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Sample records for beneath central america

  1. Mantle Structure Beneath Central South America

    Science.gov (United States)

    Vandecar, J. C.; Silver, P. G.; James, D. E.; Assumpcao, M.; Schimmel, M.; Zandt, G.

    2003-12-01

    Making use of 60 digital broadband seismic stations that have operated across central South America in recent years, we have undertaken an inversion for the upper- and uppermost lower-mantle P- and S-wave velocity structures beneath the region. We have combined data from four portable PASSCAL-type experiments as well as the 3 GTSN permanent stations (LPAZ, BDFB and CPUP) and 1 Geoscope station (SPB) located in the region. The portable data were deployed at various times between 1992 and 1999 and include: 28 sites from the Brazilian Lithosphere Seismic Project (BLSP: Carnegie Institution of Washington and Universidade de Sao Paulo), 16 sites from the Broadband ANdean JOint experiment (BANJO: Carnegie Institution of Washington and University of Arizona), 8 sites from the Seismic Exploration of the Deep Altiplano project (SEDA: Lawrence Livermore National Laboratory) and 4 sites from the University of Brasilia. The P- and S-wave relative delay times are independently obtained via a multi-channel cross correlation of band-passed waveforms for each teleseismic event. These data are then inverted using an iterative, robust, non-linear scheme which parameterizes the 3-D velocity variations as splines under tension constrained at over 120,000 nodes across South America between latitudes of 15 and 30 degrees South. Amongst other features, we robustly image the high-velocity subducting Nazca plate penetrating into the lower mantle and the high-velocity root of the ~3.2 Gyr old Sao Francisco Craton extending to depths of 200-300 km. We will discuss the consistency between our tomographic models and predictions of dynamic mantle models based on plate tectonic reconstructions of subduction.

  2. Imaging of subducted lithosphere beneath South America

    NARCIS (Netherlands)

    Engdahl, E.R.; Hilst, R.D. van der; Berrocal, J.

    1995-01-01

    Tomographic images are produced for the deep structure of the Andean subduction zone beneath western South America. The data used in the imaging are the delay times of P, pP and pwP phases from relocated teleseismic earthquakes in the region. Regionally, structural features larger than about 150 km

  3. Ecodesign in Central America

    NARCIS (Netherlands)

    Crul, M.R.M.

    2003-01-01

    This PhD thesis describes and analyses the change process started by the Ecodesign project in Central America, executed between 1998 and 2002. The project started using the concept and praxis developed in Europe. Nine ecodesign projects were performed in industry, and ecodesign was introduced to cou

  4. A magmatic probe of dynamic topography beneath western North America

    Science.gov (United States)

    Klöcking, M.; White, N. J.; Maclennan, J.

    2014-12-01

    A region centered on the Yellowstone hotspot and encompassing the Colorado Plateau sits at an elevation 2 km higher than the cratonic North America. This difference broadly coincides with tomographically observed variations in lithospheric thickness: ~120 km beneath western North America, ~240 km beneath the craton. Thermochronology of the Grand Canyon area, sedimentary flux to the Gulf of Mexico, and river profile inversion all suggest that regional uplift occurred in at least two separate stages. High resolution seismic tomographic models, using USArray data, have identified a ring of low velocity material beneath the edges of the Colorado Plateau. Magmatism coincides with these low velocity zones and shows distinct phases: an overall increase in volume around 40 Ma and a change from lithospheric to asthenospheric signatures around 5 Ma. Volcanism is also observed to migrate north-east with time. Here, we attempt to integrate these different observations with lithospheric thickness. A dynamic topography model of progressive lithospheric erosion over a hot mantle plume might account for uplift as well as the temporal and spatial distribution of magmatism across western North America. Thinning of the lithosphere around the edges of the Colorado Plateau in combination with the hotter mantle potential temperature of a plume could create isostatic and dynamic uplift as well as allowing for melt production. To test this model, we have analysed around 100 samples from volcanic centers across western North America by ICP-MS for rare earth elements (REE). Most of the samples are younger than 5 Ma, and all of them have previously been analysed by XRF. Using trace element ratios such as La/Yb and Nb/Y we assess depth of melting and melt fraction, respectively. In addition, we use REE inversion modelling to estimate melt fractions as a function of depth and temperature of melting. The results are compared to existing constraints on lithospheric thickness and mantle potential

  5. Demographic tensions in Central America.

    Science.gov (United States)

    1986-08-01

    This discussion of Central America focuses on the rapid growth of its population, its stagnating economy, and those countries that are socioeconomically advanced. Between 1950-85 the population of Central America tripled, from 9.1 million to 26. 4 million, due to marked mortality declines and the absence of off-setting fertility declines. The distribution of Central Americas's growing populations sets its population growth apart from that of other developing regions. Currently, almost half of all Central Americans live in cities. Although the average growth rate for Central American countries has fallen and is expected to drop further, the decline does not counterbalance the effect of the absolute rise in population numbers. The average annual growth rate of more than 3% annually in the 1960s fell to about 2.6% in recent years, but this decline is due primarily to socioeconomically advanced Costa Rica and Panama. Central America's age structure further complicates the population crisis. About 43% of Central Americans are under the age of 15. When the increasingly larger young population group enters it reproductive years, the potential for future growth (albeit the falling rate of population increase) is unparalleled. UN population projections show the region's population at 40 million by the year 2000. The 1973 oil crisis began a downward spiral for the buoyant post World War II Central American economy. Between 1950-79, real per capita income growth in Central America doubled, with Central American economies growing an average of 5.3% annually. By the early 1980s, overseas markets of the trade-dependent countries of Central America had dried up due to protectionism abroad and slumping basic commodity prices. These and other factors plunged Central America into its current economic malaise of falling real per capita income, rising unemployment, curtailed export led economic growth, and a rising cost of living. In general, economic growth in Central America

  6. Seismic imaging of the downwelling Indian lithosphere beneath central Tibet.

    Science.gov (United States)

    Tilmann, Frederik; Ni, James

    2003-05-30

    A tomographic image of the upper mantle beneath central Tibet from INDEPTH data has revealed a subvertical high-velocity zone from approximately 100- to approximately 400-kilometers depth, located approximately south of the Bangong-Nujiang Suture. We interpret this zone to be downwelling Indian mantle lithosphere. This additional lithosphere would account for the total amount of shortening in the Himalayas and Tibet. A consequence of this downwelling would be a deficit of asthenosphere, which should be balanced by an upwelling counterflow, and thus could explain the presence of warm mantle beneath north-central Tibet.

  7. Imaging Transition Zone Thickness Beneath South America from SS Precursors

    Science.gov (United States)

    Schmerr, N.; Garnero, E.

    2006-12-01

    We image detailed upper mantle discontinuity structure beneath a number of geologically active regions, including the South American subduction zone, the Scotia plate subduction zone, and several volcanic hotspots (e.g., the Galapagos Islands), in a region ~10,000 km by 10,000 km wide, spanning 70° S to 20° N and 20° W to 110° W. Precursors to the seismic phase SS are analyzed, which form as a result of underside reflections off seismic discontinuities beneath the midpoint of the SS path and are highly sensitive to discontinuity depth and sharpness. Our SS dataset consists of over 15,000 high-quality transverse component broadband displacement seismograms collected from the Incorporated Research Institutions for Seismology (IRIS), the Canadian National Seismic Network (CNSN), as well as data from EarthScope seismic stations, and from the Canadian Northwest Experiment (CANOE) temporary broadband array deployment. This dataset densely samples several regions in our study area and significantly improves the sampling for this area compared to previous precursor studies. Data with common central SS bouncepoints are stacked to enhance precursory phases. Solution discontinuity structure depends on a number of factors, including dominant seismic period, crustal correction, signal-to-noise ratio threshold, and tomography model used for mantle heterogeneity correction. We exclude precursor data predicted to interfere with other seismic phases, such as topside reflections (e.g., s670sS), which have been demonstrated to contaminate final stacks. Solution transition zone thickness is at least 20 km thicker than global average estimates of 242 km along the northwestern portion of the South American subduction complex (Peru, Ecuador, and Columbia); this thickening extends 1000-1500 km to the east beneath the continent, but does not appear to continue south of -20° latitude along the convergent margin. A minimum of 10 km of thickening is imaged to the west of the Scotia

  8. Ridge Subduction Beneath the Americas: Synthesis and New Research on Anomalous Tectonism and Magmatism

    Science.gov (United States)

    Thorkelson, D. J.; Madsen, J. K.; Breitsprecher, K.; Groome, W. G.; Sluggett, C.

    2006-12-01

    The west coast of the Americas has been repeatedly affected by ridge-trench interactions from Mesozoic to Recent time. Beneath North America, subduction of the Kula-Farallon, Kula-Resurrection and Farallon- Resurrection spreading ridges resulted in anomalous and time-transgressive forearc to backarc magmatism and related tectonism from the Late Cretaceous to the Eocene. Following consumption and redistribution of the Kula and Resurrection plates, the Neogene Farallon-Pacific ridge system intersected the North American trench in two locations - western Canada and northwestern Mexico / southwestern United States - causing pronounced magmatic and tectonic effects that continue to the present. Beneath Central America, divergent subduction of the Nazca and Cocos plates led to development of a slab window, with a present location beneath Panama and a probable pre-Pliocene position beneath Columbia or Ecuador. Patagonia has been the site of localized ridge subduction from the Eocene to the Recent, with the Phoenix-Farallon ridge subducting from the Eocene to the early Miocene, and the Nazca-Antarctic ridge from the Miocene to the present. Antarctica experienced diverging Antarctic-Phoenix plate subduction from the Eocene to the Pliocene. In all cases, normal arc magmatism was interrupted or eliminated by anomalous igneous activity ranging in signature from adakitic to intraplate. Our current research involves geochemical, tectonic, and thermal modeling of slab window environments. A new geochemical analysis on the effects of Miocene to Recent subduction of the northern segment of the Farallon (Juan de Fuca)-Pacific ridge is underway. A symmetrical arc-intraplate-arc geochemical pattern is evident in a transect from the northern Cascade Arc, through the volcanic fields of British Columbia, Yukon and eastern Alaska, and into the Aleutian Arc. This pattern can be explained by Neogene displacement of the arc-metasomatized mantle wedge caused by upwelling oceanic

  9. Biomass energy in Central America

    International Nuclear Information System (INIS)

    The objective of this paper is to introduce the concept of biomass to energy issues and opportunities in Central America. In this region, made up of seven countries (Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama), the biomass sector has the potential to play a crucial role in alleviating the environmental and development predicaments faced by all economies of the region. This paper assesses the available biomass resources at the regional and country levels and gives an overview of the current utilization of biomass fuels. It also describes the overall context in which the biomass-to-energy initiatives are immersed. At the regional level, biomass energy consumption accounts for more than 50% of total energy consumption. In regard to the utilization of biomass for energy purposes, it is clear that Central America faces a critical juncture at two levels, both mainly in rural areas: in the productive sector and at the household level. The absence of sustainable development policies and practices has jeopardized the availability of biomass fuels, particularly wood. Firewood is an important source of energy for rural industries such as coffee processing, which is one of the largest productive activities in the region. This paper comments on some of the most successful technological innovations already in place in the region, for instance, the rapid development of co-generation projects by the sugar cane industry, especially in El Salvador and Guatemala, the substitution of coffee husks for firewood in coffee processing plants in Costa Rica and El Salvador and the sustainable use of pine forests for co-generation in Honduras. Only one out of every two inhabitants in Central America now has access to electricity from the public grid. Biomass fuels, mainly firewood but also, to a lesser extent, other crop residues such as corn stalks, are the main source of energy for cooking and heating by most of the population. (It is foreseen that by the end

  10. Tectonic implications of tomographic images of subducted lithosphere beneath northwestern South America

    NARCIS (Netherlands)

    Hilst, R.D. van der; Mann, P.

    1994-01-01

    We used seismic tomography to investigate the complex structure of the upper mantle below northwestern South America. Images of slab structure not delineated by previous seismicity studies help us to refine existing tectonic models of subducted Caribbean-Pacific lithosphere beneath the study area. B

  11. Central and South America GPS geodesy - CASA Uno

    Science.gov (United States)

    Kellogg, James N.; Dixon, Timothy H.

    1990-01-01

    In January 1988, scientists from over 25 organizations in 13 countries and territories cooperated in the largest GPS campaign in the world to date. A total of 43 GPS receivers collected approximately 590 station-days of data in American Samoa, Australia, Canada, Colombia, Costa Rica, Ecuador, New Zealand, Norway, Panama, Sweden, United States, West Germany, and Venezuela. The experiment was entitled CASA Uno. Scientific goals of the project include measurements of strain in the northern Andes, subduction rates for the Cocos and Nazca plates beneath Central and South America, and relative motion between the Caribbean plate and South America. A second set of measurements are planned in 1991 and should provide preliminary estimates of crustal deformation and plate motion rates in the region.

  12. A First for Central America

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    FTA gives impetus to China’s trade with Costa Rica and other countries in the region The free trade agreement (FTA) between China and Costa Rica, signed in April 2010,came into effect on August 1.It was the first free trade pact between China and a Central

  13. Post-War Central America

    Directory of Open Access Journals (Sweden)

    Dirk Kruijt

    2003-10-01

    Full Text Available – Terror in the Countryside. Campesino Responses to Political Violence in Guatemala, 1954-1985, by Rachel A. May. Athens, Ohio: Ohio University Center for International Studies/Research in International Studies/Latin America Series #35, 2001. – La guerrilla fue mi camino. Epitafio para César Montes, by Julio César Macías. Guatemala: Piedra Santa/Colección Afluentes de Modernidad, 1999. – Testigo de conciencia (Periodismo de Opinión Documentado, by Marco A. Mérida. Guatemala: ARCASAVI, 2000. – Centroamérica 2002. Un nuevo modelo de desarrollo regional, edited by Klaus Bodemer and Eduardo Gamarra. Caracas: Nueva Sociedad, 2002. – Who Governs? Guatemala Five years After the Peace Accords, by Rachel Sieder, Megan Thomas, George Vickers and Jack Spence. Cambridge, Mass.: Hemispheric Initiatives/Washington Office on Latin America (WOLA, January 2002. – Pasos hacia una nueva convivencia: Democracia y participación en Centroamérica, edited by Ricardo Córdova Macías, Günther Maihold and Sabina Kurtenbach. San Salvador: FUNDAUNGO, Instituto de Estudios Iberoamericanos de Hamburgo and Instituto Iberoamericano de Berlin, 2001. – Los desafíos de la democracia en Centroamérica, by René Poitevin and Alexander Sequén-Mónchez. Guatemala: FLACSO, 2002. – Más allá de las elecciones: Diez años después de los acuerdos de paz, edited by Hector Dada Hirezi. San Salvador: FLACSO, 2002. – Guatemala, un proyecto inconcluso: La multiculturalidad, un paso hacia la democracia, by Hugo Cayzac. Guatemala: FLACSO, 2001. – La violencia en el contexto del posconflicto, según la percepción de comunidades urbanas pobres de Guatemala, by Caroline Moser and Cathy McIlwaine. Washington/Bogotá: Banco Mundial-Región de Latinoamérica y el Caribe/Tercer Mundo Editores, 2001. – El lado oscuro de la eterna primavera. Violencia, criminalidad y delincuencia en la postguerra, by Manolo Vela, Alexander Sequén-Mónchez and Hugo Antonio Solares

  14. The Mediterranean fruit fly in Central America

    International Nuclear Information System (INIS)

    Various methods of controlling the medfly are available and include the use of insecticides, bait sprays and the sterile insect technique (SIT). Each of these control strategies may be used alone or in sequence. With regard to the application of the SIT, the Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture through its Insect and Pest Control Section and Entomology Laboratory is in an excellent position to assist in containing the medfly in Central America. For the past 12 years, the laboratory has participated in all phases of medfly control by sterile insect releases in various climates. This involvement has included planning of medfly campaigns, development of pre-release techniques (bait spraying, trapping, etc.) and shipment and release of sterilized medflies. Small-scale field tests utilizing the SIT have been carried out by nine countries: Italy (Procida, Capri), Spain, Cyprus, Israel, Tunisia, Peru, Panama, Costa Rica and Nicaragua. Other field projects presently being counselled and serviced are located in Argentina, Venezuela and the Canary Islands. The research and development that are still needed to effectively stabilize and gain control of the medfly situation in Central America include: The development and use of effective quarantine procedures in various countries; Development of effective conventional medfly control procedures under the conditions found in Central America; Development of methods to determine the geographic origin of medflies introduced into new areas; Medfly mass production (viz. all aspects of rearing Central American strains); Assessing the performance (competitiveness, etc.) of various strains; Logistics, including the development of systems for releasing pre-adult stages; Genetic rearing methods: developmental research in this area is particularly promising since the preferential production of males would allow considerable savings in the rearing costs of medflies for release; Development of adequate surveillance

  15. Exploration geothermal gradient drilling, Platanares, Honduras, Central America

    Energy Technology Data Exchange (ETDEWEB)

    Goff, S.J.; Laughlin, A.W.; Ruefenacht, H.D.; Goff, F.E.; Heiken, G.; Ramos, N.

    1988-01-01

    This paper is a review and summary of the core drilling operations component of the Honduras Geothermal Resource Development Project at the Platanares geothermal prospect in Honduras, Central America. Three intermediate depth (428 to 679 m) coreholes are the first continuously cored geothermal exploration boreholes in Honduras. These coring operations are part of the Central America Energy Resource Project (CAERP) effort funded by the Agency for International Development (AID) and implemented by the Los Alamos National Laboratory (Los Alamos) in cooperation with the Empresa Nacional de Energia Electrica (ENEE) and the United States Geological Survey (USGS). This report emphasizes coring operations with reference to the stratigraphy, thermal gradient, and flow test data of the boreholes. The primary objectives of this coring effort were (1) to obtain quantitative information on the temperature distribution as a function of depth, (2) to recover fluids associated with the geothermal reservoir, (3) to recover 75% or better core from the subsurface rock units, and (4) to drill into the subsurface rock as deeply as possible in order to get information on potential reservoir rocks, fracture density, permeabilities, and alteration histories of the rock units beneath the site. The three exploration coreholes drilled to depths of 650, 428 and 679 m, respectively, encountered several hot water entries. Coring operations and associated testing began in mid-October 1986 and were completed at the end of June 1987.

  16. Pandillas and Security in Central America

    OpenAIRE

    Thomas C. Bruneau

    2014-01-01

    This article introduces the topic of pandillas (street gangs) and their implications for security in Central America. There is minimal scholarly literature on pandillas and security. In part this is due to serious challenges in analyzing pandillas. First, pandilla members consider truth to be situational; data derived directly from them is suspect. Second, those who know most about them are involved in NGOs that rely on foreign assistance for their work. The project reports the...

  17. Fragile isthmus under pressure. Central America.

    Science.gov (United States)

    Ypsilantis, J

    1992-01-01

    In Costa Rica the 1300 hectares of rainforest that comprise La Selva Biological Station support more than 1.5 times the number of plant and animal species found in California. In Central America over 2/3 of all deforestation has occurred since 1950, and closed canopy forest has shrunk dramatically during the past 40 years. The population in Central America, plus Mexico, grew by around 28% during the period 1977-87. At the same time the surface of forests and woodlands decreased by 13%, to 26% of the total land area. Croplands grew by 4% during these 10 years, to 13% of the total land area, and pastures by 2% to 37%; and unproductive lands grew by 14% to 24% of total land area. 50% of land is seriously eroded or degraded in El Salvador and over 30% in Guatemala. Central America's population was 22 million in 1980, 29 million in 1990, and it is anticipated to reach 63 million by 2025. Central America's urban population reached 46% in the 1990s: over 13 million with continuing increases in the next few decades. The growing population's need for fuelwood and the demand for agricultural land pose the main threat to forests in the coming decades. Close to 90% of the energy used by households comes from fuelwood. In the Telire reserve in Costa Rica 366 Cabecars are not yet an environmental threat for the forest. The Peten area in Guatemala is inhabited by around 300,000 people whose destructive slash and burn practices pose a serious threat to the environment which is exacerbated by a high population growth rate of 5.5% a year. PMID:12317701

  18. Understanding seismic heterogeneities in the lower mantle beneath the Americas from seismic tomography and plate tectonic history

    NARCIS (Netherlands)

    Ren, Y.; Stutzmann, E.; Hilst, R.D. van der; Besse, J.

    2007-01-01

    We combine results from seismic tomography and plate motion history to investigate slabs of subducted lithosphere in the lower mantle beneath the Americas. Using broadband waveform cross correlation, we measured 37,000 differential P and S traveltimes, 2000 PcP-P and ScS-S times along a wide corrido

  19. Sources of Economic Fluctuations in Central America

    Directory of Open Access Journals (Sweden)

    Wilfredo Toledo

    2014-06-01

    Full Text Available Using panel data from Central America, this paper studies the determining factors of inflation and aggregate output fluctuations by estimating two Structural Vector Autoregressive (SVAR models. Price and output variables are included in one of the models, whereas M2 and the price of oil are additional variables in the other one. Findings of this study suggest that price is determined by the demand, while output seems to be influenced mainly by the supply shocks in that area. It was also evidenced that the price of oil does not have a significant impact on the general price level in that region.

  20. The thermal influence of the subducting slab beneath South America from 410 and 660 km discontinuity observations

    Science.gov (United States)

    Collier, J. D.; Helffrich, G. R.

    2001-11-01

    Regional seismic network data from deep South American earthquakes to western United States and western European seismic arrays is slant stacked to detect weak near-source interactions with upper mantle discontinuities. These observations are complemented by an analysis of earlier work by Sacks & Snoke (1977) who observed S to P conversions from deep events to stations in South America, and similar observations from 1994-95 events using the BANJO and SEDA networks. Observations of the depth of the 410km discontinuity are made beneath central South America in the vicinity of the aseismic region of the subducting Nazca Plate. These results image the 410km discontinuity over a lateral extent of up to 850km perpendicular to the slab and over a distance of 2700km along the length of the slab. Away from the subducting slab the discontinuity is mainly seen near its global average depth, whilst inside the slab there is evidence for its elevation by up to around 60km but with significant scatter in the data. These results are consistent with the presence of a continuous slab through the aseismic region with a thermal anomaly of 900°C at 350km depth. This value is in good agreement with simple thermal models though our data are too sparse to accurately constrain them. Sparse observations of the 660km discontinuity agree with tomographic models suggesting penetration of the lower mantle by the slab in the north but stagnation at the base of the transition zone in the south. The geographical distribution of the data, however, does not allow us to rule out the possibility of slab stagnation at the base of the transition zone in the north. These observations, together with the presence of deep earthquakes, require more complicated thermal models than previously used to explain them, possibly including changes in slab dip and age with depth.

  1. Legislation on renewable energy sources in Central America

    International Nuclear Information System (INIS)

    This paper presents the development of renewable energy in Central America and the cooperation given by the European Comission in the promotion of renewable energy sources. Also discuss the current situation in energy demand in Central America and possible solutions linked to legislation that promotes the inversion of the private sector. The legal framework in each country of Central America is presented and its impact in the increasing of generation of energy through tax reductions, trading and prices

  2. Results From NICLAKES Survey of Active Faulting Beneath Lake Nicaragua, Central American Volcanic Arc

    Science.gov (United States)

    Funk, J.; Mann, P.; McIntosh, K.; Wulf, S.; Dull, R.; Perez, P.; Strauch, W.

    2006-12-01

    In May of 2006 we used a chartered ferry boat to collect 520 km of seismic data, 886 km of 3.5 kHz subbottom profiler data, and 35 cores from Lake Nicaragua. The lake covers an area of 7700 km2 within the active Central American volcanic arc, forms the largest lake in Central America, ranks as the twentieth largest freshwater lake in the world, and has never been previously surveyed or cored in a systematic manner. Two large stratovolcanoes occupy the central part of the lake: Concepcion is presently active, Maderas was last active less than 2000 years ago. Four zones of active faulting and doming of the lake floor were mapped with seismic and 3.5 kHz subbottom profiling. Two of the zones consist of 3-5-km-wide, 20-30-km-long asymmetric rift structures that trend towards the inactive cone of Maderas Volcano in a radial manner. The northeastern rift forms a 20-27-m deep depression on the lake bottom that is controlled by a north-dipping normal fault. The southwestern rift forms a 25-35-m deep depression controlled by a northeast-dipping normal fault. Both depressions contain mound-like features inferred to be hydrothermal deposits. Two zones of active faulting are associated with the active Concepcion stratovolcano. A 600-m-wide and 6-km-long fault bounded horst block extends westward beneath the lake from a promontory on the west side of the volcano. Like the two radial rift features of Maderas, the horst points roughly towards the active caldera of Concepcion. A second north-south zone of active faulting, which also forms a high, extends off the north coast of Concepcion and corresponds to a localized zone of folding and faulting mapped by previous workers and inferred by them to have formed by gravitational spreading of the flank of the volcano. The close spatial relation of these faults to the two volcanic cones in the lake suggests that the mechanism for faulting is a result of either crustal movements related to magma intrusion or gravitational sliding and is

  3. Commercial Agriculture and Modern Transport in Central America.

    Science.gov (United States)

    Horst, Oscar H.

    1981-01-01

    Describes an exercise for use in college-level geography courses dealing with the tandem development of transport networks and commercial agriculture in Central America. Using six maps, the author shows the parallels between highway and railroad construction and commercial crops, (coffee, bananas, and cotton) in Central America between 1855-1975.…

  4. Upper Mantle Discontinuity Structure Beneath the Western Atlantic Ocean and Eastern North America from SS Precursors

    Science.gov (United States)

    Schmerr, N. C.; Beghein, C.; Kostic, D.; Baldridge, A. M.; West, J. D.; Nittler, L. R.; Bull, A. L.; Montesi, L.; Byrne, P. K.; Hummer, D. R.; Plescia, J. B.; Elkins-Tanton, L. T.; Lekic, V.; Schmidt, B. E.; Elkins, L. J.; Cooper, C. M.; ten Kate, I. L.; Van Hinsbergen, D. J. J.; Parai, R.; Glass, J. B.; Ni, J.; Fuji, N.; McCubbin, F. M.; Michalski, J. R.; Zhao, C.; Arevalo, R. D., Jr.; Koelemeijer, P.; Courtier, A. M.; Dalton, H.; Waszek, L.; Bahamonde, J.; Schmerr, B.; Gilpin, N.; Rosenshein, E.; Mach, K.; Ostrach, L. R.; Caracas, R.; Craddock, R. A.; Moore-Driskell, M. M.; Du Frane, W. L.; Kellogg, L. H.

    2015-12-01

    Seismic discontinuities within the mantle arise from a wide range of mechanisms, including changes in mineralogy, major element composition, melt content, volatile abundance, anisotropy, or a combination of the above. In particular, the depth and sharpness of upper mantle discontinuities at 410 and 660 km depth are attributed to solid-state phase changes sensitive to both mantle temperature and composition, where regions of thermal heterogeneity produce topography and chemical heterogeneity changes the impedance contrast across the discontinuity. Seismic mapping of this topography and sharpness thus provides constraint on the thermal and compositional state of the mantle. The EarthScope USArray is providing unprecedented access to a wide variety of new regions previously undersampled by the SS precursors. This includes the boundary between the oceanic plate in the western Atlantic Ocean and continental margin of eastern North America. Here we use a seismic array approach to image the depth, sharpness, and topography of the upper mantle discontinuities, as well as other possible upper mantle reflectors beneath this region. This array approach utilizes seismic waves that reflect off the underside of a mantle discontinuity and arrive several hundred seconds prior to the SS seismic phase as precursory energy. In this study, we collected high-quality broadband data SS precursors data from shallow focus (4th root vespagrams to enhance the SS precursors and determine how they sample the mantle. Our data show detection of localized structure on the discontinuity boundaries as well as additional horizons, such as the X-discontinuity and a potential reflection from a discontinuity near the depth of the lithosphere-asthenosphere boundary. These structures are related to the transition from predominantly old ocean lithosphere to underlying continental lithosphere, as while deeper reflectors are associated with the subduction of the ancient Farallon slab. A comparison of the

  5. Seismic swarms and fluid flow offshore Central America

    Science.gov (United States)

    Dzierma, Yvonne; Thorwart, Martin; Hensen, Christian; Rabbel, Wolfgang; Wolf, Florian

    2010-05-01

    Offshore Nicaragua and Northern Costa Rica, the Cocos Plate subducts beneath the Caribbean Plate, carrying with it a large amount of fluids and volatiles. While some of these are set free at great depth beneath the volcanic arc, causing the extremely high water content observed in Nicaraguan mafic magmas (Carr et al., 2003; Kutterolf et al., 2007), some early dehydration reactions already release fluids from the subducting plate underneath the continental slope. Unlike in accretionary margins, where these fluids migrate up along the decollement towards the deformation front, fluid release at erosional margins seems to occur through fractures in the overriding plate (Ranero et al., 2008). Fluid seeps in this region have be observed at seafloor mounds, appearing as side-scan sonar backscatter anomalies or revealed by the presence of chemosynthetic communities (Sahling et al., 2008). In the framework of the General Research Area SFB 574 "Volatiles and Fluids in Subduction Zones", a network of 20 ocean-bottom-stations was deployed offshore Sta Elena Peninsula, Northern Costa Rica, from December 2005 to June 2006. Several distinct swarms of small earthquakes were observed at the seismic stations, which occurred clustered over a time period of several days and have very similar seismic waveforms. Since a correlation of fluid-release sites with the occurrence of sporadic seismic swarms would indicate that fluid migration and fracturing is the mechanism responsible for triggering the earthquake swarms, the events are re-analysed by double-difference localisation to enhance the resolution of the earthquake locations. The results are then considered to estimate the migration velocity and direction and compare the localisations with the known mound sites. Carr, M., Feigenson, M. D., Patino, L. C., and Walker, J. A., 2003: Volcanism and geochemistry in Central America: Progress and problems, in Eiler, J. (ed.), Inside the subduction factory, pp. 153-179, American Geophysical

  6. A magma-hydrothermal system beneath Hakone volcano, central Japan, revealed by highly resolved velocity structures

    Science.gov (United States)

    Yukutake, Yohei; Honda, Ryou; Harada, Masatake; Arai, Ryuta; Matsubara, Makoto

    2015-05-01

    High-resolution images of subsurface structures are necessary to understand the transport processes of crustal fluids from deep magma sources and their relationship to earthquake swarms in active volcanic regions. Based on a seismic tomography approach, we have developed a new model for the magma-hydrothermal system beneath Hakone volcano, central Japan, where shallow earthquake swarms and crustal deformation associated with inflation of an open-crack source are often observed. By applying travel-time data for local earthquakes to a tomographic inversion, we obtained highly resolved seismic velocity structures that show a region of low P-wave velocity (Vp), low S-wave velocity (Vs), and high Vp/Vs ratios at depths of 10-20 km beneath the volcano, corresponding to the location of the open-crack source. We suggest that the high Vp/Vs ratios represent a deep magma chamber with a high concentration of melt and/or fluids. Deep low-frequency earthquakes, located just beneath this high Vp/Vs zone, may indicate that magmatic fluids are supplied from below. Above the high Vp/Vs zone, a region of low Vp, low Vs, and low Vp/Vs ratios exists at depths of 3-10 km, suggesting the presence of crack-filled water or CO2 supplied from the inferred deep magma chamber. Many earthquake swarms occur in this low Vp/Vs zone, indicating that crustal fluids play an important role in generating the swarms. Similar relationships between magma reservoirs, overlying hydrothermal systems, and swarm activity have been reported from other volcanic areas and thus may be a ubiquitous feature beneath active volcanoes.

  7. A sharp lithosphere-asthenosphere boundary imaged beneath eastern North America.

    Science.gov (United States)

    Rychert, Catherine A; Fischer, Karen M; Rondenay, Stéphane

    2005-07-28

    Plate tectonic theory hinges on the concept of a relatively rigid lithosphere moving over a weaker asthenosphere, yet the nature of the lithosphere-asthenosphere boundary remains poorly understood. The gradient in seismic velocity that occurs at this boundary is central to constraining the physical and chemical properties that create differences in mechanical strength between the two layers. For example, if the lithosphere is simply a thermal boundary layer that is more rigid owing to colder temperatures, mantle flow models indicate that the velocity gradient at its base would occur over tens of kilometres. In contrast, if the asthenosphere is weak owing to volatile enrichment or the presence of partial melt, the lithosphere-asthenosphere boundary could occur over a much smaller depth range. Here we use converted seismic phases in eastern North America to image a very sharp seismic velocity gradient at the base of the lithosphere-a 3-11 per cent drop in shear-wave velocity over a depth range of 11 km or less at 90-110 km depth. Such a strong, sharp boundary cannot be reconciled with a purely thermal gradient, but could be explained by an asthenosphere that contains a few per cent partial melt or that is enriched in volatiles relative to the lithosphere.

  8. Imaging Rayleigh Wave Attenuation and Phase Velocity beneath North America with USArray

    Science.gov (United States)

    Bao, X.; Dalton, C. A.; Jin, G.; Gaherty, J. B.

    2014-12-01

    The EarthScope USArray provides an opportunity to obtain detailed images of the continental upper mantle of United States at a novel scale. The majority of mantle models derived from USArray data contain spatial variations in velocity; however, little is known about the attenuation structure of the North American upper mantle. Joint interpretation of seismic attenuation and velocity models can improve upon the interpretations based only on velocity, and provide important constraints on the temperature, composition, melt content, and volatile content of the mantle. In this study, Rayleigh wave travel time and amplitude are measured using an interstation cross-correlation version of the Generalized Seismological Data Functional algorithm, which takes advantage of waveform similarity at nearby stations. Our data are from 670 large teleseismic earthquakes that occurred from 2006 to 2014 and were recorded by 1,764 Transportable Array stations. More than 4.8 million measurements at periods between 20 and 100 s are collected into our database. Isolating the signal of attenuation in the amplitude observations is challenging because amplitudes are sensitive to a number of factors in addition to attenuation, such as focusing/defocusing and local site amplification. We generate several Rayleigh wave attenuation maps at each period, using several different approaches to account for source and receiver effects on amplitude. This suite of attenuation maps allows us to distinguish between the robust features in the maps and the features that are sensitive to the treatment of source and receiver effects. We apply Helmholtz surface-wave tomography (Lin et al., 2012) to determine velocity and attenuation maps. A significant contrast in velocity and attenuation is observed in the transition between the western and central United States along the Rocky Mountain front. We find low Q values in the western US, along the eastern coast, and the Gulf plain. These areas are also

  9. Private Higher Education in a Cold War World: Central America

    Science.gov (United States)

    Harrington, James J.

    2009-01-01

    In Central America the Cold War support of the elites by the United States was designed to ward off the communist threat. At the same time social and economic demands by the working and middle classes created revolutionary movements in the face of rigid and violent responses by Central American governments. Issues of social justice pervaded the…

  10. Collaborative studies target volcanic hazards in Central America

    Science.gov (United States)

    Bluth, Gregg J. S.; Rose, William I.

    Central America is the second-most consistently active volcanic zone on Earth, after Indonesia. Centuries of volcanic activity have produced a spectacular landscape of collapsed calderas, debris flows, and thick blankets of pyroclastic materials. Volcanic activity dominates the history, culture, and daily life of Central American countries.January 2002 marked the third consecutive year in which a diverse group of volcanologists and geophysicists conducted focused field studies in Central America. This type of multi-institutional collaboration reflects the growing involvement of a number of U.S. and non-U.S. universities, and of other organizations, in Guatemala and El Salvador (Table 1).

  11. Intestinal Parasites in Immigrant Children From Central America

    OpenAIRE

    Sarfaty, Mona; Rosenberg, Zeil; Siegel, Jay; Levin, Robert M.

    1983-01-01

    To begin to characterize the health needs of the growing number of refugees from Central America, we compiled the results of examinations for ova and parasites of a single stool specimen of each of 128 children of Central American and Mexican background who entered our health center during a four-month period. Among the 96 children who were born in Central America or Mexico, there was a 65% prevalence of parasitic infestation. Pathogens were found in 46% and multiple pathogens in 14%. Among t...

  12. 9 CFR 93.320 - Horses from Central America and the West Indies.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Horses from Central America and the... PRODUCTS; REQUIREMENTS FOR MEANS OF CONVEYANCE AND SHIPPING CONTAINERS Horses Central America and the West Indies 17 § 93.320 Horses from Central America and the West Indies. Horses from Central America and...

  13. Pathways to marriage and cohabitation in Central America

    OpenAIRE

    Kathryn Grace; Stuart Sweeney

    2014-01-01

    Background: The notion that increasing prevalence of cohabitation relative to marriage, and increasing age at first marriage are part of a broader shift in societal norms -- a second demographic transition -- is now well supported by studies focused on US and European populations. Recent research points to the similarly high prevalence of cohabitation in Latin America as perhaps signaling the diffusion of modern ideals and norms about union formation. In Central America this is unlikely to be...

  14. (Human Security in Central America: A Return to the Past?

    Directory of Open Access Journals (Sweden)

    Jordi Urgell García

    2007-02-01

    Full Text Available After having become one of the principal scenarios of the Cold War, the pacification and democratisation of Central America in the 1990s were forged under the protection of the Esquipulas Process and the birth of the concept of human security. The resulting model of security was founded on the Framework Treaty on Democratic Security, which incorporated some of the basic postulates of human security and became one of its first institutional implementations. Nevertheless, the performance of this model has been eclipsed and questioned by the evolution of events in Central America (such as the impact of 9-11 on security agendas or the emergence of new forms of violence in the region, which open the door to a new security instrument (the Rapid Reaction Force, generate fears about an eventual regression of Central America in the area of security and raise doubts about the habitual assumptions of human security.

  15. Caupolicana in Central America (Hymenoptera, Colletidae, Diphaglossinae

    Directory of Open Access Journals (Sweden)

    Charles Michener

    2009-02-01

    Full Text Available Caupolicana (Zikanapis wileyi n. sp. from Guatemala is described. New locality records are noted for other species, and the hitherto unknown female of C. (Z. rozenorum Michener, Engel, and Ayala from Guatemala is described. A key for the identification of Central American Caupolicana is provided.

  16. Mapping the subducted Nazca plate in the lower mantle beneath South America

    Science.gov (United States)

    Contenti, S. M.; Gu, Y. J.; Okeler, A.

    2009-12-01

    Recent improvements in data coverage have enabled high-resolution imaging of the morphology of subduction zones and mantle plumes. In this study, we migrate the SS precursors from over 5000 seismograms to obtain a detailed map of mid- and upper-mantle reflectors beneath the northern portion of the South American subduction zone, where the oceanic Nazca plate is descending below the South American plate. In addition to an elevated 410 and depressed 660 (as expected for a subduction zone), strong mid-mantle reflectors at 800-1100 km depth are also apparent. The amplitudes of these steeply dipping reflectors are comparable to that of the 660-kilometer discontinuity. This anomaly outlines a high-velocity (therefore presumably cold) region present in recent finite-frequency based mantle velocity models, suggesting the extension of slab material into the lower mantle. The strength of the reflection is interpreted to be caused by a relatively sharp velocity change, likely due to a strong temperature gradient in combination with mineral phase transitions, the presence of water, or other chemical heterogeneities. Significant mass and heat exchange is therefore expected between the upper- and lower-mantle beneath the study region.

  17. National Geothermal Association Trade Mission to Central America

    International Nuclear Information System (INIS)

    The United States (US) geothermal industry, the world's most technically proficient, has been unable to achieve penetration into the markets of the developing nations. This report details the findings of an industry Trade Mission to Central America, tasked with determining the reasons for this shortfall and with developing a US industry geothermal export strategy designed to achieve immediate and long-term export benefits

  18. Contextualizing the trauma experience of women immigrants from Central America, South America, and Mexico.

    Science.gov (United States)

    Kaltman, Stacey; Hurtado de Mendoza, Alejandra; Gonzales, Felisa A; Serrano, Adriana; Guarnaccia, Peter J

    2011-12-01

    Trauma has been understudied among Latina immigrants from Central and South America. This study examined the types and context of trauma exposure experienced by immigrant women from Central America, South America, and Mexico living in the United States. Twenty-eight women seeking care in primary care or social service settings completed life history interviews. The majority of the women reported some type of trauma exposure in their countries of origin, during immigration, and/or in the United States. In the interviews, we identified types of trauma important to the experience of these immigrants that are not queried by trauma assessments typically used in the United States. We also identified factors that are likely to amplify the impact of trauma exposure. The study highlights the importance of utilizing a contextualized approach when assessing trauma exposure among immigrant women.

  19. Tomographic imaging of the Nazca slab and surrounding mantle in the mantle transition zone beneath the Central Andes

    Science.gov (United States)

    Scire, A. C.; Biryol, C. B.; Zandt, G.; Beck, S. L.; Wagner, L. S.; Long, M. D.; Minaya, E.; Tavera, H.

