July 1991, and possibly in April 1994. Many of these eruptions involved a central vent eruption, a flank vent eruption, and a phreatic (steam) explosion. Ruiz is the second-most active volcano in Colombia after Galeras. One week before the eruption, the Palace of Justice siege took place. The assailants (M-19 a Marxist, Terrorist Insurgency group) planned to hold a trial involving Colombian President Belisario Betancur. He refused to participate and sent the national army into the building. The attackers were holding several hundred hostages, including the 24 Supreme Court justices and 20 other judges. In the ensuing battle between the two forces, more than 75 hostages died (including 11 judges). This disaster, coupled with the Armero tragedy, spurred the Colombian government to predict and prepare for a broad range of threats.〔 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「Armero tragedy」の詳細全文を読む スポンサード リンク
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