Repositorio Digital Sernageomin
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Tracing hotspot traces in the Andes
Full text linkTwo segments of subduction of the Nazca plate beneath the South American plate occur at low angles based on seismic hypocenter locations, approaching nearly horizontal below ~100 km in depth. In contrast with most of the rest of the subduction zone, the two segments, beneath central Chile, and central and northern Peru, lack active volcanoes along the crest of the Andes and have more subdued topography to the east of the Andean crest. Each low-angle subduction segment occurs to the east of the intersection of inferred mantle hotspot traces on the Nazca plate with the Peru-Chile Trench: the Nazca ridge (at the southern part of the Peruvian segment), and the Juan Fernández island-seamount chain (offshore the Chilean segment). A third inferred trace, the Galápagos-Carnegie ridge, may be correlated with a zone on incipient low-angle subduction beneath Colombia.The importance of such hotspot traces in contributing to low-angle subduction beneath the Andes is strengthened by updated South American-Nazca plate reconstructions, including three oceanic hotspot traces, in comparison with a new isotopic date compilation of igneous rocks from the mountain range. The Juan Fernández hotspot trace, reconstructed from Pacific-hotspot models to the Nazca-Farallon plate, encountered the subduction zone offshore southern Peru ~65 Ma, broadening arc volcanism to the east; the trace-trench intersection migrated gradually and then rapidly southward, widening the arc east to Bolivia and northern Argentina; it then stabilized about 13 Ma offshore central Chile, producing the contemporary low-angle Pampean segment. The Juan Fernández hotspot may also have been responsible for formation of the Manihiki Plateau on the Pacific plate much earlier, ~125 Ma. The Easter-Nazca hotspot trace intersected the subduction zone beneath Colombia before ~50 Ma and migrated southward beneath Ecuador beginning ~15 Ma, with progressive low-angle subduction implied by migrating volcanic cessation along the Andean crest to southern Peru. The Galápagos-Carnegie hotspot trace only recently encountered the subduction zone, apparently inducing a new low-angle segment and cessation of magmatism in Colombia. The reconstructions and magmatic history provided here strongly support a previously proposed genetic relationship of hotspot traces and low-angle subduction. Additionally, the reconstructions suggest remnants of older subducted traces in the asthenosphere may have sourced post-rift magmatism in eastern Brazil and Paraguay, which cannot be explained otherwise by simple hotspot mechanisms.pp.1-6
The Andean Southern Volcanic Zone : A review on the legacy of the latest volcanic eruptions
Full text linkThe Andean Southern Volcanic Zone (SVZ) concentrates many of the most active volcanoes of the Andean continental arc, as well as the region’s most recent and impactful volcanic eruptions. In this contribution, we briefly revise the general characteristics of the SVZ volcanism and provide a synthesis of the scientific findings related to the latest volcanic eruptions (430 peer-reviewed publications with over 9,000 citations, with large-magnitude (VEI 4-5) eruptions being the most studied. Our study shows that SVZ research has been primarily focused on environmental and atmospheric impacts (29%), eruption descriptions and physical volcanology (20%), volcanic hazard and risk assessments (15%), and other investigations complementary to volcanology. Whereas the least silicic eruptions (e.g., Llaima 2008-2009 and Villarrica 2015) shed light on magma replenishment and degassing dynamics controlling eruption styles, intermediate eruptions (andesitic-dacitic) offered clues on either rapid or slow eruption initiation, with relevant findings on phreatic-to-magmatic style transitions and eruption triggering mechanisms. On the other hand, silicic (i.e., rhyolite-rhyodacite) eruptions provided unique observations on rapid magma ascent, high-rate magma extrusion, rheology, fragmentation processes, and style transitions. These recent eruptions have also inspired a new generation of tephrochronological, tephrostratigraphical, and physical volcanology studies, aimed at assessing the long-term (kyr-scale) evolution of the volcanic systems and their associated hazards. We debate how the knowledge gained from research and the long-term human coexistence with volcanoes are relevant to reducing volcanic risk in the SVZ. Finally, we discuss how challenges and opportunities emerging from other disciplines can complement our understanding of volcanism in this active region.pp.379-41
Visita a rutas G-25 sector Las Achupallas y G-345 sector Los Maitenes, comuna de San José de Maipo, Región Metropolitana
Full text linkInforme Técnico -- Unidad Ejecutora: Unidad de Asistencias Técnicas y Emergencias Geológicas, Santiago14 p
Gravimetría del sector occidental de la Hoja Illapel, región de Coquimbo, Chile
Full text linkInforme Registrado IR-24-11658 p
Evaluación de la remoción en masa ocurrida en el sector Llancahue de Coñaripe, comuna de Panguipulli, región de Los Ríos
No full textInforme Técnico -- Unidad Ejecutora: Dirección Regional de Los Ríos, Valdivia39 p
Base de datos de geoquímica de sedimentos de la Hoja Aguas Blancas, región de Antofagasta
Full text linkContiene: Base de Datos de Geoquímica de sedimentos de la Hoja Aguas Blancas, región de Antofagasta (archivo xlsx)30 p
Evaluación de peligro de remoción en masa sector de Linco Oriente, comuna de Collipulli, región de La Araucanía
No full textInforme Técnico -- Unidad Ejecutora: Dirección Regional de Los Ríos, Valdivia22 p
Informe de observaciones de terreno socavones al suroeste de Concón, comuna de Viña del Mar, 19 de julio 2024
Full text linkInforme Técnico -- Unidad Ejecutora: Unidad de Peligros Geológicos y Ordenamiento Territorial, Unidad de Asistencias Técnicas y Emergencias Geológicas, Santiago11 p
Zonas aptas para reconstrucción de viviendas en áreas afectadas por incendios del 2 de febrero 2024, Región de Valparaíso
No full textInforme Técnico -- Unidad Ejecutora: Unidad de Peligros Geológicos y Ordenamiento Territorial, Unidad de Asistencias Técnicas y Emergencias Geológicas, Santiago35 p
Cuenta Pública 2023
No full textCuenta Pública Participativa 2024 ; Director Nacional: Patricio Aguilera Poblete42 p