The Irazú Volcano ( es, Volcán Irazú) is an active

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...

in Costa Rica, situated in the

Cordillera Central Central Cordillera refers to the New Guinea Highlands. Cordillera Central, meaning ''central range'' in Spanish, may refer to the following mountain ranges: * Cordillera Central, Andes (disambiguation), several mountain ranges in South America ** ...

close to the city of Cartago. The 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 Crater Lake (Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The lake partly fills ...

of variable depth. At 11,260 feet (3,432 m), the Irazú Volcano is the highest active volcano in Costa Rica. It is easily visited from

San José San José or San Jose (Spanish for Saint Joseph) most often refers to: *San Jose, California, United States *San José, Costa Rica, the nation's capital San José or San Jose may also refer to: Places Argentina * San José, Buenos Aires ** San ...

, with a road leading right up to the summit craters and a weekly bus service to the top. It is thus a popular

tourist Tourism is travel for pleasure or business; also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours. The World Tourism Organization defines tourism ...

spot. The summit of the volcano also houses 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 rare, and the volcano's summit is usually cloud-covered. The volcano is contained within the Irazú Volcano National Park, which spreads across 5,705 acres (2,300 ha). The national park contains both primary and secondary montane forests and is home to armadillos, owls, rabbits, foxes, woodpeckers, and hummingbirds.

Geology

The Irazú volcano is a

complex Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each ...

volcanic shield. It is the highest active volcano in Costa Rica, and has an area of . It has an irregular subconic shape, and temperatures at its summit vary between , with a record low of −3 °C(26.6 °F) and a record high of 23.2 °C(73.4 °F). Irazu volcano is a

stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and p ...

with a summit elevation of . Its five craters are easily differentiated. The most important ones, because of their activity, are The Main Crater and the Diego de la Haya crater. The Main Crater is almost circular, has very inclined walls and it measures in diameter and deep. The Diego de la Haya crater is in diameter and 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.

Radioactive dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares ...

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 Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions conta ...

explosions. Lava types include

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of a ...

and

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

erupted during different events suggesting the volcano is fed by two distinct

magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it up ...

s. Scientists believed that pulses of magma mixed together in the chamber before climbing upward—a process estimated to take several thousands of years. But Columbia University volcanologists found that the eruption of Costa Rica's Irazu volcano in 1963 was likely triggered by magma that took a nonstop route from the mantle over just a few months. Study authors called it the highway from hell.

Eruptive history

Irazú has erupted frequently in historical times — at least 23 times since its first historically recorded eruption in 1723. Its most famous eruption began in mid-March 1963, a few days before US President John F. Kennedy started a state visit to Costa Rica. It showered the capital

and much of the central highlands of Costa Rica with

ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...

. Eruptions continued for two years. Its historical eruptions generally have VEIs of 1 to 3. All historical eruptions have been

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

, and there have been many

phreatic eruption A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, occurs when magma heats ground water or surface water. The extreme temperature of the magma (anywhere from ) causes near-instantaneous evapo ...

s, and some have produced

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...

s. 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

lahar A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extreme ...

Climate

Gallery

File:Sunset from the Summit, Irazu Volcano, Costa Rica - Daniel Vargas.jpg, Sunset from the summit File:Top View of Diego de la Haya, Irazu Volcano, Costa Rica - Daniel Vargas.jpg, Top view of Diego de la Haya File:Sunset at Diego de la Haya Crater, Irazu Volcano, Costa Rica - Daniel Vargas.jpg, Sunset at Diego de la Haya crater File:Irazu Volcano.JPG, Main crater lagoon File:Crater Irazu volcano CRI 01 2020 1512.jpg, Main crater lagoon File:Main Crater Lagoon 1, Irazu Volcano, Costa Rica - Daniel Vargas.jpg, Main crater lagoon File:Inside_Irazu_Volcano,_Costa_Rica_(Diego_de_la_Haya_Crater)_-_Daniel_Vargas.jpg, Inside Diego de la Haya File:Friendly Critter 2, Irazu Volcano, Costa Rica - Daniel Vargas.jpg,

White-nosed coati The white-nosed coati (''Nasua narica''), also known as the coatimundi (), is a species of coati and a member of the family Procyonidae (raccoons and their relatives). Local Spanish names for the species include ''pizote'', ''antoon'', and ''te ...

at Irazú File:Extinct Crater, Irazu Volcano, Costa Rica - Daniel Vargas.jpg, Playa Hermosa extinct crater File:Crater Bridge, Irazu Volcano, Costa Rica - Daniel Vargas.jpg, Crater bridge (division) File:Crater Diego de la Haya Irazu volcano CRI 01 2020 3679.jpg, Diego de la Haya crater File:Diego de la Haya Lagoon, Irazu Volcano, Costa Rica - Daniel Vargas.jpg, Diego de la Haya lagoon File:Great Walls of the Main Crater, Irazu Volcano, Costa Rica - Daniel Vargas.jpg, Great crater wall File:DirkvdM irazu 1.jpg, Distant wide view of Irazu volcano File:DirkvdM irazu 2.jpg, Panoramic view of Irazu volcano File:The 1918 Irazú Volcano eruption in Costa Rica close to the city of Cartago.png, 1918 eruption File:Irazu3-9MGLeonard1963.jpg, 1963 eruption from San José File:Irazu3-16MGLeonard1963.jpg, 1963 eruption File:Irazu4-13MGLeonard1963.jpg, 1963 eruption

References

External links