Volcanoes

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Volcanoes

Volcanoes, integral part of the geologic makeup of Mexico, Central America, the Antilles, and the Andean nations of Latin America. In historic times, normally with little variation, about fifty volcanoes are active in any given year in the world. Compared with other natural hazards, volcanic eruptions are less frequent, result in relatively fewer human casualties, and ordinarily produce less economic loss. Nevertheless, several eruptions in Latin American history were remarkable for loss of life. Deadly eruptions after 1600 include Cotopaxi in Ecuador (1741: 2,000 lives lost; 1877: 1,000), Nevado del Ruiz in Colombia (1845: 1,000; 1985: ca. 25,000), Soufrière on Saint Vincent (1902: 1,560), Pelée on Martinique (1902–1905: 29,000), Santa María in Guatemala (1902: 6,000), and El Chichón in Mexico (1982: ca. 2,000). The three 1902 disasters, together with that of 1985, account for 75 percent of all twentieth-century deaths from volcanic activity worldwide.

Latin American historical documents record numerous additional eruptions. Mexico has a volcanic chain along the nineteenth parallel. There, for example, Colima had eruptions of various magnitude in 1576, 1590, 1611–1613, 1749, 1770, 1795, 1806–1808, 1818, 1869, 1885–1886, 1892, 1909, and 1913. Popocatépetl erupted with moderate to large force in 1720; Orizaba, in 1545, 1566, 1569, 1630, and 1687; San Martín, in 1664 and 1793–1794. Only two volcanoes have been born in historic times in North America, both in Mexico: Jorullo in 1759 and Paricutín in 1943.

In Central America, all but Honduras have volcanoes. Moderate to large eruptions include Arenal (Costa Rica, 1500s and 1968–1969), Momotombo (Nicaragua, 1560 and 1609), Pacaya (Guatemala, 1565, 1664, and 1965), Santa Ana (El Salvador, 1576 and 1880), San Miguel (El Salvador, 1586), Masaya (Nicaragua, 1670), San Salvador (El Salvador, 1671), Atitlán (Guatemala, 1827), Turrialba (Costa Rica, 1866), Momotombo (Ni-caragua, 1905), Irazú (Costa Rica, 1918 and 1963–1965), Acatenango (Guatemala, 1925), Izalco (El Salvador, 1955 and 1957), Poas (Costa Rica, 1961), Cerro Negro (Nicaragua, 1962, 1968, and 1971), and Rincón de la Vieja (Costa Rica, 1967). The 1835 eruption of Cosigüina in Nicaragua was one of the major volcanic events in recorded history. In addition to that of 1902, Santa María in Guatemala had sizable eruptions in 1922, 1956, and 1976. Guatemala's Fuego is the Central American volcano with the greatest number of moderate to large eruptions, a dozen from the 1580s to the 1970s. El Salvador's Ilopango, which erupted in 1875, also erupted in pre-Columbian times, probably causing shifts in settlement patterns.

In the Antilles, volcanic activity began at much studied Pelée about 13,500 years ago. Notable eruptions occurred in 1851 and 1929–1932, in addition to the 1902–1905 episode. Soufrière (Saint Vincent) erupted in 1718, 1812, 1902–1903, 1971–1972, and 1979. There has been volcanic activity in historic times on Guadeloupe, Saint Kitts, and Dominica as well.

Volcanic activity is fairly common in the Andean nations. In Colombia, Nevado del Ruiz has had twelve eruptive stages in the last 11,000 years, notably in 1595, 1845, and 1985. Galeras erupted with moderate to large force in 1535, 1590, 1616, 1717, 1834, 1869, and 1924. Puracé erupted in 1849 and 1885; Doña Juana, in 1899. Ecuador has some of the largest volcanoes in the world. Cotopaxi has had a dozen moderate to large eruptions in historic times, notably those of 1744, 1768, and 1877. Reventador has been just as active, with larger twentieth-century eruptions in 1929, 1936, 1944, 1958, and 1960. Guagua Pichincha (near Quito) erupted in 1566, 1587, 1660, and 1831; Tungurahua, in 1886 and 1918—all with moderate to large explosions. Sangay has been regularly active, especially in the 1730s, 1840s, and 1930s. Ecuador's territory includes the Galápagos with Fernandina, Cerro Azul, and Sierra Negra volcanoes.

Peru's volcanic activity has had moderate force, aside from Huayna Putina's large eruption in 1600. El Misti, Peru's most famous volcano, erupted in 1677, 1784, and 1787; Tutupaca, in 1780 and 1802. Ubinas has erupted with the greatest frequency, a dozen times between 1677 and 1969. Among Latin nations, Chile has the greatest number of active volcanoes, mainly in the less-populated south. In colonial days, Peteroa (1660 and 1762) and Nevados de Chillán (around 1750) erupted. Twentieth-century eruptions have included Puyehue (1921 and 1960), Cerro Azul (also called Quizapu, 1907, 1914, and 1932), and Llaima (1946–1947 and 1957).

Latin America's historic eruptions provide examples of diverse physical hazards: (1) Pyroclastic flows of hot rock fragments mixed with hot gases move rapidly from the volcano, as at El Chichón (1982) and Pelée (1902). (2) Lahars, or mudflows, result from ice/snowmelts or released water impoundments mixed with debris. These submerge adjacent farmland and villages, as at Cotopaxi (1877), Santa María (1902), Irazú (1964–1965), and Nevado del Ruiz (1985). (3) Tephra, or ash falls, make breathing difficult, cover vegetation, and can collapse or bury structures. Eruptions notable for the distance tephra traveled are Cosigüina (1835: 672 miles), Soufrière (1902: 792 miles), and Cerro Azul (1932: 1,776 miles). Some evidence indicates that weathered volcanic soil is especially fertile; research supports the conclusion that volcanic dust contributes to global cooling by blocking sunlight. (4) Lava, or molten rock, erupts relatively non-explosively and moves slowly. Nevertheless, it can engulf whole villages, as at Parícutin (1943). (5) Sometimes explosions send forth solid projectiles, as at Arenal (1968). (6) Toxic gases can be health hazards (Masaya, 1946). Before the twentieth century, disease and starvation were more significant longer-term results of eruptions.

See alsoEnvironment and Climate; Latin America; Science.

BIBLIOGRAPHY

Russell J. Blong, Volcanic Hazards (1984).

Centro Regional De Sismología Para América Del Sur, Riesgo volcánico: Evaluación y mitigación en América Latina (1989).

David T. Lescinsky, "Nevado del Ruiz Volcano, Colombia: A Comprehensive Bibliography," in Journal of Volcanology and Geothermal Research 42, no. 1-2 (1990): 211-224.

Payson D. Sheets and Donald K. Grayson, eds., Volcanic Activity and Human Ecology (1979).

Tom Simkin et al., Volcanoes of the World (1981).

Robert Tilling, ed., Volcanic Hazards (1989).

Volcano News (1979–1986).

Volcano Quarterly (1992).