Subaqueous landslides at the distal basin of Lago Nahuel Huapi (Argentina): Towards a tsunami hazard evaluation in Northern Patagonian lakes

The May 22nd, 1960 Valdivia earthquake, Chile (Mw 9.5) triggered a series of subaqueous mass-wasting processes (debris flows and slides) in Lago Nahuel Huapi (Argentina), generating a tsunami-like wave that hit the coasts of San Carlos de Bariloche. Aiming to provide a first preliminary insight into tsunami hazards for the lakeshore communities, in this paper we identify and characterize the subaqueous landslides at the populated distal basin of the lake. Swath bathymetric and seismic profiling surveys were carried out and high-resolution digital elevation models were derived from these data to perform a landslide inventory map. A series of morphometrical parameters (including the landslide area, the volume of displaced materials and the run-out distance, among others) were estimated upon selected events. The results indicated that landslide activity at the distal basin of Lago Nahuel Huapi has been concentrated in the vicinity of Bariloche (massive landslide triggered by the 1960 earthquake) and within steep delta fronts where the slope failures typically initiate at shallow waters (9–11 m depth). The sliding mass frequently travels basinward along a great distance (≥1000 m). At the delta fronts, the volume of material removed by landslides can reach ~40 × 104 m3 , leaving scar areas of up to 13 m thick. The periodic occurrence of rotational–translational mass movements initiating at the upper edge of the delta fronts, with vertical displacements of the mobilized materials reaching ~200 m, probably represents a potential tsunami hazard for the nearby populated coasts.Fil: Beigt, Debora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales.; ArgentinaFil: Villarosa, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales.; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: Gomez, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Manzoni, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales.; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentin

Water evacuations in remote tourist regions: evaluating case studies from natural hazards in North Patagonian lakes, Argentina

The remote North Patagonian region is a sparsely populated territory and a world famous tourist destination located on the leeward side of the Andes Mountains. Recent disasters triggered by various types of geoenvironmental hazards (including volcanic eruptions, mass-wasting processes and extreme weather events) heavily disrupted ground transport networks in a region with already limited territorial accessibilities. All these catastrophes prompted the need to evacuate or assist a number of secluded visitors, locals and livestock extemporaneously on board of coastguards and tourist passenger-ships from the shores of the many glacial lakes that make up part of the regionalattraction. Despite the recurrence of these types of events, water evacuations in the region continue to be spontaneous, improvised and hazardous procedures. This contribution reconstructs and assesses a number of recent local-scale cases of lake evacuations and assistances from a number of Patagonian urban centers, rural areas and tourist sites. For each case study, we systematically elaborated on the prime components of an evacuation process, which enabled us to recognize key achievements, failures and conditioning factors for managing emergencies via water transport, most of them inherent to the studied region. Some of the complexities to emerge from case studies referred to: complex hazard-related scenarios; limited ground-based accessibilities and risk of isolation; various inter- and intra-organizational issues, incidental to natural reserves and tourist regions; a wide range of particular demographic features; and the availability and vulnerability of water transport resources. We suggested fundamental and replicable recommendations for developing water evacuation plans, also identifying forthcoming problems to solve in order to improve the management of emergencies through this alternative means of transport.Fil: Salgado, Pablo Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; ArgentinaFil: Villarosa, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; ArgentinaFil: Beigt, Debora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; ArgentinaFil: Outes, Ana Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; Argentin

Origin of the tsunami of may 1960 in the Lake Nahuel Huapi, Patagonia: application of the high-resolution bathymetric and seism ic techniques