    2013-12-01

    The central Andes in South America is an ideal location to investigate the interaction between a subducting slab and the surrounding mantle to the base of the mantle transition zone (MTZ). We used finite-frequency teleseismic P-wave tomography to image velocity anomalies in the mantle from 100 - 700 km between 10° and 28°S in the central Andes by combining data from twelve separate networks deployed in the region between 1994 and 2013. P- and PKIKP- (diffracted PKP) arrivals were picked in multiple frequency bands for earthquakes at distances between 30° and 90° and between 155° to 180° from the array, respectively. The tomographic algorithm used calculates approximate finite frequency kernels for each ray, providing additional sampling for each model layer to potentially increase the resolution of our images. The trench-parallel, fast anomaly which appears to correspond with the subducting Nazca slab is the most prominent anomaly in our tomograms. Variations in the width of the slab anomaly in the deeper parts of the model show evidence for deformation of the slab between 300 and 660 km. Our results show localized thickening of the Nazca slab in the MTZ north of 14°S, between 16° and 18°S, and south of 25°S, in agreement with the idea that the Nazca slab stagnates at least temporarily in the transition zone before resuming subduction into the lower mantle. Our images of the deeply subducted Nazca slab also show evidence of varying degrees of thinning in the mantle transition zone, particularly at 20° and 24°S, possibly indicating that the stress state changes along strike as the slab deforms in the MTZ before resuming subduction into the lower mantle. We also image along-strike variations in the sub-slab mantle in the MTZ including a strong low velocity anomaly between 22° and 28°S which is similar to those seen in other subduction zones, and is interpreted as either a local thermal anomaly or a region of hydrated material in the MTZ. A similar

  20. Remittances in Central America: Whose Money is it Anyway?

    Directory of Open Access Journals (Sweden)

    Jose Luis Rocha

    2015-08-01

    Full Text Available In opposition to optimistic visions that present remittances as an opportunity for developing countries, this paper shows they are part and parcel of a process of economic imperialism, whereby their use and final destinations are strictly conditioned. In order to go beyond a conception of remittances as epiphenomenon, and in order to trace the role they play, this paper focuses on the transnational strategies of capital. It finds that remittances enable an increase in foreign investment and import production by facilitating the rise of a new class of consumers in Central America. Remittances create and feed a purchasing power that would not exist in their absence. Factories, fast food restaurants, communications companies, banks, travel agencies, and supermarkets are opening new branches throughout Central America in order to benefit from transnational savings that would otherwise be used differently. In this way, remittances are conditioned and co-opted by transnational capital’s strategies to sustain an ever growing market, with Central America more generally – and once again – potentially at risk of becoming characterized by enclave economies and chronic commercial deficits. The remittance-based economic model furthermore cannot be sustainable in the long run unless Central American countries keep exporting workers ad infinitum, something that is obviously not possible.

  1. Seismic imaging of the upper mantle beneath the northern Central Andean Plateau: Implications for surface topography

    Science.gov (United States)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Wagner, L. S.

    2015-12-01

    Extending over 1,800 km along the active South American Cordilleran margin, the Central Andean Plateau (CAP) as defined by the 3 km elevation contour is second only to the Tibetan Plateau in geographic extent. The uplift history of the 4 km high Plateau remains uncertain with paleoelevation studies along the CAP suggesting a complex, non-uniform uplift history. As part of the Central Andean Uplift and the Geodynamics of High Topography (CAUGHT) project, we use surface waves measured from ambient noise and two-plane wave tomography to image the S-wave velocity structure of the crust and upper mantle to investigate the upper mantle component of plateau uplift. We observe three main features in our S-wave velocity model including (1), a high velocity slab (2), a low velocity anomaly above the slab where the slab changes dip from near horizontal to a normal dip, and (3), a high-velocity feature in the mantle above the slab that extends along the length of the Altiplano from the base of the Moho to a depth of ~120 km with the highest velocities observed under Lake Titicaca. A strong spatial correlation exists between the lateral extent of this high-velocity feature beneath the Altiplano and the lower elevations of the Altiplano basin suggesting a potential relationship. Non-uniqueness in our seismic models preclude uniquely constraining this feature as an uppermost mantle feature bellow the Moho or as a connected eastward dipping feature extending up to 300 km in the mantle as seen in deeper mantle tomography studies. Determining if the high velocity feature represents a small lithospheric root or a delaminating lithospheric root extending ~300 km into the mantle requires more integration of observations, but either interpretation shows a strong geodynamic connection with the uppermost mantle and the current topography of the northern CAP.

  2. Skylab photography applied to geologic mapping in northwestern Central America

    Science.gov (United States)

    Rose, W. I., Jr.; Johnson, D. J.; Hahn, G. A.; Johns, G. W.

    1975-01-01

    Two photolineation maps of southwestern Guatemala and Chiapas were made from S190 photographs along a ground track from Acajutla, El Salvador to San Cristobal de las Casas, Mexico. The maps document a structural complexity spanning the presumed triple junction of the Cocos, Americas, and Caribbean plates. The Polochic fault zone, supposedly the Americas-Caribbean plate boundary, is a sharply delineated feature across western Guatemala. Westward of the Mexican border it splays into a large number of faults with NW to SW trends. The structural pattern is quite different to the north (Americas plate) and to the south (Caribbean plate) of the Polochic fault, though both areas are dominated by NW-trending lineations. Within the Central American volcanic chain, the lineation patterns support the segmented model of the Benioff Zone, by showing a concentration of transverse lineations in the predicted locations, most notably NE-trending elements near Quezaltenango, Guatemala. The structural pattern obtained from the maps are compared to patterns described on recently published maps of more southerly parts of Central America, to begin a synthesis of the structure of the convergent plate boundary.

  3. Results from NICLAKES Survey of Active Faulting Beneath Lake Managua,Central American Volcanic arc

    Science.gov (United States)

    McIntosh, K.; Funk, J.; Mann, P.; Perez, P.; Strauch, W.

    2006-12-01

    Lake Managua covers an area of 1,035 km2 of the Central American volcanic arc and is enclosed by three major stratovolcanoes: Momotombo to the northwest was last active in AD 1905, Apoyeque in the center on the Chiltepe Peninsula was last active ca. 4600 years BP, and Masaya to the southeast was last active in AD 2003. A much smaller volcano in the lake (Momotombito) is thought to have been active <4500 yrs B.P. In May of 2006, we used a chartered barge to collect 330 km of 3.5 kHz profiler data along with coincident 274 km of sidescan sonar and 27 km of seismic reflection data. These data identify three zones of faulting on the lake floor: 1) A zone of north-northeast-striking faults in the shallow (2.5-7.5 m deep) eastern part of the lake that extends from the capital city of Managua, which was severely damaged by shallow, left-lateral strike-slip displacements on two of these faults in 1931 (M 5.6) and 1972 (M 6.2): these faults exhibit a horst and graben character and include possible offsets on drowned river valleys 2) a semicircular rift zone that is 1 km wide and can be traced over a distance of 30 km in the central part of the lake; the rift structure defines the deepest parts of the lake ranging from 12 to 18 m deep and is concentric about the Apoyeque stratocone/Chiltepe Peninsula; and 3) a zone of fault scarps defining the northwestern lake shore that may correlate to the northwestern extension of the Mateare fault zone, a major scarp-forming fault that separates the Managua lowlands from the highlands south and west of the city. Following previous workers, we interpret the northeast- trending group of faults in the eastern part of the lake as part of a 15-km-long discontinuity where the trend of the volcanic arc is offset in a right-lateral sense. The semi-circular pattern of the rift zone that is centered on Chiltepe Peninsula appears to have formed as a distal effect of either magma intrusion or withdrawal from beneath this volcanic complex. The

  4. (Human) Security in Central America: A Return to the Past?

    OpenAIRE

    Jordi Urgell García

    2007-01-01

    After having become one of the principal scenarios of the Cold War, the pacification and democratisation of Central America in the 1990s were forged under the protection of the Esquipulas Process and the birth of the concept of human security. The resulting model of security was founded on the Framework Treaty on Democratic Security, which incorporated some of the basic postulates of human security and became one of its first institutional implementations. Nevertheless, the performance of thi...

  5. National Geothermal Association Trade Mission to Central America

    Energy Technology Data Exchange (ETDEWEB)

    1992-10-01

    The United States (US) geothermal industry, the world`s most technically proficient, has been unable to achieve penetration into the markets of the developing nations. This report details the findings of an industry Trade Mission to Central America, tasked with determining the reasons for this shortfall and with developing a US industry geothermal export strategy designed to achieve immediate and long-term export benefits.

  6. National Geothermal Association Trade Mission to Central America

    Energy Technology Data Exchange (ETDEWEB)

    1992-10-01

    The United States (US) geothermal industry, the world's most technically proficient, has been unable to achieve penetration into the markets of the developing nations. This report details the findings of an industry Trade Mission to Central America, tasked with determining the reasons for this shortfall and with developing a US industry geothermal export strategy designed to achieve immediate and long-term export benefits.

  7. Sustainability of water, sanitation and hygiene interventions in Central America

    OpenAIRE

    Sabogal, Raquel I.; Medlin, Elizabeth; Aquino, Gonzalo; Gelting, Richard J.

    2014-01-01

    The American Red Cross and U.S. Centers for Disease Control and Prevention collaborated on a sustainability evaluation of post-hurricane water, sanitation and hygiene (WASH) interventions in Central America. In 2006 and 2009, we revisited six study areas in rural El Salvador, Guatemala, Honduras and Nicaragua to assess sustainability of WASH interventions finalized in 2002, after 1998’s Hurricane Mitch. We used surveys to collect data, calculate indicators and identify factors that influence ...

  8. Narco-scapes: Cocaine Trafficking and Deforestation in Central America

    Science.gov (United States)

    Wrathall, D.; McSweeney, K.; Nielsen, E.; Pearson, Z.

    2015-12-01

    Narcotics trafficking and drug interdiction efforts have resulted in a well-documented social crisis in Central America, but more recently, has been tightly linked to environmental catastrophe and accelerated deforestation in transit zones. This talk will outline synthesis findings from multi-country, interdisciplinary research on cocaine trafficking as an engine of forest loss in Central America. During the "narco-boom" of the mid-2000s, we observed a geographical evolution of cocaine flows into Central America, and the transit of cocaine through new spaces, accompanied by specific patterns of social and environmental change in new nodes of transit. We coarsely estimated that the total amount of cocaine flowing through Central America increased from 70 metric tons in 2000 to 350 mt in 2012, implying that total cocaine trafficking revenue in the region increased from roughly 600 million dollars to 3.5 billion in that time. We describe the mechanism by which these locally captured cocaine rents resulted in a rapid conversion of forest into cattle pasture. Narco-traffickers are drawn to invest in the cattle economy, as a direct means of laundering and formalizing proceeds. Ranching is a land intensive activity, and new narco-enriched cattle pastures can be isolated from other forms forest loss solely by their spatial and temporal change characteristics. A preliminary forest change study in Honduras, for example, indicated that areas of accelerated deforestation were in close proximity to known narcotics trafficking routes and were thirteen times more extensive on average than other forest clearings. Deforested areas commonly appeared in isolated and biodiverse lowland tropical rainforest regions that often intersected with protected areas and indigenous reserves. We find that narco-deforestation is a readily identifiable signal of the extent and health of the cocaine economy. This talk will feature summaries of both ethnographic and land cover change we have observed

  9. Are the Maras Overwhelming Governments in Central America?

    OpenAIRE

    Boraz, Steven C.; Thomas C. BRUNEAU

    2006-01-01

    Military Review, November - December 2006 Violence in Central America has grown so much in the last half decade that Colombia is no longer the homicide capital of the region. In fact, it now ranks fourth in that ignominious distinction behind El Salvador, Honduras, and Guatemala.1 The violence is mostly due to the phenomenon of street gangs, also called pandillas or gangas, but most often maras. They have grown in number, sophistication, and stature and have largely...

  10. Geoenvironmental problems and cross-border cooperation in Central America

    Institute of Scientific and Technical Information of China (English)

    Marek Graniczny; Jonas Satkunas; Jurga Lazauskiene; Jiri Sebesta

    2006-01-01

    @@ The International Workshop on "Geoenvironmental problems and cross-border cooperation in Central America" was organized in Managua, Nicaragua, 5-8 December, 2005 by the Working Group International Borders-Geoenvironmental Concerns (IBC), under the IUGS Commission on Geosciences for Environmental Management (GEM) and in the framework of the IUGS funded project "Application of geosciences for sustainable development of cross-border areas(GEOCrossBorder)".

  11. Investigation of lithospheric deformation and mantle anisotropy beneath Central Anatolia from Shear Wave Splitting Analysis

    Science.gov (United States)

    Teoman, U.; Polat, G.; Sandvol, E. A.; Turkelli, N.; Kahraman, M.; Özacar, A.; Beck, S. L.; Delph, J. R.

    2015-12-01

    With the primary objective of investigating the upper mantle anisotropy beneath central Anatolia-Turkey, we have performed shear wave splitting analysis and calculated the fast polarization directions and time-delays benefiting from teleseismic earthquakes recorded by a dense temporary seismic network consisting of 65 broadband sensors that were deployed in early May 2013 and operated for two years as a part of CD-CAT project (Continental Dynamics Central Anatolian Tectonics, funded by NSF with instruments supplied by PASSCAL depository). To further enhance the station coverage in the region, we also included data from 45 permanent broadband stations of Kandilli Observatory and Earthquake Research Institute (KOERI). During the analysis, we have used the SplitLab software to determine splitting parameters of the records from only SKS and SKKS phases. Our initial results were derived from teleseismic earthquakes (with magnitudes greater than 5.8) that occurred within the time period from May-2013 to 2014. The average fast polarization directions obtained from stations located in the vicinity of the East Anatolia Fault Zone are well aligned with the fault trend indicating NE-SW orientations. Furthermore, we did not observe significant variations in the polarization directions and the delay times along the fault zone. Stations deployed in the vicinity of Central Anatolian fault zone exhibit N-S fast directions in good agreement with the fault trend. The average delay time for the whole study area is slightly higher than 1 second. Rapid spatial variations in splitting parameters are observed only in Adana region and the surrounding area. This probably suggests that the contribution of crustal anisotropy to mantle anisotropy is quite high. This observation is also consistent with the known tectonic structure of this region, which is presumably related to fabrics within deep crustal rocks preserving a record of deformation. This point should also need to be supported with

  12. Tectonics and sedimentary evolution of the Sandino forearc basin off Nicaragua, Central America

    Science.gov (United States)

    Costa Pisani, P.; Silver, E.; McIntosh, K.; Ahmed, I.; Ranero, C. R.; Taylor, B.

    2003-04-01

    The Sandino basin is the Nicaragua sector of the Central American forearc, where the Cocos plate subducts beneath the Middle America trench. Recently, Ranero et al. have interpreted a seismic section across the margin and proposed a history of formation of the forearc which is constrained by industry drilling in the basin. They suggested a late Cretaceous to Paleocene accretion event, followed by later subduction erosion processes. The margin wedge consists of the ophiolitic Nicoya complex. The seismic units, unconformities and tectonic features record a rich history of both local and regional vertical movements occurring since the Middle Eocene, which are linked to the evolution of the Pacific convergent margin. During June, 2000, 2800 kms of multichannel seismic reflection data were collected on the R/V Ewing off Nicaragua. Analysis of the 240 channels dataset indicates rapid changes along strike in the Sandino basin. The basin is relatively thin in the southern part, thinning quite rapidly southward against the Nicoya complex of the Santa Elena peninsula of Costa Rica. The forearc sediments thickness approaches and locally exceeds 10 kms in the central and northern parts of the Sandino basin. The oldest units (Upper Cretaceous-Middle Eocene) are very thick off northern Nicaragua, with relatively thin middle to late Cenozoic deposits. However, off central Nicaragua the latter units (Middle-Upper Miocene) attain great thicknesses and the older units appear to thin. This pattern suggests a history of successive deepening of the basin from north to south, after the convergent system evolved from accretion to subduction erosion processes. Present efforts are devoted to quantifying this change in development and using it to understand the dynamics of forearc basin evolution offshore of Central America.

  13. Are there trends towards drier hydrological conditions in Central America?

    Science.gov (United States)

    Hidalgo, H. G.

    2013-12-01

    A summary of hydrological projections at the end of the century from 30 General Circulation Models (GCMs) is presented; and several hydrometeorological parameters are analyzed to validate if there are hydroclimatological trends during the observational period (1982-2005) consistent with the GCMs results. At the end of the century the median of 30 GCM simulations projects a drier future for Tegucigalpa and San Jose, with a marked increment in evapotranspiration in the first half of the rainy season along with reductions of soil moisture. With respect to the observations (1982-2005): 1) the Normalized Difference Vegetation Index showed negative trends in the North Pacific coast of Costa Rica, the border of Honduras and Nicaragua, and especially in southern Mexico (except the Yucatan Peninsula). Positive trends were found in the several parts of Central America, 2) the Palmer Drought Severity Index showed strong and consistent trends from Nicaragua to the North of Central America and southern Mexico (not including Yucatan), consistent with the direction of GCM projections; 3) negative precipitation trends in satellite data were found in Nicaragua, with strong trends in its Caribbean coast; 4) NCEP/NCAR Reanalysis precipitation showed strong negative trends in northern Central America, the Central Valley, the Dry Pacific of Costa Rica and the South-Pacific coast of Nicaragua, all consistent with the direction of GCM projections; and 5) station data showed no significant trends however, and 6) Reanalysis' temperature showed positive trends in southern Mexico (not including Yucatan) and negative trends in El Salvador. It can be concluded that several trends in drought indexes and precipitation are consistent with the future projected by the GCMs; that is, with some exceptions some of the trends were validated towards a drier future for the region, especially in the northern part.

  14. Pathways to marriage and cohabitation in Central America

    Directory of Open Access Journals (Sweden)

    Kathryn Grace

    2014-01-01

    Full Text Available Background: The notion that increasing prevalence of cohabitation relative to marriage, and increasing age at first marriage are part of a broader shift in societal norms -- a second demographic transition -- is now well supported by studies focused on US and European populations. Recent research points to the similarly high prevalence of cohabitation in Latin America as perhaps signaling the diffusion of modern ideals and norms about union formation. In Central America this is unlikely to be the case given the long history and enduring acceptance of cohabitation that is unrelated to modern ideals. While there are studies that have documented this history and current prevalence, there is no research examining the intersecting life course pathways from adolescence through early adulthood that lead to marriage or cohabitation. This is not surprising given that available data for Central American countries are not ideally suited to studying the process. Methods: We use retrospective questions from large, nationally representative Central American surveys (Guatemala, Honduras, and Nicaragua to establish the timing of marriage or cohabitation and events that are closely tied to union formation. We utilize additive causespecific hazard models, and predicted transition probabilities based on selected covariate pathways, to study the competing risks of exiting from the status of never in union. Results: Our results identify sexual activity and pregnancy as the primary drivers of union formation and indicate that education serves as a protective factor against union formation. We also find distinct differences among countries and a strong indication that cohabitations are less stable unions.

  15. Geothermal corehole drilling and operations, Platanares, Honduras, Central America

    Energy Technology Data Exchange (ETDEWEB)

    Goff, S.; Rufenacht, H.D.; Laughlin, A.W.; Adams, A.; Planner, H.; Ramos, N.

    1987-01-01

    Two slim exploration coreholes to depths of 650 m and 428 m, respectively, have been completed at the Platanares geothermal site, Honduras, Central America. A third corehole is now being drilled. These boreholes have provided information on the stratigraphy, temperature variation with depth, nature and compositions of fluids, fracturing, permeability, and hydrothermal alterations associated with the geothermal reservoir. Eruptions of hot water occurred during the drilling of both the first and third boreholes. Recovery of >98% core has been obtained even under difficult superheated conditions.

  16. Violence, Rule of Law, and Punitive Policies in Central America

    Directory of Open Access Journals (Sweden)

    Verónica De la Torre

    2011-01-01

    Full Text Available This article suggests that high levels of violence and crime in the so called North Triangle of Central America (Guatemala, El Salvador and Honduras, together with the incapacity of the state of enforcing the rule of law, are causing growing anxiety among the population and are attracting the support of the community to implement authoritarian measures to fight crime. The response of the governments of the region in the face of the rise of crime and public demand for security has been the policies of "iron fist", and the use of "populist punitiveness" as a strategy to gain the backing of an electorate deeply concerned by insecurity.

  17. Are civil wars to blame for crime in Central America?

    OpenAIRE

    Ana Sofia Cardenal Izquierdo

    2008-01-01

    The countries of Central America are high up on the list of nations with the highest crime rates in the world. According to the literature, the most common argument is that these high crimerates are a legacy of the armed conflicts of the 1980s. This article subjects this theory to an empirical examination. Even though the analysis is preliminary and limited, the results serve to question theexistence of such a link between war and crime. The data show that the areas most affected by war in E...

  18. Environmental impacts during geothermal development: Some examples from Central America

    International Nuclear Information System (INIS)

    The impacts of geothermal development projects are usually positive. However, without appropriate monitoring plans and mitigation actions firmly incorporated into the project planning process, there exists the potential for significant negative environmental impacts. The authors present five examples from Central America of environmental impacts associated with geothermal development activities. These brief case studies describe landslide hazards, waste brine disposal, hydrothermal explosions, and air quality issues. Improved Environmental Impact Assessments are needed to assist the developing nations of the region to judiciously address the environmental consequences associated with geothermal development

  19. S-Wave Velocity Structure beneath Southwest North America from Seismogram Comparisons of the Mexico Earthquake on 22 June 1997

    Directory of Open Access Journals (Sweden)

    Bagus Jaya Santosa

    2008-09-01

    Full Text Available This research investigates earth structure beneath the Southwest North America landmass, especially between Mexico and California. Models based on S wave velocities for this area were obtained by carrying out seismogram fitting in time domain and three Cartesian components simultaneously. The data used is from an event, coded as C052297B that occurred in the state of Guerrero, Mexico and it was fitted to synthetic data computed with the GEMINI program at TS network stations. Earth model IASPEI91 and SPREM were used as input to create the synthetic data. Real and synthetic seismograms were subjected to a low-pass filter with a frequency corner of 20 mHz.Waveform analysis results show very unsystematic and strong deviations in the waveform, arrival times, amount of oscillation and the height of the wave amplitude. Discrepancies are met on S, Love, Rayleigh and ScS waves, where the stations epicentral distances are below 300. Deviation in analysis waveform because of the usage of model 1-D of SPREM and IASPEI91, because the 1-D was a kind of average value an elastic property at one particular depth of global earth. With the method of waveform analysis we can see how sensitive waveform is to structures within the layers of the Earth.To explain the discrepancies, a correction to the earth structure is essential. The corrections account for the thickness of the crust, speed gradient of bh, the coefficient for the bh and bv in the upper mantle for surface wave fitting, a small variation of the S speed structure at a layer under the upper mantle above 771 km for S wave fitting, and a small variation at the base the mantle layers for ScS wave fitting. At some stations, a correction for S speed structure have yielded P wave fitting. Results of this research indicate that the 1-D earth model obtained through seismogram fitting at every hypocenter-observation station pair is unique. The S-wave velocity on the upper mantle has strong negative anomalies. This

  20. Evolution of the Earthquake Catalog in Central America

    Science.gov (United States)

    Rojas, W.; Camacho, E. I.; Marroquín, G.; Molina, E.; Talavera, E.; Benito, M. B.; Lindholm, C.

    2013-05-01

    Central America (CA) is known as a seismically active region in which several historic destructive earthquakes have occurred. This fact has promoved the development of seismic hazard studies that provide necessary estimates for decision making and risk assessment efforts, requiring a complete and standardized seismic catalog. With this aim, several authors have contributed to the study of the historical seismicity of Central America (e.g. Grases, Feldaman; White y Harlow, 1993; White et al. 2004; Ambraseys y Adams, 2001; Peraldo y Montero, 1999), who complied historical data. A first catalogue was developed by Rojas (1993) that comprises the 1522 to 1993 period. This information was integrated in 2007, together with data from the International Seismological Centre (CASC) and the national catalogs of CA countries in a new regional catalogue. Since 2007 a continuous effort has been done in order to complete and update this CA earthquake catalog. In particular, two workshops were held in 2008 and 2011 in the Universidad Politécnica de Madrid (Spain), joining experts from the different CA countries who worked each one in its own catalogue covering the entire region and the border with northwestern Colombia and southern Mexico. These national catalogues were later integrated in a common regional catalogue in SEISAN format. At this aim it was necessary to solve some problems, like to avoid duplicity of events, specially close to the boundaries, to consider the different scales of magnitude adopted by different countries, to take into account the completeness by the different national networks, etc. Some solutions were adopted for obtaining a homogenized catalogue to Mw, containing historical and instrumental events with Mw > 3.5 from 1522 up to 2011. The catalogue updated to December 2007 was the basis for the first regional hazard study carried out by Benito et al., (2011) as part of the collaborative RESIS II project under coordination of NORSAR. The ones updated to

  1. Smart power and foreign policy of the People's Republic of China: the case of Central America

    Directory of Open Access Journals (Sweden)

    Manuel Villegas Mendoza

    2016-02-01

    Full Text Available This paper presents the most relevant aspects of the academic debate on smart power, in order to apply this concept to analyze the foreign policy of the Republic of China on Latin America and the Caribbean, but especially to Central America; where the dispute between China and Taiwan for international recognition is evident. It is argued that the smart power of China to Central America is expressed in the attractiveness of having privileged access to the Chinese market and its funding programs and official development assistance. While this country has a large presence in Latin America and the Caribbean, in Central America such influence is counteracted in the light of the close relationship that all Central American countries except Costa Rica, maintain with Taiwan. Based on the development of China as a world power, it is expected that this condition changed, so that this country would increase its influence in Central America.

  2. Are civil wars to blame for crime in Central America?

    Directory of Open Access Journals (Sweden)

    Ana Sofia Cardenal Izquierdo

    2008-04-01

    Full Text Available The countries of Central America are high up on the list of nations with the highest crime rates in the world. According to the literature, the most common argument is that these high crimerates are a legacy of the armed conflicts of the 1980s. This article subjects this theory to an empirical examination. Even though the analysis is preliminary and limited, the results serve to question theexistence of such a link between war and crime. The data show that the areas most affected by war in El Salvador and Guatemala are not the ones that show the highest rates of crime. Furthermore, no direct relation exists between the presence of armed conflict and crime rates at a national level. The presence of armed conflict is neither a necessary factor nor a sufficient one for criminal violence. Onthe contrary, this work points to a close link between inequality and crime rates at a national level.

  3. [Mangrove characterization of Central America with remote sensors].

    Science.gov (United States)

    Lizano, O G; Amador, J; Soto, R

    2001-12-01

    Satellite images were used to study the mangrove distribution patterns in two different climatic regions of Central America: Gulf of Fonseca in Honduras-El Salvador and Sierpe-Térraba in Costa Rica. The Gulf of Fonseca has higher temperature and solar radiation, and lower precipitation, which can explain the higher structural development and species mixing of the Sierpe-Térraba mangrove. In the latter the transition between species or between heights in the same species is clear. The automatic classification made by the Geographic Information System (IDRISI) fits well the field mangrove distribution, but it was necessary to regroup some subdivisions that represent the same land use as identified by transects and an aerial video. Mixed species and clouds produced less satisfactory results in Sierpe-Térraba indicating a need for better satellite image resolution. PMID:15264547

  4. Renewable energies. A challenge and an opportunity for Central America; Energias renovables. Un reto y una oportunidad para America Central

    Energy Technology Data Exchange (ETDEWEB)

    Guevara, Leo; Castro S, Rene [Instituto Centroamericano de Administracion de Empresas (INCAE) (Costa Rica)

    2007-07-15

    There are analyzed in this working paper the following aspects: the Central America countries and their relations with the regional energy potencies -Mexico and Venezuela- and the impact they have in the energy supply. There are also explore the following aspects: the San Jose Agreement linked to the fossil fuels supply, the emerging scope boosted by Brazil and Colombia regarding to the alternative fuels. [Spanish] Este trabajo analiza los paises centroamericanos y sus relaciones con las potencias energeticas regionales como Mexico y Venezuela, y como estas impactan el suministro de energia en la region. Tambien se exploran mecanismos como el Pacto de San Jose, ligado al suministro de combustibles fosiles y las oportunidades emergentes impulsadas por Brasil y Colombia con combustibles alternativos.

  5. 7 CFR 319.56-25 - Papayas from Central America and Brazil.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Papayas from Central America and Brazil. 319.56-25... § 319.56-25 Papayas from Central America and Brazil. The Solo type of papaya may be imported into the... section and all other applicable provisions of this subpart. (a) The papayas were grown and packed...

  6. Implications of topographic relief on the brittle-to-plastic boundary beneath the southern Central Range, Taiwan

    Science.gov (United States)

    Cavallotti, C. J.; Lewis, J. C.

    2015-12-01

    The result of the ongoing arc-continent collision between the Eurasian (EU) and Philippine Sea (PSP) plates, Taiwan is an important tool in understanding the real time mechanics of the mountain building process. We show an apparent gap in seismicity beneath Taiwan's Southern Central Range that may represent the presence of a volume of rock lacking the shear strength required to record brittle processes. A spatially accurate 3D map was created, utilizing data recorded for over 8000 seismic events beneath Taiwan and the surrounding area, and shows an elongate aseismic volume trending northeast southwest generally parallel to the topographic grain of the island. Published P-wave data shows an area nearly coincident with the aseismic zone with lower velocities at depths of 7.5km in the west to nearly 40km in the east which suggests a difference in density (and rheology) from the surrounding, seismically active, areas. Strain inversions assuming a micropolar model for crustal deformation suggest systematic changes in strain tensor geometry from east to west across the hypothesized density boundary. Preliminary results indicate that seismogenic strain along the western margin of the aseismic zone accommodates crustal thinning with stretching oblique to the orogen. In contrast, on the east side of the aseismic zone we see crustal thickening with minimum stretching (shortening) subparallel to PSP-EU motion. The profound change in strain geometry suggests that the asiesmic zone is a partially ductile volume of rock caused by interactions of the EU and PSP beneath Taiwan. We hypothesize that if the rheology contrast is sufficient, higher spatial resolution inversions may reveal that events near the seismic/aseismic interface exhibit Andersonian-like behavior wherein one principal strain axis would lie orthogonal at any given point to a surface mapped to this boundary. Alternatively, if the contrast is smaller the inverted strain geometries may vary systematically and provide

  7. Recent crustal deformation in west-central South America

    Science.gov (United States)

    Pritchard, Matthew Earl

    I use interferometric synthetic aperture radar (InSAR) to create maps of crustal deformation along the coast and within the volcanic arc of central South America. I image deformation associated with six subduction zone earthquakes, four volcanic centers, at least one shallow crustal earthquake, and several salt flats. In addition, I constrain the magnitude and location of post-seismic deformation from the aforementioned subduction zone earthquakes. I combine InSAR observations with data from the Global Positioning System (GPS) and teleseismic data to explore each source of deformation. I use the observations to constrain earthquake and volcanic processes of this subduction zone, including the plumbing system of the volcanoes and the decadal along strike variations in the subduction zone earthquake cycle. I created interferograms of over 900 volcanoes in the central Andes spanning 1992--2002, and found four areas of deformation. I constrained the temporal variability of the deformation, the depth of the sources of deformation assuming a variety of source geometries and crustal structures, and the possible cause of the deformation. I do not observe deformation associated with eruptions at several volcanoes, and I discuss the possible explanations for this lack of deformation. In addition, I constrain the amount of co-seismic and post-seismic slip on the subduction zone fault interface from the following earthquakes: 1995 Mw 8.1 Antofagasta, Chile; 1996 Mw 7.7 Nazca, Peru; 1998 Mw 7.1 Antofagasta, Chile; and 2001 Mw 8.4 Arequipa, Peru. In northern Chile, I compare the location and magnitude of co-seismic slip from 5 Mw > 7 earthquakes during the past 15 years with the post-seismic slip distribution. There is little post-seismic slip from the 1995 and 1996 earthquakes relative to the 2001 event and other recent subduction zone earthquakes.

  8. Oil and gas developments in South America, Central America, Caribbean area, and Mexico in 1987

    Energy Technology Data Exchange (ETDEWEB)

    Wiman, W.D.

    1988-10-01

    Exploration activity in South America, Central America, the Caribbean area, and Mexico in 1987 showed significant increases in seismic acquisition in Belize, Bolivia, Brazil, Costa Rica, Guatemala, Mexico, Paraguay, and Peru, and a decrease in Chile and Venezuela. Exploratory drilling increased in most major producing countries but was accompanied by a decline in development drilling. Most of the increase could be attributed to private companies fulfilling obligations under risk contracts; however, state oil companies in Bolivia, Chile, and Colombia showed significant increased activity, with only Mexico showing a decrease. Colombia again had a dramatic increase in production (29% from 1986). Noteworthy discoveries were made in Bolivia (Villamontes-1); Brazil, in the Solimoes basin (1-RUC-1-AM); Chile (Rio Honda-1); Colombia, in the Llanos basin (Austral-1, La Reforma-1, Libertad Norte-1, Cravo Este-1, and Cano Yarumal-1), in the Upper Magdalena basin (Toldado-1 and Los Mangos-1); Ecuador (Frontera-1, a joint-exploration venture with Colombia); Mexico, in the Chiapas-Tabasco region (Guacho-1 and Iridi-1), in the Frontera Norte area (Huatempo-1); Peru, in the Madre de Dios basin (Armihuari-4X); Trinidad (West East Queen's Beach-1); and Venezuela (Musipan-1X). Brazil's upper Amazon (Solimoes basin) discovery, Colombia's Upper Magdalena basin discoveries Toldado-1 and Los Mangos-1, Mexico's Chiapas-Tabasco discoveries, Peru's confirmation of the giant Cashiriari discovery of 1986, and Venezuela's success in Monagas state were the highlights of 1987. 5 figs., 8 tabs.

  9. Managing weather and climate risks to agriculture in North America, Central America and the Caribbean

    Directory of Open Access Journals (Sweden)

    Harlan D. Shannon

    2015-12-01

    Full Text Available In recent decades, numerous weather- and climate-related natural disasters have impacted North America, Central America, and the Caribbean, repeatedly demonstrating how vulnerable local agriculture is to extreme episodic events. Given this recent history, and expectations that the frequency and intensity of some episodic events will increase with climate change, it is becoming increasingly important for farmers to proactively manage weather and climate risks to agriculture to protect their livelihoods. Some farmers in this region already apply various strategies to help reduce weather and climate risks and uncertainties, including farming in multiple locations, diversifying crops and varieties, seeking alternative sources of income, and purchasing crop insurance. Such efforts often help farmers maintain a more stable income while also protecting and preserving the productivity of the land. Other farmers, however, have failed to implement basic risk management strategies despite the clear benefits. Reasons for these failures can be attributed to inadequate farmer education and training, a lack of tools to help facilitate the practical application of risk management concepts, and poor communications between the agrometeorological and farming communities. The agrometeorological community can help overcome these obstacles by building upon existing efforts that have successfully educated farmers about weather and climate risks to agriculture and have equipped farmers with the data, tools, and applications necessary to manage these risks. Farmer input is critical to preparing effective educational and training materials and developing user-friendly risk management tools. The agrometeorological community should solicit input from farmers regularly to ensure that farmers are obtaining the information necessary to effectively manage weather and climate risks to agriculture.

  10. 3D imaging of subducting and fragmenting Indian continental lithosphere beneath southern and central Tibet using body-wave finite-frequency tomography

    Science.gov (United States)

    Liang, Xiaofeng; Chen, Yun; Tian, Xiaobo; Chen, Yongshun John; Ni, James; Gallegos, Andrea; Klemperer, Simon L.; Wang, Minling; Xu, Tao; Sun, Changqing; Si, Shaokun; Lan, Haiqiang; Teng, Jiwen

    2016-06-01

    We perform a finite-frequency tomographic inversion to image 3D velocity structures beneath southern and central Tibet using teleseismic body-wave data recorded by the TIBET-31N passive seismic array as well as waveforms from previous temporary seismic arrays. High-velocity bodies dip ∼40° northward beneath the Himalaya and the Lhasa Terrane. We interpret these high-velocity anomalies as subducting Indian Continental Lithosphere (ICL). The ICL appears to extend further north in central Tibet than in eastern Tibet, reaching 350 km depth at ∼31°N along 85°E but at ∼30°N along 91°E. Low P- and S-wave velocity anomalies extend from the lower crust to ≥180 km depth beneath the Tangra Yum Co Rift, Yadong-Gulu Rift, and the Cona Rift, suggesting that rifting in southern Tibet may involve the entire lithosphere. The anomaly beneath Tangra Yum Co Rift extends down to about 180 km, whereas the anomalies west of the Yadong-Gulu Rift and east of the Cona Rift extend to more than 300 km depth. The low-velocity upper mantle west of the Yadong-Gulu Rift extends furthest north and appears to connect with the extensive upper-mantle low-velocity region beneath central Tibet. Thus the northward-subducting Indian Plate is fragmented along north-south breaks that permit or induce asthenospheric upwellings indistinguishable from the upper mantle of northern Tibet.

  11. Does the Nazca Slab Beneath Central Argentina Influence the Water Content of the Adjacent Transition Zone?

    Science.gov (United States)

    Booker, J. R.; Pomposiello, M. C.; Favetto, A.; Burd, A.

    2008-12-01

    When the Nazca flat-slab rolls over and plunges into the transition zone under Argentina, it appears to separate an electrically resistive transition zone to the west from an electrically conductive transition zone to the east. The simplest explanation for this is that the water content of the transition zone is much lower to the west than the east. The low conductivity to the west can be explained if anhydrous upper mantle mantle is being carried down into the transition zone by slab motion. The much higher conductivity to the east is beneath the Rio de la Plata Craton whose root almost certainly inhibits vertical motion east of the slab. Thus water injected by the descending slab is likely to accumulate in the transition zone. This idea was first presented in a Nature paper in 2004. Since then, we have collected more magnetotelluric data to the south where the slab dip is normal, but voluminous back-arc basaltic volcanism occurs and in the region where the slab is said to be flexing continuously between the two geometries. A goal of this work is to test whether the slab has a similar relation to transition zone conductivity along strike. The new data, originally collected along linear profiles perpendicular to the expected strike of the slab in the mantle clearly indicated that 2-D interpretation would be problematic. Indeed, analysis of new data in the flexure region using 2-D methods reveals a narrow, roughly east-west, near vertical resistive structure extending down to the top of a conductive transition zone. A possible, but controversial interpretation of this structure is that it is the signature of a slab tear rather than the widely-accepted continuous flexure geometry. If a tear is indeed correct, then there is an opportunity to test how the slab is influencing the transition zone conductivity and by inference the water content by looking at the southern edge of the plunging 'flat- slab' as it enters the transition zone. Since the original data were

  12. Geostrophic circulation between the Costa Rica Dome and Central America

    Science.gov (United States)

    Brenes, C. L.; Lavín, M. F.; Mascarenhas, Affonso S.

    2008-05-01

    The geostrophic circulation between the Costa Rica Dome and Central America is described from CTD observations collected in two surveys: (a) The Wet Cruise in September-October 1993, and the Jet Cruise in February-March 1994. Poleward coastal flow was present on both occasions, but the transition from flow around the dome to the poleward Costa Rica Coastal Current flow was quite tortuous because of the presence of mesoscale eddies. In particular, a warm anticyclonic eddy was found off the Gulf of Fonseca during both cruises, at an almost identical position and with similar dimensions (150 m deep, 250 km in diameter) and surface speed (0.5 m s -1). In the Gulf of Panama, poleward flow was also observed, weaker in February-March 1994 than in September-October 1993, when it penetrated to 600 m depth and transported 8.5 Sv. In September-October 1993, the current between the dome and the coast was mostly ˜100 m deep and weak (˜0.15 m s -1), although in its southern side it was deeper (˜450 m) and faster at 0.3 m s -1. The poleward transport between the dome and the coast was ˜7 Sv. In February-March 1994 the Costa Rica Dome was a closed ring adjacent to the continental shelf, ˜500 km in diameter, at least 400 m deep, had geostrophic surface speeds ˜0.25 m s -1, and subsurface maximum speed (0.15-0.20 m s -1) at ˜180 m depth; the associated uplift of the isotherms was ˜150 m. The flow in the south part of the dome splits into two branches, the weakest one going around the dome and the strongest one continuing east and turning south before reaching the Gulf of Panama.

  13. Validation of S-wave Velocity beneath the Ise Bay, Central Japan, Using Continuous Short-period Ambient Noise Data

    Science.gov (United States)

    Hayashida, T.; Yoshimi, M.; Horikawa, H.

