The Nevado del Ruiz, also known as La Mesa de Herveo (English: Table of Herveo), or Kumanday in the language of the local pre-Columbian indigenous people, is a volcano located on the border of the departments of Caldas and Tolima in Colombia, about 129 kilometers (80 mi) west of the capital city Bogotá. It is a stratovolcano, composed of many layers of lava alternating with hardened volcanic ash and other pyroclastic rocks. Nevado del Ruiz has been active for about two million years, since the early Pleistocene or late Pliocene epoch, with three major eruptive periods. The current volcanic cone formed during the present eruptive period, which began 150 thousand years ago.
The volcano usually generates Plinian eruptions, which produce swift-moving currents of hot gas and rock called pyroclastic flows. These eruptions often cause massive lahars (mud and debris flows), which pose a threat to human life and the environment. The impact of such an eruption is increased as the hot gas and lava melts the mountain's snowcap, adding large quantities of water to the flow. On November 13, 1985, a small eruption produced an enormous lahar that buried and destroyed the town of Armero in Tolima, causing an estimated 25,000 deaths. This event later became known as the Armero tragedy-the deadliest lahar in recorded history. Similar but less deadly incidents occurred in 1595 and 1845, consisting of a small explosive eruption followed by a large lahar.
The volcano is part of Los Nevados National Natural Park, which also contains several other volcanoes. The summit of Nevado del Ruiz is covered by large glaciers, although these have retreated significantly since 1985 because of atmospheric warming. The volcano continues to pose a threat to the nearby towns and villages, and it is estimated that up to 500,000 people could be at risk from lahars from future eruptions.
The summit of Nevado del Ruiz is covered by glaciers (nevado means "snow covered" in Spanish), which formed over many thousands of years, and have generally retreated since the last glacial maximum. From 28,000 to 21,000 years ago, glaciers occupied about 1,500 square kilometers (600 sq mi) of the Ruiz–Tolima massif. As late as 12,000 years ago, when the ice sheets from the last glacial period were retreating, they still covered 800 square kilometers (300 sq mi).
During the Little Ice Age, which lasted from about 1600 to 1900 CE, the ice cap covered approximately 100 square kilometers (40 sq mi).Since then, the glaciers have retreated further because of atmospheric warming.By 1959, the massif's glaciated area had dropped to 34 square kilometers (13 sq mi).Since the 1985 eruption, which destroyed about 10% of the summit ice cover, the area of Nevado del Ruiz covered by glaciers has halved-from 17 to 21 square kilometers (6.6 to 8.1 sq mi) just after the eruption to about 10 square kilometers (3.9 sq mi) in 2003.
The glaciers reached altitudes as low as 4,500 meters (14,800 ft) in 1985 but have now retreated to elevations of 4,800–4,900 meters (15,700–16,100 ft).The meltwater from the glaciers drains primarily to the Cauca River and Magdalena River via the western and eastern flanks of the volcano, respectively.Runoff from these glaciers and those on the surrounding volcanoes is a source of fresh water for forty surrounding towns, and Colombian scientists and government officials are concerned about the towns' water supply should the glaciers melt completely.
Flora And Fauna
Nevado del Ruiz is generally poorly forested because of its high elevation, and its forest cover decreases with increasing elevation. At lower elevations, well-developed mesic forests (20-35 meters / 66-110 ft high) are present. Above these but below the tree line, parts of the volcano are covered with dwarf forests 3-8 meters (10-30 ft) high. Above the tree line, in the Páramo zone, the vegetation is dominated by plants such as bunchgrass and Espeletia.Regional vegetation consists of different families of woody plants, including Rubiaceae, Leguminosae, Melastomataceae, Lauraceae, and Moraceae. Flowers such as Polypodiaceae s.l., Araceae, Poaceae, Asteraceae, Piperaceae, and Orchidaceae are also present in the region.
Animals living on the volcano include the mountain tapir and spectacled bear, both of which are designated as threatened.Other animals inhabiting the surrounding region include the rufous-fronted parakeet, bearded helmetcrest and Herveo plump toad. The volcano is home to 27 species of birds endemic to Colombia, with 14 of these species confined to the region around the volcano. 15 bird species in the area are considered threatened.
Los Nevados National Park
Nevado del Ruiz is one of several stratovolcanoes within Los Nevados National Natural Park, a national park located west of Bogotá in the centre of the Colombian Andes. The park is a popular tourist destination and contains several tourist shelters. The slopes of the volcano are used for winter sports, and nearby Lake Otún offers trout fishing.A number of commercially operated spas can be found nearby. In 1868-1869, German geologists Wilhelm Reiss and Alphons Stübel were the first to attempt to climb Ruiz. In 1936, W. Cunet and Augusto Gansser-Biaggi made the first successful ascent, partly by ski; they repeated the ascent in 1939.