El tsunami ocurrido en el lago Nahuel Haupi, Patagonia Argentina, el 22 de Mayo de 1960, constituye el primer ejemplo de tsunami en lagos continentales en Argentina. La batimetría de detalle obtenida con sonar batimétrico por medición de fase (SBMF) y dos perfiles sísmicos de alta resolución junto con tres testigos sedimentarios cortos del lago permitieron vincular al tsunami con el gran movimiento sísmico conocido como el terremoto de Valdivia, el sismo más fuerte registrado instrumen- talmente a escala global (Mw 9,5). El impacto de las ondas sísmicas provocó la movilización de grandes volúmenes de sedi- mentos lacustres del sustrato, especialmente por debajo de los 70-80 m de profundidad de agua. El fallo fue probablemente inducido por la presencia de una superficie de baja coherencia (tefra?) que funcionó como plano de deslizamiento posibilitan- do la remoción de sedimentos y conformando una megaturbidita en la parte más profunda. La movilización de estos mate- riales provocó el desplazamiento de un gran volumen de agua, originando el tsunami que golpeó las costas de Bariloche y des- truyó el muelle de la ciudad.The tsunami recorded in the Lake Nahuel Huapi, Patagonia Argentina, on May 22, 1960 is the first example of a tsu- nami in a continental lake in Argentina. High-resolution bathymetry (SBMF), 2 high-resolution seismic profiles together with three short sedimentary cores allowed linking this tsunami to the 1960 earthquake of Valdivia, the strongest (Mw 9.5) ever ins- trumentally recorded earthquake. The impact of the seismic waves produced huge mass-failure below 70-80 m water depth. The failure was probably induced by the presence of a non-cohesive surface (tephra layer?) that acted as a sliding surface, and the mo- bilized material evolved into a mega turbidite in the deep basin. A large volume of water was displaced by the mobilization of these sediments producing a tsunami that hit the coasts of Bariloche and destroyed the harbor of the city.Fil: Villarosa, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Outes, Ana Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Gomez, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Chapron, Emmanuel. Universidad de Orleans; FranciaFil: Ariztegui, Daniel. Universidad de Ginebra; Suiz

Tsunamis en el Lago Nahuel Huapi: Historias de deslizamientos y erupciones

El 22 de mayo de 1960 un tsunami golpeó las costas de S. C. de Bariloche. El antiguo muelle del Puerto San Carlos, que se hallaba en reconstrucción luego del incendio de 1958, colapsó durante dicho evento. ¿Cuáles fueron los mecanismos que generaron esta ola? ¿Se puede relacionar su origen con el gran sismo de Valdivia ocurrido simultáneamente? ¿Puede volver a ocurrir un evento como éste en el lago Nahuel Huapi, o en otro lago de la región? El Grupo de Estudios Ambientales del Instituto de Investigaciones en Biodiversidad y Medioambiente (CONICET/UNCo) e investigadores del Instituto Argentino de Oceanografía (CONICET/UNS) estudian los sedimentos y la topografía del lecho del lago Nahuel Huapi con el objeto de comprender cómo se generan estos eventos lacustres y evaluar la peligrosidad que representan para las poblaciones costeras.Fil: Gomez, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Beigt, Debora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Villarosa, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Outes, Ana Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Dzendoletas, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Secondary lahar hazard assessment for Villa la Angostura, Argentina, using Two-Phase-Titan modelling code during 2011 Cordón Caulle eruption

This paper presents the results of lahar modelling in the town of Villa La Angostura (Neuquén-Argentina) based on the Two-Phase-Titan modelling computer code. The purpose of this exercise is to provide decision makers with a useful tool to assess lahar hazard during the 2011 PuyehueCordón Caulle Volcanic Complex eruption. The possible occurrence of lahars mobilized from recent ash falls that could reach the city was analysed. The performance of the TwoPhase-Titan model using 15 m resolution digital elevation models (DEMs) developed from optical satellite images and from radar satellite images was evaluated. The output of these modellings showed inconsistencies that, based on field observations, were attributed to bad adjustment of the DEMs to real topography. Further testing of results using more accurate radar-based 10 m DEM, provided more realistic predictions. This procedure allowed us to simulate the path of flows from Florencia, Las Piedritas and Colorado creeks, which are the most hazardous streams for debris flows in Villa La Angostura. The output of the modelling is a valuable tool for city planning and risk management especially considering the glacial geomorphic features of the region, the strong urban development growth and the land occupation that has occurred in the last decade in Villa La Angostura and its surroundings.Fil: Córdoba, G.. Universidad de Nariño; ColombiaFil: Villarosa, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones En Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Reg.universidad Bariloche. Instituto de Investigaciones En Biodiversidad y Medioambiente; ArgentinaFil: Sheridan, M.. State University of New York at Buffalo; Estados UnidosFil: Viramonte, Jose German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energia No Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energia No Convencional; ArgentinaFil: Beigt, Debora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones En Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Reg.universidad Bariloche. Instituto de Investigaciones En Biodiversidad y Medioambiente; ArgentinaFil: Salinas de Salmuni, Nelida Graciela. Comision Nacional de Actividades Espaciales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Forecasting volcanic ash dispersal and coeval resuspension during the April-May 2015 Calbuco eruption

