DESCRIPTION:
South America Volcanoes and Volcanics

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Map, South America and Plate Tectonics

South America spans the greatest length of any continental volcanic region. Subduction of the eastern Pacific's Nazca Plate beneath South America has produced one of the Earth's highest mountain ranges, and its highest volcano Nevados Ojos del Salado (Argentina). Three distinct volcanic belts are separated by volcanically inactive gaps, where subduction is at such a shallow angle that magma is not generated by the process. ...

South America leads all other regions in population of volcanoes, with 204; it has the largest number of undated "Holocene" volcanoes (112) and is second only to Japan in the number of volcanoes with dated eruptions. The human population, however, totals less than 90 million, or approximately that of Mexico. Colombia accounts for 37 percent of the population and Argentina for 37 percent of the land area. Chile has the region's largest number of historically active volcanoes, with 36 (ranking it 5th among nations, behind Russia's 52 and ahead of Iceland's 18). Ecuador, the region's smallest in terms of population and area, is next with 16.

When South America was discovered by Columbus, on his 3rd voyage in 1498, the Inca civilization was large and highly developed, but no records survive of the Andean volcanism that they no doubt witnessed. In 1524, Pizarro started his first voyage along the Pacific coast and within 10 years Atahualpa was executed and the Inca conquered by Spain. Travel overland was slow and difficult, so the Spaniards sailed south, launching the exploration of the Andes from Peru and what is now Ecuador. A result of this pattern is that 27 16th century eruptions are known from Peru northward, while 3 are known south of Peru (and only 8 more in the 17th century). In southern Chile, where the population is sparse and the mountains remote, only 2 (of 24) volcanoes have recorded eruptions before the early 1800s.

The region's first historically documented eruption was at El Misti (Peru), sometime between 1438 and 1471, and the next two were from mainland Ecuador in the early 1530s. The Galapagos Islands were discovered in 1535, but their early visitors were largely pirates, and they were still uninhabited when the first scientific mission arrived in 1790. The first eruption was recorded near the end of that century and the first resident settled in 1807. The Chilean Islands were discovered by Juan Fernandez in 1574, but no eruptions were recorded by their only resident, Robinson Crusoe, during his 1704-09 visit: it remained for Charles Darwin to document the first (and only) certain eruption there in 1835.

South America is dominated by large, often glacier-clad stratovolcanoes (122, more than any other region), and matches Japan in having the most documented VEI greater-than-or-equal-to 4 eruptions in the past 200 years. It has had 15 percent of the world's mudflow-producing eruptions, including the tragic one at Colombia's Ruiz volcano in 1985. ...

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