    2014-12-01

    We have applied seismic interferometry to three-component ambient noise data recorded around the Ise bay area, central Japan, to validate published three-dimensional S-wave velocity models. For the bay area, detailed seismic velocity structure models have been constructed based on P-wave reflection surveys. There is no direct information on the S-wave velocities beneath the bay and the parameters are assigned by reference to those in a land area. We used one-year continuous data from 20 permanent stations of the NIED Hi-net (High-sensitivity seismograph network) to obtain stacked cross-correlation functions (CCFs) of ambient noise between station pairs that cross the bay. The CCFs were calculated, using one-hour data in the radial-radial (R-R), transverse-transverse (T-T) and vertical-vertical (Z-Z) directions for time lags of ±500s. Horizontal distances between the stations range form 15 km to 103 km. Although the Hi-net stations deploy seismometers with the natural period of 1 s, we found that the yearly stacked CCFs for selected 101 Hi-net station pairs are comparable with those derived from neighboring broadband seismic stations in the frequency range between 0.1 and 0.5 Hz, by deconvolving the instrument response. The CCFs shows clear Rayleigh waves from all directions in the R-R and Z-Z components, and clear Love waves in the T-T component with reasonable signal-to-noise ratios. The derived group velocities and waveforms of the wave trains are variable in the higher frequency range (> 0.2 Hz), indicating deep sedimentary basin beneath the bay. We compared obtained group velocities with theoretical ones to find systematic differences between the expected structure model from the CCFs and the published models in the northwest part of the bay, while the agreements are generally good for many other station pairs. This result indicates that the seismic interferometry technique provides valuable information for validation and improvement of a velocity structure

  14. Scorpionism in Central America, with special reference to the case of Panama

    OpenAIRE

    Borges, A.; RJ Miranda; JM Pascale

    2012-01-01

    Scorpionism in the Americas occurs mainly in Mexico, northern South America and southeast Brazil. This article reviews the local scorpion fauna, available health statistics, and the literature to assess scorpionism in Central America. Notwithstanding its high toxicity in Mexico, most scorpion sting cases in Guatemala, Belize, El Salvador, Nicaragua, and Costa Rica are produced by species in the genus Centruroides that are only mildly toxic to humans despite the existence of ion channel-active...

  15. Patterns of illness in travelers visiting Mexico and Central America: the GeoSentinel experience

    OpenAIRE

    Flores-Figueroa, J; Okhuysen, P C; von Sonnenburg, F.; DuPont, H L; Libman, M D; Keystone, J S; Hale, D C; Burchard, G; Han, P V; Wilder-Smith, A.; Freedman, D O

    2011-01-01

    BACKGROUND: Mexico and Central America are important travel destinations for North American and European travelers. There is limited information on regional differences in travel related morbidity. METHODS: We describe the morbidity among 4779 ill travelers returned from Mexico and Central America who were evaluated at GeoSentinel network clinics during December 1996 to February 2010. RESULTS: The most frequent presenting syndromes included acute and chronic diarrhea, dermat...

  16. Dealing with the coffee crisis in Central America - impacts and strategies

    OpenAIRE

    Varangis, Panos; Siegel, Paul; Giovannucci, Daniele; Lewin, Bryan

    2003-01-01

    Current coffee prices are at record lows and below the cost of production for many producers in Central America. Moreover, the coffee crisis is structural, and changes in supply and demand do not indicate a quick recovery of prices. So, coffee producers in Central America are facing new challenges-as are coffee laborers, coffee exporters, and others linked to the coffee sector. Coffee plays a major economic role in Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua. The coffee crisis...

  17. Dealing with the Coffee Crisis in Central America : Impacts and Strategies

    OpenAIRE

    Varangis, Panos; Siegel, Paul; Giovannucci, Daniele; Lewin, Bryan

    2003-01-01

    Current coffee prices are at record lows and below the cost of production for many producers in Central America. Moreover, the coffee crisis is structural, and changes in supply and demand do not indicate a quick recovery of prices. So, coffee producers in Central America are facing new challenges-as are coffee laborers, coffee exporters, and others linked to the coffee sector. Coffee play...

  18. Giant magmatic water reservoir beneath Uturuncu volcano and Altiplano-Puna region (Central Andes)

    Science.gov (United States)

    Laumonier, Mickael; Gaillard, Fabrice; Muir, Duncan; Blundy, Jon; Unsworth, Martyn

    2016-04-01

    Volcanism at continental arcs is the surface manifestation of long-lived crustal magmatic processes whereby mantle-derived hydrous basalt magma differentiates to more silica-rich magmas by a combination of crystallization and crustal melting. What erupts is just a fraction of the total volume of magma produced by these processes; the unerupted, plutonic residues solidify and are inaccessible to direct study until millions of years of uplift and erosion bring them to the surface. In contrast, geophysical surveys, using electromagnetic and seismic waves, can provide real-time images of subduction zone magmatic systems. Several such studies have revealed that arc volcanoes are underlain by large partially molten regions at depths of >10 km, the largest known example being the Altiplano-Puna magma body (APMB) in central Andes. Interpreting such geophysical images in terms of amount, composition and distribution of partial melts is limited by our lack of knowledge of the physical properties of silicate melts at elevated pressures and temperatures. Here we present high-pressure, in situ experimental data showing that the electrical conductivity of andesitic melts is primarily controlled by their dissolved water contents. Linking our new measurements to petrological constraints from andesites erupted on the Altiplano, we show that the APMB is composed of 10-20% of an andesitic melt containing 8-10 wt% dissolved water. This implies that the APMB is a giant water anomaly in the global subduction system, with a total mass of dissolved magmatic water about half of the water contained within the Adriatic Sea. In addition to the controls on the physical properties of the melts, the abundance of dissolved water governs the structural levels of magma ponding, equivalent to the depth of water saturation, where degassing and crystallisation promote partial melting and weakening of the upper crust. Unexpectedly, very high concentrations of water in andesite magmas shall impede their

  19. Remittances as a Development Tool in Central America: Empowering Microfinance

    OpenAIRE

    Inter-American Development Bank (IDB)

    2003-01-01

    Presents the interest of the Multilateral Investment Fund (MIF) of the Inter-American Development Bank, to increase the impact of remittances on developing countries of Latin America and the Caribbean, through the promotion of innovative projects and dissemination more comprehensive information on this market in the region.

  20. Eocene lake basins in Wyoming and Nevada record rollback of the Farallon flat-slab beneath western North America

    Science.gov (United States)

    Smith, M. E.; Cassel, E. J.; Jicha, B. R.; Singer, B. S.; Carroll, A.

    2014-12-01

    Numerical and conceptual models of flat-slab rollback predict broad initial dynamic subsidence above the slab hinge then uplift and volcanism triggered by the advection of asthenosphere beneath the overriding plate. These predicted surface effects provide a viable but largely untested explanation for lake basin formation in Cordilleran-type orogenies. We argue that the hydrologic closure of both the foreland (early Eocene) and hinterland (late Eocene) of the North American Cordillera were caused by a trenchward-migrating wave of dynamic and thermal topography resulting from progressive removal of the Farallon flat-slab. Two major episodes of hydrologic drainage closure are recorded by Eocene terrestrial strata in the western United States. The first occurred in the retroarc foreland during the early Eocene, and resulted in the deposition of the Green River Fm. The second occurred in the hinterland during the late Eocene and resulted in accumulation of the Elko Fm. In both regions, lake strata overlie fluvial strata and become progressively more evaporative up-section, and are overlain by volcaniclastic strata. Both successions were then truncated by regional unconformities that extend until the Oligocene. We interpret these stratigraphic successions to record trenchward propagation of a regional topographic wave, caused by slab rollback. Migration of the slab-hinge initially caused dynamic subsidence and initiation of lacustrine deposition. Regional surface uplift followed, and was associated with scattered volcanism. Uplift promoted formation of endorheic basins and ultimately the development of regional unconformities. The height of the uplift can be roughly approximated by the preserved thickness of lacustrine and other nonmarine deposits at both locations (0.2-1.0 km). The 40Ar/39Ar and U-Pb geochronology of Green River Fm ash beds indicate that this surface topographic wave migrated trenchward (SW) across the foreland from 53 to 47 Ma at a velocity of ~6 cm

  1. Central Wind Forecasting Programs in North America by Regional Transmission Organizations and Electric Utilities: Revised Edition

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.; Porter, K.

    2011-03-01

    The report and accompanying table addresses the implementation of central wind power forecasting by electric utilities and regional transmission organizations in North America. The first part of the table focuses on electric utilities and regional transmission organizations that have central wind power forecasting in place; the second part focuses on electric utilities and regional transmission organizations that plan to adopt central wind power forecasting in 2010. This is an update of the December 2009 report, NREL/SR-550-46763.

  2. Neurocysticercosos in South-Central America and the Indian Subcontinent: a comparative evaluation

    Directory of Open Access Journals (Sweden)

    Gagandeep Singh

    1997-09-01

    Full Text Available Neurocysticercosis is an important public health problem in South-Central America and South Asia. A review of the differences in epidemiological and clinical attributes of cysticercosis and taeniasis in South Central America and India, respectively, is undertaken in the present communication. Intestinal taeniasis is hyperendemic in several American countries. In comparison, the prevalence of Taenia solium infestation is lower in India. The clinical manifestations in several American neurocysticercosis series comprise epilepsy, intracranial hypertension and meningeal - racemose cysticercosis, in roughly equal proportions. An overwhelming majority of the Indian subjects present with seizures. The commonest pathological substrate of the disorder in Indian patients is the solitary parenchymal degenerating cyst. The reasons for the predominance of solitary forms in India, and of multilesional forms in South Central America are discussed. The magnitude of Taenia solium infestation and the frequency of pork consumption in a given population appear to influence the quantum of cyst load in affected individuals.

  3. Health outcomes among HIV-positive Latinos initiating antiretroviral therapy in North America versus Central and South America

    Science.gov (United States)

    Cesar, Carina; Koethe, John R; Giganti, Mark J; Rebeiro, Peter; Althoff, Keri N; Napravnik, Sonia; Mayor, Angel; Grinsztejn, Beatriz; Wolff, Marcelo; Padgett, Denis; Sierra-Madero, Juan; Gotuzzo, Eduardo; Sterling, Timothy R; Willig, James; Levison, Julie; Kitahata, Mari; Rodriguez-Barradas, Maria C; Moore, Richard D; McGowan, Catherine; Shepherd, Bryan E; Cahn, Pedro

    2016-01-01

    Introduction Latinos living with HIV in the Americas share a common ethnic and cultural heritage. In North America, Latinos have a relatively high rate of new HIV infections but lower rates of engagement at all stages of the care continuum, whereas in Latin America antiretroviral therapy (ART) services continue to expand to meet treatment needs. In this analysis, we compare HIV treatment outcomes between Latinos receiving ART in North America versus Latin America. Methods HIV-positive adults initiating ART at Caribbean, Central and South America Network for HIV (CCASAnet) sites were compared to Latino patients (based on country of origin or ethnic identity) starting treatment at North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD) sites in the United States and Canada between 2000 and 2011. Cox proportional hazards models compared mortality, treatment interruption, antiretroviral regimen change, virologic failure and loss to follow-up between cohorts. Results The study included 8400 CCASAnet and 2786 NA-ACCORD patients initiating ART. CCASAnet patients were younger (median 35 vs. 37 years), more likely to be female (27% vs. 20%) and had lower nadir CD4 count (median 148 vs. 195 cells/µL, p<0.001 for all). In multivariable analyses, CCASAnet patients had a higher risk of mortality after ART initiation (adjusted hazard ratio (AHR) 1.61; 95% confidence interval (CI): 1.32 to 1.96), particularly during the first year, but a lower hazard of treatment interruption (AHR: 0.46; 95% CI: 0.42 to 0.50), change to second-line ART (AHR: 0.56; 95% CI: 0.51 to 0.62) and virologic failure (AHR: 0.52; 95% CI: 0.48 to 0.57). Conclusions HIV-positive Latinos initiating ART in Latin America have greater continuity of treatment but are at higher risk of death than Latinos in North America. Factors underlying these differences, such as HIV testing, linkage and access to care, warrant further investigation. PMID:26996992

  4. Health outcomes among HIV-positive Latinos initiating antiretroviral therapy in North America versus Central and South America

    Directory of Open Access Journals (Sweden)

    Carina Cesar

    2016-03-01

    Full Text Available Introduction: Latinos living with HIV in the Americas share a common ethnic and cultural heritage. In North America, Latinos have a relatively high rate of new HIV infections but lower rates of engagement at all stages of the care continuum, whereas in Latin America antiretroviral therapy (ART services continue to expand to meet treatment needs. In this analysis, we compare HIV treatment outcomes between Latinos receiving ART in North America versus Latin America. Methods: HIV-positive adults initiating ART at Caribbean, Central and South America Network for HIV (CCASAnet sites were compared to Latino patients (based on country of origin or ethnic identity starting treatment at North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD sites in the United States and Canada between 2000 and 2011. Cox proportional hazards models compared mortality, treatment interruption, antiretroviral regimen change, virologic failure and loss to follow-up between cohorts. Results: The study included 8400 CCASAnet and 2786 NA-ACCORD patients initiating ART. CCASAnet patients were younger (median 35 vs. 37 years, more likely to be female (27% vs. 20% and had lower nadir CD4 count (median 148 vs. 195 cells/µL, p<0.001 for all. In multivariable analyses, CCASAnet patients had a higher risk of mortality after ART initiation (adjusted hazard ratio (AHR 1.61; 95% confidence interval (CI: 1.32 to 1.96, particularly during the first year, but a lower hazard of treatment interruption (AHR: 0.46; 95% CI: 0.42 to 0.50, change to second-line ART (AHR: 0.56; 95% CI: 0.51 to 0.62 and virologic failure (AHR: 0.52; 95% CI: 0.48 to 0.57. Conclusions: HIV-positive Latinos initiating ART in Latin America have greater continuity of treatment but are at higher risk of death than Latinos in North America. Factors underlying these differences, such as HIV testing, linkage and access to care, warrant further investigation.

  5. Development of Renewable Energies in the liberation of the energy market in Central America

    International Nuclear Information System (INIS)

    This paper presents the diagnostic of the current situation on renewable energy in Central America, including socio-economical situation, with economical index, supply and demand of energy and planning of wind resources. The experience of Europe in the promotion for the market of renewable energy, discussing the policies and cooperation between private sector and the government is included. A list of potential projects of renewable energy in each country of Central America based on biomass, hydro power, wind and other energy sources for power generation is presented

  6. Scholastic Achievement of Adolescent Refugees from Cambodia and Central America.

    Science.gov (United States)

    Rousseau, Cecile; Drapeau, Aline

    2000-01-01

    Central American and Cambodian students in six Canadian high schools and their parents were interviewed to assess the students' emotional problems and pre- and postmigration family environment. Findings indicate that the relationship between the emotional problems and scholastic achievement of teenaged refugees was tenuous. (Author/MKA)

  7. Improving the Monetary Policy Frameworks in Central America

    OpenAIRE

    Stephanie Medina Cas; Alejandro Carrion-Menendez; Florencia Frantischek

    2011-01-01

    Several Central American (CADR) countries with independent monetary policies are strengthening their monetary frameworks and some have implemented or are moving towards inflation targeting (IT) regimes. Strengthening the monetary policy frameworks of CADR is key to improving the effectiveness of monetary policy. The paper reviews the literature on the reforms needed for strengthening the monetary policy frameworks, and examines the experiences of IT countries, Chile, Peru, and Uruguay to help...

  8. Health System Innovations in Central America : Lessons and Impact of New Approaches

    OpenAIRE

    2005-01-01

    Health Systems Innovations in Central America reports on how these experiences fared -- a hospital in Panama, a nutrition program in Honduras, primary care extension in Guatemala, a subset of hospitals and primary care units in Costa Rica and a social security-managed health care program in Nicaragua. The studies report on the performance of the innovations, the policy environment in which...

  9. Book review: Vetter, H. 2005. Terralog. Turtles of the World. Vol. 3. Central and South America

    Directory of Open Access Journals (Sweden)

    2006-12-01

    Full Text Available Book review: Vetter, H. 2005. Terralog. Turtles of the World. Vol. 3. Central and South America/Schildkröten der Welt Band 3. Mittel- und Südamerika: 1-128, color pictures 606 + 9. Edition Chimaira, Frankfurt, Germany.ISBN 3-930612-82-8; 29.7 x 20.8 cm

  10. Planting the Seeds of a New Agriculture: Living with the Land in Central America.

    Science.gov (United States)

    Adriance, Jim

    1995-01-01

    Central America's macroeconomics, land tenure patterns, and population growth are forcing small-scale farmers to alternatives based on farmer-to-farmer teaching and farming in concert with the environment. Discusses major schools of thought that have fueled this phenomenon, and how extension services and isolated groups are joining to form a…

  11. 77 FR 51828 - Dominican Republic-Central America-United States Free Trade Agreement; Notice of Extension of the...

    Science.gov (United States)

    2012-08-27

    ... of the Secretary Dominican Republic--Central America--United States Free Trade Agreement; Notice of... Republic--Central America--United States Free Trade Agreement (CAFTA-DR). On December 22, 2011, OTLA... International Labor Affairs, U.S. Department of Labor. ACTION: Notice. The Office of Trade and Labor...

  12. A double seismic zone in the Nazca flat slab beneath central Chile (29°-34°S)

    Science.gov (United States)

    Marot, Marianne; Monfret, Tony; Pardo, Mario; Ranalli, Giorgio

    2010-05-01

    The Nazca plate subducts beneath central Chile and western Argentina (29°-34°S) with a dip angle ~27° from the trench until ~100 km depth. North of 32oS the slab becomes sub-horizontal at this depth and continues sub-horizontally for approximately 250 km eastward before resuming sinking with dip angle ~25°. The location and extent of this "Pampean" flat subduction is very well correlated, seismically and tectonically on the continent, with the continuing subduction of the Juan Fernandez Ridge (JFR). We use the recorded seismicity from three local temporary networks, OVA99 (1999-2000), CHARSME (2002-2003) and CHASE (2005-2006) to characterize the earthquake distribution within the slab in this area. Around 7000 earthquakes were located with magnitude ranging between 1.6 and 5.7, and around 1500 focal mechanisms were calculated. A double seismic zone (or DBZ) is present in the dipping part of the slab landward from the trench. The lower seismic zone of this Pampean DBZ begins at ~50 km depth and extends to 100-120 km depth, where it merges with the upper seismic zone. The separation between the two zones is ~30 km at the shallowest depth. The lower seismic zone shows higher seismic activity relative to the upper zone. Both zones show a similar magnitude distribution, with predominantly tensional focal mechanisms. The Pampean DBZ is best observed within the subducting JFR, which is marked by a dense and thick seismic activity. This seismicity drops substantially outside the JFR ridge limits, making the Pampean DBZ more difficult to detect. Focal mechanisms for earthquakes delineating the DBZ (50-100 km depth) show a strong tendency of the focal planes to strike NS, parallel to the trench axis, suggesting that intermediate-depth earthquakes in the subducting Nazca plate occur on pre-existing reactivated outer rise faults. The separation distance between the two seismic zones cannot be explained by plate age models which predict a much smaller separation distance

  13. Molecular characterization of adenovirus circulating in Central and South America during the 2006–2008 period

    Science.gov (United States)

    García, Josefina; Sovero, Merly; Laguna‐Torres, Victor Alberto; Gomez, Jorge; Chicaiza, Wilson; Barrantes, Melvin; Sanchez, Felix; Jimenez, Mirna; Comach, Guillermo; De Rivera, Ivette L.; Agudo, Roberto; Arango, Ana E.; Barboza, Alma; Aguayo, Nicolas; Kochel, Tadeusz J.

    2009-01-01

    Background  Human Adenoviruses are recognized pathogens, causing a broad spectrum of diseases. Serotype identification is critical for epidemiological surveillance, detection of new strains and understanding of HAdvs pathogenesis. Little data is available about HAdvs subtypes in Latin America. Methods  In this study, we have molecularly characterized 213 adenoviruses collected from ILI presenting patients, during 2006‐08, in Central and South America. Results  Our results indicate that 161(76%) adenoviruses belong to subgroup C, 45 (21%) to subgroup B and 7 (3%) to subtype E4. PMID:19903214

  14. Hydrogeochemical investigation of six geothermal sites in Honduras, Central America

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.E.; Truesdell, A.H.; Grigsby, C.O.; Janik, C.J.; Shevenell, L.A.; Paredes, J.R.; Gutierrez, J.W.; Trujillo, Jr.; Counce, D.A.

    1987-06-01

    We conducted detailed hydrogeochemical investigations at six geothermal sites in western Honduras: Azacualpa, El Olivar, Pavana, Platanares, Sambo Creek, and San Ignacio. None of the sites is associated with Quaternary silicic volcanism, although El Olivar lies adjacent to a small Quaternary basalt field and Pavana is part of a belt of hot spring activity parallel to and 35 km east of the Central American volcanic arc. None of the sites contains acid-sulfate waters indicative of vapor-dominated conditions. Thermal fluids are characterized by pH between 7 and 10, Cl<125 mg/l, HCO/sub 3/>Cl, SO/sub 4/greater than or equal toCl, Bless than or equal to17 mg/l, Liless than or equal to4 mg/l, and Asless than or equal to1.25 mg/l. Stable isotope analyses of the water show that recharge to the geothermal systems generally occurs from areas of higher elevation adjacent to the sites. Tritium contents of apparently undiluted thermal fluids range from 0 to 0.4 T.U., indicating residence times of fluids in the systems of more than 500 y. Various geochemical indicators show that mixing of hot and cold end-member fluids occurs in the system at Platanares and, to a lesser degree, in the systems at San Ignacio and Azacualpa. No mixing is apparent in the fluids discharging at Pavana, Sambo Creek, or El Olivar. Boiling is the dominant process responsible for subtle geochemical variations at Azacualpa and, possibly, San Ignacio. Our best estimates of subsurface reservoir temperatures are 225/sup 0/C at Platanares, 190/sup 0/C at San Ignacio, 185/sup 0/C at Azacualpa, 155/sup 0/C at Sambo Creek, 150/sup 0/C at Pavana, and 120/sup 0/C at El Olivar. The estimated power output of the three hottest sites is 45 thermal megawatts at Platanares, 14 thermal megawatts at San Ignacio, and 13 thermal megawatts at Azacualpa.

  15. A five-century sedimentary geochronology of biomass burning in Nicaragua and Central America

    International Nuclear Information System (INIS)

    In spite of the extensive use of fire as an agricultural agent in Central America today, little is known of its history of biomass burning or agriculture. As an indicator of the burning practices on the adjacent land, a sedimentary record of carbonized particles sheds light on the trends in frequency and areal extent of biomass burning. This research focuses on a sediment core recovered from an anoxic site in the Pacific Ocean adjacent to the Central American Isthmus and reports a five-century record of charcoal deposition. The research illustrates that biomass burning has been an important ecological factor in the Pacific watershed of Central America at least during the past five centuries. Fluxes of charcoal have generally decreased toward the present suggesting a reduction in the charcoal source function. Perhaps, five centuries ago, the frequency of biomass burning was greater than it is today, larger areas were burned, or biomass per unit area of burned grassland was greater. The major type of biomass burned throughout this five-century period has been grass, as opposed to woods, indicating that any major deforestation of the Pacific watershed of Central America occurred prior to the Conquest

  16. Mapping agricultural landscapes and characterizing adaptive capacity in Central America

    Science.gov (United States)

    Holland, M. B.; Imbach, P. A.; Bouroncle, C.; Donatti, C.; Leguia, E.; Martinez, M.; Medellin, C.; Saborio-Rodriguez, M.; Shamer, S.; Zamora, J.

    2013-12-01

    One of the key challenges in developing adaptation strategies for smallholder farmers in developing countries is that of a data-poor environment, where spatially-explicit information about where the most vulnerable smallholder communities are located is lacking. Developing countries tend to lack consistent and reliable maps on agricultural land use, and have limited information available on smallholder adaptive capacity. We developed a novel participatory and expert mapping process to overcome these barriers and develop detailed national-scale maps that allow for a characterization of unique agricultural landscapes based on profiles of adaptive capacity for smallholder agriculture in each area. This research focuses specifically on the Central American nations of Costa Rica, Guatemala, and Honduras, where our focus is on coffee and basic grains as the two main cropping systems. Here we present the methodology and results of a series of in-depth interviews and participatory mapping sessions with experts working within the broader agricultural sector in each country. We held individual interviews and mapping sessions with approximately thirty experts from each country, and used a detailed survey instrument for each mapping session to both spatially identify distinct agricultural landscapes, and to further characterize each area based on specific farm practices and social context. The survey also included a series of questions to help us assess the relative adaptive capacity of smallholder agriculture within each landscape. After all expert mapping sessions were completed in each country we convened an expert group to assist in both validating and refining the set of landscapes already defined. We developed a characterization of adaptive capacity by aggregating indicators into main assets-based criteria (e.g. land tenure, access to credit, access to technical assistance, sustainable farm practices) derived from further expert weighting of indicators through an online

  17. The implications of trade liberalization for diet and health: a case study from Central America

    Directory of Open Access Journals (Sweden)

    Hawkes Corinna

    2009-07-01

    Full Text Available Abstract Background Central America has undergone extensive trade liberalization over the past two decades, and has recently signed a Free Trade Agreement with the United States. The region is also experiencing a dual burden of malnutrition with the growth of dietary patterns associated with the global 'nutrition transition'. This study describes the relationship between trade liberalization policies and food imports and availability, and draws implications for diet and health, using Central America as a case study region. Methods Changes in tariff and non-tariff barriers for each country were documented, and compared with time-series graphs of import, production and availability data to show the outcome of changes in trade policy in relation to food imports and food availability. Results Changes in trade policy in Central America have directly affected food imports and availability via three avenues. First, the lowering of trade barriers has promoted availability by facilitating higher imports of a wide range of foods. Second, trade liberalization has affected food availability through promoting domestic meat production. Third, reductions in barriers to investment appear to be critical in expansion of processed food markets. This suggests that changes in trade policies have facilitated rising availability and consumption of meat, dairy products, processed foods and temperate (imported fruits in Central America. Conclusion This study indicates that the policies of trade liberalization in Central American countries over the past two decades, particularly in relation to the United States, have implications for health in the region. Specifically, they have been a factor in facilitating the "nutrition transition", which is associated with rising rates of obesity and chronic diseases such as cardiovascular disease and cancer. Given the significant cost of chronic disease for the health care system, individuals and the wider community, it is critical

  18. A rapid diversification of rainforest trees (Guatteria; Annonaceae) following dispersal from Central into South America.

    Science.gov (United States)

    Erkens, Roy H J; Chatrou, Lars W; Maas, Jan W; van der Niet, Timotheüs; Savolainen, Vincent

    2007-07-01

    Several recent studies have suggested that a substantial portion of today's plant diversity in the Neotropics has resulted from the dispersal of taxa into that region rather than vicariance, but more data are needed to substantiate this claim. Guatteria (Annonaceae) is, with 265 species, the third largest genus of Neotropical trees after Inga (Fabaceae) and Ocotea (Lauraceae), and its widespread distribution and frequent occurrence makes the genus an excellent model taxon to study diversification patterns. This study reconstructed the phylogeny of Guatteria and inferred three major biogeographical events in the history of the genus: (1) a trans-oceanic Miocene migration from Central into South America before the closing of the Isthmus of Panama; (2) a major diversification of the lineage within South America; and (3) several migrations of South American lineages back into Central America via the closed Panamanian land bridge. Therefore, Guatteria is not an Amazonian centred-genus sensu Gentry but a major Miocene diversification that followed its dispersal into South America. This study provides further evidence that migration into the Neotropics was an important factor in the historical assembly of its biodiversity. Furthermore, it is shown that phylogenetic patterns are comparable to those found in Ocotea and Inga and that a closer comparison of these genera is desirable.

  19. Health outcomes among HIV-positive Latinos initiating antiretroviral therapy in North America versus Central and South America

    OpenAIRE

    Carina Cesar; Koethe, John R; Mark J Giganti; Peter Rebeiro; Althoff, Keri N; Sonia Napravnik; Angel Mayor; Beatriz Grinsztejn; Marcelo Wolff; Denis Padgett; Juan Sierra-Madero; Eduardo Gotuzzo; Sterling, Timothy R; James Willig; Julie Levison

    2016-01-01

    Introduction: Latinos living with HIV in the Americas share a common ethnic and cultural heritage. In North America, Latinos have a relatively high rate of new HIV infections but lower rates of engagement at all stages of the care continuum, whereas in Latin America antiretroviral therapy (ART) services continue to expand to meet treatment needs. In this analysis, we compare HIV treatment outcomes between Latinos receiving ART in North America versus Latin America. Methods: HIV-positive adult...

  20. Asymmetric forest transition driven by the interaction of socioeconomic development and environmental heterogeneity in Central America

    OpenAIRE

    Redo, Daniel J.; Grau, H. Ricardo; Aide, T. Mitchell; Matthew L. Clark

    2012-01-01

    Forest transitions (FT) have been observed in many developed countries and more recently in the developing world. However, our knowledge of FT from tropical regions is mostly derived from case studies from within a particular country, making it difficult to generalize findings across larger regions. Here we overcome these difficulties by conducting a recent (2001–2010) satellite-based analysis of trends in forest cover across Central America, stratified by biomes, which we related to socioeco...

  1. Street Gangs in Central America: Combating them with Intelligence Fusion Centers

    OpenAIRE

    Bruneau, Thomas

    2014-01-01

    Street gangs – pandillas in Spanish – are a major security challenge in the three Northern Triangle countries of Central America – El Salvador, Guatemala, and Honduras.[1] They are also considered a threat in many US cities, with particular focus on the Mara Salvatrucha, MS-13. Domestic party politics in the three countries have resulted in the reliance of heavy hand (mano dura) responses to the gangs, which have mainly served to exacerbate the problem. The anomalous situation of ...

  2. Tsunami hazard assessment in El Salvador, Central America, from seismic sources through flooding numerical models

    OpenAIRE

    Álvarez-Gómez, J. A.; Í. Aniel-Quiroga; O. Q. Gutiérrez-Gutiérrez; J. Larreynaga; González, M.; M. Castro; F. Gavidia; Aguirre-Ayerbe, I.; P. González-Riancho; Carreño, E

    2013-01-01

    El Salvador is the smallest and most densely populated country in Central America; its coast has approximately a length of 320 km, 29 municipalities and more than 700 000 inhabitants. In El Salvador there have been 15 recorded tsunamis between 1859 and 2012, 3 of them causing damages and hundreds of victims. The hazard assessment is commonly based on propagation numerical models for earthquake-generated tsunamis and can be approached from both Probabilistic and D...

  3. Tsunami hazard assessment in El Salvador, Central America, from seismic sources through flooding numerical models.

    OpenAIRE

    Álvarez-Gómez, J. A.; Aniel-Quiroga, Í.; O. Q. Gutiérrez-Gutiérrez; J. Larreynaga; González, M.; M. Castro; F. Gavidia; Aguirre-Ayerbe, I.; P. González-Riancho; Carreño, E

    2013-01-01

    El Salvador is the smallest and most densely populated country in Central America; its coast has an approximate length of 320 km, 29 municipalities and more than 700 000 inhabitants. In El Salvador there were 15 recorded tsunamis between 1859 and 2012, 3 of them causing damages and resulting in hundreds of victims. Hazard assessment is commonly based on propagation numerical models for earthquake-generated tsunamis and can be approached through both probabilistic and determinis...

  4. Cetaceans and gillnet fisheries in Mexico, Central America and the Wider Caribbean: a preliminary review

    OpenAIRE

    Vidal, O.; Van Waerebeek, K.; Findley, L.T.

    1994-01-01

    This paper reviews published and unpublished information on the mortality of cetaceans in gillnets in Mexico, Central America and the wider Caribbean. Data on this incidental mortality are provided from only nine of the 36 nations in the area (Colombia, the Dominican Republic. French Guiana, Honduras, Mexico. Panama, Surinam, Trinidad and Tobago, and Venezuela); the lack of mortality records from the other countries reflects poor or non-existent documentation. We surveyed those types of passi...

  5. A dynamic landslide hazard assessment system for Central America and Hispaniola

    Directory of Open Access Journals (Sweden)

    D. B. Kirschbaum

    2015-04-01

    Full Text Available Landslides pose a serious threat to life and property in Central America and the Caribbean Islands. In order to allow regionally coordinated situational awareness and disaster response, an online decision support system was created. At its core is a new flexible framework for evaluating potential landslide activity in near real-time: Landslide Hazard Assessment for Situational Awareness. This framework was implemented in Central America and the Caribbean by integrating a regional susceptibility map and satellite-based rainfall estimates into a binary decision tree, considering both daily and antecedent rainfall. Using a regionally distributed, percentile-based threshold approach, the model outputs a pixel-by-pixel nowcast in near real-time at a resolution of 30 arcsec to identify areas of moderate and high landslide hazard. The daily and antecedent rainfall thresholds in the model are calibrated using a subset of the Global Landslide Catalog in Central America available for 2007–2013. The model was then evaluated with data for 2014. Results suggest reasonable model skill over Central America and poorer performance over Hispaniola, due primarily to the limited availability of calibration and validation data. The landslide model framework presented here demonstrates the capability to utilize globally available satellite products for regional landslide hazard assessment. It also provides a flexible framework to interchange the indiviual model components and adjust or calibrate thresholds based on access to new data and calibration sources. The availability of free, satellite-based near real-time rainfall data allows the creation of similar models for any study area with a spatiotemporal record of landslide events. This method may also incorporate other hydrological or atmospheric variables such as numerical weather forecasts or satellite-based soil moisture estimates within this decision tree approach for improved hazard analysis.

  6. Neoliberal Forms of Capital and The Rise of Social Movement Partyism in Central America

    OpenAIRE

    Paul Almeida

    2015-01-01

    Historical shifts in global economic formations shape the strategies of resistance movements in the global South. Neoliberal forms of economic development over the past thirty years in Central America have weakened traditional actors sponsoring popular mobilization such as labor unions and rural cooperatives. At the same time, the free market reforms produced new threats to economic livelihood and well-being throughout the region. The neoliberal measures that have generated the greatest level...

  7. Seismic imaging of the Cocos plate subduction zone system in central Mexico

    OpenAIRE

    Kim, YoungHee; Miller, Meghan S.; Pearce, Frederick; Clayton, Robert W.

    2012-01-01

    Broadband data from the Meso-America Subduction Experiment (MASE) line in central Mexico were used to image the subducted Cocos plate and the overriding continental lithosphere beneath central Mexico using a generalized radon transform based migration. Our images provide insight into the process of subducting relatively young oceanic lithosphere and its complex geometry beneath continental North America. The converted and reverberated phase image shows complete horizontal tectonic underplatin...

  8. Modeling the Agroecological Land Suitability for Coffea arabica L. in Central America

    Science.gov (United States)

    Lara, Leonel; Rasche, Livia; Schneider, Uwe

    2016-04-01

    Coffee production is an important income source for small farms in Central America, but climate change threatens the production. In order to develop efficient adaptation strategies, an assessment of local conditions and opportunities is essential. Lack or uncertainty of information are common challenges for such assessments. A tool to resolve these challenges is Bayesian network analysis. In this study, we developed ALECA, the first Bayesian network model to evaluate the agroecological land suitability for Coffea arabica L. A new set of suitability functions was created and subsequently used to populate the conditional probability tables of the variables. The variables include temperature, precipitation and dry season length for the climate, slope and aspect for the landform, and soil pH, cation exchange capacity and texture for the soil component. We validated ALECA by comparing a map of current coffee areas, and specific coffee areas with known suitability for coffee production in Central America to the suitability evaluations of the model; and proceeded to explore 1) the capabilities of the model to manage data uncertainty, and 2) the changes to suitability scores under climate change. The results showed that the area suitable for coffee production will decline in Central America under climate change, underlining the need for models like ALECA, which can be used to produce reliable land evaluations at local, national and regional scales under uncertainty.

  9. Parvitermes (Isoptera, Termitidae, Nasutitermitinae) in Central America: Two new termite species and reassignment of Nasutitermes mexicanus

    Science.gov (United States)

    Scheffrahn, Rudolf H.

    2016-01-01

    Abstract The termite genus Parvitermes is now recognized on the Central American mainland to include Parvitermes mexicanus, new combination (previously in Nasutitermes) and two new species, Parvitermes mesoamericanus sp. n. and Parvitermes yucatanus sp. n., herein described from soldiers and workers. These three species, nine West Indian Parvitermes, and Antillitermes subtilis all share characteristic enteric valve spines that orientate against intestinal flow. All species are subterranean nesters and cellulose feeders. Evidence is mounting that generic-level endemicity may be completely absent among the West Indian nasutitermitine fauna and that its origins stem from Central America. PMID:27667954

  10. Making central-local relations work:Comparing America and China environmental governance systems

    Institute of Scientific and Technical Information of China (English)

    Dan GUTTMAN; SONG Yaqin

    2007-01-01

    The challenge of making central requirements work at local levels is a common problem for environmental governance throughout the world.Countries can learn from one another's approaches,but must understand the local con text in which they are set.This paper compares the features of the China and US environmental governance systems that need be understood by those working between the systems.Key features include:(1) common values which shape the environmental governance choices in both countries,but which may have different practical meanings in each country;(2) America's common law-based environmental governance system,and China's civil law system,which involves plan(s)as well as law;(3) America's Federal central-local system,and China's unitary central local system.This paper concludes by suggesting areas in which further comparative understanding may be of value,including:(1) better under standing of the role of plan and law in China's governance system;(2) comparing the American Federal-state agreement system for implementation of environmental law with the China central-local system of target responsibility agreements for plan implementation;(3) improving understanding of nongovernmental resources needed to assure compliance with environmental laws and plans;(4) identifying institutions that can coordinate central-local and cross-border environmental governance.

  11. Prevalence, Distributions and Determinants of Obesity and Central Obesity in the Southern Cone of America

    Science.gov (United States)

    Bazzano, Lydia; Rubinstein, Adolfo; Calandrelli, Matias; Chen, Chung-Shiuan; Elorriaga, Natalia; Gutierrez, Laura; Manfredi, Jose A.; Seron, Pamela; Mores, Nora; Poggio, Rosana; Ponzo, Jacqueline; Olivera, Hector; He, Jiang; Irazola, Vilma E.

    2016-01-01

    Background Obesity is a major determinant of cardiovascular disease in South America. However, population-based data are limited. Methods A total of 7,524 women and men, aged 35 to 74 years old, were randomly selected from 4 cities in the Southern Cone of Latin America between February 2010 and December 2011. Obesity clinical measurements and cardiovascular risk factors were measured using standard methodology. Results The prevalence of obesity and central obesity were 35.7% and 52.9%, respectively. The prevalence of obesity and central obesity were higher in women, and even higher in women with lower education compared with women with higher education. In men and women obesity was associated with a higher prevalence of diabetes, odds ratio (OR) 2.38 (95% Confidence Interval [CI]: 1.86 to 3.05) and 3.01 (95%CI 2.42 to 3.74) respectively, hypertension (OR 2.79 (95%CI 2.32 to 3.36) and 2.40 (95%CI 2.05 to 2.80) respectively, dyslipidemia (OR 1.83 (95%CI 1.50 to 2.24) and 1.69 (95%CI 1.45 to 1.98), respectively, low physical activity (OR 1.38(95%CI 1.14 to 1.68) and 1.38 (95%CI 1.18 to 1.62) respectively and a lower prevalence of smoking (OR, 0.65 (95%CI 0.53 to 0.80) and 0.58(95%CI 0.48 to 0.70) respectively. Conclusions Obesity and central obesity are highly prevalent in the general population in the Southern Cone of Latin America and are strongly associated with cardiovascular risk factor prevalence. These data suggest that efforts toward prevention, treatment, and control of obesity should be a public health priority in the Southern Cone of Latin America. PMID:27741247

  12. SHRIMP zircon dating and LA-ICPMS Hf analysis of early Precambrian rocks from drill holes into the basement beneath the Central Hebei Basin, North China Craton

    Institute of Scientific and Technical Information of China (English)

    Yusheng Wan; Runlong Fan; Huiyi Sun; Xianzheng Zhao; Zejiu Wang; Dunyi Liu; Alfred Kröner; Chunyan Dong; Hangqian Xie; Yuansheng Geng; Yuhai Zhang

    2014-01-01

    The Central Hebei Basin (CHB) is one of the largest sedimentary basins in the North China Craton, extending in a northeastesouthwest direction with an area of>350 km2. We carried out SHRIMP zircon dating, Hf-in-zircon isotopic analysis and a whole-rock geochemical study on igneous and metasedi-mentary rocks recovered from drill holes that penetrated into the basement of the CHB. Two samples of gneissic granodiorite (XG1-1) and gneissic quartz diorite (J48-1) have magmatic ages of 2500 and 2496 Ma, respectively. Their zircons also record metamorphic ages of 2.41e2.51 and w2.5 Ga, respec-tively. Compared with the gneissic granodiorite, the gneissic quartz diorite has higher SREE contents and lower Eu/Eu* and (La/Yb)n values. Two metasedimentary samples (MG1, H5) mainly contain w2.5 Ga detrital zircons as well as late Paleoproterozoic metamorphic grains. The zircons of different origins haveεHf (2.5 Ga) values and Hf crustal model ages ranging from 0 to 5 and 2.7 to 2.9 Ga, respectively. Therefore, w2.5 Ga magmatic and Paleoproterozoic metasedimentary rocks and late Neoarchean to early Paleoproterozoic and late Paleoproterozoic tectono-thermal events have been identified in the basement beneath the CHB. Based on regional comparisons, we conclude that the early Precambrian basement beneath the CHB is part of the North China Craton.

