RUKA PILLAÑ, THE MAPUCHE GREAT SPIRIT'S HOUSE

Today, The Grandma has been reading about volcanos. She loves them and she has been interested in Ruka Pillañ, the Chilean volcano that began a strombolian eruption causing lahars that destroyed half of the town of Coñaripe, on a day like today in 1964.

Ruka Pillañ or Villarrica is one of Chile's most active volcanoes, rising above the lake and town of the same name, 750 km south of Santiago.

It is also known as Rucapillán, a Mapuche word meaning great spirit's house. It is the westernmost of three large stratovolcanoes that trend northwest to southeast obliquely perpendicular to the Andean chain along the Mocha-Villarrica Fault Zone, and along with Quetrupillán and the Chilean portion of Lanín, are protected within Villarrica National Park. Guided ascents are popular during summer months.

Ruka Pillañ, 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.

Ruka Pillañ 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.

Ruka Pillañ  stands just east of 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.

More information: Volcanoes Stop Trumps

Ruka Pillañ 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.

Ruka Pillañ 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.

The volcano resumed eruptive activity on March 8, 1963.

On March 12 a flank vent some 250 metres below the summit begun to pour lava that ended up making a 1000 m long and 150-meter broad lava flow. The lava flow had stopped by March 19. Concurrently with this the summit crater continued its strombolian eruption.

Explosive eruptions begun once again on May 2, 1963, and the eruption had definitely turned effusive by May 21. The last consequences of this cycle of eruptions were lahars that flowed down the volcano on May 24.

In the two last weeks of February 1964, Villarrica produced small, violent lava effusions and tremors.

On 2 March, at 2:45 am, it began a strombolian eruption, and residents of Coñaripe, a wood-logging town, fled to the surrounding hills. At some point, the inhabitants of Coñaripe decided to return to their houses in search of shelter from the heavy rainfall.

Some Mapuches blamed settlers for the disaster claiming they had provoked it by cursing the town of Coñaripe. Such view reflect the belief that nature was allied with the Indians.

More information: Smithsonian Institution-Global Volcanism Program

The paradox of volcanoes was
that they were symbols of destruction but also life.
Once the lava slows and cools,
it solidifies and then breaks down
over time to become soil -rich, fertile soil.

Matt Haig