Villarrica (volcano)

Volcán Villarrica.jpg
Villarrica Volcano is located in Chile
Villarrica ( /ˌvəˈrkə/ VEE-ə-REE-kə) (Spanish: Volcán Villarrica, Mapudungun: Ruka Pillañ) is one of Chile's most active volcanoes, rising above the lake and town of the same name, 750 km (470 mi) south of Santiago. It is also known as Rucapillán, a Mapuche word meaning "devil's house". It is the westernmost of three large stratovolcanoes that trend NW-SW obliquely perpendicular to the Andean chain along the Mocha-Villarrica Fault Zone, along with Quetrupillán and the Chilean portion of Lanín, are protected within Villarrica National Park. Guided ascents are popular during summer months.

Villarrica, with its lava of basaltic-andesitic composition, is one of a small number worldwide known to have an active (but in this case intermittent) lava lake within its crater. The volcano usually generates strombolian eruptions with ejection of incandescent pyroclasts and lava flows. Rainfall plus melted snow and glacier ice can cause massive lahars (mud and debris flows), such as during the eruptions of 1964 and 1971.

Villarrica is one of 9 volcanoes currently monitored by the Deep Earth Carbon Degassing Project. The project is collecting data on the carbon dioxide and sulphur dioxide emission rates from subaerial volcanoes.

Villarica stands in the Chilean Central Valley as the westernmost of an alignment of three large stratovolcanoes. The alignment is attributed to the existence of an old fracture in the crust, the North West-South East trending Mocha-Villarrica Fault Zone, the other volcanoes in the chain, Quetrupillán and Lanín, are far less active. The alignment is unusual as it crosses the N-S running Liquiñe-Ofqui Fault, along which several active volcanoes are aligned.

Villarrica covers an area of 400 km2 and has an estimated volume of 250 km3. It contains volcanic caves and about 26 scoria cones. The constant degassing at the lava lake turns the otherwise quite effusive lava more viscous, heightening its explosive potential. Two large ignimbrite layers are visible; the Licán Ignimbrite and the more recent Pucón Ignimbrite.

Villarrica emerged during the Middle Pleistocene and grew forming a large stratocone of similar dimensions to the current edifice. 100,000 years ago during the Valdivia Interglacial the ancestral Villarrica collapsed following an eruption and formed a large elliptical caldera of 6.5 and 4.2 km in diameter. During the Llanquihue glaciation Villarrica produced pyroclastic flow deposits, subglacial andesite lavas and dacite dykes. It collapsed once again 13,700 years ago forming a new smaller caldera, among other pyroclastic flows the Licán Ignimbrite has been related to this event. Beginning with the Licán Ignimbrite, generated just after the last deglaciation, activity continued in similar fashion. The Pucón Ignimbrite was ejected during a minor collapse of the uppermost stratocone 3,700 years ago.

This page was last edited on 12 June 2018, at 14:46.
Reference: under CC BY-SA license.

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