  13. Spanish Cooperation with Central America: Political will or Transfer of Resources?

    Directory of Open Access Journals (Sweden)

    Mª Àngels Miralpeix i Güell

    1995-11-01

    Full Text Available The economies of the six states of Central America do not form a homogeneous block although they share the common denominators of underdevelopment and dependence. The great dependence of Central American economies on only a few export products whose value has been drastically reduced in international markets was one of the fundamental causes of the economic crisis. The reactivation of the subregional economy largely depends on the opening up of foreign markets, the availability of modern technology, debt renegotiation and the fostering of direct investments.Spanish foreign policy towards Central America has been characterized by a clear political committment to the peace process which set it on the long road towards the end of the so-called Central American crisis. But we can show that the Spanish Policy for Development and Cooperation towards the isthmus has not always been translated into the transfer of resources. The present study which has, as its objective, the analysis of this policy, is based on the study of the PACI-Report (1990-1992 and on the PACIPrevisions (1987-1989 and 1993-1994 given the non-availability of its documented achievements in these years. In order that the political committments taken on by Spain are translated into the assuming of economic responsibilites, it is inevitable that the cooperation be largely technical, based on projects designed in connection with the governments of the isthmus as well as with regional institutions.Political peace will be impossible to reach if the grave economic and social problems are not solved and if the process of democratization and modernization of the State is not consolidated. All these challenges cannot be confronted without intense external support such as that given during the political crisis; regional integration both political (strengthening the Central American Parlament and economic (reactivation of the Central American Common Market offers a clear opportunity for

  14. Scorpionism in Central America, with special reference to the case of Panama

    Directory of Open Access Journals (Sweden)

    A Borges

    2012-01-01

    Full Text Available Scorpionism in the Americas occurs mainly in Mexico, northern South America and southeast Brazil. This article reviews the local scorpion fauna, available health statistics, and the literature to assess scorpionism in Central America. Notwithstanding its high toxicity in Mexico, most scorpion sting cases in Guatemala, Belize, El Salvador, Nicaragua, and Costa Rica are produced by species in the genus Centruroides that are only mildly toxic to humans despite the existence of ion channel-active toxins in their venoms. Regional morbidity is low with the exception of Panama, where an incidence of 52 cases per 100,000 inhabitants was recorded for 2007, with 28 deaths from 1998 to 2006. Taxa belonging to the genus Tityus (also present in the Atlantic coast of Costa Rica are responsible for fatalities in Panama, with Tityus pachyurus being the most important species medically. Most Tityus species inhabiting Panama are also found in northern South America from which they probably migrated upon closure of the Panamanian isthmus in the Miocene era. Incorporation of Panama as part of the northern South American endemic area of scorpionism is thereby suggested based on the incidence of these accidents and the geographical distribution of Panamanian Tityus species.

  15. Landscape evolution within a retreating volcanic arc, Costa Rica, Central America

    Science.gov (United States)

    Marshall, Jeffrey S.; Idleman, Bruce D.; Gardner, Thomas W.; Fisher, Donald M.

    2003-05-01

    Subduction of hotspot-thickened seafloor profoundly affects convergent margin tectonics, strongly affecting upper plate structure, volcanism, and landscape evolution. In southern Central America, low-angle subduction of the Cocos Ridge and seamount domain largely controls landscape evolution in the volcanic arc. Field mapping, stratigraphic correlation, and 40Ar/39Ar geochronology for late Cenozoic volcanic rocks of central Costa Rica provide new insights into the geomorphic response of volcanic arc landscapes to changes in subduction parameters (slab thickness, roughness, dip). Late Neogene volcanism was focused primarily along the now-extinct Cordillera de Aguacate. Quaternary migration of the magmatic front shifted volcanism northeastward to the Caribbean slope, creating a new topographic divide and forming the Valle Central basin. Stream capture across the paleo Aguacate divide led to drainage reversal toward the Pacific slope and deep incision of reorganized fluvial networks. Pleistocene caldera activity generated silicic ash flows that buried the Valle Central and descended the Tárcoles gorge to the Orotina debris fan at the coast. Growth of the modern Cordillera Central accentuated relief along the new divide, establishing the Valle Central as a Pacific slope drainage basin. Arc migration, relocation of the Pacific-Caribbean drainage divide, and formation of the Valle Central basin resulted from slab shallowing as irregular, hotspot-thickened crust entered the subduction zone. The geomorphic evolution of volcanic arc landscapes is thus highly sensitive to changes in subducting plate character.

  16. A crustal section of northern Central America as inferred from wide angle reflections from shallow earthquakes

    Science.gov (United States)

    Kim, J. J.

    A three-layered crustal structure for a portion of northern Central America is derived using both travel time and amplitude data from seismograms recorded at Tegucigalpa, Honduras. The sources are shallow earthquakes that occurred along the Motagua fault in Guatemala 200 to 450 km (25-50 seconds in terms of S-P time) from the station. Since ray paths are almost parallel to the axis of the Middle America trench, approximately 250 km away, a homogeneous, horizontally layered crust may be reasonably assumed. At this distance range, which is far beyond critical distance for reflections from within the crust, shallow sources always generate a small first arrival followed by several large later arrivals. The first arrival is interpreted as Pn (the head wave from the Mohorovicic discontinuity) and the later arrivals are interpreted as wide angle (over-critical) reflections from layer boundaries. Three wide angle reflections (PmP, PiP, and PgP) are identified.

  17. Climate change in Central America and Mexico: regional climate model validation and climate change projections

    Energy Technology Data Exchange (ETDEWEB)

    Karmalkar, Ambarish V. [University of Oxford, School of Geography and the Environment, Oxford (United Kingdom); Bradley, Raymond S. [University of Massachusetts, Department of Geosciences, Amherst, MA (United States); Diaz, Henry F. [NOAA/ESRL/CIRES, Boulder, CO (United States)

    2011-08-15

    Central America has high biodiversity, it harbors high-value ecosystems and it's important to provide regional climate change information to assist in adaptation and mitigation work in the region. Here we study climate change projections for Central America and Mexico using a regional climate model. The model evaluation shows its success in simulating spatial and temporal variability of temperature and precipitation and also in capturing regional climate features such as the bimodal annual cycle of precipitation and the Caribbean low-level jet. A variety of climate regimes within the model domain are also better identified in the regional model simulation due to improved resolution of topographic features. Although, the model suffers from large precipitation biases, it shows improvements over the coarse-resolution driving model in simulating precipitation amounts. The model shows a dry bias in the wet season and a wet bias in the dry season suggesting that it's unable to capture the full range of precipitation variability. Projected warming under the A2 scenario is higher in the wet season than that in the dry season with the Yucatan Peninsula experiencing highest warming. A large reduction in precipitation in the wet season is projected for the region, whereas parts of Central America that receive a considerable amount of moisture in the form of orographic precipitation show significant decreases in precipitation in the dry season. Projected climatic changes can have detrimental impacts on biodiversity as they are spatially similar, but far greater in magnitude, than those observed during the El Nino events in recent decades that adversely affected species in the region. (orig.)

  18. Characterising droughts in Central America with uncertain hydro-meteorological data

    Science.gov (United States)

    Quesada Montano, B.; Westerberg, I.; Wetterhall, F.; Hidalgo, H. G.; Halldin, S.

    2015-12-01

    Droughts studies are scarce in Central America, a region frequently affected by droughts that cause significant socio-economic and environmental problems. Drought characterisation is important for water management and planning and can be done with the help of drought indices. Many indices have been developed in the last decades but their ability to suitably characterise droughts depends on the region of application. In Central America, comprehensive and high-quality observational networks of meteorological and hydrological data are not available. This limits the choice of drought indices and denotes the need to evaluate the quality of the data used in their calculation. This paper aimed to find which combination(s) of drought index and meteorological database are most suitable for characterising droughts in Central America. The drought indices evaluated were the standardised precipitation index (SPI), deciles (DI), the standardised precipitation evapotranspiration index (SPEI) and the effective drought index (EDI). These were calculated using precipitation data from the Climate Hazards Group Infra-Red Precipitation with station (CHIRPS), CRN073, the Climate Research Unit (CRU), ERA-Interim and station databases, and temperature data from the CRU database. All the indices were calculated at 1-, 3-, 6-, 9- and 12-month accumulation times. As a first step, the large-scale meteorological precipitation datasets were compared to have an overview of the level of agreement between them and find possible quality problems. Then, the performance of all the combinations of drought indices and meteorological datasets were evaluated against independent river discharge data, in form of the standardised streamflow index (SSI). Results revealed the large disagreement between the precipitation datasets; we found the selection of database to be more important than the selection of drought index. We found that the best combinations of meteorological drought index and database were

  19. Climate change in Central America and Mexico: regional climate model validation and climate change projections

    Science.gov (United States)

    Karmalkar, Ambarish V.; Bradley, Raymond S.; Diaz, Henry F.

    2011-08-01

    Central America has high biodiversity, it harbors high-value ecosystems and it's important to provide regional climate change information to assist in adaptation and mitigation work in the region. Here we study climate change projections for Central America and Mexico using a regional climate model. The model evaluation shows its success in simulating spatial and temporal variability of temperature and precipitation and also in capturing regional climate features such as the bimodal annual cycle of precipitation and the Caribbean low-level jet. A variety of climate regimes within the model domain are also better identified in the regional model simulation due to improved resolution of topographic features. Although, the model suffers from large precipitation biases, it shows improvements over the coarse-resolution driving model in simulating precipitation amounts. The model shows a dry bias in the wet season and a wet bias in the dry season suggesting that it's unable to capture the full range of precipitation variability. Projected warming under the A2 scenario is higher in the wet season than that in the dry season with the Yucatan Peninsula experiencing highest warming. A large reduction in precipitation in the wet season is projected for the region, whereas parts of Central America that receive a considerable amount of moisture in the form of orographic precipitation show significant decreases in precipitation in the dry season. Projected climatic changes can have detrimental impacts on biodiversity as they are spatially similar, but far greater in magnitude, than those observed during the El Niño events in recent decades that adversely affected species in the region.

  20. Seismic hazard maps of Mexico, the Caribbean, and Central and South America

    Science.gov (United States)

    Tanner, James G.; Shedlock, Kaye M.

    2004-10-01

    The growth of megacities in seismically active regions around the world often includes the construction of seismically unsafe buildings and infrastructures due to an insufficient knowledge of existing seismic hazard and/or economic constraints. Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. We have produced a suite of seismic hazard estimates for Mexico, the Caribbean, and Central and South America. One of the preliminary maps in this suite served as the basis for the Caribbean and Central and South America portion of the Global Seismic Hazard Map (GSHM) published in 1999, which depicted peak ground acceleration (pga) with a 10% chance of exceedance in 50 years for rock sites. Herein we present maps depicting pga and 0.2 and 1.0 s spectral accelerations (SA) with 50%, 10%, and 2% chances of exceedance in 50 years for rock sites. The seismicity catalog used in the generation of these maps adds 3 more years of data to those used to calculate the GSH Map. Different attenuation functions (consistent with those used to calculate the U.S. and Canadian maps) were used as well. These nine maps are designed to assist in global risk mitigation by providing a general seismic hazard framework and serving as a resource for any national or regional agency to help focus further detailed studies required for regional/local needs. The largest seismic hazard values in Mexico, the Caribbean, and Central and South America generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes. High hazard values occur in areas where shallow-to-intermediate seismicity occurs frequently.

  1. Seismic hazard maps of Mexico, the Caribbean, and Central and South America

    Science.gov (United States)

    Tanner, J.G.; Shedlock, K.M.

    2004-01-01

    The growth of megacities in seismically active regions around the world often includes the construction of seismically unsafe buildings and infrastructures due to an insufficient knowledge of existing seismic hazard and/or economic constraints. Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. We have produced a suite of seismic hazard estimates for Mexico, the Caribbean, and Central and South America. One of the preliminary maps in this suite served as the basis for the Caribbean and Central and South America portion of the Global Seismic Hazard Map (GSHM) published in 1999, which depicted peak ground acceleration (pga) with a 10% chance of exceedance in 50 years for rock sites. Herein we present maps depicting pga and 0.2 and 1.0 s spectral accelerations (SA) with 50%, 10%, and 2% chances of exceedance in 50 years for rock sites. The seismicity catalog used in the generation of these maps adds 3 more years of data to those used to calculate the GSH Map. Different attenuation functions (consistent with those used to calculate the U.S. and Canadian maps) were used as well. These nine maps are designed to assist in global risk mitigation by providing a general seismic hazard framework and serving as a resource for any national or regional agency to help focus further detailed studies required for regional/local needs. The largest seismic hazard values in Mexico, the Caribbean, and Central and South America generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes. High hazard values occur in areas where shallow-to-intermediate seismicity occurs frequently. ?? 2004 Elsevier B.V. All rights reserved.

  2. Diarrhea and respiratory symptoms among travelers to Asia, Africa, and South and Central America from Scotland.

    Science.gov (United States)

    Redman, Christopher Allan; Maclennan, Alice; Wilson, Eleanor; Walker, Eric

    2006-01-01

    Surveillance using admissions to hospital, while being useful, is a poor indicator of the real incidence of disease encountered by travelers. An alternative is self-reported illness among those who attended at a pretravel clinic prior to their travels. Estimates of incidence and risk factors were determined for attendees at a travel clinic in Scotland using a questionnaire. Analysis for risk factors was carried out for those travelers visiting countries in Africa, Asia, or South and Central America, who had traveled for 1 week or more and had returned between 1997 and 2001 (N= 4,856). Multivariate logistic regression was used to test the hypotheses that time abroad and age-group would be significant for both respiratory and diarrheal symptoms regardless of which of the three geographical areas are visited. From 2006 returned questionnaires (response rate = 41.3%), diarrhea and respiratory symptoms were reported by 44.2 and 16.8% of respondents, respectively; the incidence was significantly greater among travelers to Asia for both diarrheal (55.5%) and respiratory (23.7%) symptoms than among travelers to Africa (36.6 and 12.2%, respectively) or South and Central America (39.5 and 16.2%, respectively). For diarrhea, age was a highly significant risk factor for travelers to Asia, South and Central America, and Africa. Being a self-organized tourist/backpacker, traveling to Asia was associated with increased risk, while for Africa and South and Central America visiting family or friends was associated with a lower risk. For travelers to Asia, traveling to the Indian subcontinent was significantly associated with increased risk. The majority of travelers had an adverse event while traveling abroad, with diarrhea and respiratory conditions being especially common despite attending a travel clinic for advice prior to departure. However, the limitations of this surveillance-based strategy have highlighted the requirement for more research to understand more fully the

  3. Interannual variability of the midsummer drought in Central America and the connection with sea surface temperatures

    Science.gov (United States)

    Maldonado, Tito; Rutgersson, Anna; Alfaro, Eric; Amador, Jorge; Claremar, Björn

    2016-04-01

    The midsummer drought (MSD) in Central America is characterised in order to create annual indexes representing the timing of its phases (start, minimum and end), and other features relevant for MSD forecasting such as the intensity and the magnitude. The MSD intensity is defined as the minimum rainfall detected during the MSD, meanwhile the magnitude is the total precipitation divided by the total days between the start and end of the MSD. It is shown that the MSD extends along the Pacific coast, however, a similar MSD structure was detected also in two stations in the Caribbean side of Central America, located in Nicaragua. The MSD intensity and magnitude show a negative relationship with Niño 3.4 and a positive relationship with the Caribbean low-level jet (CLLJ) index, however for the Caribbean stations the results were not statistically significant, which is indicating that other processes might be modulating the precipitation during the MSD over the Caribbean coast. On the other hand, the temporal variables (start, minimum and end) show low and no significant correlations with the same indexes.The results from canonical correlation analysis (CCA) show good performance to study the MSD intensity and magnitude, however, for the temporal indexes the performance is not satisfactory due to the low skill to predict the MSD phases. Moreover, we find that CCA shows potential predictability of the MSD intensity and magnitude using sea surface temperatures (SST) with leading times of up to 3 months. Using CCA as diagnostic tool it is found that during June, an SST dipole pattern upon the neighbouring waters to Central America is the main variability mode controlling the inter-annual variability of the MSD features. However, there is also evidence that the regional waters are playing an important role in the annual modulation of the MSD features. The waters in the PDO vicinity might be also controlling the rainfall during the MSD, however, exerting an opposite effect at

  4. The social perspective of desertification: Analysis of the public administration perception in Central America

    International Nuclear Information System (INIS)

    Desertification is a complex problem and not only represents terrestrial ecosystems degradation. Today, it is well known that this process is linked to environmental deterioration as well as to economic and social factors, producing relevant impact in food security, poverty, migration and imbalance in many countries. Desertification perception analysis is essential in the design of the policies to fight this problem. Perception analysis in Central America is a very controversial issue and should be part of administration instruments and application strategies such as international agreements that will be included in public policies of the different States.

  5. Nature and melting processes of the lithosphere beneath the North-East Qiangqtang terrane, Central Tibet, during Eocene times.

    Science.gov (United States)

    Goussin, Fanny; Guillot, Stéphane; Schulmann, Karel; Cordier, Carole; Oliot, Emilien; Replumaz, Anne; Roperch, Pierrick; Dupont-Nivet, Guillaume

    2016-04-01

    pyroxene xenocrysts, suggest that enrichment occurred at the source by metasomatism of the lithospheric mantle. Further work will precise which mechanisms could have accounted for such a metasomatism of the mantle beneath the Northern Qiangtang terrane during Eocene, and whether the lower crust had an autochtonous or allochtonous nature.

  6. Achievements and pending issues in psychiatric reform in Panama and Spanish speaking Central America

    Directory of Open Access Journals (Sweden)

    Víctor Aparicio Basauri

    2012-11-01

    Full Text Available The return to democracy in Central America has led to economic and social development policies that have had effects on the health sector and, likewise, on mental health plans. From 2001, the World Health Organization (WHO developed a mental health strategy with the purpose of reducing the gap between mental health population needs and resources that are effectively assigned to this area. This article describes and analyzes the results of mental health care systems assessments that were undertaken in the Central American countries based on the Assessment Instrument for Mental Health Systems (WHO. These results lead to optimism in the implementation of the Regional Strategy and Action Plan for Mental Health of the Pan-American Health Organization for 2010-2019, but also open the way to new challenges for the region.

  7. SALTRA: a regional program for workers' health and sustainable development in Central America.

    Science.gov (United States)

    Wesseling, Catharina; Aragón, Aurora; Elgstrand, Kaj; Flores, Reinaldo; Hogstedt, Christer; Partanen, Timo

    2011-01-01

    In 2003, the university-based Program on Work and Health in Central America, SALTRA, was launched to build national and regional capacities in occupational safety and health with the goal of preventing and reducing poverty in Central America. SALTRA has implemented 20 projects including action projects in priority sectors (e.g., construction, sugarcane, hospitals, migrant coffee workers); strengthening of surveillance (occupational health profiles, carcinogenic exposures, fatal injuries and pesticides); a participatory model for training and risk monitoring by workers; building occupational health capacity for professionals, employers, and workers, with collaborating networks between the countries; strengthening of universities in work, environment, and health; studies of serious occupational and environmental situations; communication channels; and continued efforts to raise political awareness. SALTRA has placed issues of workers' health on political, business, and academic agendas throughout the region and has laid the foundations for achieving substantial future improvements in health conditions of all workers in the region. External evaluators envisioned SALTRA as an innovative development model.

  8. Do pathogens become more virulent as they spread? Evidence from the amphibian declines in Central America.

    Science.gov (United States)

    Phillips, Ben L; Puschendorf, Robert

    2013-09-01

    The virulence of a pathogen can vary strongly through time. While cyclical variation in virulence is regularly observed, directional shifts in virulence are less commonly observed and are typically associated with decreasing virulence of biological control agents through coevolution. It is increasingly appreciated, however, that spatial effects can lead to evolutionary trajectories that differ from standard expectations. One such possibility is that, as a pathogen spreads through a naive host population, its virulence increases on the invasion front. In Central America, there is compelling evidence for the recent spread of pathogenic Batrachochytrium dendrobatidis (Bd) and for its strong impact on amphibian populations. Here, we re-examine data on Bd prevalence and amphibian population decline across 13 sites from southern Mexico through Central America, and show that, in the initial phases of the Bd invasion, amphibian population decline lagged approximately 9 years behind the arrival of the pathogen, but that this lag diminished markedly over time. In total, our analysis suggests an increase in Bd virulence as it spread southwards, a pattern consistent with rapid evolution of increased virulence on Bd's invading front. The impact of Bd on amphibians might therefore be driven by rapid evolution in addition to more proximate environmental drivers.

  9. Phylogeny and biogeography of the Poecilia sphenops species complex (Actinopterygii, Poeciliidae) in Central America.

    Science.gov (United States)

    Alda, Fernando; Reina, Ruth G; Doadrio, Ignacio; Bermingham, Eldredge

    2013-03-01

    We inferred the phylogenetic relationships among members of the Poecilia sphenops species complex to resolve the colonization process and radiation of this group in Central America. We analyzed 2550 base pairs (bp) of mitochondrial DNA (mtDNA), including ATP synthase 6 and 8, cytochrome oxidase subunit I and NADH dehydrogenase subunit 2 genes, and 906bp of the nuclear S7 ribosomal protein of 86 ingroup individuals from 61 localities spanning most of its distribution from Mexico to Panama. Our mitochondrial data rendered a well-supported phylogeny for the P. sphenops complex that differed with the nuclear data set topology, which did not recover the monophyly of the P. mexicana mitochondrial lineage. Coalescent-based simulations tests indicated that, although hybridization cannot be completely ruled out, this incongruence is most likely due to incomplete lineage sorting in this group, which also showed the widest geographic distribution. A single colonization event of Central America from South America was estimated to have occurred between the early Paleocene and Oligocene (53-22millionyears ago). Subsequently, two largely differentiated evolutionary lineages diverged around the Early Oligocene-Miocene (38-13million years ago), which are considered two separate species complexes: P. sphenops and P. mexicana, which can also be distinguished by their tricuspid and unicuspid inner jaw teeth, respectively. Ultimately, within lineage diversification occurred mainly during the Miocene (22-5million years ago). All major cladogenetic events predated the final closure of the Isthmus of Panama. The allopatric distribution of lineages together with the long basal internodes suggest that vicariance and long term isolations could be the main evolutionary forces promoting radiation in this group, although dispersal through water barriers might also have occurred. Lastly, our results suggest the need to review the current species distribution and taxonomy of the P. sphenops

  10. Seismogenic Structure Beneath Décollement Inferred from 2009/11/5 ML 6.2 Mingjian Earthquake in Central Taiwan

    Directory of Open Access Journals (Sweden)

    Che-Min Lin

    2014-01-01

    Full Text Available One decade after the 1999 Chi-Chi earthquake, central Taiwan experienced more strong ground shaking [Central Weather Bureau (CWB, intensity VII] induced by a ML 6.2 earthquake on 5th November 2009. This earthquake occurred in the Mingjian Township of Nantou County, only 12 km southwest of the Chi-Chi earthquake epicenter. The broadband microearthquake monitoring network operated by the National Center for Research on Earthquake Engineering (NCREE observed numerous aftershocks in the five days following the mainshock. The relocated aftershocks and the mainshock focal mechanism indicated a NE-SW striking fault dipping _ toward the northwest. This fault plane is inside the pre-Miocene basement and the rupture extends from the lower crust to 10 km depth just beneath the basal décollementdécollement of the thin-skinned model that is generally used to explain the regional tectonics in Taiwan. The fault plane is vertically symmetrical with the Chelungpu fault by the basal décollement.décollement. The NW-SE compressive stress of plate collision in Taiwan, as well as the deep tectonic background, resulted in the seismogenic structure of the Mingjian earthquake at this location.

  11. Localized double-array stacking analysis of PcP: D″ and ULVZ structure beneath the Cocos plate, Mexico, central Pacific, and north Pacific

    Science.gov (United States)

    Hutko, Alexander R.; Lay, Thorne; Revenaugh, Justin

    2009-01-01

    A large, high quality P-wave data set comprising short-period and broadband signals sampling four separate regions in the lowermost mantle beneath the Cocos plate, Mexico, the central Pacific, and the north Pacific is analyzed using regional one-dimensional double-array stacking and modelling with reflectivity synthetics. A data-screening criterion retains only events with stable PcP energy in the final data stacks used for modelling and interpretation. This significantly improves the signal stacks relative to including unscreened observations, allows confident alignment on the PcP arrival and allows tight bounds to be placed on P-wave velocity structure above the core–mantle boundary (CMB). The PcP reflections under the Cocos plate are well modelled without any ultra-low velocity zone from 5 to 20°N. At latitudes from 15 to 20°N, we find evidence for two P-wave velocity discontinuities in the D″ region. The first is ∼182 km above the CMB with a δln Vp of +1.5%, near the same depth as a weaker discontinuity (<+0.5%) observed from 5 to 15°N in prior work. The other reflector is ∼454 km above the CMB, with a δln Vp of +0.4%; this appears to be a shallower continuation of the joint P- and S-wave discontinuity previously detected south of 15° N, which is presumed to be the perovskite to post-perovskite phase transition. The data stacks for paths bottoming below Mexico have PcP images that are well matched with the simple IASP91 structure, contradicting previous inferences of ULVZ presence in this region. These particular data are not very sensitive to any D″ discontinuities, and simply bound them to be <∼2%, if present. Data sampling the lowermost mantle beneath the central Pacific confirm the presence of a ∼15-km thick ultra-low velocity zone (ULVZ) just above the CMB, with δln Vp and δln Vs of around −3 to −4% and −4 to −8%, respectively. The ULVZ models predict previous S-wave data stacks well. The data for this region

  12. Comparative phylogeography of Oryzomys couesi and Ototylomys phyllotis; historic and geographic implications for the Central America conformation

    Directory of Open Access Journals (Sweden)

    Tania Anaid Gutiérrez-García

    2013-12-01

    Full Text Available Central America is an ideal region for comparative phylogeographic studies because of its intricate geologic and biogeographic history, diversity of habitats and dynamic climatic and tectonic history. The aim of this work was to assess the phylogeography of two rodents codistributed throughout Central America, in order to identify if they show concordant genetic and phylogeographic patterns. The synopsis includes four parts: (1 an overview of the field of comparative phylogeography; (2 a detailed review that describes how genetic and geologic studies can be combined to elucidate general patterns of the biogeographic and evolutionary history of Central America; and a phylogeographic analysis of two species at both the (3 intraspecific and (4 comparative phylogeographic levels. The last incorporates specific ecological features and evaluates their influence on the species’ genetic patterns. Results showed a concordant genetic structure influenced by geographic distance for both rodents, but dissimilar dispersal patterns due to ecological features and life history. 

  13. Heat tracing to examine seasonal groundwater flow beneath a low-gradient stream in rural central Illinois, USA

    Science.gov (United States)

    Bastola, Hridaya; Peterson, Eric W.

    2016-02-01

    The thermal profile of a streambed is affected by a number of factors including: temperatures of stream water and groundwater, hydraulic conductivity, thermal conductivity, heat capacity of the streambed, and the geometry of hyporheic flow paths. Changes in these parameters over time cause changes in thermal profiles. In this study, temperature data were collected at depths of 30, 60, 90 and 150 cm at six streambed wells 5 m apart along the thalweg of Little Kickapoo Creek, in rural central Illinois, USA. This is a third-order low-gradient baseflow-fed stream. A positive temperature gradient with inflection at 90-cm depth was observed during the summer period. A negative temperature gradient with inflection at 30 cm was observed during the winter period, which suggests greater influence of stream-water temperatures in the substrate during the summer. Thermal models of the streambed were built using VS2DHI to simulate the thermal profiles observed in the field. Comparison of the parameters along with analysis of temperature envelopes and Peclet numbers suggested greater upwelling and stability in temperatures during the winter than during the summer. Upwelling was more pronounced in the downstream reach of the pool in the riffle and pool sequence.

  14. Neogene north American-Caribbean plate boundary across Northern Central America: Offset along the polochic fault

    Science.gov (United States)

    Burkart, Burke

    1983-12-01

    The Polochic fault was a segment of the North American-Caribbean plate boundary across Central America in the Neogene. Its 130 km of left slip was previously determined by matching structures and stratigraphie outcrop patterns of northwest and central Guatemala across the fault. Additional support for the model and the youthfulness of the recorded offset comes from an essentially perfect match of major geomorphic features across the fault. A reconstruction process which eliminates 123 km of left slip brings together rivers and drainage divides that existed before the Polochic became active. With the reconstruction carried across the isthmus on an east-west fault the regional structural geology assumes the coherent pattern of a continuous orogenic belt whose geometry is compatible with the model of collisional tectonics centered on the Motagua "suture zone". Confined within this belt, narrowed to some 60 km by the reconstruction, lie the major Laramide thrusts, folds and tectonically emplaced serpentinites of Guatemala. Crystalline rocks of Guatemala re-join the Chiapas Massif and Paleozoic sedimentary rocks, exposed in the core of an almost-continuous anticlinorium, extend from southern Chiapas to Lake Izabal. The Polochic does not bend in eastern Guatemala but continues eastward to the Motagua fault where it dies. Westward drift of the northern block resulted in rifting which extended from eastern Guatemala into the Caribbean along the Cayman trough. The Honduras depression may represent an element of a triple junction along with the Polochic and Izabal-Cayman rift. The Polochic continues westward into the Pacific Ocean and offsets the Middle America trench. The Polochic has offset the Miocene volcanic belt of northern Central America, confirming the previous estimate of a Neogene time of movement. About 300 km of relative east-west Neogene displacement has been recorded on the Mid-Cayman rise, only 130 km of which can be accounted for across the Polochic. It is

  15. Simulating Climate Change in Central America Using PRECIS Regional Modeling System

    Science.gov (United States)

    Karmalkar, A. V.; Bradley, R. S.; Diaz, H. F.

    2006-12-01

    Highland tropical forests are rich in endemic species and crucial in maintaining freshwater resources in many regions. Much of their remarkable biodiversity is due to the steep climate gradients found on tropical mountains. These gradients are significantly altered due to warming, affecting many species living on the mountain slopes. Costa Rica's Monteverde Cloud Forest shows biological changes associated with changes in climatic patterns. Our goal is to understand climate change at areas of high relief in the tropics and its potential impacts on ecosystem dynamics. We address this question by focusing on Central America, which is considered to be a biodiversity hotspot. The model used is the UK Hadley Center PRECIS(Providing REgional Climates for Impact Studies) model. The model is based on HadAM3H, an improved version of the atmospheric component of the latest Hadley Center coupled AOGCM, HadCM3 and is forced at the lateral boundaries by HadAM3P GCM. The surface boundary conditions include observed SSTs and sea-ice. We carried out a baseline run (1961-1990) and a doubled CO2 run (SRES A2 2071-2100) at a resolution of 25 km (0.22°) over the region of Central America that includes several biodiversity hotspots. Model verification is performed by comparing control run results with observations and reanalysis data. Preliminary analysis shows that PRECIS has successfully captured present-day spatial and temporal climate variability that has been observed in Central America. Elevation dependency of temperature is one of the important results of this study and will be investigated in great detail. The SRES A2 run shows average warming of about 3K, with more warming at higher altitudes in general. Precipitation and relative humidity analysis shows drier conditions in the region in 2 × CO2 world. Additional techniques are being developed to better quantify model performance in areas of high relief. We plan to expand this project to other models, and to additional

  16. Drought assessment for cropland of Central America using course-resolution remote sensing data

    Science.gov (United States)

    Chen, C. F.; Nguyen, S. T.; Chen, C. R.; Chiang, S. H.; Chang, L. Y.; Khin, L. V.

    2015-12-01

    Drought is one of the most frequent and costliest natural disasters, which imposes enormous effects to human societies and ecosystems. Agricultural drought is referred to an interval of time, such as weeks or months, when the soil moisture supply of a region consistently falls below the appropriate moisture supply leading to negative impacts on agricultural production. Millions of households in Central America were dependent upon major food crops, including maize, beans, and sorghum, for their daily subsistence. In recent years, impacts of climate change through global warming in forms of higher temperature and widespread rainfall deficits have however triggered severe drought during the primera cropping season (April-August) in the study region, causing profound impacts on agriculture, crop production losses, increased market food prices, as well as food security issues. This study focuses on investigating agricultural droughts for cropland of Central America using the Moderate Resolution Imaging Spectroradiometer (MODIS) data. We processed the data for a normal year 2013 and an abnormal year 2014 using a simple vegetation health index (VHI) that is developed based on the temperature condition index (TCI) and vegetation condition index (VCI). The VHI results were validated using the Advanced Microwave Scanning Radiometer 2 (AMSR2) precipitation data and temperature vegetation dryness index (TVDI) that is developed based on the empirical analysis of TCI and VCI data. The correlation coefficients (r) obtained by comparisons between the VHI data and the AMSR2 precipitation and TVDI data were higher than 0.62 and -0.61, respectively. The severe drought was intensive during the dry season (January-April) and likely backed to normal conditions in May with the onset of rainy season. The larger area of serve drought was observed for the 2014 primera season, especially during April-July. When investigating the cultivated areas affected by severe drought in the primera

  17. Depositional conditions of the coal-bearing Hirka Formation beneath Late Miocene explosive volcanic products in NW central Anatolia, Turkey

    Indian Academy of Sciences (India)

    Mehmet Şener

    2007-04-01

    This work focuses on the relationship between the coal deposition and explosive volcanism of the Miocene basin, NW central Anatolia, Turkey. The coal-bearing Hirka Formation was deposited over the Galatian Andesitic Complex and/or massive lagoonal environments during the Miocene. The investigated lignite is a high ash (from 32 to 58%) and sulphur (from 1.43 to 3.03%) lignite which is petrographically characterised by a high humunite content. The mineral matter of the studied lignite samples is made up of mainly clay minerals (illite–smectite and kaolinite), plagioclase and quartz in Bolu coal field, clay minerals (illite–smectite, smectite and illite), quartz, calcite, plagioclase and gypsum in Seben coal field, quartz, K-feldspar, plagioclase and clay minerals (kaolinite and illite) in Kıbrıscık, and dolomite, quartz, clinoptilolite, opal CT and gypsum in C¸ amlıdere coal field. The differences in these four types of lignite with specific mineralogical patterns may be due to the explosive volcanic events and depositional conditions which changed from one coal field to the others. There is a zonation from SW to SE in the studied area for zeolites such as Opal CT+smectite-clinoptilolite-analcime-K-feldspar. Carbonate minerals are commonly calcite in Seben and Kıbrıscık coal fields. In Bolu, coal samples are devoid of calcite and dolomite. These analyses show that there is an increase in the amount of Mg and a decrease in the amount of Na from the northwestern part to the southern part in the study area.

  18. Multi-year GNSS monitoring of atmospheric IWV over Central and South America for climate studies

    Science.gov (United States)

    Bianchi, Clara Eugenia; Mendoza, Luciano Pedro Oscar; Fernández, Laura Isabel; Natali, María Paula; Meza, Amalia Margarita; Francisco Moirano, Juan

    2016-07-01

    Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazard assessment systems benefit from real-time observations, whereas long-term records contribute to climate studies. Nowadays, ground-based global navigation satellite system (GNSS) products have become widely employed, complementing satellite observations over the oceans. Although the past decade has seen a significant development of the GNSS infrastructure in Central and South America, its potential for atmospheric water vapour monitoring has not been fully exploited. With this in mind, we have performed a regional, 7-year-long and homogeneous analysis, comprising 136 GNSS tracking stations, obtaining high-rate and continuous observations of column-integrated water vapour and troposphere zenith total delay. As a preliminary application for this data set, we have estimated local water vapour trends, their significance, and their relation with specific climate regimes. We have found evidence of drying at temperate regions in South America, at a rate of about 2 % per decade, while a slow moistening of the troposphere over tropical regions is also weakly suggested by our results. Furthermore, we have assessed the regional performance of the empirical model GPT2w to blindly estimate troposphere delays. The model reproduces the observed mean delays fairly well, including their annual and semi-annual variations. Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited from the underlying atmospheric reanalysis. Additionally, the complete data set has been made openly available as supplementary material.

  19. Suitability of soil bioengineering techniques in Central America: a case study in Nicaragua

    Directory of Open Access Journals (Sweden)

    A. Petrone

    2008-02-01

    Full Text Available In the last few years "D. I. A. F." (Department of Agriculture and Forestry Engineering of Florence University, has been testing the effectiveness of Soil Bio-Engineering techniques in Central America. The focus of the present study was to find out which native plants were most suited for soil bio-engineering purposes, particularly in the realization of riverbank protection. Furthermore, we have also been aiming at economic efficiency. In the context of sustainable watershed management, these techniques seem to be appropriate, especially in underdeveloped countries. Concerning the plants to be used, we considered three native species, Gliricidia Sepium, Cordia dentata and Jatropha curcas, to be appropriate for this type of work. Economically speaking, the low cost of such interventions in underdeveloped countries, has been shown by the construction of riverbank protection using vegetated crib-walls in Nicaragua.

  20. Suitability of soil bioengineering techniques in Central America: a case study in Nicaragua

    Science.gov (United States)

    Petrone, A.; Preti, F.

    2008-10-01

    In the last few years "D. I. A. F." (Department of Agriculture and Forestry Engineering of Florence University), has been testing the effectiveness of soil bioengineering techniques in Central America. The focus of the present study was to find out which native plants were most suited for soil bioengineering purposes, particularly in the realization of riverbank protection in Nicaragua. Furthermore, we have also been aiming at economic efficiency. These techniques are appropriate for sustainable watershed management especially in underdeveloped countries. Concerning the plants to be used we experimented four native species. Gliricidia Sepium, Cordia dentata and Jatropha curcas are suitable for soil bioengineering more than Bursera Simaruba. Economically speaking, the sustainability of such interventions in underdeveloped countries, has been shown by the evaluation of the cost of riverbank protection using vegetated crib-walls in Nicaragua compared to the cost in different contexts.

  1. The Spanish decentralised international cooperation in Central America in the area of municipalism and decentralisation

    Directory of Open Access Journals (Sweden)

    Mariana Haedo

    2005-05-01

    Full Text Available In an attempt to link the international dimension with the local one, this article lays out an approach to the situation of Spanish decentralised international cooperation in the area of municipalism and decentralisation in the countries of Central America. In the firstplace, it offers a characterisation of the current state of Spanish decentralised cooperation in order to thus frame the cooperation actions carried out by the Barcelona Provincial Council; the UIM (Unión Iberoamericana de Municipios together with CEMCI (Centro de Estudios Municipales y de Cooperación Internacional; and the Confederación de Fondos de Cooperación y Solidaridad. Finally, it describes bankruptcies and it recovers some of the achievements ofthis kind of cooperation specifically in reference to the field of municipalism.

  2. Geothermal power plants of Mexico and Central America: a technical survey of existing and planned installations

    Energy Technology Data Exchange (ETDEWEB)

    DiPippo. R.

    1978-07-01

    In this report, the fifth in a series describing the geothermal power plants of the world, the countries of Mexico and of Central America are studied. The geothermal plants are located in areas of recent and active volcanism; the resources are of the liquid-dominated type. Details are given about the plants located at Cerro Prieto in Mexico and at Ahuachapan in El Salvador. In both cases, attention is paid to the geologic nature of the fields, the well programs, geofluid characteristics, energy conversion systems, materials of construction, effluent handling systems, economic factors and plant operating experience. Exploration and development activities are described for other promising geothermal areas in Mexico and El Salvador, along with those in the countries of Costa Rica, Nicaragua, Guatemala, Honduras, and Panama.

  3. First record of the invasive Asian fish tapeworm Bothriocephalus acheilognathi in Honduras, Central America

    Directory of Open Access Journals (Sweden)

    Salgado-Maldonado Guillermo

    2015-01-01

    Full Text Available This paper provides the first report of the invasive Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934, in Honduras. The cestode was found in Profundulus portillorum (Cyprinodontiformes: Profundulidae, which represents a new host record, and which is a member of a genus faced with a variety of conservation challenges, now potentially complicated by the presence of this pathogenic cestode. Nearly complete sequence data from the ITS-1 5.8S and ITS-2 regions corroborate the determination based on morphological characteristics. Several species of carp were introduced to Honduras for aquaculture purposes in the early 1980s and the presence of the Asian fish tapeworm in Honduras may be related to these introductions. In addition, this report documents the currently known geographical distribution of this parasite in Central America, first recorded from Panamá and now from Honduras.

  4. First record of the invasive Asian fish tapeworm Bothriocephalus acheilognathi in Honduras, Central America.

    Science.gov (United States)

    Salgado-Maldonado, Guillermo; Matamoros, Wilfredo A; Kreiser, Brian R; Caspeta-Mandujano, Juan Manuel; Mendoza-Franco, Edgar F

    2015-01-01

    This paper provides the first report of the invasive Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934, in Honduras. The cestode was found in Profundulus portillorum (Cyprinodontiformes: Profundulidae), which represents a new host record, and which is a member of a genus faced with a variety of conservation challenges, now potentially complicated by the presence of this pathogenic cestode. Nearly complete sequence data from the ITS-1 5.8S and ITS-2 regions corroborate the determination based on morphological characteristics. Several species of carp were introduced to Honduras for aquaculture purposes in the early 1980s and the presence of the Asian fish tapeworm in Honduras may be related to these introductions. In addition, this report documents the currently known geographical distribution of this parasite in Central America, first recorded from Panamá and now from Honduras.

