Instituto Geologico Minero y Metalurgico

Lima, Peru

Instituto Geologico Minero y Metalurgico

Lima, Peru
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The Cordillera Blanca in northern Peru is the most external geodynamics active areas in Perú. There have been occurred the biggest glacier source debris flow in the Peruvian history, most of them became on major disasters and claimed thousands of lives. On April 11th, 2010, the Laguna 513, located in the center of the Cordillera Blanca, suffered a partial GLOF due a massive rock and ice fall from Nevado Hualcán (5500 masl). This event, despite being of considerable size, did not generate large losses or affect any major city. Using numerical simulations we study the dynamics of the consequent GLOF and debris flow. We determined the volume and turbulence as well as also explained the role of the geomorphology of the area in the flow deceleration process and the river flood subsequent behavior. The FLO 2D simulations are validated with post event satellite image and field data.

Hermanns R.L.,Norges Geologiske Undersokelse | Valderrama P.,Instituto Geologico Minero y Metalurgico | Fauque L.,Servicio Geologico Minero Argentino | Penna I.M.,University of Buenos Aires | And 4 more authors.
Revista de la Asociacion Geologica Argentina | Year: 2012

Landslides in the Andes are some of the highest natural threats to society with single events killing up to several thousand people. Landslide mapping and landslide research became a more widely spread discipline in geosciences in the Andean countries. However efforts today by far do not match the threat and both more investigations and more mapping activities are needed to support decision makers in land use planning. In this communication we discussed five key issues that we suggest to focus on in upcoming years: Impact of climatic change on landslides occurrence, landslides susceptibility and hazard maps, prediction of megalandslides, seismically triggered landslides, and temporal spatial distribution of mud and debris flows potential.

Willner A.P.,University of Stuttgart | Willner A.P.,Ruhr University Bochum | Tassinari C.C.G.,University of Sao Paulo | Rodrigues J.F.,University of Porto | And 3 more authors.
Journal of South American Earth Sciences | Year: 2014

High-pressure conditions of 11-13. kbar/500-540°C during maximum burial were derived for garnet amphibolite in the Tapo Ultramafic Massif in the Eastern Cordillera of Peru using a PT pseudosection approach. A Sm-Nd mineral-whole rock isochron at 465±24. Ma dates fluid influx at peak temperatures of ~600°C and the peak of high pressure metamorphism in a rodingite of this ultramafic complex. The Tapo Ultramafic Complex is interpreted as a relic of oceanic crust which was subducted and exhumed in a collision zone along a suture. It was buried under a metamorphic geotherm of 12-13°C/km during collision of the Paracas microcontinent with an Ordovician arc in the Peruvian Eastern Cordillera. The Ordovician arc is represented by the western Marañon Complex. Here, low PT conditions at 2.4-2.6kbar, 300-330°C were estimated for a phyllite-greenschist assemblage representing a contrasting metamorphic geotherm of 32-40°C/km characteristic for a magmatic arc environment. © 2014 Elsevier Ltd.

Tassinari C.C.G.,University of Sao Paulo | Castroviejo R.,Technical University of Madrid | Rodrigues J.F.,National Laboratory of Energy and Geology | Acosta J.,Instituto Geologico Minero y Metalurgico | Pereira E.,National Laboratory of Energy and Geology
Journal of South American Earth Sciences | Year: 2011

