Volcanoes in Costa Rica

Costa Rica, officially the Republic of Costa Rica (Spanish: Costa Rica or República de Costa Rica, is a country in Central America, bordered by Nicaragua to the north, Panama to the east and south, the Pacific Ocean to the west and south and the Caribbean Sea to the east

Costa Rica, which means "Rich Coast", constitutionally abolished its army permanently in 1949. It is the only Latin American country included in the list of the world's 22 older democracies. Costa Rica has consistently been among the top Latin American countries in the Human Development Index, ranked 62nd in the world in 2010, and is cited by the UNDP as one of the countries that has attained much higher human development than other countries at the same income levels. The country is ranked 3rd in the world, and 1st among the Americas, in terms of the 2010 Environmental Performance Index.

In 2007 the Costa Rican government announced plans for Costa Rica to become the first carbon neutral country by 2021. According to the New Economics Foundation, Costa Rica ranks first in the Happy Planet Index and is the "greenest" country in the world.

The highest point in the country is Cerro Chirripó, at 3,819 metres (12,530 ft), and is the fifth highest peak in Central America. The highest volcano in the country is the Irazú Volcano (3,431 m or 11,257 ft). The largest lake in Costa Rica is Lake Arenal.

The Irazú Volcano (Spanish: Volcán Irazú) is an active volcano in Costa Rica, situated in the Cordillera Central close to the city of Cartago. Its name could come from either the combination of "ara" (point) and "tzu" (thunder) or a corruption of Iztarú, which was the name of an indigenous village on the flanks of the volcano. In Costa Rica it is known by the name of "El Coloso" (The Colossus) due to the catastrophes that it has provoked in the past.

The volcano's summit has several craters, one of which contains Diego de la Haya, a green crater lake of variable depth. It is the highest active volcano in Costa Rica. It is easily visited from San José, with a road leading right up to the summit craters and a weekly bus service to the top. It is thus a popular tourist spot. The volcano summit also spots a few television transmitters for television stations in San José.

From the top it is possible to see both the Atlantic and Pacific Oceans on a clear day. However, such clear days are very rare indeed, and it is typical for the volcano's summit to be covered in cloud for much of the time.

GeologyThe Irazú volcano is a complex volcanic shield. It is the highest active volcano in Costa Rica, and has an area of 500 km2 (190 sq mi)It has an irregular subconic shape, and its temperature oscillates between 3 °C and 17 °C. It is a stratovolcano with a summit elevation of 3432 metres. Its five craters are easily differentiated.[1] The most important ones, because of their activity, are The Main Crater, which is almost circular has very inclined walls and it measures 1050 meters in diameter and 300 meters depth; The Diego de la Haya crater is 600 meters diameter and 100 meters deep. Other craters are Playa Hermosa, La Laguna, and El Piroclastico.

Irazú is the southernmost of the ten Quaternary volcanoes which form a northwest-trending line through central and northern Costa Rica.[2] Radioactive dating has shown an age of at least 854,000 years with eruption peaks at 570,000 years and the most recent active phase from 136,000 years to present. The most recent activity includes lava flows along with strombolian and phreatomagmatic explosions. Lava types include basalt and andesite erupted during different events suggesting the volcano is fed by two distinct magma chambers.

Eruptive history
Irazú has erupted frequently in historical times — at least 23 times since its first historically recorded eruption in 1723. Its most famous recent eruption began in 1963 and continued until 1965. It began on the day US President John F. Kennedy started a state visit to Costa Rica and showered the capital San José and much of the central highlands of Costa Rica with ash.[citation needed]

Its historical eruptions generally have VEIs of 1 to 3. All historical eruptions have been explosive, and there have been many phreatic eruptions, and some have produced pyroclastic flows. The latest eruption lasted only 1 day, and occurred on December 8 1994. It occurred at a flank vent and was a phreatic eruption, which produced lahars.

In Spanish: http://www.ovsicori.una.ac.cr/vulcanologia/volcanes/irazu.htm