  5. A new species of arboreal pitviper from the Atlantic versant of northern Central America.

    Science.gov (United States)

    Campbell, J A; Smith, E N

    2000-12-01

    A new species of green, prehensile-tailed pitviper of the genus Bothriechis is described from the Atlantic slopes of eastern Guatemala and western Honduras. This species appears to be most closely related to B. bicolor of the Pacific versant of Chiapas (Mexico) and Guatemala. Several other species of Bothriechis occur on the Atlantic versant of northern Central America, including two montane species, B. aurifer and B. marchi but, with one possible exception, these are not known to be sympatric with the new species and occur in different mountain ranges. The widespread B. schlegelii occurs up to at least 900 m on the Sierra de Caral, where the lowest elevation recorded for the new species is 885 m. PMID:11487920

  6. Characterization of Trypanosoma rangeli Strains Isolated in Central and South America: an Overview

    Directory of Open Access Journals (Sweden)

    Grisard Edmundo C

    1999-01-01

    Full Text Available Trypanosoma rangeli is a hemoflagelate parasite that infects domestic and sylvatic animals, as well as man, in Central and South America. T. rangeli has an overlapping distribution with T. cruzi, the etiological agent of Chagas disease, sharing several animal reservoirs and triatomine vectors. We have isolated T. rangeli strains in the State of Santa Catarina, in southern Brazil, which dramatically increased the distribution area of this parasite. This brief review summarizes several studies comparing T. rangeli strains isolated in Santa Catarina with others isolated in Colombia, Honduras and Venezuela. The different methods used include indirect immunofluorescence and western blot assays, lectin agglutination, isoenzyme electrophoresis and random amplified polymorphic DNA analysis, triatomine susceptibility, in vitro cell infection assays, and mini-exon gene analysis.

  7. Screening of anti-bacterial activity of medicinal plants from Belize (Central America).

    Science.gov (United States)

    Camporese, A; Balick, M J; Arvigo, R; Esposito, R G; Morsellino, N; De Simone, F; Tubaro, A

    2003-07-01

    Twenty-one extracts from seven herbal drugs, Aristolochia trilobata (Aristolochiaceae) leaves and bark, Bursera simaruba (Burseraceae) bark, Guazuma ulmifolia (Sterculiaceae) bark, Hamelia patens (Rubiaceae) leaves and Syngonium podophyllum (Araceae) leaves and bark, used in traditional medicine of Belize (Central America) as deep and superficial wound healers, were evaluated for their anti-bacterial properties. Activity was tested against standard strains of Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212. Almost all the extracts were able to inhibit the growth of one or more of the bacterial strains, except that of Enterococcus faecalis. For the first time an anti-microbial activity is reported for Aristolochia trilobata as well as for Syngonium podophyllum. The hexane extracts of Aristolochia trilobata leaves and bark were the most active extracts against Staphylococcus aureus (MIC=0.31 and 0.625mg/ml, respectively).

  8. Satellite-based detection of volcanic sulphur dioxide from recent eruptions in Central and South America

    Directory of Open Access Journals (Sweden)

    D. Loyola

    2008-01-01

    Full Text Available Volcanic eruptions can emit large amounts of rock fragments and fine particles (ash into the atmosphere, as well as several gases, including sulphur dioxide (SO2. These ejecta and emissions are a major natural hazard, not only to the local population, but also to the infrastructure in the vicinity of volcanoes and to aviation. Here, we describe a methodology to retrieve quantitative information about volcanic SO2 plumes from satellite-borne measurements in the UV/Visible spectral range. The combination of a satellite-based SO2 detection scheme and a state-of-the-art 3D trajectory model enables us to confirm the volcanic origin of trace gas signals and to estimate the plume height and the effective emission height. This is demonstrated by case-studies for four selected volcanic eruptions in South and Central America, using the GOME, SCIAMACHY and GOME-2 instruments.

  9. GIS Representation of Coal-Bearing Areas in North, Central, and South America

    Science.gov (United States)

    Tewalt, Susan J.; Kinney, Scott A.; Merrill, Matthew D.

    2008-01-01

    Worldwide coal consumption and international coal trade are projected to increase in the next several decades (Energy Information Administration, 2007). A search of existing literature indicates that in the Western Hemisphere, coal resources are known to occur in about 30 countries. The need exists to be able to depict these areas in a digital format for use in Geographic Information System (GIS) applications at small scales (large areas) and in visual presentations. Existing surficial geology GIS layers of the appropriate geologic age have been used as an approximation to depict the extent of coal-bearing areas in North, Central, and South America, as well as Greenland (fig. 1). Global surficial geology GIS data were created by the U.S. Geological Survey (USGS) for use in world petroleum assessments (Hearn and others, 2003). These USGS publications served as the major sources for the selection and creation of polygons to represent coal-bearing areas. Additional publications and maps by various countries and agencies were also used as sources of coal locations. GIS geologic polygons were truncated where literature or hardcopy maps did not indicate the presence of coal. The depicted areas are not adequate for use in coal resource calculations, as they were not adjusted for geologic structure and do not include coal at depth. Additionally, some coal areas in Central America could not be represented by the mapped surficial geology and are shown only as points based on descriptions or depictions from scientific publications or available maps. The provided GIS files are intended to serve as a backdrop for display of coal information. Three attributes of the coal that are represented by the polygons or points include geologic age (or range of ages), published rank (or range of ranks), and information source (published sources for age, rank, or physical location, or GIS geology base).

  10. Seismic hazard map of North and Central America and the Caribbean

    Directory of Open Access Journals (Sweden)

    K. M. Shedlock

    1999-06-01

    Full Text Available Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. National, state, and local governments, decision makers, engineers, planners, emergency response organizations, builders, universities, and the general public require seismic hazard estimates for land use planning, improved building design and construction (including adoption of building construction codes, emergency response preparedness plans, economic forecasts, housing and employment decisions, and many more types of risk mitigation. The seismic hazard map of North and Central America and the Caribbean is the concatenation of various national and regional maps, involving a suite of approaches. The combined maps and documentation provide a useful regional seismic hazard framework and serve as a resource for any national or regional agency for further detailed studies applicable to their needs. This seismic hazard map depicts Peak Ground Acceleration (PGA with a 10% chance of exceedance in 50 years. PGA, a short-period ground motion parameter that is proportional to force, is the most commonly mapped ground motion parameter because current building codes that include seismic provisions specify the horizontal force a building should be able to withstand during an earthquake. This seismic hazard map of North and Central America and the Caribbean depicts the likely level of short-period ground motion from earthquakes in a fifty-year window. Short-period ground motions effect short-period structures (e.g., one-to-two story buildings. The highest seismic hazard values in the region generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes.

  11. The Crust and Mantle Relationships Beneath Central and Southern Iberian Peninsula constrained by a 550 km long multiseismic transect

    Science.gov (United States)

    Ehsan, Siddique Akhtar; Carbonell, Ramon; Simancas, Jose Fernando; Martinez Poyatos, David; Azor, Antonio; Ayarza, Puy; Storti, Fabrizio

    2013-04-01

    A composite lithospheric cross section which is composed by data from controlled source multiseismic experiments strongly constrains the lithospheric structure of southwestern Iberia. The data includes coincident normal incidence and wide-angle profiles along an, approximately, 550 km long transect. This transect goes across, from North-to-South, the major tectonic zones that build up Southwestern part of the Iberian Peninsula (the Central Iberian Zone -CIZ-, the Ossa-Morena Zone -OMZ- and the South Portuguese Zone -SPZ-). The knowledge provided by these datasets constitutes the base to develop multidisciplinary models of the lithosphere. The multichannel deep seismic high resolution (60-90 fold) profiles, IBERSEIS & ALCUDIA were acquired in summer 2001 and 2007 are about 300 and 250 km long respectively. The transects image 20 s (TWTT), about 70 km depth. To address the crust and upper mantle structural relationships a reassessment of the normal incidence seismic reflection transect ALCUDIA has been carried out. We revised the key processing steps and applied advance analysis on the ALCUDIA transect with the aim to improve the signal to noise ratio especially in the deep parts and to produce a depth migrated image. The velocity model generated through wide-angle seismic survey (2003) was used to convert IBERSEIS time migrated stack image into depth. The new data processing flow provide better structural constraints on the shallow and deep structures as the current images reveal indentation features which strongly suggest horizontal tectonics. The ALCUDIA transect shows slightly less reflective upper crust about 13 km thick decoupled from the comparatively reflective lower crust. The reflectivity of the lower crust is continuous, high amplitude, horizontal and parallel though evidences of deformation are present as flat-ramp-flat geometry on the northeastern portion and a "Crocodile structure" wedging into the upper mantle on the southwestern portion of the ALCUDIA

  12. Warm and Dry Spells (WDS in Austral Winter over Central South America

    Directory of Open Access Journals (Sweden)

    P. Satyamurty

    2007-06-01

    Full Text Available The horizontal and vertical structure of unusually warm and dry spells (WDS over the central parts of South America during the winter and post-winter months (JJAS are studied. During WDS the mean temperature and humidity anomalies over central Brazil are about +4.1°C and −13.2%, respectively. The mean duration of WDS is 11 days and their mean frequency is less than one per year during the months of JJAS. Apparently, WDS have no preference for the phase of ENSO. Widespread and persistent subsidence in the middle troposphere is observed in tropical Brazil during WDS, which renders the lower tropospheric air warm and dry. The negative anomalies of the specific humidity are observed to be associated with the subsidence regions. A strong, slow moving ridge in the eastern South Pacific and a low-pressure center in northern Argentina are important surface characteristics during the WDS. A more detailed investigation of two specific WDS events, a strong event (August–September 1999 and a moderate one (June 2002, shows a blocking-like situation in the 500-hPa geopotential and surface pressure fields in the Pacific. The South Atlantic subtropical high somewhat approaches the continent. Strong northerlies over the central and eastern parts of Brazil are also observed in the lower troposphere. During WDS the regional circulation acquires summertime characteristics, except for the absence of precipitation, and the circulation in the meridional plane is in the opposite sense from the Hadley circulation. A frontal system, supported by a 500-hPa trough, advances into central Brazil, causing the dissipation of the anomalous situation.

  13. Phylogeny and biogeography of Poecilia (Cyprinodontiformes: Poeciliinae) across Central and South America based on mitochondrial and nuclear DNA markers.

    Science.gov (United States)

    Ho, Adeljean L F C; Pruett, Christin L; Lin, Junda

    2016-08-01

    Poeciliids are a diverse group of small Neotropical fishes, and despite considerable research attention as models in ecology and evolutionary biology, our understanding of their biogeographic and phylogenetic relationships is still limited. We investigated the phylogenetic relationships of South and Central American Poecilia, by examining 2395 base pairs of mitochondrial DNA (ATPase 8/6, COI) and nuclear DNA (S7) for 18 species across six subgenera. Fifty-eight novel sequences were acquired from newly collected specimens and 20 sequences were obtained from previously published material. Analyses of concatenated and partitioned mitochondrial DNA and nuclear DNA sets resulted in a well-supported phylogeny that resolved several monophyletic groups corresponding to previously hypothesized subgenera and species complexes. A divergence-dating analysis supported the hypothesis of the genus Poecilia dispersing into Central America in the early Pliocene (ancestors of Psychropoecilia+Allopoecilia+Mollienesia: 7.3-2.0Mya) from predominantly South America. Subsequently, one lineage (subgenus Allopoecilia: 5.1-1.3Mya) expanded deeper into South America from Lower-Central America, and one lineage expanded from Nuclear-Central America into South America (subgenus Mollienesia: 0.71-0.14Mya). The subgenus Mollienesia diverged into three monophyletic groups that can be identified by nuptial male dorsal fin morphology and inner jaw dentition. A subclade of the unicuspid short-fins (subgenus Mollienesia) was the lineage that expanded into South America during the middle Pleistocene. Species in this subclade are now distributed across northern South America, where they are partially sympatric with Allopoecilia. However the P. (A.) caucana complex was not monophyletic, with P. (A.) wandae clustering in the Mollienesia subclade that expanded into South America. It is apparent that characters (body size, scale count, pigmentation, and gonopodium morphology) used to define the P. (A

  14. 75 FR 53370 - RailAmerica, Inc., Palm Beach Holding, Inc., RailAmerica Transportation Corp., Central Railroad...

    Science.gov (United States)

    2010-08-31

    .... (DTC), subject to labor protective conditions. Pursuant to an agreement that CERA, a Class III rail carrier, intends to enter into with Bunge North America (East), LLC (Bunge), the parent company of DTC, CERA will acquire from Bunge all of the issued and outstanding shares of stock of DTC and will...

  15. A Single Early Introduction of HIV-1 Subtype B into Central America Accounts for Most Current Cases

    OpenAIRE

    W. Murillo; Veras, N.; Prosperi, M; de Rivera, I L; Paz-Bailey, G.; Morales-Miranda, S.; Juarez, S. I.; Yang, C; Devos, J.; Marin, J. P.; Mild, M.; J. Albert; Salemi, M.

    2013-01-01

    Human immunodeficiency virus type 1 (HIV-1) variants show considerable geographical separation across the world, but there is limited information from Central America. We provide the first detailed investigation of the genetic diversity and molecular epidemiology of HIV-1 in six Central American countries. Phylogenetic analysis was performed on 625 HIV-1 pol gene sequences collected between 2002 and 2010 in Honduras, El Salvador, Nicaragua, Costa Rica, Panama, and Belize. Published sequences ...

  16. Attitudes to and visions of civil society/state relations in Central America: implications for sustainable development

    OpenAIRE

    Cannon, Barry; Hume, Mo

    2010-01-01

    This paper will present results of a research project on civil society held in three Central American states, El Salvador, Nicaragua and Honduras, in July and August, 2009, as part of the Irish Aid funded and DCU led Active Citizenship in Central America project. The paper is based on a wide range of events and interviews held in these three countries, with five distinct populations, many of them involved in the Active Citizenship Project: students of NGO Management and Municipal Leadership D...

  17. A revision of the Yelicones species (Hymenoptera: Braconidae: Rogadinae) from Central America, with descriptions of sixteen new species

    NARCIS (Netherlands)

    Quicke, D.L.J.; Chishti, M.J.K.; Basibuyuk, H.H.

    1996-01-01

    The genus Yelicones Cameron, 1887, from North and Central America is revised. Ninteen species are recognized: Y. arizonus spec. nov. from U.S.A. (Arizona) and Mexico; Y. barroci spec. nov. from Panama; Y. bicoloripes spec. nov. from Costa Rica and Panama; Y. canalensis spec. nov. from Panama; Y. con

  18. Promoting Healthy Living and Aging in Central America : Multi-sectoral Approaches to Prevent Chronic Noncommunicable Diseases

    OpenAIRE

    Bonilla-Chacin, Maria Eugenia; Vásquez, Luis T. Marcano

    2012-01-01

    Non-communicable diseases (NCDs) are the main cause of death and disability in Central America. However, communicable diseases and maternal and child conditions remain important causes of death and disability as well as injuries. With the aging of the population and improvements in the control of infectious diseases, the share of NCDs in the total burden of disease is likely to increase. H...

  19. Anti-gang policies and gang responses in the Northern Triangle : The Evolution of the Gang Phenomenon in Central America

    NARCIS (Netherlands)

    van der Borgh, G.J.C.; Savenije, W.

    2014-01-01

    During the past decade, gangs have become a powerful and violent presence in El Salvador, Guatemala and Honduras, the ‘Northern Triangle’ of Central America. 1 The particular evolution of the gang phenomenon has been deeply shaped by a series of reactions and adaptations to ill-developed security po

  20. A comparative study of Taiwan's short-term medical missions to the South Pacific and Central America

    Directory of Open Access Journals (Sweden)

    Chiu Ya-Wen

    2012-12-01

    Full Text Available Abstract Background Taiwan has been dispatching an increasing number of short-term medical missions (STMMs to its allied nations to provide humanitarian health care; however, overall evaluations to help policy makers strengthen the impact of such missions are lacking. Our primary objective is to identify useful strategies by comparing STMMs to the South Pacific and Central America. Methods The data for the evaluation come from two main sources: the official reports of 46 missions to 11 countries in Central America and 25 missions to 8 countries in the South Pacific, and questionnaires completed by health professionals who had participated in the above missions. In Central America, STMMs were staffed by volunteer health professionals from multiple institutions. In the South Pacific, STMMs were staffed by volunteer health professionals from single institutions. Results In comparison to STMMs to Central America, STMMs to the South Pacific accomplished more educational training for local health providers, including providing heath-care knowledge and skills (p Conclusions Health-care services provided by personnel from multiple institutions are as efficient as those from single institutions. Proficiency in the native language and provision of education for local health-care workers are essential for conducting a successful STMM. Our data provide implications for integrating evidence into the deployment of STMMs.

  1. International relations among Tom Thumbs: Taiwan as provider of aid Central America

    Directory of Open Access Journals (Sweden)

    Francisco Javier Haro Navejas

    2007-06-01

    Full Text Available This paper analyzes the Official Development Aid (AOD that has as its source Taiwan and as its destination Central America. It has three basic aims: Firstly, there is a huge bibliographic vacuum on the topic of these pages. Beginning filling it is an academic need. Even some intellectuals feel that they should lean against either Beijing or Taipei, that if they write on Taiwan they should defend or attack one of the contending parties. Here it is seen that a study close to objectivity is possible. Secondly, most of the research in International Relations has been focused on topics related with power itself or with just elements related with hard power. AOD is both hard and soft power, therefore this paper shades light to the dark side partially viewing international relations from a theoretical perspective were interactions help to construct identities and cooperation is an essential variable of world politics. Finally, it will be seen below that the Taiwanese cooperativeeconomic actions are helpful to the progress of poor parts of the Central American region and are helpful to create domestic markets with strong links with the world market deepening the economic integration both regional and global. Aid from Taiwan and some other countries, mainly through the transmission of know how, could be of assistance in surmounting huge troubles. Aid is vital because some of Central American’s problems are being exported mainly to México and the United States under the form, just to give an example, of Mara Salvatrucha gangs source of violence and drug trafficking. It is not meaningless to stress that Taiwanese ODA is by far not enough and is very small in the international context.

  2. Projected impact of twenty-first century ENSO changes on rainfall over Central America and northwest South America from CMIP5 AOGCMs

    Science.gov (United States)

    Steinhoff, Daniel F.; Monaghan, Andrew J.; Clark, Martyn P.

    2015-03-01

    Due to the importance that the El Niño-Southern Oscillation (ENSO) has on rainfall over the tropical Americas, future changes in ENSO characteristics and teleconnections are important for regional hydroclimate. Projected changes to the ENSO mean state and characteristics, and the resulting impacts on rainfall anomalies over Central America, Colombia, and Ecuador during the twenty-first century are explored for several forcing scenarios using a suite of coupled atmosphere-ocean global climate models (AOGCMs) from the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Mean-state warming of eastern tropical Pacific sea surface temperatures, drying of Central America and northern Colombia, and wetting of southwest Colombia and Ecuador are consistent with previous studies that used earlier versions of the AOGCMs. Current and projected future characteristics of ENSO (frequency, duration, amplitude) show a wide range of values across the various AOGCMs. The magnitude of ENSO-related rainfall anomalies are currently underestimated by most of the models, but the model ensembles generally simulate the correct sign of the anomalies across the seasons around the peak ENSO effects. While the models capture the broad present-day ENSO-related rainfall anomalies, there is not a clear sense of projected future changes in the precipitation anomalies.

  3. Trench-parallel flow beneath the nazca plate from seismic anisotropy.

    Science.gov (United States)

    Russo, R M; Silver, P G

    1994-02-25

    Shear-wave splitting of S and SKS phases reveals the anisotropy and strain field of the mantle beneath the subducting Nazca plate, Cocos plate, and the Caribbean region. These observations can be used to test models of mantle flow. Two-dimensional entrained mantle flow beneath the subducting Nazca slab is not consistent with the data. Rather, there is evidence for horizontal trench-parallel flow in the mantle beneath the Nazca plate along much of the Andean subduction zone. Trench-parallel flow is attributale utable to retrograde motion of the slab, the decoupling of the slab and underlying mantle, and a partial barrier to flow at depth, resulting in lateral mantle flow beneath the slab. Such flow facilitates the transfer of material from the shrinking mantle reservoir beneath the Pacific basin to the growing mantle reservoir beneath the Atlantic basin. Trenchparallel flow may explain the eastward motions of the Caribbean and Scotia sea plates, the anomalously shallow bathymetry of the eastern Nazca plate, the long-wavelength geoid high over western South America, and it may contribute to the high elevation and intense deformation of the central Andes.

  4. Application of scientific core drilling to geothermal exploration: Platanares, Honduras and Tecuamburro Volcano, Guatemala, Central America

    Energy Technology Data Exchange (ETDEWEB)

    Goff, S.J.; Goff, F.E.; Heiken, G.H. [Los Alamos National Lab., NM (United States); Duffield, W.A. [Geological Survey, Flagstaff, AZ (United States); Janik, C.J. [Geological Survey, Menlo Park, CA (United States)

    1994-04-01

    Our efforts in Honduras and Guatemala were part of the Central America Energy Resource Project (CAERP) funded by the United States Agency for International Development (AID). Exploration core drilling operations at the Platanares, Honduras and Tecuamburro Volcano, Guatemala sites were part of a geothermal assessment for the national utility companies of these countries to locate and evaluate their geothermal resources for electrical power generation. In Honduras, country-wide assessment of all thermal areas determined that Platanares was the site with the greatest geothermal potential. In late 1986 to middle 1987, three slim core holes were drilled at Platanares to a maximum depth of 680 m and a maximum temperature of 165{degree}C. The objectives were to obtain information on the geothermal gradient, hydrothermal alterations, fracturing, and possible inflows of hydrothermal fluids. Two holes produced copious amounts of water under artesian conditions and a total of 8 MW(t) of energy. Geothermal investigations in Guatemala focused on the Tecuamburro Volcano geothermal site. The results of surface geological, volcanological, hydrogeochemical, and geophysical studies at Tecuamburro Volcano indicated a substantial shallow heat source. In early 1990 we drilled one core hole, TCB-1, to 808 m depth. The measured bottom hole temperature was 238{degree}C. Although the borehole did not flow, in-situ samples indicate the hole is completed in a vapor-zone above a probable 300{degree}C geothermal reservoir.

  5. Asymmetric forest transition driven by the interaction of socioeconomic development and environmental heterogeneity in Central America.

    Science.gov (United States)

    Redo, Daniel J; Grau, H Ricardo; Aide, T Mitchell; Clark, Matthew L

    2012-06-01

    Forest transitions (FT) have been observed in many developed countries and more recently in the developing world. However, our knowledge of FT from tropical regions is mostly derived from case studies from within a particular country, making it difficult to generalize findings across larger regions. Here we overcome these difficulties by conducting a recent (2001-2010) satellite-based analysis of trends in forest cover across Central America, stratified by biomes, which we related to socioeconomic variables associated with human development. Results show a net decrease of woody vegetation resulting from 12,201 km(2) of deforestation of moist forests and 6,825 km(2) of regrowth of conifer and dry forests. The Human Development Index was the socioeconomic variable best associated with forest cover change. The least-developed countries, Nicaragua and Guatemala, experienced both rapid deforestation of moist forests and significant recovery of conifer and dry forests. In contrast, the most developed countries, Panama and Costa Rica, had net woody vegetation gain and a more stable forest cover configuration. These results imply a good agreement with FT predictions of forest change in relation to socioeconomic development, but strong asymmetry in rates and directions of change largely dependent upon the biome where change is occurring. The FT model should be refined by incorporating ecological and socioeconomic heterogeneity, particularly in multicountry and regional studies. These asymmetric patterns of forest change should be evaluated when developing strategies for conserving biodiversity and environmental services. PMID:22615408

  6. Comparison of GNSS integrated water vapor and NWM reanalysis data over Central and South America

    Science.gov (United States)

    Fernández, Laura Isabel; Natali, Maria Paula; Meza, Amalia; Mendoza, Luciano; Bianchi, Clara

    2016-07-01

    Integrated water vapor (IWV) derived from Global Navigation Satellite Systems (GNSS) and Numerical Weather Models (NWM) reanalysis data were compared in order to assess the consistency between the different datasets over the extended geographical region of Central and South America. The analysis was performed for the seven years period between 2007 and 2013. We analyzed two different NWM: the European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis data (ERA Interim) and the Modern-Era Retrospective analysis for Research and Applications (MERRA) from the National Aeronautics and Space Administration (NASA). The statistical analysis of the differences was performed in 110 GNSS sites (GPS + GLONASS), although the most interesting results came from the 73 sites which have more than 5 years of data. The selected area involves different climate types, from polar to tropical, and it is characterized by large temporal variability of the integrated total humidity content. Moreover, the scarce coverage of operational radio sounding stations is noticeable in large areas of the selected region; hence the contribution of IWV-GNSS is essential to improve the weather understanding. Considering that the atmospheric water vapor has a highly variable and complex distribution which knowledge is essential for weather prediction and local meteorological studies. This study aims to provide IWV-GNSS observations able to be assimilated by operational weather centers, for both prediction and simulation, as well for improving regional modeling.

  7. Ash Layers: The Controlling Factor On Translational Sliding Offshore Central America?

    Science.gov (United States)

    Harders, R.; Brueckmann, W.; Feeser, V.; Hensen, C.; Kutterolf, S.

    2006-12-01

    The erosive convergent margin of Central America is dominated by the fast subduction of the rough Pacific plate. Off Costa Rica the morphology of the subducted oceanic plate is characterized by numerous seamounts and the Cocos Ridge. Off Nicaragua fewer seamounts and bend ing-related faults dominate the morphology. In both areas seamount subduction with resulting slope uplift or subduction erosion at the base of the upper plate causes oversteepening and frequent slope failure. Our investigation focuses on translational slides off Nicaragua (Skempton ratio pelagic sediments. Firstly they have higher contents of silt and sand causing higher intrinsic permeabilities. Secondly they consist of disc shaped glass shards which causes higher consolidation rates. This is proved by our first laboratory shear box tests, where ash matter compacted with much higher values than spherical grain shaped reference material of the same grain size. Both factors together could cause a peak pore pressure if ashes compacted rapidly, for instance in a seismic event like the earthquake 1992 off Nicaragua. This would effectively reduce the shear strength between the ash particles and facilitate translational failure. To test this hypothesis and to analyse the relation between pore water pressures and shear strengths under drained conditions, we have modified a shear box, to simultaneously measure pore water pressure and shear strength. We will present field observations from cruise M66 as well as first results from laboratory deformation experiments, supporting our model.

  8. Microsatellite data suggest significant population structure and differentiation within the malaria vector Anopheles darlingi in Central and South America

    Directory of Open Access Journals (Sweden)

    Achee Nicole L

    2008-03-01

    Full Text Available Abstract Background Anopheles darlingi is the most important malaria vector in the Neotropics. An understanding of A. darlingi's population structure and contemporary gene flow patterns is necessary if vector populations are to be successfully controlled. We assessed population genetic structure and levels of differentiation based on 1,376 samples from 31 localities throughout the Peruvian and Brazilian Amazon and Central America using 5–8 microsatellite loci. Results We found high levels of polymorphism for all of the Amazonian populations (mean RS = 7.62, mean HO = 0.742, and low levels for the Belize and Guatemalan populations (mean RS = 4.3, mean HO = 0.457. The Bayesian clustering analysis revealed five population clusters: northeastern Amazonian Brazil, southeastern and central Amazonian Brazil, western and central Amazonian Brazil, Peruvian Amazon, and the Central American populations. Within Central America there was low non-significant differentiation, except for between the populations separated by the Maya Mountains. Within Amazonia there was a moderate level of significant differentiation attributed to isolation by distance. Within Peru there was no significant population structure and low differentiation, and some evidence of a population expansion. The pairwise estimates of genetic differentiation between Central America and Amazonian populations were all very high and highly significant (FST = 0.1859 – 0.3901, P DA and FST distance-based trees illustrated the main division to be between Central America and Amazonia. Conclusion We detected a large amount of population structure in Amazonia, with three population clusters within Brazil and one including the Peru populations. The considerable differences in Ne among the populations may have contributed to the observed genetic differentiation. All of the data suggest that the primary division within A. darlingi corresponds to two white gene genotypes between Amazonia (genotype 1

  9. The Banded Elm Bark Beetle, Scolytus schevyrewi Semenov (Coleoptera, Curculionidae, Scolytinae in North America: a taxonomic review and modifications to the Wood (1982 key to the species of Scolytus Geoffroy in North and Central America

    Directory of Open Access Journals (Sweden)

    James LaBonte

    2010-09-01

    Full Text Available In 2003, an Asian bark beetle, Scolytus schevyrewi Semenov (Coleoptera: Curculionidae: Scolytinae, the banded elm bark beetle, was detected for the first time in North America. This paper modifies the Wood (1982 key to the species of Scolytus Geoffroy to enable identification of S. schevyrewi in North and Central America. Variation of diagnostic characters in S. schevyrewi is discussed.

  10. The Banded Elm Bark Beetle, Scolytus schevyrewi Semenov (Coleoptera, Curculionidae, Scolytinae) in North America: a taxonomic review and modifications to the Wood (1982) key to the species of Scolytus Geoffroy in North and Central America

    OpenAIRE

    James LaBonte

    2010-01-01

    Abstract In 2003, an Asian bark beetle, Scolytus schevyrewi Semenov (Coleoptera: Curculionidae: Scolytinae), the banded elm bark beetle, was detected for the first time in North America. This paper modifies the Wood (1982) key to the species of Scolytus Geoffroy to enable identification of Scolytus schevyrewi in North and Central America. Variation of diagnostic characters in Scolytus schevyrewi is discussed.

  11. Geomorphological impact on agroforestry systems in the interior highlands of Nicaragua, Central America

    Science.gov (United States)

    Mentler, Axel; Wriessnig, Karin; Ottner, Franz; Schomakers, Jasmin; Benavides González, Álvaro; Cisne Contreras, José Dolores; Querol Lipcovich, Daniel

    2013-04-01

    Cerro el Castillo is located in the NW of Nicaragua, Central America, close to the border of Honduras (Provincia Central de las Cordilleras) at 1000-1200m above sea level. In this region, small and medium-sized farms are agroforestry systems with mangos, avocados, coffee, papayas, bananas, strawberries, maize, pumpkins, beans and other vegetables. The production systems are strongly linked to facilities for raising small domestic animals and cows. Main regional agricultural production problems are steep slopes, soil erosion, varying precipitation and distribution, water management and the unstable family income. An investigation of topsoil properties with comparable management systems showed on small scales significant differences in key values of soil chemistry and mineralogy. The outline of the analytical parameters included determination of pH, electrical conductivity (EC), cation exchange capacity (CEC), organic carbon (TOC), dissolved organic carbon (DOC), total nitrogen (TN) and dissolved nitrogen (DN) in soil solution, and plant available nutrients (P and K). The soil's mineralogical composition was determined by X-ray diffraction analysis. The area is a highly weathered karst landscape within a tropical limestone region displaying different amounts of volcanic pyroclastic parent material. The dominant Nitisoils and Andosols show degraded argic and andic horizons along the upper half of the mountainside. The pH values in the topsoil are moderate from pH 5.0 to 5.6. The upland topsoil is decalcified and the amount of plant available phosphorous is very low with significant low Ca concentration at the sorption complex. The mineralogical composition points to the high weathering intensity of this area (high content of kaolinite and a lower concentration of potassium and plagioclase feldspars and andesite). Along the upper half of the mountain, the soil profiles show wider C:N ratios and lower amounts of organic matter. Topsoil at lower altitude and with a lower

  12. Tsunami hazard assessment in El Salvador, Central America, from seismic sources through flooding numerical models.

    Science.gov (United States)

    Álvarez-Gómez, J. A.; Aniel-Quiroga, Í.; Gutiérrez-Gutiérrez, O. Q.; Larreynaga, J.; González, M.; Castro, M.; Gavidia, F.; Aguirre-Ayerbe, I.; González-Riancho, P.; Carreño, E.

    2013-11-01

    El Salvador is the smallest and most densely populated country in Central America; its coast has an approximate length of 320 km, 29 municipalities and more than 700 000 inhabitants. In El Salvador there were 15 recorded tsunamis between 1859 and 2012, 3 of them causing damages and resulting in hundreds of victims. Hazard assessment is commonly based on propagation numerical models for earthquake-generated tsunamis and can be approached through both probabilistic and deterministic methods. A deterministic approximation has been applied in this study as it provides essential information for coastal planning and management. The objective of the research was twofold: on the one hand the characterization of the threat over the entire coast of El Salvador, and on the other the computation of flooding maps for the three main localities of the Salvadorian coast. For the latter we developed high-resolution flooding models. For the former, due to the extension of the coastal area, we computed maximum elevation maps, and from the elevation in the near shore we computed an estimation of the run-up and the flooded area using empirical relations. We have considered local sources located in the Middle America Trench, characterized seismotectonically, and distant sources in the rest of Pacific Basin, using historical and recent earthquakes and tsunamis. We used a hybrid finite differences-finite volumes numerical model in this work, based on the linear and non-linear shallow water equations, to simulate a total of 24 earthquake-generated tsunami scenarios. Our results show that at the western Salvadorian coast, run-up values higher than 5 m are common, while in the eastern area, approximately from La Libertad to the Gulf of Fonseca, the run-up values are lower. The more exposed areas to flooding are the lowlands in the Lempa River delta and the Barra de Santiago Western Plains. The results of the empirical approximation used for the whole country are similar to the results

  13. Tsunami hazard assessment in El Salvador, Central America, from seismic sources through flooding numerical models

    Directory of Open Access Journals (Sweden)

    J. A. Álvarez-Gómez

    2013-05-01

    Full Text Available El Salvador is the smallest and most densely populated country in Central America; its coast has approximately a length of 320 km, 29 municipalities and more than 700 000 inhabitants. In El Salvador there have been 15 recorded tsunamis between 1859 and 2012, 3 of them causing damages and hundreds of victims. The hazard assessment is commonly based on propagation numerical models for earthquake-generated tsunamis and can be approached from both Probabilistic and Deterministic Methods. A deterministic approximation has been applied in this study as it provides essential information for coastal planning and management. The objective of the research was twofold, on the one hand the characterization of the threat over the entire coast of El Salvador, and on the other the computation of flooding maps for the three main localities of the Salvadorian coast. For the latter we developed high resolution flooding models. For the former, due to the extension of the coastal area, we computed maximum elevation maps and from the elevation in the near-shore we computed an estimation of the run-up and the flooded area using empirical relations. We have considered local sources located in the Middle America Trench, characterized seismotectonically, and distant sources in the rest of Pacific basin, using historical and recent earthquakes and tsunamis. We used a hybrid finite differences – finite volumes numerical model in this work, based on the Linear and Non-linear Shallow Water Equations, to simulate a total of 24 earthquake generated tsunami scenarios. In the western Salvadorian coast, run-up values higher than 5 m are common, while in the eastern area, approximately from La Libertad to the Gulf of Fonseca, the run-up values are lower. The more exposed areas to flooding are the lowlands in the Lempa River delta and the Barra de Santiago Western Plains. The results of the empirical approximation used for the whole country are similar to the results obtained

  14. Impingement of Deep Mantle-Derived Upwelling Beneath Northern, Subducted Extension of the East Pacific Rise and Palinspastically Restored Cenozoic Mafic Magmatism in Western North America

    Science.gov (United States)

    Rowley, D. B.; Moucha, R.; Forte, A. M.; Mitrovica, J. X.; Simmons, N. A.; Grand, S. P.

    2009-12-01

    Reconstruction of the retrodicted whole mantle flow, based on presently imaged distribution of variations in seismic velocity and its correlation to density (Simmons et al. 2009), over the past 30 Ma, in the North American fixed frame of reference, reveals that the northern, now subducted, extension of the East Pacific Rise is coincident with mantle buoyancy arising from near the core-mantle boundary and extending to the base of the lithosphere (Moucha et al. 2009 GRL, in press). Divergence of the reconstructed flow near the surface is independent of the surface plate(s) and results in predicted geological manifestations distinct from those predicted by traditional plate driven models of flow. Most particularly the retrodicted flow-related dynamic topography results in progressive west to east sweep of surface uplift, that is now centered on the Colorado Plateau (Moucha et al. 2008, 2009 GRL, in press). In addition, and the primary focus of the current study is the relationship between this retrodicted mantle-wide flow and the history of magmatism within the western U.S. and adjacent Mexico. There is a close spatial correlation between the impingement of upwelling with palinspastic restored western North America (McQuarrie and Wernicke, 2005) and onset and distribution of magmatism, particularly of mafic compositions as revealed in the Navdat (www.navdat.org) database. Although often attributed to effects of opening of a slab window (Snyder and Dickinson, 1979, McQuarrie and Oskins, 2008) associated with continued plate-driven separation, this model predicts active mantle flow induced upwelling and divergence resulting in mantle melting that sweeps across east-northeast across southern Basin and Range to the Rio Grande Rift with time and as seen in the distribution of magmatism in this region.

  15. Enterocytozoon bieneusi (ORDEN MICROSPORIDIA, FAMILIA Entrerocytozoonidae) IN COSTA RICA: REPORT OF THE FIRST HUMAN CASE IN CENTRAL AMERICA

    OpenAIRE

    MISAEL CHINCHILLA; LILLIANA REYES; OLGA M GUERRERO; MAURICIO FRAJAN; MARCO T MORALES

    1997-01-01

    The first case of microsporidiosis in Central America is described in an AIDS patient from Costa Rica. Electronic microscopy studies indicate that the spores were not included in a parasitophorous vacuola, but they are in direct contact with the cell cytoplasm. Sporogonic proliferative plasmodial forms presence ana localization of the polar tubes in the anterior region of the spore, confirmed the specie Enterocytozoon bieneusi as the cause of this microsporidian infection

  16. A new evaluation of Seismic Hazard for the Central America Region in the frame of the RESIS II Project.

    OpenAIRE

    Benito Oterino, Belen; Lindholm, Conrad; Camacho, Eduardo; Climent, Alvaro; Marroquín, Griselda; Molina, Enrique; Rojas, Wilfredo; Segura, José Jorge; Talavera, Emilio

    2008-01-01

    A new evaluation of seismic hazard in the Central America region has been carried out, in the frame of the cooperation project RESIS II, financed by the Norway Cooperation Agency (NORAD). Different experts in seismic hazard from Costa Rica, Guatemala, Nicaragua , El Salvador, Norway and Spain participated in the study, which was aimed at obtaining results suitable for seismic design purposes. The analysis started with an exhaustive revision of the seismic catalogues of each country from which...

  17. Tsunami hazard assessment in El Salvador, Central America, from seismic sources through flooding numerical models

    OpenAIRE

    Álvarez-Gómez, José Antonio; Aniel-Quiroga Zorrilla, Íñigo; Gutiérrez Gutiérrez, Omar Quetzalcóatl; Larreynaga Murcia, Jeniffer; González Rodríguez, Ernesto Mauricio; M. Castro; Gavidia Medina, Francisco; Aguirre Ayerbe, Ignacio; González-Riancho Calzada, Pino; Carreño Herrero, Emilio

    2013-01-01

    ABSTRACT. El Salvador is the smallest and most densely populated country in Central America; its coast has an approximate lenght of 320 km, 29 municipalities and more than 700.000 inhabitants. In El Salvador there were 15 recorded tsunamis between 1859 and 2012, 3 of them causing damages and resulting in hundreds of victims. Hazard assessment is commonly based on propagation numerical models for earthquake-generated tsunamis and can be approached through both probabilistic and deterministic m...

  18. Micro and Macroscale Drivers of Nutrient Concentrations in Urban Streams in South, Central and North America

    Science.gov (United States)

    Loiselle, Steven A.; Gasparini Fernandes Cunha, Davi; Shupe, Scott; Valiente, Elsa; Rocha, Luciana; Heasley, Eleanore; Belmont, Patricia Pérez; Baruch, Avinoam

    2016-01-01

    Global metrics of land cover and land use provide a fundamental basis to examine the spatial variability of human-induced impacts on freshwater ecosystems. However, microscale processes and site specific conditions related to bank vegetation, pollution sources, adjacent land use and water uses can have important influences on ecosystem conditions, in particular in smaller tributary rivers. Compared to larger order rivers, these low-order streams and rivers are more numerous, yet often under-monitored. The present study explored the relationship of nutrient concentrations in 150 streams in 57 hydrological basins in South, Central and North America (Buenos Aires, Curitiba, São Paulo, Rio de Janeiro, Mexico City and Vancouver) with macroscale information available from global datasets and microscale data acquired by trained citizen scientists. Average sub-basin phosphate (P-PO4) concentrations were found to be well correlated with sub-basin attributes on both macro and microscales, while the relationships between sub-basin attributes and nitrate (N-NO3) concentrations were limited. A phosphate threshold for eutrophic conditions (>0.1 mg L-1 P-PO4) was exceeded in basins where microscale point source discharge points (eg. residential, industrial, urban/road) were identified in more than 86% of stream reaches monitored by citizen scientists. The presence of bankside vegetation covaried (rho = –0.53) with lower phosphate concentrations in the ecosystems studied. Macroscale information on nutrient loading allowed for a strong separation between basins with and without eutrophic conditions. Most importantly, the combination of macroscale and microscale information acquired increased our ability to explain sub-basin variability of P-PO4 concentrations. The identification of microscale point sources and bank vegetation conditions by citizen scientists provided important information that local authorities could use to improve their management of lower order river

  19. Emerging deforestation trends in tropical dry forests ecoregions of Mexico and Central America

    Science.gov (United States)

    Portillo, C. A.; Cao, G.; Smith, V.

