Repositorio Digital Sernageomin
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Evaluación de la susceptibilidad de remoción en masa en ladera norte de playa Cheuque Comuna de Mariquina, Región de Los Ríos
No full textInforme Técnico -- Unidad Ejecutora: Dirección Regional de Los Ríos, Valdivia17 p
Estratigrafía de las riberas del lago Chapo y su relación con procesos erosivos, comuna de Puerto Montt, región de Los Lagos
Get PDFInforme Técnico -- Unidad Ejecutora: Dirección Regional Los Lagos22 p
Tracing hotspot traces in the Andes
No full textTwo 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
Recent fluctuations of the Alerce glacier (1953-2020), North Patagonian Andes
No full textIn recent decades, glacier retreat has been observed in all the world’s mountain ranges. Over the last 20 years, glaciers in the Andes have lost mass at one of the highest rates on record. Particularly, glaciers in the northern Patagonian Andes show the highest rate of loss of all the Andean regions for the last decade. Detailed records of long-term variations in glacier extent are crucial to put current climate change into context and quantify its impact on mountain areas. In the present study, a reconstruction of the extension (length and area) of the Alerce glacier (41.15° S-71.81° W) for the last 70 years was carried out. By means of historical documents and satellite images (Landsat and Pléiades), detailed maps of glacier fluctuations were generated for the period 1953-2020. Four methodologies were evaluated to measure the front position: i) central flow line; ii) curvilinear box; iii) multiline; and iv) variable box. The magnitude of the front position variations depends on the methodology applied. The method that best addresses glacier front variations over the period analyzed is the variable box method. Between 1953 and 2020, the Alerce glacier lost 35% of its area (1.1±0.1 km2) and 67% of its total length (1.49±0.04 km). It is possible to distinguish periods with different rates of retreat. A stage of slight retreat (-11.3±0.5 ma-1) between 1953 and 1976, followed by a period of stability (-6.7±0.5 ma-1) between 1977 and 1983, then a strong retreat (-58.7±0.5 ma-1) between 1984 and 1999, followed by another period of stability (-5.4±0.5 ma-1) between 2000 and 2009 and, finally, another retreat (-8.7±0.5 ma-1) between 2010 and 2020. The retreat rates for the Alerce glacier mimic those observed in other glaciers in the region, possibly representing a regional climatic signal.pp.247-26
Evaluación de peligro de remoción en masa en camino de acceso a localidad de Pon Pon, comuna de Mariquina, región de Los Ríos
No full textInforme Técnico -- Unidad Ejecutora: Dirección Regional de Los Ríos, Valdivia18 p
Estadísticas de Accidentabilidad Industria Extractiva Minera Año 2023 : Reporte al 31 de Diciembre 2023
No full textDepartamento de Investigación de Accidentes y Sanciones38 p
Estadísticas de Accidentabilidad Industria Extractiva Minera Año 2023 : Reporte al 31 de Diciembre 2023
No full textDepartamento de Investigación de Accidentes y Sanciones38 p
Evaluación geológica de terreno para el emplazamiento del hospital de Castro, comuna de Castro, región de Los Lagos
Get PDFInforme Técnico -- Unidad Ejecutora: Dirección Regional Los Lagos12 p
Opinión técnica de peligro geológico en predio Estero Las Leñas, comuna de Valdivia, Región de Los Ríos
No full textInforme Técnico -- Unidad Ejecutora: Unidad de Geología Aplicada, Dirección Regional de Los Ríos, Valdivia14 p