The ultramafic-mafic rocks of the Tapo Complex are exposed in the Eastern Cordillera of the Central Peruvian Andes. This complex is composed of serpentinised peridotites and metabasites with some podiform chromitite lenses and chromite disseminations and overlies the sandstones, conglomerates, and tuffs of the Carboniferous Ambo Group. The metagabbros and amphibolites show a tholeiitic affiliation and a flat REE spider diagram, with a slight LREE depletion and a positive Eu anomaly suggesting magmatic accumulation of plagioclase, in an ocean ridge or ocean island environment. Sm-Nd isotopic analyses were performed on chromite as well as on whole rock from the gabbro. All samples yielded an Sm-Nd isochrone age of 718 ± 47 Ma with an initial 143Nd/ 144Nd of 0.51213 ± 0.00005. The e{open} Nd (718 Ma) values calculated for both chromite and gabbro are in close agreement, around 8.0, implying that they were formed at the same time from the same mantelic magma source. Furthermore a K-Ar age on amphibole of 448 ± 26 Ma was obtained, interpreted as the cooling age of a younger orogenic event. These rocks represent slices of oceanic crust (from a dismembered ophiolitic complex), metamorphosed and later overthrust on upper Palaeozoic continental formations. © 2011 Elsevier Ltd.

Franco R.D.V.,RDVGeoconsulting | Thouret J.-C.,CNRS Magmas and Volcanoes Laboratory | Delaite G.,CNRS Magmas and Volcanoes Laboratory | Van Westen C.,International Institute for Geoinformation Science and Earth Observation | And 5 more authors.
Special Paper of the Geological Society of America | Year: 2010

Studies of the type, extent, and volume of Holocene pyroclastic and lahar deposits have concluded that future eruptions of El Misti volcano, even if moderate in magnitude, will pose a serious threat to the city of Arequipa, Peru. After describing the most probable volcanic scenarios at El Misti, this paper concentrates on lahar and flood risk assessment. Scenarios were derived with the help of the simulation codes LAHARZ and TITAN2D. The lahar risk assessment varies significantly depending on the method selected. LAHARZ simulations indicate that a considerable part of the urban areas and infrastructure could be severely affected. Losses due to impacts inflicted by lahars in three selected parts of the urban area are estimated to be in the order of 40-100 million U.S. dollars. In the case of TITAN2D, the resulting laharaffected area only includes infrastructure assets mainly located along the Río Chili. Results indicate that although simulation codes could be useful tools in the analysis of lahar hazard scenarios, it is still premature to regard them as accurate sources of information for actual decision making related to risk mitigation at the local level. More research is required to further adjust simulation codes and refine risk scenarios. The first priority for the mitigation of the volcanic hazard faced by the city of Arequipa should be improvement of the risk map (a hazard map has already been drawn and is under scrutiny) and the preparation of contingency plans. © 2010 The Geological Society of America. All rights reserved.

Zavala Carrion B.,Instituto Geologico Minero y Metalurgico | Rosado M.,Instituto Geologico Minero y Metalurgico | Lu Leon S.,Instituto Geologico Minero y Metalurgico
Revista de la Asociacion Geologica Argentina | Year: 2012

On February 22, 2010, an old slide on the slopes the hill Rodeopampa was reactivated, causing damming Sócota Valley, a tributary of the Marañón River affect agricultural land and some houses of Rodeopampa in the body and head of the slip and St. Luis de Lucma in the Run up and reservoir, both located in the provinces of Chota and Cutervo, Cajamarca region, northern Peru. He formed a reservoir of 1640 m long and 400 m wide with a shut height of 70 to 90 m, which remained for months before being opened up naturally by the river. As this slide, different gravitational processes occurred during the anomalous rainfall in 2008, 1998 and 1983 in the northern region, being affected major routes into the mountains and forests of the region Cajamarca. These areas previously evaluated in the study of geological risk in the region, particularly Rodeopampa sector were compared with the susceptibility map produced. These areas are located in areas of high and very high susceptibility to landslides, helped to validate the map and its usefulness for disaster prevention and development planning.