    2015-12-01

    Neotropical dry forests (TDF) have experienced an unprecedented deforestation that is leading to the loss of tropical biodiversity at a rapid pace, but information on deforestation dynamics in TDF is scarce. In this study, we present a sub-continental and national level assessment of TDF loss patterns in Mexico and Central America at high spatial and temporal resolution using remote sensing and GIS technologies. We used the Global Forest Change (GFC) dataset published by Hansen et al. (2013) which shows results from time-series analysis of Landsat images in characterizing global forest extent and change from 2000 through 2013. We analyzed forest loss within and around mapped TDF cover mapped by Portillo-Quintero et al. 2010. In order to minimize errors in source data, we overlaid a 25 x 25 km grid on top of the regional dataset and conducted a cell by cell and country by country inspection at multiple scales using high resolution ancillary data. We identified trends in the clustering of space-time TDF deforestation data using ArcGIS, categorizing trends in: new, consecutive, intensifying, persistent, diminishing, sporadic, oscillating and historical hotspots (high frequency of deforestation events) and cold spots (low frequency of deforestation). In general, the region is experiencing less frequent deforestation events with a higher number of intensifying and new cold spots across TDF landscapes. However, an important number of intensifying and persistent hotspots exist so no general trend in forest loss was detected for the period 2001-2013, except for El Salvador which shows a significant decreasing trend in forest loss. Mexico, Nicaragua, Honduras and Guatemala are the major sources of intensifying, persistent and new deforestation hot spots. These were identified in the southern pacific coast and the Yucatan Peninsula in Mexico, northwestern Guatemala, both western and eastern Honduras and around Lake Nicaragua in Nicaragua.

  20. Applications of a GIS on Georisks for Nicaragua and Central America

    Science.gov (United States)

    Strauch, W.; Chavez, G.; Gutierrez, V.; Feldhaus, L.; Schillinger, S.; Schmidt, R.

    2007-05-01

    A GIS on Georisks in Nicaragua was developed in the last years at the Instituto Nicaraguense de Estudios Territoriales (INETER) in cooperation with Federal Institute for Geosciences and Natural Resources (BGR, Germany). This GIS includes extensive topographical coverage and a large part of the data obtained in Nicaragua in many recent projects on natural hazard, vulnerability and risk. It contains numerous data on elements under risk, for instance cadastre data of Nicaraguan cities. Activities include the integration of the GIS with the monitoring and early warning systems of INETER to update certain parts of the data base continuously and in real time. The GIS is used on a routine basis at INETER and the GIS data base provides an efficient starting point for multiple new projects on georisks in Nicaragua which after their termination deliver their products to the GIS to assure the continuous growth of the system. Local universities, governmental institutions, local administrations, NGO´s make use of the GIS data base. Examples of important datasets are the seismicity data of Nicaragua with around 30,000 events, landslide coverage with 17,000 events, seismic vulnerability of 212,000 buildings in Managua city, seismic microzonation data of several towns, and multidisciplinary hazard and vulnerability data for 30 municipalities in Western Nicaragua. An interdisciplinary group of Nicaraguan geoscientists, informatics engineers and GIS specialists at INETER was trained to develop and use the GIS in their daily work. Web mapping services were put onto INETER´s website to provide the general public in Nicaragua with direct access to the data. Based on the experience in Nicaragua a regional GIS on Georisks for Central America is under development in cooperation with other institutions in El Salvador, Guatemala and Honduras.

  1. Atmospheric circulation associated with extreme generalized frosts persistence in central-southern South America

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Gabriela V. [Centro de Investigaciones Cientificas y Transferencia de Tecnologia a la Produccion, Diamante (CICYTTTP-CONICET), Diamante, Entre Rios (Argentina); Berri, Guillermo J. [Servicio Meteorologico Nacional - CONICET, Buenos Aires (Argentina)

    2012-03-15

    Generalized frosts (GF) in central-southern South America have a strong impact due to their spatial extension, and they are especially important when they become persistent. This paper aims at identifying the atmospheric circulation features that determine the extreme GF persistence, i.e. very persistent and without persistence, and the differences between them, during the 1961-1990 winters. Since the GF without persistence group outnumbers the other one, two subgroups are composed with events selected from winters with maximum and minimum frequency of GF occurrence, respectively. Additionally, the individual event of July 1988 within the very persistent GF group is analyzed due to its exceptional persistence. GF persistence is mainly conditioned by two large-scale dynamic factors. One is the Rossby wave train propagation across the Pacific Ocean, and the other one is the location with respect to the continent and the magnitude of the confluence in the jet entrance region in subtropical latitudes. A predominantly meridional Rossby wave train propagation with a confluence region to the west of the continent prior to the event favors GF with intermediate (null) persistence depending on the greater (lesser) jet acceleration. This is conditioned by the magnitude of the confluence, which, in turn, depends on the disposition of the wave train propagation pattern. Instead, an essentially zonal propagation with a confluence region to the east of the continent favors the GF persistence for several days, yet if there is no confluence the event does not persist. The greatest persistence of an event combines the confluence/diffluence of the jet entrance/exit region, which depends on the disposition with respect to the continent of the zonally propagating Rossby wave trains. (orig.)

  2. Constraining the Fore-Arc Flux Along the Central America Margin

    Science.gov (United States)

    Hilton, D. R.; Barry, P. H.; Ramirez, C. J.; Kulongoski, J. T.; Patel, B. S.; Blackmon, K.

    2014-12-01

    The transport of carbon to the deep mantle via subduction zones is interrupted by outputs via the fore-arc, volcanic front, and back-arc regions. Whereas output fluxes for the front and back-arc locales are well constrained for Central America (CA) [1], the fore-arc flux via cold seeps and groundwaters is virtually unknown. We present new He and CO2 data for the inner fore-arc of Costa Rica and western Panama to complement our study [2] of offshore CO2fluxes on the outer-forearc. On the Nicoya Peninsula, the Costa Rica Pacific coastline (including the Oso Peninsula) and the Talamanca Mountain Range, as well as coastal seeps in Panama, coupled CO2-He studies allow recognition of mantle (3He/4He up to 6RA) and crustal inputs to the volatile inventory. We associate the crustal component with CO2 derived from limestone (L) and organic sediments (S) on the subducting slab, and see a decrease in the L/S ratio trench-ward with the lowest values akin to those of diatomaceous ooze in the uppermost sequence of the subducting sediment package. This observation is consistent with the removal of the uppermost organic-rich sediment from deep subduction by under-plating. As the input carbon fluxes of the individual sedimentary layers are well constrained [3], we can limit the potential steady-state flux of carbon loss at the subaerial fore-arc to ~ 6 × 107 gCkm-1yr-1, equivalent to ~88% of the input flux of C associated with the ooze, or mass balance studies at subduction zones. [1] De Leeuw et al., EPSL, 2007; [2] Furi et al., G-cubed, 2010; [3] Li and Bebout, JGR, 2005.

  3. Offspring production in three freshwater crab species (Brachyura: Pseudothelphusidae from the Amazon region and Central America

    Directory of Open Access Journals (Sweden)

    Ingo S. Wehrtmann

    2010-01-01

    Full Text Available Freshwater crabs are an important component of the fauna of limnic environments, and out of the two true freshwater crab families present in the Neotropics, Pseudothelphusidae is the most diverse. Considering the lack of information regarding reproductive features of neotropical freshwater crabs, we studied, for the first time, the fecundity and the presence of juveniles carried by females of two pseudothelphusids from the Amazon region - Kingsleya latifrons (Randall, 1840 and Kingsleya ytupora Magalhães, 1986 - and one from Central America - Potamocarcinus magnus (Rathbun, 1896. The two Kingsleya species produced relatively few (56-114 and large eggs (1.9-3.7 mm, typical for species with an abbreviated or direct development. Recently produced eggs were substantially larger in K. latifrons (mean 2.83 mm when compared to those of K. ytupora (mean 1.87 mm; however, at the end of the embryogenesis, mean egg diameter was similar in both species. Therefore, it is assumed that hatchlings in both species should have a similar size. A brief description of attached juveniles of K. ytupora is provided. The number of juveniles varied between 30 (K. ytupora and 179 (P. magnus; two size groups of juveniles were found, which indicates that the offspring cling to their mother for a prolonged period of time. There was no significant loss of eggs and juveniles; it is assumed that parental care diminishes the loss of their offspring. We compiled the available information of reproductive aspects from freshwater crabs: egg diameter was in the range of 2-3 mm, independent of female size and fecundity, and reported egg number varied between 9 and 417 eggs.

  4. [Agrarian movements, development alternatives and food security in Central America: scenarios of transition].

    Science.gov (United States)

    Rodriguez Rojas, R

    1991-01-01

    This article, based on personal experiences with a network of organizations of small and medium agricultural producers in Central America, aims to present the views of peasant organizations concerning agrarian problems in the region. The 3 major sections of work define the place of peasant agriculture in the traditional agrarian structure and the new problems resulting from the structural adjustment programs of the 1980s; separately describe the new peasant movements emerging in Honduras, El Salvador, Nicaragua, Costa Rica, and Panama, identifying common themes an efforts at international collaboration; and explore the positions of the peasant organizations on the optimal strategies for agricultural development and agrarian change. Agriculture remains the backbone of the Central American economies. But because the economic model in the region is 1 of accumulation characterized by dependency, concentration of capital, and social marginalization, the agrarian structure is at the basis of social tensions. Efforts to develop peasant agriculture and to give small producers access to marketing and credit services have been weak and sporadic. The new peasant movements are less inclined than those of the past to employ tactics of confrontation in their efforts to secure access to land and better working conditions. The new movement is the expression of small market producers sometimes grouped into associations who are oriented to production of basic foodstuffs for the internal market. A new concern with adaptation and negotiation is evident. The new organizations have in common a belief in their ability to propose new solutions to regional problems. Their views are founded on a positive assessment of the ability of peasant agriculture to produce food and add dynamism to the regional economy after barriers to credit, technological progress, and modernization in general are removed. Signs of increased cooperation are evident between peasant organizations and other groups

  5. Neglected tropical diseases in Central America and Panama: review of their prevalence, populations at risk and impact on regional development.

    Science.gov (United States)

    Hotez, Peter J; Woc-Colburn, Laila; Bottazzi, Maria Elena

    2014-08-01

    A review of the literature since 2009 reveals a staggering health and economic burden resulting from neglected tropical diseases in Panama and the six countries of Central America (referred to collectively here as 'Central America'). Particularly at risk are the 10.2million people in the region who live on less than $2 per day, mostly in Guatemala, Honduras, Nicaragua and El Salvador. Indigenous populations are especially vulnerable to neglected tropical diseases. Currently, more than 8million Central American children require mass drug treatments annually (or more frequently) for their intestinal helminth infections, while vector-borne diseases are widespread. Among the vector-borne parasitic infections, almost 40% of the population is at risk for malaria (mostly Plasmodium vivax infection), more than 800,000 people live with Chagas disease, and up to 39,000 people have cutaneous leishmaniasis. In contrast, an important recent success story is the elimination of onchocerciasis from Central America. Dengue is the leading arbovirus infection with 4-5million people affected annually and hantavirus is an important rodent-borne viral neglected tropical disease. The leading bacterial neglected tropical diseases include leptospirosis and trachoma, for which there are no disease burden estimates. Overall there is an extreme dearth of epidemiological data on neglected tropical diseases based on active surveillance as well as estimates of their economic impact. Limited information to date, however, suggests that neglected tropical diseases are a major hindrance to the region's economic development, in both the most impoverished Central American countries listed above, as well as for Panama and Costa Rica where a substantial (but largely hidden) minority of people live in extreme poverty.

  6. Is violence associated with increased risk behavior among MSM? Evidence from a population-based survey conducted across nine cities in Central America

    OpenAIRE

    Wheeler, Jennifer; Anfinson, Katherine; Valvert, Dennis; Lungo, Susana

    2014-01-01

    Background/Objective: There is a dearth of research examining the linkages between violence and HIV risk behavior among men who have sex with men (MSM), including those who identify as transgender women (TW), particularly in Central America where violence is widespread. In this paper, we use population-based survey results to independently examine the correlations between physical, emotional and sexual violence and HIV risk behavior among MSM populations in five countries in Central America.D...

  7. Chronological refinement of an ice core record at Upper Fremont Glacier in south central North America

    International Nuclear Information System (INIS)

    The potential to use ice cores from alpine glaciers in the midlatitudes to reconstruct paleoclimatic records has not been widely recognized. Although excellent paleoclimatic records exist for the polar regions, paleoclimatic ice core records are not common from midlatitude locations. An ice core removed from the Upper Fremont Glacier in Wyoming provides evidence for abrupt climate change during the mid-1800s. Volcanic events (Krakatau and Tambora) identified from electrical conductivity measurements (ECM) and isotopic and chemical data from the Upper Fremont Glacier were reexamined to confirm and refine previous chronological estimates of the ice core. At a depth of 152 m the refined age-depth profile shows good agreement (1736±10 A.D.) with the 14C age date (1729±95 A.D.). The δ18O profile of the Upper Fremont Glacier (UFG) ice core indicates a change in climate known as the Little Ice Age (LIA). However, the sampling interval for δ18O is sufficiently large (20 cm) such that it is difficult to pinpoint the LIA termination on the basis of δ18O data alone. Other research has shown that changes in the δ18O variance are generally coincident with changes in ECM variance. The ECM data set contains over 125,000 data points at a resolution of 1 data point per millimeter of ice core. A 999-point running average of the ECM data set and results from f tests indicates that the variance of the ECM data decreases significantly at about 108 m. At this depth, the age-depth profile predicts an age of 1845 A.D. Results indicate the termination of the LIA was abrupt with a major climatic shift to warmer temperatures around 1845 A.D. and continuing to present day. Prediction limits (error bars) calculated for the profile ages are ±10 years (90% confidence level). Thus a conservative estimate for the time taken to complete the LIA climatic shift to present-day climate is about 10 years, suggesting the LIA termination in alpine regions of central North America may have occurred

  8. Tomographic images of subducted oceans matched to the accretionary records of orogens - Case study of North America and relevance to Central Asia

    Science.gov (United States)

    Sigloch, Karin; Mihalynuk, Mitchell G.; Hosseini, Kasra

    2016-04-01

    Accretionary orogens are the surface record of subduction on the 100-million-year timescale; they aggregate buoyant crustal welts that resisted subduction. The other record of subduction is found in the deep subsurface: oceanic lithosphere preserved in the mantle that records ocean basin closure between successive generations of arcs. Seismic tomography maps out these crumpled paleo-oceans down to the core-mantle boundary, where slab accumulates. One such accumulation of enormous scale is under Eastern Asia, recording the assembly of the Central Asian Orogenic Belt (CAOB). Deep CAOB slab has hardly been explored because tomographic image resolution in the lowermost mantle is limited, but this is rapidly improving. We present new images of the CAOB slabs from our P-wave tomography that includes core-diffracted waves as a technical novelty. The previous slab blur sharpens into the type of elongated geometries expected to trace paleo-trench lines. Since the North American Cordillera is younger than the CAOB (mostly 10,000 km long. North America converged on the two microcontinents by westward subduction of two intervening basins (which we name Mezcalera and Angayucham oceans), culminating in diachronous suturing between ~150 Ma and ~50 Ma. Hence geophysical subsurface evidence negates the widely accepted "Andean-style" model of Farallon-beneath-continent subduction since at least 180 Ma, and supports a Jura-Cretaceous paleogeography closer to today's Southwestern Pacific, or to the Paleozoic CAOB. Though advocated since the 1970's by a minority of geologists, this scenario had not gained wide acceptance due to a record obscured by overprinting, margin-parallel translation, and oroclinal bending. The new subsurface evidence provides specific indications where to seek the decisive Mezcalera-Angayucham suture. The suture is evident in a trail of collapsed Jura-Cretaceous basin relics that run the length of the Cordillera. Reference: Sigloch, K., & Mihalynuk, M. G. (2013

  9. Central Bank independence in Latin America La independencia de la Banca Central en América Latina

    Directory of Open Access Journals (Sweden)

    Junguito Bonnet Roberto

    1996-06-01

    Full Text Available This article describes the origin and evolution of the central banks of Argentina, Brazil, Chile, Colombia, Mexico, and Venezuela, and analyzes their respective institutional structures. It also studies the contribution of the central bank to stabilization and the problems for maintaining this independence into the future.Este artículo describe el origen y la evolución de los Bancos Centrales de Argentina, Brasil, Chile, Colombia, México y Venezuela, y analiza sus respectivas estructruras institucionales. También estudia la contribución de la banca central a la estabilización y los problemas para que esta independencia se mantenga en el futuro.

  10. Soil water storage and groundwater behaviour in a catenary sequence beneath forest in central Amazonia: I. Comparisons between plateau, slope and valley floor

    Directory of Open Access Journals (Sweden)

    M. G. Hodnett

    1997-01-01

    Full Text Available Soil water storage was monitored in three landscape elements in the forest (plateau, slope and valley floor over a 3 year period to identify differences in sub-surface hydrological response. Under the plateau and slope, the changes of storage were very similar and there was no indication of surface runoff on the slope. The mean maximum seasonal storage change was 156 mm in the 2 m profile but it was clear that, in the dry season, the forest was able to take up water from below 3.6 m. Soil water availability was low. Soil water storage changes in the valley were dominated by the behaviour of a shallow water table which, in normal years, varied between 0.1 m below the surface at the end of the wet season and 0.8 m at the end of the dry season. Soil water storage changes were small because root uptake was largely replenished by groundwater flow towards the stream. The groundwater behaviour is controlled mainly by the deep drainage from beneath the plateau and slope areas. The groundwater gradient beneath the slope indicated that recharge beneath the plateau and slope commences only after the soil water deficits from the previous dry season have been replenished. Following a wet season with little recharge, the water table fell, ceasing to influence the valley soil water storage, and the stream dried up. The plateau and slope, a zone of very high porosity between 0.4 and 1.1 m, underlain by a less conductive layer, is a probable route for interflow during, and for a few hours after, heavy and prolonged rainfall.

  11. Mid-term evaluation of the NRECA (National Rural Electric Cooperative Association) Central America Rural Electrification Support Program (CARES)

    Energy Technology Data Exchange (ETDEWEB)

    Perlack, R.D. (Oak Ridge National Lab., TN (USA)); Jones, H.G. (Oak Ridge Associated Universities, Inc., TN (USA)); Garcia, A. III (Texas A and M Univ., College Station, TX (USA). Dept. of Agricultural Engineering); Flores, E. (Flores (Edgar), Guatemala City (Guatemala))

    1990-09-01

    Oak Ridge National Laboratory was requested by the Regional Office for Central America and Panama to conduct a mid-term evaluation of the Cares Project, which is being implemented by the National Rural Electric Cooperative Association. This evaluation was conducted over a three week period by a four person team. Overall, the project has had numerous successes and is highly valued by local counterpart utilities and USAID Missions. Notwithstanding the significant results of the project, changes can be made in certain operating procedures and in the direction of some programmatic activities that can lead to an even more effective project.

  12. Geophysical study of the crust and upper mantle beneath the central Rio Grande rift and adjacent Great Plains and Colorado Plateau

    Energy Technology Data Exchange (ETDEWEB)

    Ander, M.E.

    1981-03-01

    As part of the national hot dry rock (HDR) geothermal program conducted by Los Alamos Scientific Laboratory, a regional deep magnetotelluric (MT) survey of Arizona and New Mexico was performed. The main objective of the MT project was to produce a regional geoelectric contour map of the pervasive deep electrical conductor within the crust and/or upper mantle beneath the Colorado Plateau, Basin and Range Province, and Rio Grande rift. Three MT profiles cross the Jemez lineament. Preliminary one-dimensional analysis of the data suggest the lineament is associated with anomalously high electrical conductivity very shallow in the crust. An MT/audiomagnetotelluric (AMT) study of a 161 km/sup 2/ HDR prospect was performed on the Zuni Indian Reservation, New Mexico. Two-dimensional gravity modeling of a 700-km gravity profile at 34/sup 0/30'N latitude was used to study the crust and upper mantle beneath the Rio Grande rift. Several models of each of three consecutive layers were produced using all available geologic and geophysical constraints. Two short-wavelength anomalies along the gravity profile were analyzed using linear optimization techniques.

  13. The complex biogeography of the plant pathogen Xylella fastidiosa: genetic evidence of introductions and Subspecific introgression in Central America.

    Directory of Open Access Journals (Sweden)

    Leonard Nunney

    Full Text Available The bacterium Xylella fastidiosa is a plant pathogen with a history of economically damaging introductions of subspecies to regions where its other subspecies are native. Genetic evidence is presented demonstrating the introduction of two new taxa into Central America and their introgression into the native subspecies, X. fastidiosa subsp. fastidiosa. The data are from 10 genetic outliers detected by multilocus sequence typing (MLST of isolates from Costa Rica. Six (five from oleander, one from coffee defined a new sequence type (ST53 that carried alleles at six of the eight loci sequenced (five of the seven MLST loci diagnostic of the South American subspecies Xylella fastidiosa subsp. pauca which causes two economically damaging plant diseases, citrus variegated chlorosis and coffee leaf scorch. The two remaining loci of ST53 carried alleles from what appears to be a new South American form of X. fastidiosa. Four isolates, classified as X. fastidiosa subsp. fastidiosa, showed a low level of introgression of non-native DNA. One grapevine isolate showed introgression of an allele from X. fastidiosa subsp. pauca while the other three (from citrus and coffee showed introgression of an allele with similar ancestry to the alleles of unknown origin in ST53. The presence of X. fastidiosa subsp. pauca in Central America is troubling given its disease potential, and establishes another route for the introduction of this economically damaging subspecies into the US or elsewhere, a threat potentially compounded by the presence of a previously unknown form of X. fastidiosa.

  14. The complex biogeography of the plant pathogen Xylella fastidiosa: genetic evidence of introductions and Subspecific introgression in Central America.

    Science.gov (United States)

    Nunney, Leonard; Ortiz, Beatriz; Russell, Stephanie A; Ruiz Sánchez, Rebeca; Stouthamer, Richard

    2014-01-01

    The bacterium Xylella fastidiosa is a plant pathogen with a history of economically damaging introductions of subspecies to regions where its other subspecies are native. Genetic evidence is presented demonstrating the introduction of two new taxa into Central America and their introgression into the native subspecies, X. fastidiosa subsp. fastidiosa. The data are from 10 genetic outliers detected by multilocus sequence typing (MLST) of isolates from Costa Rica. Six (five from oleander, one from coffee) defined a new sequence type (ST53) that carried alleles at six of the eight loci sequenced (five of the seven MLST loci) diagnostic of the South American subspecies Xylella fastidiosa subsp. pauca which causes two economically damaging plant diseases, citrus variegated chlorosis and coffee leaf scorch. The two remaining loci of ST53 carried alleles from what appears to be a new South American form of X. fastidiosa. Four isolates, classified as X. fastidiosa subsp. fastidiosa, showed a low level of introgression of non-native DNA. One grapevine isolate showed introgression of an allele from X. fastidiosa subsp. pauca while the other three (from citrus and coffee) showed introgression of an allele with similar ancestry to the alleles of unknown origin in ST53. The presence of X. fastidiosa subsp. pauca in Central America is troubling given its disease potential, and establishes another route for the introduction of this economically damaging subspecies into the US or elsewhere, a threat potentially compounded by the presence of a previously unknown form of X. fastidiosa. PMID:25379725

  15. Age and geochemistry of basaltic complexes in western Costa Rica: Contributions to the geotectonic evolution of Central America

    Science.gov (United States)

    Hauff, Folkmar; Hoernle, Kaj; van den Bogaard, Paul; Alvarado, Guillermo; Garbe-Schönberg, Dieter

    2000-05-01

    The age and origin of magmatic complexes along the Pacific Coast of Central America have important implications for the origin and tectonic evolution of this convergent plate margin. Here we present new 40Ar/39Ar laser age dates, major and trace element data, and initial Sr-Nd-Pb isotope ratios. The 124-109 Ma tholeiitic portions of the Santa Elena complex formed in a primitive island arc setting, believed to be part of the Chortis subduction zone. The geochemical similarities between the Santa Elena and Tortugal alkaline volcanic rocks suggest that Chortis block may extend south of the Hess Escarpment. The Nicoya, Herradura, Golfito, and Burica complexes and the tholeiitic Tortugal unit formed between 95 and 75 Ma and appear to be part of the Caribbean Large Igneous Province, thought to mark the initiation of the Galápagos hotspot. The Quepos and Osa complexes (65-59 Ma) represent accreted sections of an ocean island and an aseismic ridge, respectively, interpreted to reflect part of the Galápagos paleo-hotspot track. An Oligocene unconformity throughout Central America may be related to the mid-Eocene accretion of the Quepos and Osa complexes.

  16. Firm dollar debt and central bank dollar reserves: Empirical evidence from Latin America

    OpenAIRE

    Rajeswari Sengupta

    2014-01-01

    I explore an empirically robust but previously undocumented association between the foreign exchange reserves accumulated by central banks of emerging market economies and dollar-denominated debt held in the balance sheets of non financial sector firms. Borrowing in dollars can have damaging effects on corporate balance sheets in the event of exchange rate depreciation. However, firms may discount such risk because of the implicit insurance provided by the central banks ex-ante reserve accumu...

  17. Sub-continental lithospheric mantle structure beneath the Adamawa plateau inferred from the petrology of ultramafic xenoliths from Ngaoundéré (Adamawa plateau, Cameroon, Central Africa)

    Science.gov (United States)

    Nkouandou, Oumarou F.; Bardintzeff, Jacques-Marie; Fagny, Aminatou M.

    2015-11-01

    Ultramafic xenoliths (lherzolite, harzburgite and olivine websterite) have been discovered in basanites close to Ngaoundéré in Adamawa plateau. Xenoliths exhibit protogranular texture (lherzolite and olivine websterite) or porphyroclastic texture (harzburgite). They are composed of olivine Fo89-90, orthopyroxene, clinopyroxene and spinel. According to geothermometers, lherzolites have been equilibrated at 880-1060 °C; equilibrium temperatures of harzburgite are rather higher (880-1160 °C), while those of olivine websterite are bracketed between 820 and 1010 °C. The corresponding pressures are 1.8-1.9 GPa, 0.8-1.0 GPa and 1.9-2.5 GPa, respectively, which suggests that xenoliths have been sampled respectively at depths of 59-63 km, 26-33 km and 63-83 km. Texture and chemical compositional variations of xenoliths with temperature, pressure and depth on regional scale may be ascribed to the complex history undergone by the sub-continental mantle beneath the Adamawa plateau during its evolution. This may involve a limited asthenosphere uprise, concomitantly with plastic deformation and partial melting due to adiabatic decompression processes. Chemical compositional heterogeneities are also proposed in the sub-continental lithospheric mantle under the Adamawa plateau, as previously suggested for the whole Cameroon Volcanic Line.

  18. Biologic and genetic characteristics of Toxoplasma gondii isolates in free-range chickens from Nicaragua, Central America

    DEFF Research Database (Denmark)

    Dubey, J.P.; Sundar, N.; Pineda, N.;

    2006-01-01

    :10 or less were pooled and fed to three T. gondii-free cats. Hearts and brains of 66 chickens with titers of 1:20 or higher were bioassayed in mice. Feces of cats were examined for oocysts. The cat fed tissues from eight chickens with titers of 1:10 shed T. gondii oocysts. The two cats fed tissues of 24...... from the same household, indicating multiple genotypes were circulating in the same environment. This may explain the high frequency of mixed infections observed. High rate of mixed infection in intermediate hosts such as chickens may facilitate genetic exchange between different parasite lineages...... in definitive feline hosts. This is the first report of genetic characterization of T. gondii isolates from Nicragua, Central America....

  19. Carbon cycle dynamics and solar activity embedded in a high-resolution 14C speleothem record from Belize, Central America

    Science.gov (United States)

    Lechleitner, Franziska A.; Breitenbach, Sebastian F. M.; McIntyre, Cameron; Asmerom, Yemane; Prufer, Keith M.; Polyak, Victor; Culleton, Brendan J.; Kennett, Douglas J.; Eglinton, Timothy I.; Baldini, James U. L.

    2015-04-01

    Speleothem 14C has recently emerged as a potentially powerful proxy for climate reconstruction. Several studies have highlighted the link between karst hydrology and speleothem 14C content, and a number of possible causes for this relationship have been proposed, such as dripwater flow dynamics in the karst and changes in soil organic matter (SOM) turnover time (e.g. Griffiths et al., 2012). Here we present a high resolution 14C record for a stalagmite (YOK-I) from Yok Balum cave in southern Belize, Central America. YOK-I grew continuously over the last 2000 years, and has been dated very precisely with the U-Th method (40 dates, mean uncertainty ventilation and hydrologic resilience to seismic activity, Journal of Cave and Karst Studies

  20. Structural Vulnerability among Migrating Women and Children Fleeing Central America and Mexico:The Public Health Impact of Humanitarian Parole

    Directory of Open Access Journals (Sweden)

    Elizabeth Salerno Valdez

    2015-06-01

    Full Text Available Since October 2013, US Customs and Border Patrol (USCBP has apprehended 15,979 families on the Southwest Border of the United States. Daily, migrating women and children from Mexico and Central America that qualify for humanitarian parole are released from immigration detention to a humanitarian aid organization in Southern Arizona. After several days in detention facilities, these families arrive tired, hungry, dehydrated, and with minimal direction regarding their final destination, and adherence to the parameters of their parole. Project Helping Hands (PHH utilizes a network of volunteers to provide the women and children with food, water, clothing, hygiene products, hospitality, and legal orientation. The aim of this assessment was to document the experiences of families granted humanitarian parole through the lens of structural vulnerability. Here we apply qualitative methods to elicit PHH lead volunteer perspectives regarding the migration experience of migrating families. Using inductive analysis, we found six major themes emerged from the qualitative data: reasons for leaving, experience on the journey, dehumanization in detention, family separation, vulnerability, and resiliency.These findings elucidate the different physical and psychological distresses that migrating families from Mexico and Central America experience before, during and after their arrival at the US-Mexico border. We posit that these distresses are a result of, or exacerbated by, structural vulnerability. Structural vulnerability has life-long health implications for a sub-population of young mothers and their children. The number of migrating families who have experienced traumatic events before, and during their migration experience continues to expand and thus warrants consideration of mental health surveillance and intervention efforts for these families. More public health research is needed to better understand and combat the health challenges of this growing

  1. Higher Education in Central America: Historical Foundations for Its Future Projection.

    Science.gov (United States)

    Arriaza, Ricardo Sol

    1996-01-01

    Three trends in Central American higher education are examined in historical context: (1) inertia from lack of mobility, bureaucracy, and corporate influence; (2) elitism as a response to budgetary constraints; and (3) attempts to increase responsiveness to educational needs and demands. Issues examined include earlier attempts at change, slow…

  2. Rainforest understory beetles of the Neotropics: Mizotrechus Bates 1872, a generic synopsis with descriptions of new species from Central America and northern South America (Coleoptera, Carabidae, Perigonini

    Directory of Open Access Journals (Sweden)

    Terry Erwin

    2011-11-01

    Full Text Available Information on the single previously described species, Mizotrechus novemstriatus Bates 1872 (type locality: Brazil – Amazonas, Tefé, is updated and 17 new species for the genus from Nicaragua, Costa Rica, Panamá, Colombia, Venezuela, and Guyane are described. The species records in the literature and on determined specimens in some collections of M. novemstriatus Bates from Central America are not that species; currently, M. novemstriatus is known only from its type locality in Amazonian Brazil. For the new species described, their known general distributions are as follows: Mizotrechus batesi sp. n. (Guyane, Mizotrechus bellorum sp. n. (Guyane, Mizotrechus brulei sp. n. (Guyane, Mizotrechus belevedere sp. n. (Guyane, Mizotrechus costaricensis sp. n. (Costa Rica, Mizotrechus dalensi sp. n. (Guyane, Mizotrechus edithpiafae sp. n. (provenance unknown, Mizotrechus fortunensis sp. n. (Panamá, Mizotrechus gorgona. sp. n. (Colombia, Mizotrechus grossus sp. n. (Guyane, Mizotrechus jefe sp. n. (Panamá, Mizotrechus marielaforetae sp. n. (Guyane, Mizotrechus minutus sp. n. (Guyane, Mizotrechus neblinensis sp. n. (Guyane, Venezuela, Mizotrechus poirieri sp. n. (Guyane, and Mizotrechus woldai sp. n. (Panamá. Long-term use of flight intercept traps in Guyane provided so many new species that apparently the use of FITs is the way to collect adults of this taxon, previously known from very few specimens. Many more species of this genus can be expected to be discovered throughout the Neotropics; the present contribution is a preliminary synopsis with identification key and adult images of all known species. Likely numerous species are yet to be discovered throughout tropical climes.

  3. New evidence about the subduction of the Copiapó ridge beneath South America, and its connection with the Chilean-Pampean flat slab, tracked by satellite GOCE and EGM2008 models

    Science.gov (United States)

    Álvarez, Orlando; Gimenez, Mario; Folguera, Andres; Spagnotto, Silvana; Bustos, Emilce; Baez, Walter; Braitenberg, Carla

    2015-11-01

    Satellite-only gravity measurements and those integrated with terrestrial observations provide global gravity field models of unprecedented precision and spatial resolution, allowing the analysis of the lithospheric structure. We used the model EGM2008 (Earth Gravitational Model) to calculate the gravity anomaly and the vertical gravity gradient in the South Central Andes region, correcting these quantities by the topographic effect. Both quantities show a spatial relationship between the projected subduction of the Copiapó aseismic ridge (located at about 27°-30° S), its potential deformational effects in the overriding plate, and the Ojos del Salado-San Buenaventura volcanic lineament. This volcanic lineament constitutes a projection of the volcanic arc toward the retroarc zone, whose origin and development were not clearly understood. The analysis of the gravity anomalies, at the extrapolated zone of the Copiapó ridge beneath the continent, shows a change in the general NNE-trend of the Andean structures to an ENE-direction coincident with the area of the Ojos del Salado-San Buenaventura volcanic lineament. This anomalous pattern over the upper plate is interpreted to be linked with the subduction of the Copiapó ridge. We explore the relation between deformational effects and volcanism at the northern Chilean-Pampean flat slab and the collision of the Copiapó ridge, on the basis of the Moho geometry and elastic thicknesses calculated from the new satellite GOCE data. Neotectonic deformations interpreted in previous works associated with volcanic eruptions along the Ojos del Salado-San Buenaventura volcanic lineament is interpreted as caused by crustal doming, imprinted by the subduction of the Copiapó ridge, evidenced by crustal thickening at the sites of ridge inception along the trench. Finally, we propose that the Copiapó ridge could have controlled the northern edge of the Chilean-Pampean flat slab, due to higher buoyancy, similarly to the control

  4. Active tectonics and Quaternary landscape evolution across the western Panama block, Costa Rica, Central America

    Science.gov (United States)

    Marshall, Jeffrey Scott

    Three aspects of active tectonism are examined across central Costa Rica: (1) fault kinematics; (2) volcanic arc retreat; and (3) spatially variable coastal uplift. Diffuse faulting along the Central Costa Rica Deformed Belt (CCRDB) defines the western margin of the Panama block and aligns with the rough-smooth boundary (RSB) on the subducting Cocos plate. Sub-horizontal subduction of rough, hotspot thickened crust (Cocos Ridge and seamounts) shifts active shortening into the volcanic arc along the CCRDB. Mesoscale faults express variable kinematics across three domains: transtension in the forearc, transcurrent motion across the volcanic arc, and transpression in the back arc. Fault kinematics agree with seismicity and GPS data, and isotopic ages confirm that faulting postdates the late Neogene onset of shallow subduction. Stratigraphic correlation augmented by 40Ar/39Ar dating constrain the timing of Quaternary arc migration from the Neogene Aguacate range to the modern Cordillera Central. The Valle Central basin, between the cordilleras, filled with thick sequences of lavas, pyroclastic flows, and lahars. Middle Pleistocene drainage capture across the Aguacate arc linked the Valle Central with the Pacific slope and ash flows descended onto the coastal Orotina debris fan. Arc retreat reflects slab shallowing and enhanced tectonic erosion as rough crust entered the subduction zone. Differing subduction parameters across the RSB (crustal age, slab dip, roughness) produce marked contrasts in coastal tectonism. Varying uplift rates across coastal faults reflect sub-horizontal subduction of seamount roughness. Three groups (I--III) of fluvial terraces are correlated along the coast by isotopic ages and geomorphic characteristics. Base level fluctuations and terrace genesis reflect interaction between eustatic sea level and spatially variable rock uplift. Low uplift rates (north of RSB), yield one surface per terrace group, whereas moderate rates (south of RSB

  5. Mesoproterozoic diamondiferous ultramafic pipes at Majhgawan and Hinota, Panna area, central India: Key to the nature of sub-continental lithospheric mantle beneath the Vindhyan basin

    Indian Academy of Sciences (India)

    N V Chalapathi Rao

    2006-02-01

    Amongst all the perceptible igneous manifestations (volcanic tuffs and agglomerates,minor rhyolitic flows and andesites,dolerite dykes and sills near the basin margins,etc.)in the Vindhyan basin,the two Mesoproterozoic diamondiferous ultramafic pipes intruding the Kaimur Group of sediments at Majhgawan and Hinota in the Panna area are not only the most conspicuous but also well-known and have relatively deeper mantle origin.Hence,these pipes constitute the only yet available ‘direct ’mantle samples from this region and their petrology,geochemistry and iso-tope systematics are of profound significance in understanding the nature of the sub-continental lithospheric mantle beneath the Vindhyan basin.Their emplacement age (∼1100 Ma)also constitutes the only reliable minimum age constrain on the Lower Vindhyan Group of rocks.The Majhgawan and Hinota pipes share the petrological,geochemical and isotope characteristics of kimberlite,orangeite (Group II kimberlite)and lamproite and hence are recognised as belonging to a ‘transitional kimberlite –orangeite –lamproite ’rock type.The name majhagwanite has been proposed by this author to distinguish them from other primary diamond source rocks.The parent magma of the Majhgawan and Hinota pipes is envisaged to have been derived by very small (> 1%)degrees of partial melting of a phlogopite-garnet lherzolite source (rich in titanium and barium)that has been previously subjected to an episode of initial depletion (extensive melting during continent formation)and subsequent metasomatism (enrichment).There is absence of any subduction-related characteristics,such as large negative anomalies at Ta and Nb,and therefore, the source enrichment (metasomatism)of both these pipes is attributed to the volatile-and K-rich, extremely low-viscosity melts that leak continuously to semi-continuously from the asthenosphere and accumulate in the overlying lithosphere.Lithospheric/crustal extension,rather than decompression

  6. Vulnerability, poverty and socio-natural disasters in Central America and The Caribbean

    OpenAIRE

    Salas, J

    2007-01-01

    [EN] This paper analyses and quantifi es the relative level of risk in a geographical area that is vulnerable to natural phenomena and with a high proportion of its population in a situation of residential poverty. We deduce that the hazard in the area, composed of nine Central American and Caribbean countries, is signifi cantly higher than the world average. The fi rst aspect is covered in the sections Population at risk and Natural phenomena, which analyse the ‘st...

  7. A Regional GIS of the Central Andes, South America - Integration of Satellite and Geophysical Data Sets

    OpenAIRE

    Hofmann, K; F. K. List;  

    1996-01-01

    The Central Andes of northern Chile, southwestern Bolivia and northwestern Argentina are studied by a research project supported by the Deutsche Forschungsgemeinschaft (SFB 267). The main topics of these geological and geophysical investigations are the orogeny of the Andean mountains and the crustal development at an active continental margin. The "Andean GIS" is designed as a tool for data collection, management, overview, analysis and mapping. The integration of different data supports the...

  8. One Rural Hospital's Experience Implementing the Society for Healthcare Epidemiology of America Guidelines to Decrease Central Line Infections.

    Science.gov (United States)

    Curlej, Maria H; Katrancha, Elizabeth

    2016-01-01

    In an effort to take advantage of the Highmark Quality Blue Initiative () requiring information from hospitals detailing their central line-associated blood stream infections (CLABSIs) surveillance system, quality improvement program, and statistics regarding the CLABSI events, this institution investigated the latest evidence-based recommendations to reduce CLABSIs. Recognizing the baseline rate of 2.4 CLABSIs per 1,000 central line days and its effect on patient outcomes and medical costs, this hospital made a commitment to improve their CLABSI outcomes. As a result, the facility adopted the Society for Healthcare Epidemiology of America (SHEA) guidelines. The purpose of this article is to review the CLABSI rates and examine the prevention strategies following implementation of the SHEA guidelines. A quantitative, descriptive retrospective program evaluation examined the hospital's pre- and post-SHEA implementation methods of decreasing CLABSIs and the subsequent CLABSI rates over 3 time periods. Any patient with a CLABSI infection admitted to this hospital July 2007 to June 2010 (N = 78). CLABSI rates decreased from 1.9 to 1.3 over the study period. Compliance with specific SHEA guidelines was evaluated and measures were put into place to increase compliance where necessary. CLABSI rates at this facility remain below the baseline of 2.4 for calendar year 2013 (0.79), 2014 (0.07), and 2015 (0.33). PMID:27618377

  9. Differential effects of landscape-level environmental features on genetic structure in three codistributed tree species in Central America.

