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| Andean Southern Volcanic Zone | |
|---|---|
| Name | Southern Volcanic Zone of the Andes |
| Location | Chile, Argentina |
| Length km | 1000 |
| Range | Andes |
| Type | Volcanic arc |
Andean Southern Volcanic Zone The Southern Volcanic Zone is a major volcanic arc segment of the Andes located principally in Chile and extending into Argentina. It forms part of the circum-Pacific Ring of Fire where the Nazca Plate subducts beneath the South American Plate, producing active stratovolcanoes such as Villarrica, Llaima, and Lonquimay. The region has produced historic eruptions documented by Spanish Empire chroniclers, monitored by institutions like the Servicio Nacional de Geología y Minería and studied by researchers from Universidad de Chile, CONICET, and international groups.
The zone occupies a north–south belt from roughly the latitude of Maule Region and Ñuble Region in Chile through Araucanía Region, Los Ríos Region, and into southern Los Lagos Region and adjacent Neuquén Province, Río Negro Province in Argentina. Major physiographic elements include the Chilean Central Valley, the Patagonian Andes, glaciated peaks near Puyehue, and intermontane basins such as the Llanquihue Basin. Coastal features interact with inland ranges near Valdivia and Temuco. The arc parallels the trench system formed at the Peru–Chile Trench and interfaces with backarc basins like the Chile Ridge spreading environment.
Tectonics are dominated by oblique convergence of the Nazca Plate beneath the South American Plate, with variations introduced by the southward younging of the Nazca Plate and the influence of the Antarctic Plate margin near the Chile Triple Junction. Slab geometry changes, including flat-slab segments associated with the Juan Fernández Ridge and slab rollback episodes documented in studies by teams from Oxford University and Massachusetts Institute of Technology, control volcanic distribution and crustal deformation recorded by InSAR campaigns and GPS networks coordinated through Instituto Geofísico observatories. Crustal shortening in the Andes and lithospheric delamination models published by researchers at University of California, Berkeley and Geological Survey of Argentina explain variations in magma genesis and volcanic front migration.
The volcanic front hosts numerous composite volcanoes and caldera complexes including Villarrica, Llaima, Lonquimay, Calbuco, Osorno, Copahue, Tolhuaca, Antuco, and the Puyehue-Cordón Caulle complex. Central volcanoes such as Lanín and Quetrupillán display glacially sculpted edifice morphologies. Calderas like Mocho-Choshuenco and fissure systems linked to Caviahue are associated with rhyolitic and dacitic eruptions documented by expeditions from Smithsonian Institution teams and field campaigns supported by European Research Council grants. Pyroclastic flows, lava domes, and basaltic to andesitic lava fields are widespread across named volcanic centers.
Magma compositions across the arc range from basaltic-andesite to dacite and rhyolite, reflecting processes of slab-derived fluid fluxing, crustal assimilation beneath thickened Andean crust, and fractional crystallization analyzed in papers from Stanford University and Universidad Católica de Chile. Isotopic work involving Sr-Nd-Pb isotopes and trace-element modeling performed by teams at Max Planck Institute and University of Tokyo reveal contributions from altered oceanic crust and subducted sediments traced to events such as the emplacement of the Nazca Ridge and recycling of Oceanic plateau materials. Petrologic studies link volatile concentrations and crystal cargoes to eruption styles observed at named centers.
Historic eruptions include major 20th-century events at Llaima and the 2011 Puyehue-Cordón Caulle eruption that produced far-reaching ash clouds affecting Buenos Aires and Sydney. Tephrostratigraphy ties Holocene layers to specific eruptions recorded in paleoclimate proxies studied by National Oceanic and Atmospheric Administration and PAGES initiatives. Hazards include pyroclastic density currents, ashfall impacting aviation managed by International Civil Aviation Organization, lahars threatening communities such as Pucón and Coihaique, and volcanic gases that affected air quality monitored by World Health Organization guidelines. Economic impacts have involved regional tourism centered on hot springs and ski resorts near Villarrica National Park as well as disruptions to coal and agriculture sectors.
Monitoring is conducted by agencies including Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de los Andes del Sur, and international collaborations with USGS and Instituto Nacional de Prevención Sísmica. Techniques employed encompass seismic arrays, gas flux measurements building on protocols from International Volcanological Congress, thermal satellite surveillance via NASA missions, and community-based early warning systems coordinated with municipal authorities of Temuco and Puerto Montt. Risk mitigation strategies involve hazard zoning enacted by regional governments, evacuation planning with Red Cross units, and communication campaigns aligned with standards from the United Nations Office for Disaster Risk Reduction.
Scientific exploration dates from 19th-century surveys by explorers linked to institutions such as Royal Geographical Society and 20th-century mapping by national geological surveys including Servicio Nacional de Geología y Minería and Geological Survey of Argentina. Landmark studies include tephrochronology syntheses by teams at University of Cambridge and University of Auckland, geodetic studies by Woods Hole Oceanographic Institution, and petrogenetic models advanced by researchers at ETH Zurich. Recent interdisciplinary projects funded by FONDECYT and the European Union have produced high-resolution hazard maps and eruption forecasting frameworks published in journals like Nature Geoscience and Journal of Volcanology and Geothermal Research.
Category:Volcanic arcs Category:Andes Category:Volcanism of Chile Category:Volcanism of Argentina