Villarrica (volcano)

Villarrica (/ˌviːəˈriːkə/ 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 "House of the Pillán" or "House of the spirit". It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain along the Gastre Fault. Villarrica, 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.

Geography and geology

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 Gastre 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 (Last 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.

Glaciers

The upper part of Villarrica is permanently covered by snow and has some 40 km² of glaciers, the largest of which is the Pichillancahue-Turbio Glacier situated on its southeastern flank. Ash from the eruptions can increase the ablation of snow and ice by absorption of solar radiation. Some ash coverings are thicker than 5 cm and insulate the glacier, decreasing ablation instead of enhancing it. Between 1961 and 2003, Villarrica lost 25% of its glaciated surface and the glaciers shrank at an average rate of -0.4 km² each year.

Tourism

Villarrica is popular for climbing with guided hikes to the crater from the town of Pucón, but these may be suspended due to cloud or volcanic activity. Helicopter over-flights have been available since 2007. In the winter (Julyâ€"September) a ski resort operates on the northern slopes.

Eruptive history

Villarrica is one of Chile's most active volcanoes; eruptions have been recorded since the conquest of Chile and the founding of the city of Villarrica in 1552. There are uncertainties in the eruptive record in the first half of the 17th century due to the Mapuche and Huilliche uprising which lead to the surrender or abandonment of Spanish settlements during the destruction of the Seven Cities. The earliest recorded eruption occurred in 1558, followed by at least 65 others with assumed Volcanic Explosivity Indexes of 1-3.

1964 eruption

In the two last weeks of February 1964 Villarrica produced small, violent lava effusions and tremors. On 1 March, at 2:45 am, it begun a strombolian eruption, and residents of Coñaripe, a wood-logging town, fled to the surrounding hills. Melting snow and ice from the Pichillancahue-Turbio Glacier combined with heavy rainfall to produce several lahars. Coñaripe, on the north-western shores of Calafquén Lake, had about half of its buildings destroyed, necessitating reconstruction further east.

1971 eruption

On 29 October 1971, at 4:00 am, there were several explosions in the crater and a column of black and white smoke appeared. One month later, at quarter to midnight on 29 December, Villarrica begun a new eruptive cycle. Pyroclasts were ejected and the snow surrounding the crater melted. After a brief halt in activity lava pored from a new vent on the north-east side, melting considerable amounts of water and causing lahars. These lahars affected Pichaye, El Turbio, Collentañe, Minetué, Molco, Voipir and Curarrehue, all of them in the Trancura River basin. Toxic sulphurous gases made the air unbreathable in Villarrica and Pucón where at least 15 deaths were reported.

2015 eruption

On February 7th, 2015, Villarrica triggered yellow alarms at both Servicio Nacional de Geología y Minería and Onemi. Minor explosions and low emissions of ashes were visible. It erupted at 3 am on Tuesday 3 March, sending ash and lava into the sky and forcing the evacuation of 3,385 people in nearby communities.

Gallery

See also

• List of volcanoes in Chile
• List of Ultras of South America

References

• "Villarrica". Global Volcanism Program. Smithsonian Institution. 

External links

• Satellite photo of Villarrica Volcano
• Villarrica Volcano info on SummitPost.com
• top of the volcano ...
• Villarrica Volcano Visual Observation Project
• "Volcán Villarrica, Chile" on Peakbagger