    Science.gov (United States)

    Poelchau, Monica F; Hamrick, J L

    2012-10-01

    Landscape genetic studies use spatially explicit population genetic information to determine the physical and environmental causes of population genetic structure on regional scales. Comparative studies that identify common barriers to gene flow across multiple species within a community are important to both understand the evolutionary trajectories of populations and prioritize habitat conservation. Here, we use a comparative landscape genetic approach to ask whether gradients in temperature or precipitation seasonality structure genetic variation across three codistributed tree species in Central America, or whether a simpler (geographic distance) or more complex, species-specific environmental niche model is necessary to individually explain population genetic structure. Using descriptive statistics and causal modelling, we find that different factors best explain genetic distance in each of the three species: environmental niche distance in Bursera simaruba, geographic distance in Ficus insipida and historical barriers to gene flow or cryptic reproductive barriers for Brosimum alicastrum. This study confirms suggestions from previous studies of Central American tree species that imply that population genetic structure of trees in this region is determined by complex interactions of both historical and current barriers to gene flow.

  10. Anxiety and depression during pregnancy in Central America : a cross-sectional study among pregnant women in the developing country Nicaragua

    NARCIS (Netherlands)

    Verbeek, T.; Arjadi, R.; Vendrik, J. J.; Burger, H.; Berger, M. Y.

    2015-01-01

    Background: Around the world, maternal psychopathology during pregnancy is associated with a range of negative consequences for mother and child. Nevertheless, in Central America the magnitude of this public health problem is still unknown. The objective of this first explorative study was to invest

  11. Discovery of new Ohbayashinema spp. (nematoda: heligomosomoidea) in Ochotona princeps and O. cansus (lagomorpha: ochotonidae) from western North America and central Asia, with considerations of historical biogeography

    Science.gov (United States)

    Three new species of Ohbayashinema (Nematoda, Heligmosomoidea) are described from localities in western North America and central Asia. Two of these species, Ohbayashinema nearctica n. sp and O. aspeira n. sp. are parasitic in American pika, Ochotona princeps. Ohbayashinema nearctica is differentiat...

  12. Trichospermum lessertianum comb. nov., the correct name for the Cuban species of Trichospermum (Malvaceae: Grewioideae also found in Mexico and Central America

    Directory of Open Access Journals (Sweden)

    Laurence J. Dorr

    2011-02-01

    Full Text Available The correct name for the Cuban species of Trichospermum Bl. (Malvaceae: Grewioideae also found in Mexico and Central America is T. lessertianum (Hochr. Dorr, comb. n. The name T. mexicanum (DC. Baill., incorrectly applied to this Cuban species, should be restricted to a species endemic to western and southern Mexico.

  13. Trichospermum lessertianum comb. n., the correct name for the Cuban species of Trichospermum (Malvaceae, Grewioideae) also found in Mexico and Central America

    OpenAIRE

    Dorr, Laurence J.

    2011-01-01

    Abstract The correct name for the Cuban species of Trichospermum Bl. (Malvaceae: Grewioideae) also found in Mexico and Central America is Trichospermum lessertianum (Hochr.) Dorr, comb. n. The name Trichospermum mexicanum (DC.) Baill., incorrectly applied to this Cuban species, should be restricted to a species endemic to western and southern Mexico.

  14. Health care providers and human trafficking: what do they know, what do they need to know? Findings from the middle East, the Caribbean, and central america

    NARCIS (Netherlands)

    Viergever, R.F.; West, H.; Borland, R.; Zimmerman, C.

    2015-01-01

    BACKGROUND: Human trafficking is a crime that commonly results in acute and chronic physical and psychological harm. To foster more informed health sector responses to human trafficking, training sessions for health care providers were developed and pilot-tested in the Middle East, Central America,

  15. Understanding key drivers controlling daily stable isotope variations in precipitation of Costa Rica, Central America

    Science.gov (United States)

    Sanchez-Murillo, Ricardo; Welsh, Kristin; Birkel, Christian; Esquivel-Hernández, Germain; Corrales-Salazar, Jose; Boll, Jan; Brooks, Erin; Roupsard, Olivier; Katchan, Irina; Arce-Mesén, Rafael; Soulsby, Chris; Araguás-Araguás, Luis

    2015-04-01

    Costa Rica is located on the Central American Isthmus, which receives direct moisture inputs from the Caribbean Sea and the Pacific Ocean. The relatively narrow, but high relief Central American land bridge is characterized by unique mountainous and lowland microclimates. However, only limited knowledge exists about the impact of relief and regional atmospheric circulation patterns on precipitation origin, transport, and isotopic composition in this tropical region. Therefore, the main scope of this study is to identify the key drivers controlling variations in meteoric waters of Costa Rica using stable isotopes based on daily sample collection for the year 2013. The monitoring sites comprise three strategic locations across Costa Rica: Heredia (Central Valley), Turrialba (Caribbean slope), and Caño Seco (South Pacific slope). Sporadic dry season rain is mostly related to isolated enriched events ranging from -5.8‰ d18O up to -0.9‰ d18O. By mid-May, the Intertropical Convergence Zone reaches Costa Rica resulting in a notable depletion in isotope ratios (up to -18.5‰ d18O). HYSPLIT back air mass trajectories indicate the strong influence on the origin and transport of precipitation of two main moisture transport mechanisms, the Caribbean Low Level Jet and the Colombian Low Level Jet as well as localized convection events. Multiple linear regression models constructed based on Random Forests of surface meteorological information and atmospheric sounding profiles suggest that Lifted Condensation Level and surface relative humidity are the main factors controlling isotopic variations. These findings diverge from the recognized 'amount effect' in monthly composite samples across the tropics. Understanding of stable isotope dynamics in tropical precipitation can be used to enhance catchment and groundwater modeling efforts in ungauged basins where scarcity of long-term monitoring data drastically limit current and future water resources management.

  16. Reconstructing the timing and dispersion routes of HIV-1 subtype B epidemics in the Caribbean and Central America: a phylogenetic story.

    Science.gov (United States)

    Pagán, Israel; Holguín, Africa

    2013-01-01

    The Caribbean and Central America are among the regions with highest HIV-1B prevalence worldwide. Despite of this high virus burden, little is known about the timing and the migration patterns of HIV-1B in these regions. Migration is one of the major processes shaping the genetic structure of virus populations. Thus, reconstruction of epidemiological network may contribute to understand HIV-1B evolution and reduce virus prevalence. We have investigated the spatio-temporal dynamics of the HIV-1B epidemic in The Caribbean and Central America using 1,610 HIV-1B partial pol sequences from 13 Caribbean and 5 Central American countries. Timing of HIV-1B introduction and virus evolutionary rates, as well as the spatial genetic structure of the HIV-1B populations and the virus migration patterns were inferred. Results revealed that in The Caribbean and Central America most of the HIV-1B variability was generated since the 80 s. At odds with previous data suggesting that Haiti was the origin of the epidemic in The Caribbean, our reconstruction indicated that the virus could have been disseminated from Puerto Rico and Antigua. These two countries connected two distinguishable migration areas corresponding to the (mainly Spanish-colonized) Easter and (mainly British-colonized) Western islands, which indicates that virus migration patterns are determined by geographical barriers and by the movement of human populations among culturally related countries. Similar factors shaped the migration of HIV-1B in Central America. The HIV-1B population was significantly structured according to the country of origin, and the genetic diversity in each country was associated with the virus prevalence in both regions, which suggests that virus populations evolve mainly through genetic drift. Thus, our work contributes to the understanding of HIV-1B evolution and dispersion pattern in the Americas, and its relationship with the geography of the area and the movements of human populations.

  17. Reconstructing the timing and dispersion routes of HIV-1 subtype B epidemics in the Caribbean and Central America: a phylogenetic story.

    Directory of Open Access Journals (Sweden)

    Israel Pagán

    Full Text Available The Caribbean and Central America are among the regions with highest HIV-1B prevalence worldwide. Despite of this high virus burden, little is known about the timing and the migration patterns of HIV-1B in these regions. Migration is one of the major processes shaping the genetic structure of virus populations. Thus, reconstruction of epidemiological network may contribute to understand HIV-1B evolution and reduce virus prevalence. We have investigated the spatio-temporal dynamics of the HIV-1B epidemic in The Caribbean and Central America using 1,610 HIV-1B partial pol sequences from 13 Caribbean and 5 Central American countries. Timing of HIV-1B introduction and virus evolutionary rates, as well as the spatial genetic structure of the HIV-1B populations and the virus migration patterns were inferred. Results revealed that in The Caribbean and Central America most of the HIV-1B variability was generated since the 80 s. At odds with previous data suggesting that Haiti was the origin of the epidemic in The Caribbean, our reconstruction indicated that the virus could have been disseminated from Puerto Rico and Antigua. These two countries connected two distinguishable migration areas corresponding to the (mainly Spanish-colonized Easter and (mainly British-colonized Western islands, which indicates that virus migration patterns are determined by geographical barriers and by the movement of human populations among culturally related countries. Similar factors shaped the migration of HIV-1B in Central America. The HIV-1B population was significantly structured according to the country of origin, and the genetic diversity in each country was associated with the virus prevalence in both regions, which suggests that virus populations evolve mainly through genetic drift. Thus, our work contributes to the understanding of HIV-1B evolution and dispersion pattern in the Americas, and its relationship with the geography of the area and the movements of

  18. A GPS and modelling study of deformation in northern Central America

    Science.gov (United States)

    Rodriguez, M.; DeMets, C.; Rogers, R.; Tenorio, C.; Hernandez, D.

    2009-09-01

    We use GPS measurements at 37 stations in Honduras and El Salvador to describe active deformation of the western end of the Caribbean Plate between the Motagua fault and Central American volcanic arc. All GPS sites located in eastern Honduras move with the Caribbean Plate, in accord with geologic evidence for an absence of neotectonic deformation in this region. Relative to the Caribbean Plate, the other stations in the study area move west to west-northwest at rates that increase gradually from 3.3 +/- 0.6 mm yr-1 in central Honduras to 4.1 +/- 0.6 mm yr-1 in western Honduras to as high as 11-12 mm yr-1 in southern Guatemala. The site motions are consistent with slow westward extension that has been inferred by previous authors from the north-striking grabens and earthquake focal mechanisms in this region. We examine the factors that influence the regional deformation by comparing the new GPS velocity field to velocity fields predicted by finite element models (FEMs) that incorporate the regional plate boundary faults and known plate motions. Our modelling suggests that the obliquely convergent (~20°) direction of Caribbean-North American Plate motion relative to the Motagua fault west of 90°W impedes the ENE-directed motion of the Caribbean Plate in southern Guatemala, giving rise to extension in southern Guatemala and western Honduras. The FEM predictions agree even better with the measured velocities if the plate motion west of the Central American volcanic arc is forced to occur over a broad zone rather than along a single throughgoing plate boundary fault. Our analysis confirms key predictions of a previous numerical model for deformation in this region, and also indicates that the curvature of the Motagua fault causes significant along-strike changes in the orientations of the principal strain-rate axes in the fault borderlands, in accord with earthquake focal mechanisms and conclusions reached in a recent synthesis of the structural and morphologic data

  19. Lithospheric structure beneath the Caribbean- South American plate boundary from S receiver functions

    Science.gov (United States)

    Masy, J.; Levander, A.; Niu, F.

    2010-12-01

    We have analyzed teleseismic S-wave data recorded by the permanent national seismic network of Venezuela and the BOLIVAR broadband array (Broadband Onshore-offshore Lithospheric Investigation of Venezuela and the Antilles arc Region) deployed from 2003 to 2005. A total of 28 events with Mw > 5.7 occurring at epicentral distances from 55° to 85° were used. We made Sp receiver functions to estimate the rapid variations of lithospheric structure in the southern Caribbean plate boundary region to try to better understand the complicated tectonic history of the region. Estimated Moho depth ranges from ~20 km beneath the Caribbean Large Igneous Provinces to ~50 km beneath the Mérida Andes in western Venezuela and the Sierra del Interior in northeastern Venezuela. These results are consistent with previous receiver functions studies (Niu et al., 2007) and active source profiles (Schmitz et al., 2001; Bezada et al., 2007; Clark et al., 2008; Guedez, 2008; Magnani et al., 2009). Beneath the Maracaibo Block we observe a signal at a depth of 100 km dipping ~24° towards the continent, which we interpret as the top of the oceanic Caribbean slab that is subducting beneath South America from the west. The deeper part of the slab was previously imaged using P-wave tomography (Bezada et al, 2010), and the upper part inferred from intermediate depth seismicity (Malavé and Suarez, 1995). These studies indicate flat slab subduction beneath northern Colombia and northwestern Venezuela with the slab dipping between 20° - 30° beneath Lake Maracaibo. Like others we attribute the flat slab subduction to the uplift of the Mérida Andes (for example Kellogg and Bonini, 1982). In eastern Venezuela beneath the Sierra del Interior we also observe a deep signal that we interpret as deep South American lithosphere that is detaching from the overriding plate as the Atlantic subducts and tears away from SA (Bezada et al., 2010; Clark et al, 2008). The lithosphere-asthenosphere boundary (LAB

  20. CO{sub 2} emissions, energy usage, and output in Central America

    Energy Technology Data Exchange (ETDEWEB)

    Apergis, Nicholas [Department of Banking and Financial Management, University of Piraeus, Karaoli and Dimitriou 80, Piraeus, ATTIKI 18534 (Greece); Payne, James E. [College of Arts and Sciences, Illinois State University, Campus Box 4100, Normal, IL 61790-4100 (United States)

    2009-08-15

    This study extends the recent work of Ang (2007) [Ang, J.B., 2007. CO{sub 2} emissions, energy consumption, and output in France. Energy Policy 35, 4772-4778] in examining the causal relationship between carbon dioxide emissions, energy consumption, and output within a panel vector error correction model for six Central American countries over the period 1971-2004. In long-run equilibrium energy consumption has a positive and statistically significant impact on emissions while real output exhibits the inverted U-shape pattern associated with the Environmental Kuznets Curve (EKC) hypothesis. The short-run dynamics indicate unidirectional causality from energy consumption and real output, respectively, to emissions along with bidirectional causality between energy consumption and real output. In the long-run there appears to be bidirectional causality between energy consumption and emissions. (author)

  1. The Structure of the Crust and Uppermost Mantle Beneath the Central Andes from Ambient Noise Tomography: Imaging the Neogene to Modern Batholith

    Science.gov (United States)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Porter, R. C.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2012-12-01

    The Central Andes of southern Peru, Bolivia, and northern Chile (between ~10°S and ~35°S) comprise the largest orogenic plateau in the world associated with abundant arc volcanism, the Central Andean Plateau (CAP). The goal of this continental-scale Ambient Noise Tomography (ANT) project is to incorporate broadband seismic data from ~20 seismic networks deployed incrementally in the Central and Southern Andes from May 1994 through March 2012, to image the vertically polarized shear-wave velocity (Vsv) structure of the CAP. First-order correlations with our shallow results (~5 km) and the morphotectonic provinces as well as subtler geological features indicate our results are robust. Our major results include mapping a pervasive mid-crustal low-velocity zone (images do not resolve a high conductivity anomaly across our low-velocity zone as expected in the presence of aqueous fluids or large interconnected zones of partial melt. Therefore, we dismiss them as likely explanations for our imaged low-velocity body outside of the APVC location. Working under the hypothesis that voluminous ignimbrites are the surface expression of batholith formation at depth as exemplified by the APVC, we combine our results with the locations of known Neogene ignimbrite eruptive centers and negative isostatic residual gravity anomalies and suggest the 3.25 km/s shear-wave velocity contour at 15 km depth generally outlines the extent of a Neogene to modern batholith, with isolated pockets of partial melt where velocities dip below 3.0 km/s. A velocity of 3.25 km/s at this pressure and temperature regime is too low for an isotropic granitic composition and must be explained without invoking significant partial melt. Previous work in Tibet, a region with thick crust analogous to the CAP, suggests a zone of mid-crustal radial anisotropy may separate horizontally and vertically polarized shear-wave velocities by as much as 20%. The effective isotropic shear velocity may be ~10% faster than

  2. The Pacific and Philippine Sea slabs in contact beneath Tokyo, central Japan: their roles in defining hazardous interaction earthquakes and in limiting the southern extent of Tohoku-oki aftershocks

    Science.gov (United States)

    Okaya, D. A.; Sato, H.; Lavier, L. L.; Tan, E.; Wu, F. T.; Hirata, N.

    2011-12-01

    The M9 Tohoku-oki earthquake produced over 11,000 >M3 aftershocks within the first four months after its 2011 March 11 occurrence date. The majority of these aftershocks define the earthquake source region between the subducting Pacific plate (PAC) and its overlying Eurasian plate (EUR) along the Japan Trench. While this portion of the trench boundary extends southward to the Boso triple junction (latitude ~34.3 oN), the Tohoku-oki aftershocks predominantly terminate at ~35.7 oN. Between these two latitudes there is a marked dropoff in aftershocks, most noticably offshore of Boso Peninsula, eastern Kanto, which we refer to as the off-Boso aftershock gap. Inside this gap, aftershocks that have occurred form two narrow-width streaks that radiate from the triple junction and extend into central Kanto. There is a correlation between the location of the off-Boso aftershock gap and the northern extent of the Philippine Sea plate (PHS). The PHS is sandwiched between the PAC-EUR plates beneath Kanto. While the majority of Tohoku-oki aftershocks occur within the one-slab PAC-EUR system to the north, the off-Boso gap is updip of where the PHS slab is resident inside the PAC-EUR mantle wedge. Furthermore, the northern of the two aftershock streaks spatially correlates with the downdip extent of the PHS with many located at the PHS-PAC contact based on published tomographic/seismicity studies. The presence of PHS changes the conditions of PAC-EUR slip. Preliminary finite-source studies from web sources (e.g., Univ Tokyo, Harvard) show that Tohoku-oki rupture terminated just north of the off-Boso gap. Apparently, the presence of the Philippine Sea plate may have been a contributing factor to inhibiting this rupture from propagating further southward. The megathrust source faults beneath Kanto are associated with the tops of Philippine Sea and Pacific plates. These shallow source faults have been the focus of much recent geological and geophysical study including seismicity and

  3. Towards a Political Economy of Weak Institutions and Strong Elites in Central America

    Directory of Open Access Journals (Sweden)

    Benedicte Bull

    2014-10-01

    Full Text Available A common conclusion of studies on Central America’s democracies and political economy is that the weakness of institutions and the strength of elites are a main reason for the region’s problems. Recently, a set of studies have attempted to scrutinize these elites in detail, focussing on their strategies and resources. The purpose of this article is to reflect upon what these studies can tell us about the question: what is strong when institutions are weak? I argue that in the Northern Triangle particularly the answer is elite networks and their command over and competition for the control over four sets of resources: money, means of force, information, and ideas and ideologies, including religion. A systematic study of such networks and how they interact with formal institutions may give us a more realistic view of the current state of Central American political economies. Resumen: Hacia una economía política de instituciones débiles y élites fuertes en Centroamérica Una conclusión común a la que llegan los estudios sobre la economía política y las democracias centroamericanas es que la debilidad de las instituciones y la fuerza de las élites son una razón fundamental para los problemas de la región. Últimamente, una serie de estudios han intentado estudiar a fondo dichas élites, enfocándose en sus estrategias y recursos. El objetivo del presente artículo es reflexionar sobre lo que dichos estudios pueden aportarnos a la respuesta de la pregunta: ¿qué es fuerte cuando las instituciones son débiles? Yo sostengo que en el Triángulo Norte, en particular, la respuesta son las redes de las élites y su control, así como su competencia por dicho control, de cuatro categorías de recursos: el dinero, los medios de coacción, la información y las ideas e ideologías, incluida la religión. Un estudio sistemático de dichas redes y sobre cómo interactúan con las instituciones formales podría facilitarnos una visión m

  4. Late Cretaceous-recent tectonic assembly of diverse crustal blocks in Central America, the Nicaraguan Rise, the Colombian Basin and northern South America as seen on a 1600-km-long, geologic and structural transect

    Science.gov (United States)

    Sanchez, J.; Mann, P.

    2015-12-01

    We have constructed a 1600-km-long transect from northern Honduras to northern Colombia that crosses northeastward-striking crustal blocks using a combination of offshore seismic data, gravity and magnetic data, well subsidence information, nearby outcrop information, and results from previous thermochronological, geochronological, geochemical and paleostress studies. The transect defines three major crustal and structural provinces: 1) Precambrian-Paleozoic, Chortis continental block whose northern edge is defined by the North America-Caribbean plate boundary. Events in this ~20-25-km-thick province include two major unconformities at the top of the Cretaceous and Eocene, associated southeast-dipping thrust faults related to collision of the Great Arc of the Caribbean (GAC) and Caribbean Large Igneous Province (CLIP) with the Chortis continental block. A third event is Eocene to recent subsidence and transtensional basins formed during the opening of the Cayman trough; 2) Late Cretaceous GAC and CLIP of oceanic arc and plateau origin, whose northern, deformed edge corresponds to the mapped Siuna belt of northern Nicaragua. This crustal province has a ~15-20-km-thick crust and is largely undeformed and extends across the Lower Nicaraguan Rise, Hess fault, to the southern limit of the Colombian basin where about 300 km of this province has been subducted beneath the accretionary wedge of the South Caribbean deformed belt of northwestern South America; and 3) Eocene to recent accretionary prism and intramontane basins on continental crust of northern South America, where Miocene accelerated exhumation and erosion of Paleogene and Cretaceous rocks reflect either shallow subduction of the CLIP or the Panama collisional event to the southwest.

  5. Geology of the Pavana geothermal area, Departamento de Choluteca, Honduras, Central America: Field report

    Energy Technology Data Exchange (ETDEWEB)

    Eppler, D.B.; Heiken, G.; Wohletz, K.; Flores, W.; Paredes, J.R.; Duffield, W.A.

    1987-09-01

    The Pavana geothermal area is located in southern Honduras near the Gulf of Fonseca. This region is underlain by late Tertiary volcanic rocks. Within ranges near the geothermal manifestations, the rock sequences is characterized by intermediate to mafic laharic breccias and lavas overlain by silicic tuffs and lavas, which are in turn overlain by intermediate to mafic breccias, lavas, and tuffs. The nearest Quaternary volcanoes are about 40 km to the southwest, where the chain of active Central American volcanoes crosses the mouth of the Gulf of Fonseca. Structure of the Pavana area is dominated by generally northwest-trending, southwest-dipping normal faults. This structure is topographically expressed as northwest-trending escarpments that bound blocks of bedrock separated by asymmetric valleys that contain thin alluvial deposits. Thermal waters apparently issue from normal faults and are interpreted as having been heated during deep circulation along fault zones within a regional environment of elevated heat flow. Natural outflow from the main thermal area is about 3000 l/min of 60/sup 0/C water. Geothermometry of the thermal waters suggests a reservoir base temperature of about 150/sup 0/C.

  6. Nazca-South America interactions and the late Eocene-late Oligocene flat-slab episode in the central Andes

    Science.gov (United States)

    O'Driscoll, Leland J.; Richards, Mark A.; Humphreys, Eugene D.

    2012-04-01

    The most prominent features of the Andean range are the Altiplano and Puna plateaus, which were constructed by crustal shortening and uplift over the past ˜45 Myr. The early construction of these plateaus may have controlled subsequent growth of the orogen. Proposed models have suggested that an abrupt acceleration in relative motion between the Nazca plate and the South American plate at ˜30 Ma may have led to compression of the continent. However, the major plate motion change occurred at 25-23 Ma, and paleomagnetic rotations and crustal shortening of the Andean forearc require that the Arica Bend formed prior to about 25 Ma. Inferred history of flat-slab subduction along the Altiplano section of the Andean margin and the structure of the adjacent South American cratonic shield combine to suggest an alternate scenario, based partly upon geodynamic models of oceanic-continental plate interactions in subduction zones. We propose that central Andean tectonism may have been controlled by two distinct regimes of subduction: (1) oblique subduction along the central Andean margin during the late Eocene and Oligocene accompanied by downdip alignment with the center of the Amazonian Shield (flat-slab activity in this phase of orogenesis may have been caused by a combination of cratonic root enhanced tectonics and oceanic plateau subduction) and (2) an abrupt transition to trench-normal subduction after ˜25 Ma toward the more distal São Francisco Craton was accompanied by a return to normal angle subduction. Similar interactions are hypothesized to have occurred during the Laramide Orogeny in western North America.

  7. Zonda downslope winds in the central Andes of South America in a 20-year climate simulation with the Eta model

    Science.gov (United States)

    Antico, Pablo L.; Chou, Sin Chan; Mourão, Caroline

    2015-12-01

    The Zonda wind is a local version of the alpine foehn in the central Andes Mountains in South America. It blows on the eastern slopes and produces an extremely warm and dry condition in Argentina. In this study, the occurrence of Zonda wind events during a 20-year simulation from the regional Eta model is analyzed and results are compared to previous studies of Zonda wind events based on weather observations. We define a set of parameters to account for the zonal pressure gradient across the mountain, vertical movement, and air humidity typical of Zonda wind events. These parameters are applied to characterize Zonda wind events in model run and to classify them as surface-level or high-level episodes. The resulting annual distribution of Zonda occurrences based on composite analyses shows a preference for winter and spring with rare occurrences during summer. For the surface-level Zonda wind events, the highest frequency occurs during spring. Whereas surface-level Zonda wind episodes more commonly initiate in the afternoon, high-level Zonda wind events show no preference for a given initiation time. Our results are mostly in agreement with previous observational results.

  8. Porphyry copper assessment of Central America and the Caribbean Basin: Chapter I in Global mineral resource assessment

    Science.gov (United States)

    Gray, Floyd; Hammarstrom, Jane M.; Ludington, Stephen; Zürcher, Lukas; Nelson, Carl E.; Robinson, Gilpin R., Jr.; Miller, Robert J.; Moring, Barry C.

    2014-01-01

    Mineral resource assessments provide a synthesis of available information about distributions of mineral deposits in the Earth’s crust. The U.S. Geological Survey prepared a probabilistic mineral resource assessment of undiscovered resources in porphyry copper deposits in Central America and the Caribbean Basin in collaboration with geoscientists from academia and the minerals industry. The purpose of the study was to (1) delineate permissive areas (tracts) for undiscovered porphyry copper deposits within 1 kilometer of the surface at a scale of 1:1,000,000; (2) provide a database of known porphyry copper deposits and significant prospects; (3) estimate numbers of undiscovered deposits within the permissive tracts; and (4) provide probabilistic estimates of amounts of copper, molybdenum, gold, and silver that could be contained in undiscovered deposits. The assessment was done using a three-part mineral resource assessment based on established mineral deposit models. Permissive tracts were delineated based primarily on distributions of mapped igneous rocks related to magmatic arcs that formed in tectonic settings associated with convergent plate margins. Five permissive tracts were delineated: the Early Cretaceous through Eocene Santiago tract, the Late Cretaceous through Oligocene Chortis tract, the Paleocene through Oligocene Darién tract, the Miocene and Pliocene Cocos tract, and the Eocene to Holocene Lesser Antilles tract. These tracts range in size from about 3,000 to about 204,000 square kilometers.

  9. Herbarium specimens reveal the footprint of climate change on flowering trends across north-central North America.

    Science.gov (United States)

    Calinger, Kellen M; Queenborough, Simon; Curtis, Peter S

    2013-08-01

    Shifting flowering phenology with rising temperatures is occurring worldwide, but the rarity of co-occurring long-term observational and temperature records has hindered the evaluation of phenological responsiveness in many species and across large spatial scales. We used herbarium specimens combined with historic temperature data to examine the impact of climate change on flowering trends in 141 species collected across 116,000 km(2) in north-central North America. On average, date of maximum flowering advanced 2.4 days °C(-1), although species-specific responses varied from - 13.5 to + 7.3 days °C(-1). Plant functional types exhibited distinct patterns of phenological responsiveness with significant differences between native and introduced species, among flowering seasons, and between wind- and biotically pollinated species. This study is the first to assess large-scale patterns of phenological responsiveness with broad species representation and is an important step towards understanding current and future impacts of climate change on species performance and biodiversity. PMID:23786499

  10. A snow hydroclimatology of the central and southern Appalachian Mountains, United States of America

    Science.gov (United States)

    Graybeal, Daniel Y.

    Background. A significant vulnerability to snowmelt-related flooding in the Appalachians was demonstrated by massive events in March, 1936; January, 1996; and January, 1998. Yet, no quantitative estimate of this vulnerability has been published for these mountains. High elevations extending far southward confound the extrapolation of snow hydroclimatology from adjacent regions. Objectives. The principal objective was to develop a complete snow hydroclimatology of the central and southern Appalachians, considering the deposition, detention, and depletion phases of snow cover. A snowfall climatology addressed whether and how often sufficient snow falls to create a flood hazard, while a snow cover climatology addressed whether and how often snow is allowed to build to floodrisk proportions. A snowmelt hydroclimatology addressed whether and how often snowmelt contributes directly to large peakflows in a representative watershed. Approach. Monthly and daily temperature, precipitation, and snow data were obtained from approximately 1000 cooperative-network stations with >=10 seasons (Oct-May) of snow data. Mean, maximum, percentiles, and interseasonal and monthly variability were mapped. Time series were analyzed, and proportions of seasonal snowfall from significant events determined, at select stations. A spatially distributed, index snow cover model facilitated classification of Cheat River, WV, peakflows by generating process. Confidence intervals about fitted peakflow frequency curves were used to evaluate differences among processes. Results. Climates in which snow significantly affects floods have been discriminated in the literature by 150 cm mean seasonal snowfall, 30 days mean snow cover duration, or 50 cm mean seasonal maximum snow depth. In the Appalachian Mountains south to North Carolina, these criteria lie within 95% confidence intervals about the median or mean values of these parameters. At return periods of 10 and 20 years, these thresholds are usually

  11. Phenotypic and genotypic heterogeneity among Streptococcus iniae isolates recovered from cultured and wild fish in North America, Central America and the Caribbean Islands

    Science.gov (United States)

    Streptococcus iniae, the etiological agent of streptococcosis in fish, is an important pathogen of cultured and wild fish worldwide. During the last decade outbreaks of streptococcosis have occurred in a wide range of cultured and wild fish in the Americas and Caribbean islands. To gain a better und...

  12. Cold episodes in the Peruvian Central Andes: Composites, Types, and their Impacts over South America (1958-2014)

    Science.gov (United States)

    Sulca, J. C.; Vuille, M. F.; Roundy, P. E.; Trasmonte, G.; Silva, Y.; Takahashi, K.

    2015-12-01

    The Mantaro basin (MB) is located in the central Peruvian Andes. Occasionally, cold episodes are observed during austral summer (January-March), that strongly damage crops. However, little is known about the causes and impacts of such cold episodes. The main goal of this study is thus to characterize cold episodes in the MB and assess their large-scale circulation and teleconnections over South America (SA) during austral summer. To identify cold events in the MB daily minimum temperature (Tmin) for the period 1958-2014 from Huayao station, located within the MB was used. A cold episode is defined when daily minimum temperature drops below its 10-percentile for at least one day. Additionally, to study the sensitivity between physical mechanisms associated with cold episodes and temperature, cold episodes are classified in three groups: Weak cold episodes (7.5 ≤ Tmin ≤ 10 percentile), strong cold episodes (Tmin ≤ 2.5 percentile), but excluding the 9 coldest events (Tmin ≤ 0 ͦ C), henceforth referred to as extraordinary cold episodes. Several gridded reanalysis were used to characterize the large-scale circulation, cloud cover and rainfall over SA associated with these events. Weak and strong cold episodes in the MB are mainly associated with a weakening of the Bolivian High-Nordeste Low system by tropical-extratropical interactions. Both types of cold episodes are associated with westerly wind anomalies at mid- and upper-tropospheric levels aloft the Peruvian Central Andes, which inhibit the influx of humid air masses from the lowlands to the east and hence limit the development of cloud cover (e.g., positive OLR anomalies over MB). The resulting clear sky conditions cause nighttime temperatures to drop, leading to cold extremes below 10-percentile. Simultaneously, northeastern Brazil (NEB) registers negative OLR anomalies, strong convection and enhanced cloud cover because displacement of the South Atlantic Convergence Zone (SACZ) toward the northeast of

  13. Geomorphic analysis of transient landscapes in the Sierra Madre de Chiapas and Maya Mountains (northern Central America): implications for the North American–Caribbean–Cocos plate boundary

    OpenAIRE

    L. Andreani; R. Gloaguen

    2016-01-01

    We use a geomorphic approach in order to unravel the recent evolution of the diffuse triple junction between the North American, Caribbean, and Cocos plates in northern Central America. We intend to characterize and understand the complex tectonic setting that produced an intricate pattern of landscapes using tectonic geomorphology, as well as available geological and geophysical data. We classify regions with specific relief characteristics and highlight uplifted relict landsc...

  14. Data on medicinal plants used in Central America to manage diabetes and its sequelae (skin conditions, cardiovascular disease, kidney disease, urinary problems and vision loss

    Directory of Open Access Journals (Sweden)

    Peter Giovannini

    2016-06-01

    Full Text Available The data described in this article is related to the review article “Medicinal plants used in the traditional management of diabetes and its sequelae in Central America: a review” (Giovannini et al., 2016 [1]. We searched publications on the useful plants of Central America in databases and journals by using selected relevant keywords. We then extracted reported uses of medicinal plants within the disease categories: diabetes mellitus, kidney disease, urinary problems, skin diseases and infections, cardiovascular disease, sexual dysfunction, vision loss, and nerve damage. The following countries were included in our definition of Central America: Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and Panama. Data were compiled in a bespoke Access database. Plant names from the published sources were validated against The Plant List (TPL, (The Plant List, 2013 [2] and accepted names and synonyms were extracted. In total, the database includes 607 plant names obtained from the published sources which correspond to 537 plant taxa, 9271 synonyms and 1055 use reports.

  15. Linking National Parks with its Gateway Communities for Tourism Development in Central America: Nindiri, Nicaragua, Bagazit, Costa Rica and Portobelo, Panama

    Directory of Open Access Journals (Sweden)

    Aguirre G., J. A.

    2006-01-01

    Full Text Available Protected areas and national parks are becoming one of the most important forms of land use in Central America. All the projections made by the World Tourism Organization seems to agree that by 2010 Central America, maybe receiving between eight and ten millions tourists, a figure that is almost twice what the region is receiving today. A study was conducted base on 369 direct field surveys conducted in three Central American communities: Bagazit gateway community to Palo Verde National Park, Costa Rica, Nindiri, gateway community to Volcan Masaya National Park, Nicaragua and Portobelo, gateway community to Por-tobelo National Park, Panama. The study found that relative to the socio-demographic variables, that there were no significance differences at the 95% probability level in all four variables, age, sex, education and monthly income of the family. Educational level seems to be the socio-demographic variables affecting more the state of relations. The perception variable being has taken into account in the decision that affects the communities and responsibility to help with community problems are present in two of the three models. The perception variables related to tourism, feel trained to take care of the tourist and existence of businesses that can caters to tourist seem to be key elements in the community perception about the state of relation. Tourism related economic activities and community participation in park decisions are today and will be in the future essential elements in the shaping of community/park relations in Central America as tourism becomes a major economic sector in the region economy.

  16. Neotectonic development of the El Salvador Fault Zone and implications for deformation in the Central America Volcanic Arc: Insights from 4-D analog modeling experiments

    Science.gov (United States)

    Alonso-Henar, Jorge; Schreurs, Guido; Martinez-Díaz, José Jesús; Álvarez-Gómez, José Antonio; Villamor, Pilar

    2015-01-01

    The El Salvador Fault Zone (ESFZ) is an active, approximately 150 km long and 20 km wide, segmented, dextral strike-slip fault zone within the Central American Volcanic Arc striking N100°E. Although several studies have investigated the surface expression of the ESFZ, little is known about its structure at depth and its kinematic evolution. Structural field data and mapping suggest a phase of extension, at some stage during the evolution of the ESFZ. This phase would explain dip-slip movements on structures that are currently associated with the active, dominantly strike slip and that do not fit with the current tectonic regime. Field observations suggest trenchward migration of the arc. Such an extension and trenchward migration of the volcanic arc could be related to slab rollback of the Cocos plate beneath the Chortis Block during the Miocene/Pliocene. We carried out 4-D analog model experiments to test whether an early phase of extension is required to form the present-day fault pattern in the ESFZ. Our experiments suggest that a two-phase tectonic evolution best explains the ESFZ: an early pure extensional phase linked to a segmented volcanic arc is necessary to form the main structures. This extensional phase is followed by a strike-slip dominated regime, which results in intersegment areas with local transtension and segments with almost pure strike-slip motion. The results of our experiments combined with field data along the Central American Volcanic Arc indicate that the slab rollback intensity beneath the Chortis Block is greater in Nicaragua and decreases westward to Guatemala.

  17. Invasion of the Indo-Pacific blenny Omobranchus punctatus (Perciformes: Blenniidae on the Atlantic Coast of Central and South America

    Directory of Open Access Journals (Sweden)

    Oscar Lasso-Alcalá

    2011-01-01

    Full Text Available We examined 308 specimens of the Indo-Pacific blenniid Omobranchus punctatus deposited in four museum collections, and analyzed data on their collection locations to assess its invasion on the Atlantic coast of Central and South America. This species occurs in shoreline estuarine and marine habitats in the Indo-West Pacific. Previous sampling and recent records in the Tropical West Atlantic from 1930 to 2004 produced 20 records for: Panamá, Colombia, Venezuela, Trinidad and Brazil. In this work, we provide data on 17 new records for the Gulfs of Venezuela and Paria in Venezuela, as well as four records for Maranhão and Pará states in NE Brazil. The temporal pattern of collections (1930 - 2009 and the proximity of most localities to ports and zones of ship traffic indicate that O. punctatus was initially introduced to the Atlantic by ships travelling from India to Trinidad. Within Brazil the introduction is linked to shipping connected to petroleum platforms. In Maranhão and Pará the introduction may have occurred as a result of fish sheltering in fouling on hulls of ships moving between ports around the mouth of the Amazon River. Alternatively, the spread of this species along of the American coast may reflect the expansion of the range of O. puntactus through larval dispersal in northward flowing currents. We recommend monitoring of this introduced species, and studies of its ecology in West Atlantic areas.Nós examinamos 308 espécimes do blenídeo Omobranchus punctatus, de origem Indo-Pacífica, depositados em coleções de quatro museus. Os dados de distribuição foram analisados com o objetivo de avaliar a invasão das águas costeiras do Oceano Atlântico nas Américas do Sul e Central. Em sua área de distribuição original, O. punctatus ocorre em ambientes marinhos e estuarinos. Amostragens datadas de 1930 e de 2004 produziram 20 registros da espécie no Atlântico Oeste tropical, incluindo amostras do Panamá, Col

  18. On the Development of Multi-Hazard Early Warning Networks: Practical experiences from North and Central America.

    Science.gov (United States)

    Mencin, David; Hodgkinson, Kathleen; Braun, John; Meertens, Charles; Mattioli, Glen; Phillips, David; Blume, Fredrick; Berglund, Henry; Fox, Otina; Feaux, Karl

    2015-04-01

    The GAGE facility, managed by UNAVCO, maintains and operates about 1300 GNSS stations distributed across North and Central America as part of the EarthScope Plate Boundary Observatory (PBO) and the Continuously Operating Caribbean GPS Observational Network (COCONet). UNAVCO has upgraded about 450 stations in these networks to real-time and high-rate (RT-GNSS) and included surface meteorological instruments. The majority of these streaming stations are part of the PBO but also include approximately 50 RT-GNSS stations in the Caribbean and Central American region as part of the COCONet and TLALOCNet projects. Based on community input UNAVCO has been exploring ways to increase the capability and utility of these resources to improve our understanding in diverse areas of geophysics including seismic, volcanic, magmatic and tsunami deformation sources, extreme weather events such as hurricanes and storms, and space weather. The RT-GNSS networks also have the potential to profoundly transform our ability to rapidly characterize geophysical events, provide early warning, as well as improve hazard mitigation and response. Specific applications currently under development with university, commercial, non-profit and government collaboration on national and international scales include earthquake and tsunami early warning systems and near real-time tropospheric modeling of hurricanes and precipitable water vapor estimate assimilation. Using tsunami early warning as an example, an RT-GNSS network can provide multiple inputs in an operational system starting with rapid assessment of earthquake sources and associated deformation which informs the initial modeled tsunami. The networks can then can also provide direct measurements of the tsunami wave heights and propagation by tracking the associated ionospheric disturbance from several 100's of km away as the waves approaches the shoreline. These GNSS based constraints can refine the tsunami and inundation models and potentially

  19. Seismicity of the Earth 1900-2007, Nazca Plate and South America

    Science.gov (United States)

    Rhea, Susan; Hayes, Gavin P.; Villaseñor, Antonio; Furlong, Kevin P.; Tarr, Arthur C.; Benz, Harley

    2010-01-01

    The South American arc extends over 7,000 km, from the Chilean triple junction offshore of southern Chile to its intersection with the Panama fracture zone, offshore the southern coast of Panama in Central America. It marks the plate boundary between the subducting Nazca plate and the South America plate, where the oceanic crust and lithosphere of the Nazca plate begin their decent into the mantle beneath South America. The convergence associated with this subduction process is responsible for the uplift of the Andes Mountains, and for the active volcanic chain present along much of this deformation front. Relative to a fixed South America plate the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80 mm/yr in the south to approximately 70mm/yr in the north.

