Repositorio Digital Sernageomin
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The April 2015 Calbuco eruption pyroclastic density currents : Deposition, impacts on woody vegetation, and cooling on the northern flank of the cone
No full textThe 22-23 April 2015 eruption of the Calbuco volcano (Southern Andes, Chile) led to extensive pyroclastic density currents (PDCs) interactions with vegetation. We seek to describe the PDCs which affected both Tepu and Frío rivers, northern Calbuco, from their timing and deposition to cooling and erosion, as well as their impacts on forests. Our investigation is based on field stratigraphy, forest disturbance assessment, and geothermometry from degassing pipes and charcoal. These PDCs reached at least ~540-603 °C, as estimated from fumaroles, and consisted of both concentrated and dilute PDCs during the first pulse (22 April) at Tepu and mainly during the second pulse (23 April) at Frío. Effects of PDCs on forest vegetation recorded in Tepu consisted of heating, abrasion, burial, and impact force. On the valley floor, trees were buried with up to 4 m of deposits from the concentrated PDCs, and all trees in this deposition zone died with no subsequent sprouting. Conversely, in the margins of the valley, defoliated fallen trees and standing shrubs indicate scorching due to the passage of dilute PDCs, and some of them were later sprouting. Estimated impact forces required to produce toppling range from 1.5 to 3.7 kPa, and PDC velocities reached up to 36 m s-1. Charring of the buried wood involved an emplacement temperature of 400-550 °C within PDC deposits. The rapid watershed formation may have facilitated infiltration, decreasing the temperature in the basal part within the deposits at the Tepu river. Runoff during the subsequent months triggered lahars and caused the rivers to incise the deposits and transport sediment downstream. This set of observations provides valuable insights into how the interaction between volcanic phenomena and margine forest on the valley floors informs eruptive processes, dynamics, and impacts. Our study is also relevant to interpret the thermal history and potential hazards of PDCs.pp.319-34
On the validity of the Macrochorobates scalabrinii Biozone (early Huayquerian Stage/Age, Late Miocene). Multi-proxy analysis of the enigmatic Arenas Blancas site (Buenos Aires Province, Argentina)
Get PDFArenas Blancas is a poorly known fossiliferous site located in the lower reach of the Chasicó creek (Buenos Aires Province, Argentina), with great relevance from a biostratigraphic viewpoint. The Macrochorobates scalabrinii Biozone was defined in this site, proposed as the biostratigraphic basis of the early Huayquerian Stage/Age (Late Miocene); however, the geological context and faunal record of this site have never been studied in detail. In this work, we perform a multi-proxy analysis of the Arenas Blancas site, as well as a nearby site here called Curva de la Vaca, and provide new interpretations on their origin, age, and biostratigraphy. Sedimentological, stratigraphic, and geomorphological characteristics of both sites suggest that the sequences include fluvial/alluvial deposits that represent Quaternary terraces. The taxonomic analysis of the Arenas Blancas faunal assemblage evidences the presence of 14 mammal taxa, together with some fishes, reptiles, and birds; the assemblage is correlated with the assemblage from the Cerro Azul Formation assigned to the Chasicoan Stage/Age (Late Miocene), also recovered from the lower reach of the Chasicó creek. The use of the taxa proposed in previous works to characterize the Macrochorobates scalabrinii Biozone (including this species) is not supported due to their taxonomic status and/or temporal distribution. Taphonomic evaluation indicates that the assemblage is constituted by reworked specimens; in this frame, it is proposed that fluvio/alluvial events, occurred during the Late Pleistocene-Holocene, eroded the Upper Miocene substrate and reworked fossil remains. Based on the present evidence, the Macrochorobates scalabrinii Biozone is here rejected as a valid biostratigraphic unit.pp.22-5
Visita técnica por condición de estabilidad de laderas en cerro La Virgen y caleta Punta Lavapie, comuna de Arauco, región del Biobío
No full textRevisor: Carolina Jara. -- Informe Técnico -- Unidad Ejecutora: Dirección Regional de Los Ríos, Valdivia15 p
Observaciones geológicas del talud de población Michelle Bachelet, comuna de Puerto Varas, región de Los Lagos
No full textInforme Técnico -- Unidad Ejecutora: Oficina Técnica de Puerto Varas14 p
Caracterización de los deslizamientos ocurridos en invierno 2022 en la comuna de Calbuco, región de Los Lagos
Get PDFInforme Técnico -- Unidad Ejecutora: Oficina Técnica Puerto Varas21 p
Peligros del Volcán Melimoyu, región de Aysén del General Carlos Ibáñez del Campo
No full textContiene Anexos: Anexo I.Catastro de actividad eruptiva ; Anexo II.Columnas estratigráficas ; Anexo III.Volcanes análogos ; Anexo IV.Tablas de procesos volcánicos , Anexo V.Análisis químicos ; Anexo VI.Glosario ; Escala: 1:75.000 ; Coordenadas: 44,07° S-72,28° O64 p
Análisis de susceptibilidad de remoción en masa en ladera de humedal urbano Quebrada Gramado colindante con pasaje Machmar, comuna de Puerto Varas, región de Los Lagos
Get PDFInforme Técnico -- Unidad Ejecutora: Oficina Técnica Puerto Varas21 p
Long-term irrigation as an earthflow trigger in Chenque Malal, Northern Patagonia, Argentina
No full textBecause of their social, ecological, and economic impacts, landslides are an issue of global concern. Episodes occurring worldwide have been associated with natural and human causes, although the latter have been poorly explored. Despite recent scientific insight into intensive irrigation as a cause, research remains scarce. This paper focuses on determining the anthropogenic influence on the triggering of earth flows by long-term intensive irrigation, based on temporal and geospatial information. This analysis covers a sector of Northern Patagonia in Argentina, an area of transhumant pastoralism. Our results show that excessive water input creates favorable conditions for the triggering and evolution of earth flows in the region, even under water deficit conditions. As a result, on 22 September 2020, a collapse was recorded which mobilized ~19,000 m³ of earth debris along 360 m and produced economic losses estimated at 168,000 USD. Other landslides are expected to occur in the area if irrigation amounts remain at the same level.pp.372-38
Minuta : Caída de bloques menores en camino vecinal El Arenal, Pelluco Alto, ciudad de Puerto Montt, región de Los Lagos
No full textMinuta técnica4 p
Caracterización de remociones en masa : Ladera Angelmó y calle Ecuador, comuna de Puerto Montt, región de Los Lagos
No full textInforme Técnico -- Unidad Ejecutora: Oficina Técnica de Puerto Varas15 p