Margirier A.,CNRS Institute of Earth Sciences | Audin L.,CNRS Institute of Earth Sciences | Carcaillet J.,CNRS Institute of Earth Sciences | Schwartz S.,CNRS Institute of Earth Sciences | Benavente C.,Instituto Geologico Minero y Metalurgico
Earth Surface Dynamics | Year: 2015

The contribution of landslides to the Quaternary evolution of relief is poorly documented in arid contexts. In southern Peru and northern Chile, several massive landslides disrupt the arid western Andean front. The Chuquibamba landslide, located in southern Peru, belongs to this set of large landslides. In this area, the Incapuquio fault system captures the intermittent drainage network and localizes rotational landslides. Seismic activity is significant in this region with recurrent Mw9 subduction earthquakes; however, none of the latest seismic events have triggered a major landslide. New terrestrial cosmogenic dating of the Chuquibamba landslide provides evidence that the last major gravitational mobilization of these rotational landslide deposits occurred at ∼ 102 ka, during the Ouki wet climatic event identified on the Altiplano between 120 and 98 ka. Our results suggest that wet events in the arid and fractured context of the Andean forearc induced these giant debris flows. Finally, our study highlights the role of tectonics and climate on (i) the localization of large Andean landslides in the Western Cordillera and on (ii) the long-term mass transfer to the trench along the arid Andean front. © 2015 Author(s).

The upper reaches of the Río Santa (Huaraz, Perú) are highly affected by the mining activities of generally small and very small mining companies located in two specific areas, Cordillera Blanca, and Cordillera Negra, with the largest mining claims located in the districts of Recuay and Ticapampa. To assess the mobility and bioavailability of heavy metals in the abandoned tailings pond belonging to the Alianza mining company in the district of Ticapampa, and to identify the fractions to which they are associated we applied a sequential chemical extraction. The results were compared with studies into their mineralogical characterization, a quantitative chemical analysis and a determination of potential acidity and potential neutralization by the ABA (acid-base accounting) method applied to samples of tailings. The sequential extraction procedure confirmed the mode of general alteration observed in the area through mineralogical studies: a relatively easy mobility of Pb, and Cd, and considerable immobility with regard to Ag, Cr and Co, as well as an intermediate mobility of Cu, Zn, and As. Significant cadmium and lead contents found in the most mobile fractions of the tailings may represent an environmental threat, bea- ring in mind the toxic nature of these elements. Despite the low mobility of arsenic, the total quantities of this element are so high that the waters of the Río Santa are being affected.

Villacorta S.,Instituto Geologico Minero y Metalurgico | Fidel L.,Instituto Geologico Minero y Metalurgico | Zavala Carrion B.,Instituto Geologico Minero y Metalurgico
Revista de la Asociacion Geologica Argentina | Year: 2012

In 2009, the Geological Survey of Peru through the Direction of Environmental Geology and Geological Hazard, concluded the National Inventory of Geologic Hazard. One of products of this work is the "Susceptibility Map of Mass Movements in Peru" on scale 1:1.000.000. The objectives of this map are to set up a model that indicates the zones of high propensity to mass movements, in order to count with a dynamic tool for the risk management; to prioritize scenarios where specific studies are necessary, as well to raise the measures of prevention or mitigation adapted to assure the physical stability of urban zones and vulnerable infrastructures; this tool is also to contribute with the ecologic-economical zoning and land ordering, national objectives to 2021. The obtaining of these objectives had like previous step, the cartography of mass movements. The susceptibility has been obtained using a multi-variate heuristic model, which implies the crossed analysis of maps and geoprocessing operations. For the validation of the model, it was used the Inventory of geological hazard at national level, according to that, near 86% of the mass movements inventoried were concentrates in high and very high susceptibility categories. As a result of the analysis it is possible to conclude that the mass movement higher susceptibility zones in Peru are locate at: 1) To the western of the Peruvian Andes between Cajamarca-La Libertad-Ancash-Lima-Huancavelica; 2) Ayacucho-Apurimac-Cusco-Puno, in the southwestern; 3) Arequipa-Moquegua-Tacna, in the southeastern; 4) Junín-Pasco-Huanuco-San Martin, in the central and northeastern region; 5) Other smaller strips.

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