Мексикадағы жанартау: Пико-де-Орисаба

Volcano in Mexico

Pico de Orizaba, also known as Citlaltépetl (from Nahuatl citlal(in) = star, and tepētl = mountain), is an active volcano, the highest mountain in Mexico and third highest in North America, after Denali of United States and Mount Logan of Canada. Pico de Orizaba is also the highest volcano in North America. It rises above sea level in the eastern end of the Trans Mexican Volcanic Belt, on the border between the states of Veracruz and Puebla.

The peak of Citlaltépetl rises dramatically to an elevation of above sea level; it has a topographic prominence of Regionally dominant, Pico de Orizaba is the highest peak in Mexico and the highest volcano in North America; it is also the third highest peak in North America after Denali and Mount Logan. Orizaba is ranked 7th in the world in topographic prominence. It is the second most prominent volcanic peak in the world after Africa's Mount Kilimanjaro, and the volcano is ranked 16th in the world for topographic isolation. About to the west of the port of Veracruz, its peak is visible to ships approaching the port in the Gulf of Mexico, and at dawn rays of sunlight strike the Pico while Veracruz still lies in shadow. The topography of Pico de Orizaba is asymmetrical from the center of the crater; the eastern face is the steepest side of the volcano and the northwestern face the most gradual side. The gradual slopes of the northwestern face of the volcano allow for the presence of large glaciers and provide the most traveled route for hikers traveling to the summit.

Pico de Orizaba is one of only three volcanoes in México that continue to support glaciers and is home to the largest glacier in Mexico, Gran Glaciar Norte. Orizaba has nine known glaciers: Gran Glaciar Norte, Lengua del Chichimeco, Jamapa, Toro, Glaciar de la Barba, Noroccidental, Occidental, Suroccidental, and Oriental. The equilibrium line altitude (ELA) is not known for Orizaba. Snow on the south and southeast sides of the volcano melts quickly because of solar radiation, but lower temperatures on the northwest and north sides allow for glaciers. The insolation angle and wind redeposition on the northwest and north sides allow for constant accumulation of snow providing a source for the outlet glaciers. On the north side of Orizaba, the Gran Glaciar Norte fills the elongated highland basin and is the source for seven outlet glaciers. The main glacier extends north of the crater rim, has a surface area of about descending from to about It has a slightly irregular and stepped profile that is caused in part by the configuration of the bedrock. Most crevasses show an ice thickness of approximately
Below the in elevation on the north side of the volcano, the outlet glaciers Lengua del Chichimeco and Jamapa extend north and northwest another and , respectively. The terminal lobe of Lengua del Chichimeco at , having a gradient of only , is a low, broad ice fan that has a convex upward profile, a front typical of almost all Mexican glaciers. The most distinct glacier is Glaciar de Jamapa, which leaves Gran Glaciar Norte at about and, after with a gradient of , divides into two small tongues that end at and Both tongues terminate in broad convex upward ice fans thinning along their edges. The retreat of these tongues prior to 1994 produced much erosion downstream and buried their edges by ablation rock debris. 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 and a conjugate diameter measuring The crater has an estimated with a maximum depth of 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 north eastern 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.

Pico de Orizaba is located at 19°1′48″N 97°16′12″W, about west of the Gulf of Mexico and east of Mexico City, on the border between the states of Veracruz and Puebla. The volcano is approximately south of the Tropic of Cancer. Orizaba anchors the south eastern end of the Trans Mexican Volcanic Belt, a volcanic chain that runs from west to east across Central Mexico. A companion peak lying about six km to the southwest of Pico de Orizaba is the Sierra Negra, at This subsidiary peak is significantly lower than its massive neighbour, but the road to the observatory on its summit is the highest road in North America. Pico de Orizaba, as part of 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.

Pico de Orizaba was important in pre Hispanic cultures, such as those of the Nahuatl speaking Aztecs and the Totonacs. The volcano is part of many native mythologies. During the Spanish Conquest of Mexico, Hernán Cortés passed through the foothills of Pico de Orizaba; the volcano and the surrounding mountains made his journey to Tenochtitlan more difficult and delayed him for many days. During the 1600s, the Spanish Crown financed several roads to be built that would circumvent Citlaltépetl. One of the roads was routed south of the volcano through the cities of Orizaba and Fortín de las Flores, which became the main trade route between Mexico City and Veracruz on the Gulf Coast. A short road was later built by Jesuits to establish settlements at the base of Pico de Orizaba. The Spanish used the volcano as a landmark to guide themselves to the port of Veracruz. Many battles were fought near this volcano throughout Mexico's struggle for independence. In 1839, Henri Galeotti was the first European to explore the volcano, but did not hike to the summit. During the American occupation of Mexico in 1848, two American soldiers, F. Maynard and William F. Raynolds, were the first known hikers to reach the summit of Pico de Orizaba. In 1851, the French explorer Alejandro Doignon also reached the summit and found the flagpole left behind by the Americans in 1848. During the mid 19th century Citlaltépetl was explored by many scientists, including the German botanist Hugo Fink, who was the first to record the numerous species of flora found on the volcano. In 1873, Martin Tritschler raised the Mexican flag at the summit.

On December 16, 1936, President Lázaro Cárdenas, in an effort to protect the natural beauty of Pico de Orizaba, created a national park with an area of that included the volcano with the surrounding area and the settlements of Tlachichuca, Ciudad Serdán, La Perla, Mariano Escobedo, and Calcahualco. The federal decree became federal law on January 4, 1937.

Pico de Orizaba attracts a large number of international climbers every year. There are multiple routes for approaching and climbing the volcano, and many people attempt it. Most people climb the mountain during the period from October to March when the weather is favorable; temperatures do not vary much month to month due to being in the tropics and April through September are rainy months in the region. The most frequented route begins from the base camp Piedra Grande Hut ("refugio") via the Jamapa Glacier, located at an elevation of above sea level. Another option as a starting point is high camp located at the base of the glacier about above sea level. For a more technical challenge for the experienced climber, there is a technical ice climb called the Serpents Head, which involves 10 pitches of grade 3 ice. Additionally, the southern side offers another challenging option; although the trail is shorter, it is also steeper and more difficult. No glaciers are found on the southern side. The final ascent to the summit is via a normally straightforward and crevasse free glacier route. The caldera can be circumnavigated with relative ease, although at one point this requires a short, exposed traverse of steep rock and ice above the Glacier Este.