Pico de Orizaba

The Pico de Orizaba, or Citlaltépetl (from Nahuatl citlal(in) = star, and tepētl = mountain), is a stratovolcano, the highest mountain in Mexico and the third highest in North America. It rises 5,636 metres (18,491 ft) above sea level in the eastern end of the Trans-Mexican Volcanic Belt, on the border between the states of Veracruz and Puebla. The volcano is currently dormant but not extinct with the last eruption taking place during the 19th century. It is the second most prominent volcanic peak in the world after Africa's Mount Kilimanjaro.

location

Pico de Orizaba is located at 19°1′48″N 97°16′12″W at a distance of 100 kilometres (62 mi) from the shores of the Gulf of Mexico. Orizaba is located 200 kilometres (120 mi) east of Mexico City lies on the border between the states of Veracruz and Puebla. The volcano is approximately 480 kilometres (300 mi) south of the Tropic of Cancer. Orizaba is found at the southeastern end of the Trans-Mexican Volcanic Belt, a volcanic chain that runs from west to east across Central Mexico; it is the only historically active volcano in the area. A companion peak lying about six km to the southwest of Pico de Orizaba is the Sierra Negra, at 4,640 metres (15,223 ft). This subsidiary peak is significantly lower than its massive neighbor, but is traversed by the highest road in North America passing over its summit.

Pico de Orizaba, like the Sierra Madre Oriental, forms a barrier between the coastal plains of the Gulf of Mexico and the Mexican Plateau. The volcano blocks the moisture from the Gulf of Mexico from saturating central Mexico and influences the climates of both areas. Both the state of Veracruz and Puebla depend on Pico de Orizaba for supplying fresh water. The largest river originating on the volcano is the Jamapa River.

Geology

Pico de Orizaba evolved in three stages, the most recent initiating about 16,000 years ago during the late Pleistocene and Holocene. Citlaltépetl consists of three superimposed stratovolcanoes and dome intrusions which are: Torrecillas (650–250 ka), Espolón de Oro (210– 16 ka), and Citlaltépetl (16 ka to present). The volcano was formed by thick andesitic and dacitic lavas that followed repetitive explosive eruptions and lava effusions which created the iconic cone structure. The volcano is currently dormant but not extinct. The latest eruption of the volcano occurred in 1846 with a magnitude of VEI 2. Previous eruptions occurred in: 1687, 1613, 1589–1569, 1566, 1555–1545,1539–1533, 1351, 1260, 1187, 1175, 1157, 220 AD, 140 AD, 90 AD, 40 AD, ~780 BC, ~1500 BC, ~2110 BC, ~2300, ~2500, ~2780, ~4690, ~6220, ~6710, ~7030, and ~7530. The most violent eruption in the volcano's history is thought to have occurred around 6710 BC reaching a magnitude of VEI 5 characterized by lava dome extrusion and pyroclastic flow.

The volcano's crater is elliptical with a transverse diameter measuring 478 m (1,568 ft) and a conjugate diameter measuring 410 m (1,350 ft). The crater has an estimated 154,830 m2 (1,666,600 sq ft) with a maximum depth of 300 m (980 ft). Pico de Orizaba is constantly covered by an ice cap consisting of several glaciers. An outlet glacier, known as Jamapa Glacier is located on the northeastern side of the peak; it has been a powerful force in shaping the volcano. The Jamapa Glacier is responsible for a significant portion of the geomorphologic evolution of the region surrounding the volcano.