Huequi

Huequi (Template:Sfn) is a volcano in the Los Lagos Region of Chile. It is in the Southern Volcanic Zone, in the centre of Ayacara Peninsula and close to the Gulf of Ancud. It is made up of a lava dome complex situated in a depression of unclear origin, a postglacial lava dome Calle and a Pleistocene volcano with Holocene parasitic cones, with a sharp summit at . There were reports of eruptions 1890–1920, and it is said to have "smoked" in 1935.

Geography and geology

The volcano is also known as Hueque, Relibuentu and Huequen.Template:Sfn It is in a remote region of southern Chile with no road access. There are only a few villages along the coast,Template:Sfn and little human modification of the environment.Template:Sfn

Huequi lies roughly at the centre of the Ayacara Peninsula east of the Gulf of Ancud.Template:Sfn Huequi is part of the Southern Volcanic Zone (SVZ), lying in its southern sector between the volcanoes Hornopiren and Chaiten-Minchinmavida;Template:Sfn Chaiten erupted in 2008.Template:Sfn Compared to other volcanoes in the SVZ it is small, rising only from a curved depressionTemplate:Sfn to an elevation of , and it lacks glaciers.Template:Sfn Huequi consists of a pile of lava domes that are heavily eroded and cut by sector collapses. A partially collapsed dome forms the summit.Template:Sfn A summit crater was reported as "narrow" in 1909Template:Sfn and as wide by the Global Volcanism Program.Template:Sfn Debris avalanches, partly channelled by a northwestward trending valley in the edifice, have formed a fan on that side of Huequi.Template:Sfn Pumice from the volcano has been carried to the sea by the Huequi River, which originates at the foot of Huequi.Template:Sfn Two additional cones are named Porcelana and Barranes ColoradoTemplate:Sfn or Barranco Colorado;Template:Sfn there is also the Calle postglacial lava dome.Template:Sfn The Huequi volcano may be part of larger volcanic complexes that are now eroded.Template:Sfn The basement is formed by faulted granite and metamorphic rocksTemplate:Sfn of the North Patagonian Batholith.Template:Sfn

The subduction of the Nazca Plate under the South American Plate gives rise to the volcanism of the Andes.Template:Sfn In the southern sector between Yate and Cerro Hudson, where Huequi is located, the crust is thin and does not heavily influence the basaltic and basaltic andesite magmas.Template:Sfn East of the volcano passes the Liquine-Ofqui Fault Zone in a fjord;Template:Sfn the volcano lies on a separate, northwest-trending lineament.Template:Sfn

Composition

Huequi has erupted andesite and basaltic andesite, which have grey and red colours and feature both layered and brecciated sequences.Template:Sfn Dacite has also been reported.Template:Sfn The volcanic rocks define a calc-alkaline suiteTemplate:Sfn that resembles the adakites of Nevado de Longavi.Template:Sfn The main phenocryst phase is plagioclase, followed by orthopyroxene and hornblende.Template:Sfn The lava domes contain columnar forms exposed in cliffs and dense porphyries. Compared to other volcanoes in this sector of the Southern Volcanic Zone, Huequi's magmas are water-rich. This may explain some peculiarities about its eruptive activity, as the water escapes from the magma and leaves a viscous andesite.Template:Sfn

Climate and vegetation

The region has a humid climate, with storm systems from the Pacific Ocean bringing about Template:Sfn or Template:Sfn of precipitation during autumn and winter. Mean annual temperatures are about .Template:Sfn It is covered by the Valdivian rainforest, with Amomyrtus meli, Drimys winteri, Luma apiculata, Nothofagus nitida and Podocarpus as representative plant species.Template:Sfn

Eruption history

Southeast of Huequi lie three small volcanoes, which probably erupted during the Pleistocene.Template:Sfn Porcelana is of Pleistocene age.Template:Sfn During the Holocene, the volcano repeatedly produced lava domes that frequently collapsed, and explosive eruptions that deposited tephra.Template:Sfn The debris avalanche deposits consist of older volcanic rocks, pumice and lithics from the basement. The collapses were not energetic, with most of the debris being confined by the surrounding topography; their heavy vegetation cover indicates that they are older than the most recent eruption.Template:Sfn Tephra layers in Lago Futalaufquen have been correlated to an eruption in AD 1645–1745.Template:Sfn

There are sparse reports of eruptions between 1890–1920,Template:Sfn with reports from the years 1890–91, 1893–94, 1895–96, 1906, 1917, 1920, and 1922.Template:Sfn The activity was visible from ChiloeTemplate:Sfn and Puerto Montt.Template:Sfn Some of this activity may relate to the 1906 Valparaíso earthquake.Template:Sfn These eruptions reached a volcanic explosivity index of 2–3Template:Sfn and deposited patches of tephra to the north of the volcano.Template:Sfn Contemporary records indicate that the 1890 eruption deposited ash from Chiloe into Argentina.Template:Sfn The tephra consists of red and black scoria and pumice, formed presumably by Vulcanian eruptions.Template:Sfn The summit dome may have formed during this sequence.Template:Sfn The volcano was reportedly "smoking" in 1935.Template:Sfn

Porcelana geyser and Porcelana hot spring lie on the Ayacara Peninsula and are associated with Huequi.Template:Sfn The Porcelana geysers have produced pinnacles of travertine reaching heights of ; this extreme size in a highly erosive environment may be due to microbial chemical processes.Template:Sfn The area has good potential for geothermal energy.Template:Sfn

See also

• List of volcanoes in Chile
• Huinay
• Pumalín Park
• Chaitén

References

Sources

• Template:Cite gvp

External links

• SERNAGEOMIN