Costa Rica is the land born of volcanoes. As part of the Circum-Pacific Ring of fire, over 200 volcanic centers have been recognized in the country, but only about 20 of them are trule recognizable as such. From these twenty, only five (Rincón de la Vieja, Arenal, Poás, Irazú and Turrialba) have had eruptive activity in the past 400 years, even though the rest have certain level of activity (residual action) as fumaroles or gaseous emanation.
|El Hacha Peak|
|Rincon de la Vieja (and Santa María) A||Rincón de la Vieja|
|Miravalles (and Paleomiravalles) R|
|Tenorio (Montezuma-Tenorio) R||Tenorio
|Arenal (and Chato) A||Arenal|
Costa Rica has four mountain ranges, which are from NW to SE: Guanacaste, Tilarán, Central Volcanic and Talamanca. Most of the Costa Rican volcanoes are located in the Guanacaste and Central Volcanic range. The Central Volcanic range has more active volcanoes, and are also younger (less than 1 my) than the volcanoes of the Guanacaste range (less than 2 my).
In the Guanacaste Range it is usual that what receives the name of a volcano is actually a massif with several craters or volcanic peaks. From NW to SE, this are the volcanoes of the Guanacaste Range: El Hacha Peak, Orosi-Cacao, Rincón de la Vieja-Santa María, Miravalles, Montezuma-Tenorio. All these volcanoes except for the Miravalles are part of National Parks (see above). The largest volcanoes in this range are the Rincón de la Vieja and the Miravalles, and the only active (in terms of eruption) is the Rincón de la Vieja, which is also a national park. A geothermic project run by the Instituto Costarricense de Electricidad (Costa Rican Electricity Institute) takes place in the Miravalles volcano. The volcanic massifs could have small volcanic-tectonic structures in their summits (Cacao, Miravalles, Tenorio) or great depressions or calderas at their bases (Rincón de la Vieja, Miravalles and Tenorio).
The Chato and Arenal are located between the Guanacaste and Central Volcanic ranges. The Arenal Volcano was almost a perfect cone, until 1968, when after almost 500 years of inactivity the volcano exploded and more craters developed. Since that date, the Arenal has been active with lava emanations alternating with clouds of gas and steam.
The central volcanic range is the one with more active volcanoes, and are less than one million years old Poás, Irazú, and Turrialba volcanoes are historically active; the current activity of the Barva are sulfur exhalations and thermal waters. Most of these volcanoes and the surrounding areas are protected as National Parks, they are very close to San Jose city and visit one of them is a perfect one-day trip.
Sources: Observatorio Vulcanológico y Sismológico de Costa Rica- OVSICORI
Chavarría, O. 2005. Costa Rica: Land of Volcanoes. EUNED. 360 p.