Atmospheric dispersion of volcanic ash from explosive eruptions or from subsequent fallout deposit resuspension causes a range of impacts and disruptions on human activities and ecosystems. The April-May 2015 Calbuco eruption in Chile involved eruption and resuspension activities. We overview the chronology, effects, and products resulting from these events, in order to validate an operational forecast strategy for tephra dispersal. The modelling strategy builds on coupling the meteorological Weather Research and Forecasting (WRF/ARW) model with the FALL3D dispersal model for eruptive and resuspension processes. The eruption modelling considers two distinct particle granulometries, a preliminary first guess distribution used operationally when no field data was available yet, and a refined distribution based on field measurements. Volcanological inputs were inferred from eruption reports and results from an Argentina-Chilean ash sample data network, which performed in-situ sampling during the eruption. In order to validate the modelling strategy, results were compared with satellite retrievals and ground deposit measurements. Results indicate that the WRF-FALL3D modelling system can provide reasonable forecasts in both eruption and resuspension modes, particularly when the adjusted granulometry is considered. The study also highlights the importance of having dedicated datasets of active volcanoes furnishing first-guess model inputs during the early stages of an eruption.Fil: Reckziegel, Florencia Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Bustos, Emilce. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Leonardo, Mingari. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Baez, Walter Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Villarosa, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Folch Duran, Arnau. Barcelona Supercomputing Center - Centro Nacional de Supercomputacion; EspañaFil: Collini, E.. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; ArgentinaFil: Viramonte, Jose German. Universidad Nacional de Salta; ArgentinaFil: Romero, J.. Centro de Investigación y Difusión de Volcanes de Chile; Chile. Universidad de Atacama; ChileFil: Osores, María Soledad. Comision Nacional de Actividades Espaciales; Argentina. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

An 18,000 year-long eruptive record from Volcán Chaitén, northwestern Patagonia:Paleoenvironmental and hazard-assessment implications

The 2008 eruption of Volcán Chaitén (VCha) in northwestern Patagonia was the first explosive rhyolitic eruption to have occurred within a century and provided an unprecedented scientific opportunity to examine all facets of the eruption ranging from magma rheology/ascent rates to ash-fall effects on biota and infrastructure. Up to very recently it was thought that the latest eruption prior to the 2008 event occurred c. 9750 cal. a BP. Although a number of researchers have recognised additional eruptive products, but their stratigraphy, age, and geochemical attributes have not been systematically described and/or recorded. In this study, we provide a detailed examination of andic cover-beds and tephra-bearing lake sequences located both proximally and distally to VCha, which record a series of hitherto unknown rhyolitic eruptive products and place all previous observations firmly within a coherent stratigraphic framework. Through major- and trace-element glass shard geochemistry we are able to confidently verify eruptive source. A total of 20 discrete tephra beds are recognised, with at least 10 having widespread areal distributions and/or depositional imprints broadly comparable to, or greater than, the 2008-tephra event. This record indicates that VCha has been continuously but intermittently active as far back as the end of the Last Glacial Maximum (c. 18,000 cal a BP) with two dominant, genetically related magma types and an intermediary ¿mixed¿ type. Before this the eruptive record has been largely obscured and/or erased by widespread Andean piedmont glaciation. However, based on the tempo of VCha activity over the last c. 18,000 years, older VCha eruptives can be anticipated to occur as well as future hazardous explosive events. The new eruptive inventory will ultimately be useful for correlating equivalent-aged sequences and refining long-term eruptive tempo as well as corresponding temporal changes in magmatic evolution

Measurements and modeling of snow albedo at Alerce Glacier, Argentina: effects of volcanic ash, snow grain size and cloudiness

The relevance of light absorbing impurities in snow albedo (and its effects in seasonal snow or glacier mass balance) have been under study for several decades. However, the effect of volcanic ash has been much less studied, and most articles studied only the effect of thick layers after direct deposition. There is also a knowledge gap in field measurements of seasonal snow and glaciers of the southern Andes, that only recently has started to be filled.We present here the first field measurements on Argentinian Andes, combined with albedo and mass balance modeling activities.Measured impurities content (1.1mgkg−1 to 30000 mgkg−1) varied abruptly in snow pits and snow/firn cores, due to high surface enrichment during ablation season and possibly local/regional wind driven resuspension and redeposition of dust and volcanic ash. In addition, we observed a high spatial hetereogeneity, due to seasonality, glacier topography and prevailing wind direction. Microscopical characterization showed that the major component was ash from recent Calbuco (2015) and Cordón Caulle (2011) volcanic eruption, with 10 minor presence of mineral dust and Black Carbon. We also found a wide range of measured snow albedo (0.26 to 0.81), whichreflected mainly the impurities content and the snow/firn grain size (due to aging). SNICAR model has been updated to model snow albedo taking into account the effect of cloudiness on incident radiation spectra, improving the match of modeled and measured values. We also ran sensitivity studies on the main measured parameters (impurities content and composition, snow grain size, layer thickness, etc) to assess which field measurements precision can improve the uncertainty of albedo modeling. Finally, we studied the impact of these albedo reductions in Alerce glacier using a spatially distributed surface mass-balance model. We found a large impact of albedo changes in glacier mass balance, and we estimated that the effect of observed ash concentrations can be as high as a 1.25mwe decrease in the glacier-wide annual mass balance (due to a 34 % of increase inthe melt during the ablation season).Fil: Gelman Constantin, Julián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); ArgentinaFil: Ruiz, Lucas Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Villarosa, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: Outes, Ana Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; ArgentinaFil: Bajano, Facundo N.. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); ArgentinaFil: He, Cenlin. National Center for Atmospheric Research; Estados UnidosFil: Bajano, Héctor. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); ArgentinaFil: Dawidowski, Laura Elena. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentin

Secondary lahar hazard assessment for Villa la Angostura, Argentina, using Two-Phase-Titan modelling code during 2011 Cordón Caulle eruption

This paper shows the results of secondary lahar modelling in Villa La Angostura town (Neuquén-Argentina) based on the Two-Phase-Titan modelling computer code, which aimed to provide decision makers a useful tool to assess lahar hazard during the 2011 Puyehue-Cordón Caulle Volcanic Complex eruption. Possible occurrence of secondary lahars that could reach the city was analized. The performance of the Two-Phase-Titan model using 15 m resolution DEMs developed from optical satellite images and from radar satellite images was evaluated. The output of these modellings showed inconsis- tencies that, based on field observations, were attributed to bad adjustment of DEMs to real topography. Further testing of results using more accurate radar based 10 m DEM, proved more realistic predictions. The procedure allowed to simulate the path of flows from Florencia, Las Piedritas and Colorado creeks, which are the most influenc- ing streams in Villa La Angostura. The output of the modelling is a valuable tool for city planning and risk management especially considering the glacial geomorphology features of the region, the strong urban development growth and the land occupation tendencies observed in last decade in Villa La Angostura and its surroundings

Census indicators as a tool for assessing social vulnerability to the fall of volcanic ash: the case of Villa La Angostura (Argentina) during the eruption of Cordón Caulle, 2011

La vulnerabilidad está definida por las condiciones socioeconómicas previas a la ocurrencia de un evento catastrófico. La erupción del Cordón Caulle iniciada en junio de 2011 trajo consecuencias a la región del Nahuel Huapi, principalmente Villa La Angostura, en actividades económicas, servicios básicos, transportes y comunicaciones, entre otras. El objetivo del trabajo es desarrollar una herramienta metodológica para evaluar la vulnerabilidad social frente a la caída de ceniza volcánica a partir de indicadores provistos por el Censo Nacional de Población, Hogares y Viviendas realizado en el año 2010, que muestra el escenario previo a dicha erupción, a la vez que facilita su replicabilidad a partir de datos disponibles a nivel nacional. Los indicadores fueron mapeados, analizados por radios censales y se cotejaron con información disponible sobre las medidas adoptadas durante la emergencia y se elaboró un mapa fi nal de vulnerabilidad. Se destacó la oportunidad y pertinencia que presentan los datos censales para anticipar sitios vulnerables, especialmente cuando se consideran las condiciones habitacionales, el abastecimiento de agua potable y los materiales e inclinación de los techos, así como también las mejoras realizadas luego de la emergencia, por ejemplo, en el sistema de abastecimiento y distribución del agua de red.Vulnerability is defined by the socioeconomic conditions prior to the occurrence of a catastrophic event. The eruption of Cordón Caulle in June 2011 brought consequences to the Nahuel Huapi region, mainly in Villa La Angostura. Economic activities, basic services, transport and communication systems, among others, were all affected by the ash fall. The objective of this paper is to develop a methodological tool to assess the social vulnerability to the fall of volcanic ash from the indicators provided by the 2010 National Household and Housing Population Census which shows the scenario prior to the eruption. At the same time, it facilitates its replicability based on data available at the national level. The indicators were mapped, analyzed by census radios and collated with available information on the measures adopted during the emergency so that a final vulnerability map was drawn up. The opportunity and relevance of census data to anticipate vulnerable sites was highlighted especially when considering the housing conditions, drinking water supply system and the materials and roofâ s slope, as well as the improvements made after the emergency (e.g. drinking water supply and distribution systems).Centro de Investigaciones Geográfica