Palcacocha (possibly from Quechua pallqa, p'allqa, p'alqa forked, branched, fork, qucha lake) is a glacier lake in the Andes mountain range of South America in northwestern Peru located in the Ancash Region, Huaraz Province. Location Palcacocha is located at in the Ancash Region in Cordillera Blanca at an elevation of 4,566 m, just below the summits of Palcaraju (6,274 m) and Pucaranra (6,156 m). The lake is one of several lakes supplying the town Huaraz with water, 23 km to the southwest. 1941 mudflow On the early morning of 13 December 1941 a huge chunk of the adjacent glacier or a large avalanche fell into Lake Palcacocha causing the breaking of the moraine walls that limit the lake downhill. The wave hurtled down the Cojup valley, destroying Lake Jiracocha on its way and carrying blocks of ice, large rock boulders and liquid mud towards the Santa River valley. Within 15 minutes the mudslide reached Huaraz, with 400 m³ of debris burying parts of the town and killing approximately 1,800 to 7,000 inhabitants. The outburst is estimated to have reduced the volume of the lake from about 10 million cubic metres to half a million. In 1974 drainage structures were built to maintain the level eight metres below the height of the damming moraine in order to protect against overtopping in the event of an avalanche or ice fall into the lake. But an adjacent glacier to the lake has receded since the incident increasing the size of the lake. Also because of climate-change-related melting of the glacier the lake's water input has also increased dramatically since the disaster. By 2009 its volume was about 17 million cubic metres. Recent developments In April 2003, NASA scientists discovered a fissure in the glacier above Lake Palcacocha on Terra satellite images of November 2001. Their warnings reached Peru just two weeks after the staff of the UGRH (Unidad de Glaciologia y Recursos Hidricos) had done some field mapping of Lake Palcacocha, where a moraine rupture had caused a minor flood on 19 March 2003 which the safety constructions from the 1940s had captured. According to research done by scientists of the Innsbruck university in Austria, the ensuing panic among the inhabitants and economic damage to Huaraz' tourism industry could have been prevented, as from their findings the NASA warnings were a misinterpretation of satellite data. The water volume of Lake Palcacocha has increased