  20. Energy transactions in Mexico, Central and South America. 1. ed.; Transacciones energeticas en Mexico, Centro y Sudamerica

    Energy Technology Data Exchange (ETDEWEB)

    Quintanilla Martinez, Juan [ed.] [Programa Universitario de Energia (PUE), Universidad Nacional Autonoma de Mexico (UNAM), (Mexico)

    1997-07-01

    This document contains the technical proceedings of the Second National Congress of the Mexican Association for the Economy of Energy that took place the days 23, 24 and 25 of September of 1996. In this seminar it was spoken on the global overview of the energy markets; the exploration and oil production in Latin America: present and future; oil-producing and petrochemistry in Latin America; regional and global markets; the deregulation of the electrical sector; experiences and perspective in Latin America; environmental externalisation in the energy systems; amelioration of the impact on the costs and the prices of the energy by means of technology and energy efficiency. [Spanish] Este documento contiene la memoria tecnica del segundo congreso nacional de la Asociacion Mexicana para la Economia Energetica A. C. llevado a efecto los dias 23, 24 y 25 de septiembre de 1996. En este seminario se hablo sobre la panoramica global de los mercados energeticos; la exploracion y produccion petrolera en America Latina: presente y futuro; petroliferos y petroquimica en America Latina: mercados regionales y globales; la desregulacion del sector electrico: experiencias y perspectivas en Latinoamerica; externalidades ambientales en los sistemas energeticos: mitigacion por medio de tecnologia y eficiencia energetica e impacto sobre los costos y los precios de la energia.

  1. Imaging Magma Plumbing Beneath Askja Volcano, Iceland

    Science.gov (United States)

    Greenfield, T. S.; White, R. S.

    2015-12-01

    Using a dense seismic network we have imaged the plumbing system beneath Askja, a large central volcano in the Northern Volcanic Zone, Iceland. Local and regional earthquakes have been used as sources to solve for the velocity structure beneath the volcano. We find a pronounced low-velocity anomaly beneath the caldera at a depth of ~7 km around the depth of the brittle-ductile transition. The anomaly is ~10% slower than the initial best fitting 1D model and has a Vp/Vs ratio higher than the surrounding crust, suggesting the presence of increased temperature or partial melt. We use relationships between mineralogy and seismic velocities to estimate that this region contains ~10% partial melt, similar to observations made at other volcanoes such as Kilauea. This low-velocity body is deeper than the depth range suggested by geodetic studies of a deflating source beneath Askja. Beneath the large low-velocity zone a region of reduced velocities extends into the lower crust and is coincident with seismicity in the lower crust. This is suggestive of a high temperature channel into the lower crust which could be the pathway for melt rising from the mantle. This melt either intrudes into the lower crust or stalls at the brittle-ductile boundary in the imaged body. Above this, melt can travel into the fissure swarm through large dikes or erupt within the Askja caldera itself.We generate travel time tables using a finite difference technique and the residuals used to simultaneously solve for both the earthquake locations and velocity structure. The 2014-15 Bárðarbunga dike intrusion has provided a 45 km long, distributed source of large earthquakes which are well located and provide accurate arrival time picks. Together with long-term background seismicity these provide excellent illumination of the Askja volcano from all directions.hhhh

  2. Determinism beneath Quantum Mechanics

    CERN Document Server

    Hooft, G

    2002-01-01

    Contrary to common belief, it is not difficult to construct deterministic models where stochastic behavior is correctly described by quantum mechanical amplitudes, in precise accordance with the Copenhagen-Bohr-Bohm doctrine. What is difficult however is to obtain a Hamiltonian that is bounded from below, and whose ground state is a vacuum that exhibits complicated vacuum fluctuations, as in the real world. Beneath Quantum Mechanics, there may be a deterministic theory with (local) information loss. This may lead to a sufficiently complex vacuum state, and to an apparent non-locality in the relation between the deterministic ("ontological") states and the quantum states, of the kind needed to explain away the Bell inequalities. Theories of this kind would not only be appealing from a philosophical point of view, but may also be essential for understanding causality at Planckian distance scales.

  3. Nuevo registro de Gomphotherium hondurensis (Frick, 1933 (Proboscidea, Gomphoteriidae para el Mioceno Superior de El Salvador, América Central A new record of Gomphotherium hondurensis (Frick, 1933 (Proboscidea, Gomphoteriidae on the Upper Miocene of El Salvador, Central America

    Directory of Open Access Journals (Sweden)

    Daniel H. Aguilar

    2011-12-01

    Full Text Available Se describe un molar inferior, aislado, del proboscídeo endémico de América Central Gomphotherium hondurensis (Frick, 1933, recuperado en el valle del río Torola en la localidad fosilífera de Corinto, la cual fue estudiada y caracterizada en los años 70 por los paleontólogos estadounidenses David S. Webb y Stephen Perrigo; la fauna local de Corinto es considerada una de las más importantes localidades fosilíferas del Mioceno Superior de América Central.An isolated lower molar of the endemic Central America Proboscidea Gomphotherium hondurensis (Frick, 1933, recovered at the Valley of Torola River is described here. This locality corresponds with the outcrops of the Corinto local fauna, previously studied and defined by the American paleontologists David S. Webb and Stephen Perrigo during the 70’s years; which is considered as one of the most important fossiliferous localities of the Upper Miocene of Central America

  4. Geomorphic analysis of transient landscapes from the Sierra Madre de Chiapas and Maya Mountains (northern Central America): implications for the North American-Caribbean-Cocos plate boundary

    Science.gov (United States)

    Andreani, L.; Gloaguen, R.

    2015-09-01

    We use a geomorphic approach in order to unravel the recent evolution of the diffuse triple junction between the North American, Caribbean, and Cocos plates in northern Central America. The complex tectonic setting produced an intricate pattern of landscapes that we try to systemize using remote sensing tectonic geomorphology and available geological and geophysical data. We classify regions with specific relief characteristics and highlight uplifted relict landscapes in northern Central America. We also analyze the drainage network from the Sierra Madre de Chiapas and Maya Mountains in order to extract information about potential vertical displacements. Our results suggest that most of the landscapes of the Sierra Madre de Chiapas and Maya Mountains are in transient stage. Topographic profiles and morphometric maps highlight elevated relict surfaces that are characterized by a low amplitude relief. The river longitudinal profiles display upper reaches witnessing these relict landscapes while lower segments characterized by multiple knickpoints, that adjust to new base-level conditions. These results backed by published GPS and seismotectonic data allow us to refine and extend existing geodynamic models of the triple junction. Relict landscapes are delimited by faults and thus result from a tectonic control. The topography of the Sierra Madre de Chiapas evolved as the result of (1) the inland migration of deformation related to the coupling between the Chiapas Massif and the Cocos fore-arc sliver, and (2) the compression along the northern tip of the Central America Volcanic Arc. Although most of the shortening between the Cocos fore-arc sliver and the North American plate is accommodated within the Sierra de Chiapas and Sierra de los Cuchumatanes, a small part may be still transmitted to the Maya Mountains and the Belize margin through a "rigid" Petén basin.

  5. A review of the genus Agapetus Curtis (Trichoptera: Glossosomatidae) in eastern and central North America, with description of 12 new species

    Science.gov (United States)

    Etnier, David A.; Parker, Charles R.; Baxter, John T.; Long, Todd M.

    2010-01-01

    Twenty-nine species of caddisflies in the genus Agapetus Curtis in eastern and central North America are reviewed. Twelve are described as new species: Agapetus aphallus (known only from females); Agapetus baueri, Agapetus flinti, Agapetus harrisi, Agapetus hesperus, Agapetus ibis, Agapetus kirchneri, Agapetus meridionalis, Agapetus pegram, Agapetus ruiteri, Agapetus stylifer, and Agapetus tricornutus. Agapetus rossi Denning 1941 is recognized as a junior subjective synonym of Agapetus walkeri (Betten and Mosely 1940), new synonym. A key to males is provided, and species’ distributions are mapped.

  6. Airborne LIDAR Measurements of Water Vapor, Ozone, Clouds, and Aerosols in the Tropics Near Central America During the TC4 Experiment

    Science.gov (United States)

    Kooi, Susan; Fenn, Marta; Ismail, Syed; Ferrare, Richard; Hair, John; Browell, Edward; Notari, Anthony; Butler, Carolyn; Burton, Sharon; Simpson, Steven

    2008-01-01

    Large scale distributions of ozone, water vapor, aerosols, and clouds were measured throughout the troposphere by two NASA Langley lidar systems on board the NASA DC-8 aircraft as part of the Tropical Composition, Cloud, and Climate Coupling Experiment (TC4) over Central and South America and adjacent oceans in the summer of 2007. Special emphasis was placed on the sampling of convective outflow and transport, sub-visible cirrus clouds, boundary layer aerosols, Saharan dust, volcanic emissions, and urban and biomass burning plumes. This paper presents preliminary results from this campaign, and demonstrates the value of coordinated measurements by the two lidar systems.

  7. Educacion y Pueblos Indigenas en Centroamerica: Un Balance Critico (Education and Indigenous People in Central America: A Critical Balance).

    Science.gov (United States)

    Amadio, Massimo, Comp.; And Others

    Global society is polarized between the modern capitalist sector and the marginal sector, which is composed of indigenous, poor, and ethnic, tribal people. The problems of education for groups in Latin America, key issues in planning to meet their needs, and strategies to resolve them, are the focus of this publication. Nine papers provide a…

  8. 25 YEARS EXPERIENCES OF CHINA MADE SMALL HYDROELECTRIC UNITS WITH USA MADE DIGITAL TECHNOLOGY INSTALLED IN USA AND CENTRAL AMERICA

    Institute of Scientific and Technical Information of China (English)

    DR.ALEXANDERA

    2005-01-01

    Twenty-five years ago America's small hydroelectric power generations were reactivated by private, municipal, and local governments to utilize the renewable energy from the small hydro sties available 10,000 existing dams, small rivers and/or streams, and energy recovery facilities at many water transmission and delivery systems.

  9. Shear wave velocity structure in North America from large-scale waveform inversions of surface waves

    Science.gov (United States)

    Alsina, D.; Woodward, R.L.; Snieder, R.K.

    1996-01-01

    A two-step nonlinear and linear inversion is carried out to map the lateral heterogeneity beneath North America using surface wave data. The lateral resolution for most areas of the model is of the order of several hundred kilometers. The most obvious feature in the tomographic images is the rapid transition between low velocities in the technically active region west of the Rocky Mountains and high velocities in the stable central and eastern shield of North America. The model also reveals smaller-scale heterogeneous velocity structures. A high-velocity anomaly is imaged beneath the state of Washington that could be explained as the subducting Juan de Fuca plate beneath the Cascades. A large low-velocity structure extends along the coast from the Mendocino to the Rivera triple junction and to the continental interior across the southwestern United States and northwestern Mexico. Its shape changes notably with depth. This anomaly largely coincides with the part of the margin where no lithosphere is consumed since the subduction has been replaced by a transform fault. Evidence for a discontinuous subduction of the Cocos plate along the Middle American Trench is found. In central Mexico a transition is visible from low velocities across the Trans-Mexican Volcanic Belt (TMVB) to high velocities beneath the Yucatan Peninsula. Two elongated low-velocity anomalies beneath the Yellowstone Plateau and the eastern Snake River Plain volcanic system and beneath central Mexico and the TMVB seem to be associated with magmatism and partial melting. Another low-velocity feature is seen at depths of approximately 200 km beneath Florida and the Atlantic Coastal Plain. The inversion technique used is based on a linear surface wave scattering theory, which gives tomographic images of the relative phase velocity perturbations in four period bands ranging from 40 to 150 s. In order to find a smooth reference model a nonlinear inversion based on ray theory is first performed. After

  10. Central Bank autonomy in Europe and Latin America: analysis of differences and applications Autonomía de la banca central en Europa y América Latina

    Directory of Open Access Journals (Sweden)

    Rollinat Robert

    1996-06-01

    Full Text Available This article makes a comparative analysis of the experiences of the independent central bank in Latin America and Europe. After reviewing the problems and theories of central bank autonomy, it studies the recent evolution of the Latin American central bank in comparison with the European central bank, high lights the perverse effects of the reforms, and shows that their objective is more the stability of the financial system than the stability of prices. Finally, it describes the tests to which the new Latin American central banks have been subjected and the effects on their credibility. It concludes that these entities have had to correct and pay for the incoherences and errors of the market, and that their independence or autonomy depends on their continuing to ful fill this role, not only for economíc or monetary reasons but for the needs of political and social democracy.Este artículo hace un análisis comparativo de las experiencias de la banca central independiente en América Latina y Europa. Después de revisar los problemas y las teorías de la autonompia de los bancos centrales, estudia la reciente evolución de la banca central latinoamericana en comparación con la europea, destaca los efectos perversos de estas reformas u muestra que sus objetivo es más la estabilidad del sistema financiero que la de los precios. Finalmente, describe las pruebas a que han sido sometidos los nuevos bancos centrales latinomaericanos y los efectos de sus credibilidad. Concluye que estas entidades han tenido que corregir y pagar las incoherencias y los errrores del mercado, y que su 'independencia' o autonomía depende de que sigan cumpliendo con ese papel no sólo por razones económicas o monetarias sino por las necesidades de la democracia política y social.

  11. South America Geologic Map (geo6ag)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — South America is part of Region 6 (Central and South America) for the World Energy Assessment. The geologic map of South America was digitized so that we could use...

  12. Mapping Tectonic features beneath the Gulf of California using Rayleigh and Love Waves Group Velocities

    Science.gov (United States)

    Persaud, P.; Di Luccio, F.; Clayton, R. W.

    2012-12-01

    This study contributes to our understanding of the Pacific-North America lithospheric structure beneath the Gulf of California and its western and eastern confining regions, by mapping fundamental mode surface wave group velocities. We measure the dispersion of Rayleigh and Love surface waves to create a series of 2D maps of group velocities, which provide important information on the earth structure beneath the study region. Although several surface waves studies were published in the last decade, all of them were done using phase velocity measurements based on the two stations method. Here we combine dispersion measurements at the regional scale with data at teleseismic distances to provide a more complete dataset for studies of earth structure. We also analyze group velocities from short to long periods in order to define structural features at both crustal and mantle scales. Our study uses earthquakes recorded by the Network of Autonomously Recording Seismographs (NARS-Baja), a set of 14 broadband seismic stations that flank the Gulf of California. From the NEIC bulletin we selected 140 events recorded by the NARS-Baja array. In order to have dispersion measurements in a wide range of periods, we used regional earthquakes with M > 4.2 and teleseismic events with M > 6.9. We first computed the dispersion curves for the surface wave paths crossing the region. Then, the along path group velocity measurements for multiple periods are converted into tomographic images using kernels which vary in off-path width with the square root of the period. Dispersion measurements show interesting and consistent features for both Rayleigh and Love waves. At periods equal to or shorter than 15 s, when surface waves are primarily sensitive to shear velocity in the upper 15 km of the crust, slow group velocities beneath the northern-central Gulf reveal the presence of a thick sedimentary layer, relative to the southern Gulf. Group velocities beneath the northwestern side of Baja

  13. Migration and wintering areas of American Bitterns (Botaurus lentiginosus) that summer in central North America as determined by satellite and radio telemetry, 1998-2003

    Science.gov (United States)

    Huschle, Guy; Toepfer, John E.; Douglas, David C.

    2013-01-01

    Twenty adult male American Bitterns (Botaurus lentiginosus) were marked on summer range in central North America with satellite tracking Platform Transmitter Terminals (PTTs) to document migration routes and wintering range. Nineteen complete fall migration routes were documented for 17 individuals. Of the successful migrations, 63% (n = 12) went to southern Florida, 32% (n = 6) to southern Louisiana, and 5% (n = 1) to the Gulf coast of Texas. Spring migrations for nine birds were documented, and 78% (n = 7) showed fidelity to breeding range. Two complete migrations for two individuals were documented, and they demonstrated fidelity to winter range. The longest, fastest movement documented was 2,300 km in less than 74 hr. Extensive, post-breeding dispersal was not observed in the adult male American Bitterns in this study. Six male American Bitterns were marked with PTTs on winter range in Florida and Texas. Spring migration for these birds was documented to Nebraska, North Dakota, Saskatchewan, Manitoba and Ontario. Sixty-seven American Bitterns were marked with Very High Frequency radio transmitters on summer ranges, and 16% (n = 11) were located on wintering grounds used by the satellite-tracked birds, further documenting the importance of the Everglades and the Louisiana coast as winter habitat for American Bitterns that breed in Central North America.

  14. Magma Plumbing beneath Askja Volcano, Iceland

    Science.gov (United States)

    Greenfield, T. S.; White, R. S.

    2013-12-01

    Through a combination of accurate earthquake locations and tomography we have imaged the melt feeding network beneath Askja, a large central volcano, in the Northern Volcanic Zone, Iceland. We have deployed and operated a dense network of 3-component, broadband seismometers around the volcano since 2006 and have recorded a large number of events (on the order of 150 a day). The majority of these are due to an extensive geothermal area within the caldera and tectonically induced earthquakes to the northeast which are not related to the magma plumbing system. More intriguing are the less numerous deeper earthquakes situated in three distinct areas within the volcanic system. These have a lower frequency content to the shallower events which may be the result of highly attenuating lower crust. The deep earthquakes extend from 12-25 km depth, significantly below a well defined brittle-ductile boundary at 8-9 km. These earthquakes indicate the presence of melt moving or degassing at depth as only high strain rates or increased pore fluid pressures would cause brittle fracture in what is normally an aseismic region in the ductile zone. To image the structure beneath Askja, local and regional earthquakes have been used as sources to solve for the velocity structure beneath the volcano. Travel-time tables were created using a finite difference technique and the residuals were used to solve simultaneously for both the earthquake locations and velocity structure. Results showed a pronounced low-velocity anomaly beneath the caldera at a depth of ~5 km. The anomaly is ~10% slower than the initial best fitting 1D model and has a Vp/Vs ratio higher than the surrounding crust, suggesting the presence of increased temperature or partial melt. The body is unlikely to be entirely melt as S-waves are still detected at stations directly above the anomaly. This low-velocity body is slightly deeper than the depth range suggested by InSAR and GPS studies of a deflating source beneath

  15. Geometry and seismic properties of the subducting Cocos plate in central Mexico

    OpenAIRE

    Kim, Y.; Clayton, R. W.; Jackson, J. M.

    2010-01-01

    The geometry and properties of the interface of the Cocos plate beneath central Mexico are determined from the receiver functions (RFs) utilizing data from the Meso America Subduction Experiment (MASE). The RF image shows that the subducting oceanic crust is shallowly dipping to the north at 15° for 80 km from Acapulco and then horizontally underplates the continental crust for approximately 200 km to the Trans-Mexican Volcanic Belt (TMVB). The crustal image also shows that there is no contin...

  16. Geomorphic analysis of transient landscapes in the Sierra Madre de Chiapas and Maya Mountains (northern Central America): implications for the North American-Caribbean-Cocos plate boundary

    Science.gov (United States)

    Andreani, L.; Gloaguen, R.

    2016-01-01

    We use a geomorphic approach in order to unravel the recent evolution of the diffuse triple junction between the North American, Caribbean, and Cocos plates in northern Central America. We intend to characterize and understand the complex tectonic setting that produced an intricate pattern of landscapes using tectonic geomorphology, as well as available geological and geophysical data. We classify regions with specific relief characteristics and highlight uplifted relict landscapes in northern Central America. We also analyze the drainage network from the Sierra Madre de Chiapas and Maya Mountains in order to extract information about potential vertical displacements. Our results suggest that most of the landscapes of the Sierra Madre de Chiapas and Maya Mountains are in a transient stage. Topographic profiles and morphometric maps highlight elevated relict surfaces that are characterized by a low-amplitude relief. The river longitudinal profiles display upper reaches witnessing these relict landscapes. Lower reaches adjust to new base-level conditions and are characterized by multiple knickpoints. These results backed by published GPS and seismotectonic data allow us to refine and extend existing geodynamic models of the triple junction. Relict landscapes are delimited by faults and thus result from a tectonic control. The topography of the Sierra Madre de Chiapas evolved as the result of (1) the inland migration of deformation related to the coupling between the Chiapas Massif and the Cocos forearc sliver and (2) the compression along the northern tip of the Central American volcanic arc. Although most of the shortening between the Cocos forearc sliver and the North American Plate is accommodated within the Sierra de Chiapas and Sierra de los Cuchumatanes, a small part may be still transmitted to the Maya Mountains and the Belize margin through a "rigid" Petén Basin.

  17. The geometry of the Wadati-Benioff zone under southern Central America and its tectonic significance: results from a high-resolution local seismographic network

    Science.gov (United States)

    Protti, Marino; Gu¨ndel, Federico; McNally, Karen

    1994-07-01

    We present here a detailed geometry of the Wadati-Benioff zone under Costa Rica, obtained from seismicity recorded by a dense local seismographic network jointly operated by the Costa Rica Volcanological and Seismological Observatory, National University, and the Charles F. Richter Seismological Laboratory, University of California, Santa Cruz. Underneath the Nicaragua-Costa Rica border the Wadati-Benioff zone smoothly contorts (from steep to shallow dip angles, NW to SE), but does not show evidence of a brittle tear, as postulated by others. However, further to the SE, NE of Puerto Caldera, Costa Rica, the Wadati-Benioff zone does show a segmentation (the Quesada Sharp Contortion) at intermediate depths ( h > 70km). NW of this sharp contortion the deepest portion of the seismically active slab dips at about 80° and reaches maximum depths ranging from 200 km, near the Nicaragua-Costa Rica border, to 135 km under Ciudad Quesada. To the SE the deeper portion of the Wadati-Benioff zone dips at about 60° and the seismicity does not extend below depths ranging from 125 km, behind the volcanic arc, to 50 km, east of Quepos. In southern Costa Rica, east of 83°55'W, we find no evidence of the Wadati-Benioff zone deeper than 50 km. The obtained geometry and other known tectonic features related to the subduction of the Cocos plate under the Caribbean plate along the southern terminus of the Middle America Trench (Nicaragua and Costa Rica) correlate well with along-trench variations in age of the subducted Cocos plate. Some of these tectonic features are: (1) the shallowing of Middle America Trench bathymetry from NW to SE; (2) variations in the energy release within the subducted slab; (3) differences in coupling between Cocos and Caribbean plates; (4) the termination of the Central America Volcanic Chain in central Costa Rica; (5) distinct stress field variations on the overriding Caribbean plate. The subduction of the Cocos Ridge under southern Costa Rica is partially

  18. Intraplate mountain building in response to continent continent collision—the Ancestral Rocky Mountains (North America) and inferences drawn from the Tien Shan (Central Asia)

    Science.gov (United States)

    Dickerson, Patricia Wood

    2003-04-01

    The intraplate Ancestral Rocky Mountains of western North America extend from British Columbia, Canada, to Chihuahua, Mexico, and formed during Early Carboniferous through Early Permian time in response to continent-continent collision of Laurentia with Gondwana—the conjoined masses of Africa and South America, including Yucatán and Florida. Uplifts and flanking basins also formed within the Laurentian Midcontinent. On the Gondwanan continent, well inboard from the marginal fold belts, a counterpart structural array developed during the same period. Intraplate deformation began when full collisional plate coupling had been achieved along the continental margin; the intervening ocean had been closed and subduction had ceased—that is, the distinction between upper versus lower plates became moot. Ancestral Rockies deformation was not accompanied by volcanism. Basement shear zones that formed during Mesoproterozoic rifting of Laurentia were reactivated and exerted significant control on the locations, orientations, and modes of displacement on late Paleozoic faults. Ancestral Rocky Mountain uplifts extend as far south as Chihuahua and west Texas (28° to 33°N, 102° to 109°W) and include the Florida-Moyotes, Placer de Guadalupe-Carrizalillo, Ojinaga-Tascotal and Hueco Mountain blocks, as well as the Diablo and Central Basin Platforms. All are cored with Laurentian Proterozoic crystalline basement rocks and host correlative Paleozoic stratigraphic successions. Pre-late Paleozoic deformational, thermal, and metamorphic histories are similar as well. Southern Ancestral Rocky Mountain structures terminate along a line that trends approximately N 40°E (present coordinates), a common orientation for Mesoproterozoic extensional structures throughout southern to central North America. Continuing Tien Shan intraplate deformation (Central Asia) has created an analogous array of uplifts and basins in response to the collision of India with Eurasia, beginning in late

  19. Comparison of bean biochemical composition and beverage quality of Arabica hybrids involving Sudanese-Ethiopian origins with traditional varieties at various elevations in Central America.

    Science.gov (United States)

    Bertrand, Benoit; Vaast, Philippe; Alpizar, Edgardo; Etienne, Hervé; Davrieux, Fabrice; Charmetant, Pierre

    2006-09-01

    For buyers of Arabica coffee (Coffea arabica L.) in Central America, elevation and variety are important indicators of quality. We compared coffee produced by three types of varieties established in various trials at elevations ranging from 700-1600 m in three countries (El Salvador, Costa Rica and Honduras). Arabica hybrids resulting from crosses of Sudanese-Ethiopian origins with either traditional varieties or with introgressed lines derived from the hybrid of Timor (C. arabica x Coffea canephora Pierre ex Froehn) were compared with traditional cultivars (TC). Effects of elevation and variety on bean biochemical composition (caffeine, chlorogenic acid, trigonelline, fat and sucrose) were evaluated by predictive models based on calibration of near-infrared (NIR) spectra and by chemometric analysis of the global NIR spectrum. Beverage quality tests were performed by a panel of ten professional cup-tasters. Experiment 1 was carried out on the slopes of the Poas volcano (Costa Rica) with the traditional cultivar 'Caturra'. Experiment 2 compared the three varieties in a network of trials established in three countries of Central America. Significant linear regressions with elevation were observed in Experiment 1 with Caturra and in Experiment 2 for the traditional cultivars, and trends were established relating variation in biochemical compounds and cup quality to elevation. Convergence or divergence of the new hybrids in relation to these trends was observed. For the traditional cultivars, elevation had a significant effect on bean biochemical composition, with chlorogenic acid and fat concentrations increasing with increasing elevation. For the Arabica hybrids, elevation explained little of the variation in chlorogenic acid concentration and none of the variation in fat concentration. Nevertheless, Arabica hybrids had 10-20% higher fat concentrations than the traditional varieties at low elevations and similar fat concentrations at high elevations. The samples

  20. Paleobiogeografía del arribo de mamíferos suramericanos al sur de América Central de previo al gran intercambio biótico americano: un vistazo al GABI en América Central Paleobiogeography of the arrival of south american mammals to southern Central America prior to the great american biotic interchange: a look at the GABI in Central America

    Directory of Open Access Journals (Sweden)

    César A Laurito

    2012-06-01

    of South American mammals to the Southern Central America region, not known until now. The arrival of South American mammals to the Panama Region was due to a series of factors such as the development of the Costa Rica-Panamá Island Arc by subduction processes, the collision and the deformation of the Island Arc with the North-Western Colombia territories and the prevailing climate factors which stimulated the predominance of warm, humid and basal forests, both in Colombia and in southern Central America. This permitted the xenarthrans, which are considered strong swimmers and islands hoppers to migrate to the North. These conditions on the other hand, limited the migration to the South of the North American mammals, whose arrival in South America was postponed until the Blancan age with drier climatic conditions and the new land corridor that was established in the region. Additionally, the current state of the Great American Biotic Interchange in Central America (GABI is analyzed

  1. Interannual Variability of the Bimodal Distribution of Summertime Rainfall Over Central America and Tropical Storm Activity in the Far-Eastern Pacific

    Science.gov (United States)

    Curtis, Scott; Starr, David OC. (Technical Monitor)

    2002-01-01

    The summer climate of southern Mexico and Central America is characterized by a mid summer drought (MSD), where rainfall is reduced by 40% in July as compared to June and September. A mid-summer reduction in the climatological number of eastern Pacific tropical cyclones has also been noted. Little is understood about the climatology and interannual variability of these minima. The present study uses a novel approach to quantify the bimodal distribution of summertime rainfall for the globe and finds that this feature of the annual cycle is most extreme over Pan America and adjacent oceans. One dominant interannual signal in this region occurs the summer before a strong winter El Nino/Southern Oscillation ENSO. Before El Nino events the region is dry, the MSD is strong and centered over the ocean, and the mid-summer minimum in tropical cyclone frequency is most pronounced. This is significantly different from Neutral cases (non-El Nino and non-La Nina) when the MSD is weak and positioned over the land bridge. The MSD is highly variable for La Nina years, and there is not an obvious mid-summer minimum in the number of tropical cyclones.

  2. Hypericum species in the Páramos of Central and South America: a special focus upon H. irazuense Kuntze ex N. Robson

    Science.gov (United States)

    Crockett, Sara; Eberhardt, Marianne; Kunert, Olaf; Schühly, Wolfgang

    2010-01-01

    Knowledge about members of the flowering plant family Clusiaceae occurring in the tropical mountain regions of the world is limited, in part due to endemism and restricted distributions. High altitude vegetation habitats (Páramos) in Central and South America are home to numerous native Hypericum species. Information related to the phytochemistry of páramo Hypericum, as well as ecological factors with the potential to influence chemical defenses in these plants, is briefly reviewed. Results of the phytochemical analysis of Hypericum irazuense, a species collected in the páramo of the Cordillera de Talamanca in Costa Rica, are presented. Lastly, guidelines for the viable and sustainable collections of plant material, to facilitate future investigations of these interesting plants, are given. PMID:21151765

  3. Is violence associated with increased risk behavior among MSM? Evidence from a population-based survey conducted across nine cities in Central America

    Directory of Open Access Journals (Sweden)

    Jennifer Wheeler

    2014-10-01

    Full Text Available Background/Objective: There is a dearth of research examining the linkages between violence and HIV risk behavior among men who have sex with men (MSM, including those who identify as transgender women (TW, particularly in Central America where violence is widespread. In this paper, we use population-based survey results to independently examine the correlations between physical, emotional and sexual violence and HIV risk behavior among MSM populations in five countries in Central America. Design: As part of USAID's Combination Prevention for HIV program in Central America, PASMO conducted population based surveys using respondent-driven sampling (RDS in nine cities in Guatemala, El Salvador, Nicaragua, Costa Rica, and Panama. Initial seeds were recruited using the following criteria: individuals who represented subgroups of MSM by self-identification (homosexual vs. heterosexual or bisexual vs. transgender, social economic strata, and by sex work practices. This study examines the association between violence and 1 HIV risk behaviors relevant to the study populations; 2 protective behaviors; and 3 reported STIs. Individualized RDS estimator weights for each outcome variable were calculated using RDSAT software, and logistic regression analysis was used to determine associations between different forms of violence and the outcome variables. Results: MSM who experienced physical violence were more likely to be engaged in transactional sex (OR: 1.76 [1.42–2.18], have multiple partners in the past 30 days (OR: 1.37 [1.09–1.71], and have engaged in sex under the influence of alcohol or drugs (OR: 1.51 [1.24–1.83]. Both physical violence and psychological/verbal violence were also associated with reporting STI symptoms or diagnosis within the past 12 months (OR: 1.72 [1.34–2.21] and 1.80 [1.45–2.23]. The effects of violence on the outcomes were observed after controlling for other risk factors. Transgender women were 3.9 times more likely

  4. Magmas with slab fluid and decompression melting signatures coexisting in the Gulf of Fonseca: Evidence from Isla El Tigre volcano (Honduras, Central America)

    Science.gov (United States)

    Mattioli, Michele; Renzulli, Alberto; Agostini, Samuele; Lucidi, Roberto

    2016-01-01

    Isla El Tigre volcano is located in the Gulf of Fonseca (Honduras) along the Central America volcanic front, where a significant change in the strike of the volcanic chain is observed. The studied samples of this poorly investigated volcano are mainly subalkaline basic to intermediate lavas (basalts and basaltic andesites) and subordinate subalkaline/alkaline transitional basalts, both having the typical mineralogical and geochemical characteristics of arc volcanic rocks. On the basis of petrographic and geochemical features, two groups of rocks have been distinguished. Lavas from the main volcanic edifice are highly porphyritic and hy-qz normative, and have lower MgO contents ( 5 wt.%), are ol-hy normative and show lower HFSE depletions relative to LILE and LREE, with lower Ba/La, Ba/Nb and Zr/Nb ratios. This suggests that mantle-derived magmas were not produced by the same process throughout the activity of the volcano. The bulk rock geochemistry and 87Sr/86Sr (0.70373-0.70382), 143Nd/144Nd (0.51298-0.51301), 206Pb/204Pb (18.55-18.58), 207Pb/204Pb (15.54-15.56) and 208Pb/204Pb (38.23-38.26) isotopic data of Isla El Tigre compared with the other volcanoes of the Gulf of Fonseca and all available literature data for Central America suggests that this stratovolcano was mainly built by mantle-derived melts driven by slab-derived fluid-flux melting, while magmas erupted through its parasitic cones have a clear signature of decompression melting with minor slab contribution. The coexistence of these two different mantle melting generation processes is likely related to the complex geodynamic setting of the Gulf of Fonseca, where the volcanic front changes direction by ca. 30° and two fundamental tectonic structures of the Chortis continental block, mainly the N-S Honduras Depression and the NE-SW Guayape Fault Zone, cross each other.

  5. Working Together to Make a Difference in Rural America: North Central Regional Center for Rural Development, 2010 Annual Report

    Science.gov (United States)

    North Central Regional Center for Rural Development, 2011

    2011-01-01

    The North Central Regional Center for Rural Development (NCRCRD) is one of four regional centers in the United States that have worked to improve the quality of life in rural communities for nearly 40 years. With funding from the USDA National Institute of Food and Agriculture and the land-grant universities in our 12-state region, the NCRCRD…

  6. The University as Agent of Social Transformation: The Case of the University of Central America in El Salvador

    Science.gov (United States)

    Valiente, Orfilio Ernesto

    2015-01-01

    In 1965, the Jesuit-run Central American University (UCA) was launched in El Salvador as the wealthy family's educational alternative to the increasingly leftist National University. But within a decade, the UCA would shift its focus to the inequalities and injustice experienced by the country's popular majorities and to its own role as society's…

  7. Education for Management in Central America. The Role of the Library of the Instituto Centroamericano de Administracion de Empresas

    Science.gov (United States)

    Bloch, Thomas

    1973-01-01

    The institute, established in 1968, is a multinational organization for education in management at the post-graduate level. Its library, with five staff members, now has 4,000 volumes and receives 300 periodical publications: it should eventually become a Central American business and economic management information and research center. (Author/SJ)

  8. Inorganic particles in the skin of inhabitants of volcanic areas of Central America: their possible immunomodulatory influence in leishmaniasis and leprosy.

    Science.gov (United States)

    Convit, J; Ulrich, M; Castillo, J; De Lima, H; Pérez, M; Caballero, N; Hung, J; Arana, B; Pérez, P

    2006-08-01

    We have evaluated biopsies from patients with atypical nodular and typical ulcerated lesions of cutaneous leishmaniasis, from leishmanin reactions and skin from normal individuals from Nicaragua, Honduras and Guatemala for the presence of inorganic particles using confocal microscopy with a polarised light source and conventional histopathological techniques. Analysis by semiquantitative confocal microscopy permitted the demonstration of significantly larger numbers of particles in atypical lesions. Silica and aluminium, important components of these particles, were less abundant in particles from normal skin. The histology of these atypical lesions, characterised by 'naked' sarcoidal granulomas with epithelioid differentiation but very few lymphocytes, was very similar to the histological reaction observed after 14 days in persisting inflammation at leishmanin skin test sites. The presence of these unusual lesions in areas of Central American countries characterised by the presence of large amounts of volcanic ash, as well the unexpectedly low prevalence of leprosy in Central America, suggest that environmental factors may contribute significantly to the frequency and clinical manifestations of these infections. Among possible environmental features, the presence of inorganic particles with immunomodulatory properties in the skin may be a significant factor.

  9. Transmitted drug-resistance in human immunodeficiency virus-infected adult population in El Salvador, Central America.

    Science.gov (United States)

    Holguín, Á; Yebra, G; Martín, L; de Pineda, A T; Ruiz, L E; Quezada, A Y; Nieto, A I; Escobar, G

    2013-12-01

    El Salvador harbours one of the largest Central American human immunodeficiency virus (HIV) epidemics, but few studies have analysed it in depth. Here, we describe the presence of transmitted drug resistance (TDR) and HIV variants in the HIV-infected adult population in El Salvador. Dried blood spots from 119 HIV-infected antiretroviral-naive adults attended in El Salvador were collected in 2011. The TDR was assessed according to the list recommended by the WHO. HIV-1 variants were described using phylogeny. Pol sequences could be amplified in 88 patients (50.6% men), with a mean age of 35 years. Almost all (96.7%) were infected with HIV through sexual practice and 58.7% were recently diagnosed. The mean CD4(+) count was 474 cells/mm(3) and 43.1% and 15.5% of patients showed moderate (100 000 copies/mL in 24.7% of patients and Salvador, lower than in other Central American studies. Periodical studies are essential to monitor and prevent TDR emergence in low-income and middle-income regions. Also, more efforts are needed to promote early diagnosis and prevention of infection in El Salvador.

  10. Radical, reformist and aborted liberalism: origins of national regimes in Central America Liberalismo radical, reformista y frustrado: orígenes de los regímenes nacionales en América central

    Directory of Open Access Journals (Sweden)

    James MAHONEY

    2011-06-01

    Full Text Available During the twentieth century, the countries of Central America were characterized by remarkably different political regimes: military-authoritarianism in Guatemala and El Salvador, progressive democracy in Costa Rica and traditional-authoritarianism in Honduras and Nicaragua. This article explains these contrasting regime outcomes by exploring the agrarian and state-building reforms pursued by political leaders during the nineteenth– and early twentieth century liberal reform period. Based on differences in the transformation of state and class structures, three types of liberalism are identified: radical liberalism in Guatemala and El Salvador, reformist liberalism in Costa Rica and aborted liberalism in Honduras and Nicaragua. It is argued that these types of liberalism set the Central American countries on contrasting paths of political development, culminating in diverse regime outcomes.Durante el siglo XX, los países de América Central se caracterizaron por tener regímenes políticos muy diferentes: el autoritarismo militar en Guatemala y El Salvador; la democracia progresista en Costa Rica y el autoritarismo tradicional en Honduras y Nicaragua. Este artículo explica los resultados de estos distintos regímenes mediante la exploración de las reformas agrarias y de la construcción del Estado llevadas a cabo por los líderes políticos durante el siglo XIX y principios del periodo de reformas liberales del siglo XX. Basándose en las diferencias de la transformación del Estado y de las estructuras de clases, se pueden identificar tres tipos de liberalismo: liberalismo radical en Guatemala y El Salvador; liberalismo reformista en Costa Rica y liberalismo frustrado en Honduras y Nicaragua. Se argumenta que estos tipos de liberalismo condujeron a los países de América Central a caminos contrarios al desarrollo político, culminando así en regímenes con resultados diversos.

  11. GPS-derived coupling estimates for the Central America subduction zone and volcanic arc faults: El Salvador, Honduras and Nicaragua

    Science.gov (United States)

    Correa-Mora, F.; DeMets, C.; Alvarado, D.; Turner, H. L.; Mattioli, G.; Hernandez, D.; Pullinger, C.; Rodriguez, M.; Tenorio, C.

    2009-12-01

    We invert GPS velocities from 32 sites in El Salvador, Honduras and Nicaragua to estimate the rate of long-term forearc motion and distributions of interseismic coupling across the Middle America subduction zone offshore from these countries and faults in the Salvadoran and Nicaraguan volcanic arcs. A 3-D finite element model is used to approximate the geometries of the subduction interface and strike-slip faults in the volcanic arc and determine the elastic response to coupling across these faults. The GPS velocities are best fit by a model in which the forearc moves 14-16 mmyr-1 and has coupling of 85-100 per cent across faults in the volcanic arc, in agreement with the high level of historic and recent earthquake activity in the volcanic arc. Our velocity inversion indicates that coupling across the potentially seismogenic areas of the subduction interface is remarkably weak, averaging no more than 3 per cent of the plate convergence rate and with only two poorly resolved patches where coupling might be higher along the 550-km-long segment we modelled. Our geodetic evidence for weak subduction coupling disagrees with a seismically derived coupling estimate of 60 +/- 10 per cent from a published analysis of earthquake damage back to 1690, but agrees with three other seismologic studies that infer weak subduction coupling from 20th century earthquakes. Most large historical earthquakes offshore from El Salvador and western Nicaragua may therefore have been intraslab normal faulting events similar to the Mw 7.3 1982 and Mw 7.7 2001 earthquakes offshore from El Salvador. Alternatively, the degree of coupling might vary with time. The evidence for weak coupling indirectly supports a recently published hypothesis that much of the Middle American forearc is escaping to the west or northwest away from the Cocos Ridge collision zone in Costa Rica. Such a hypothesis is particularly attractive for El Salvador, where there is little or no convergence obliquity to drive the

  12. Imaging magma plumbing beneath Askja volcano, Iceland

    Science.gov (United States)

    Greenfield, Tim; White, Robert S.

    2015-04-01

    Volcanoes during repose periods are not commonly monitored by dense instrumentation networks and so activity during periods of unrest is difficult to put in context. We have operated a dense seismic network of 3-component, broadband instruments around Askja, a large central volcano in the Northern Volcanic Zone, Iceland, since 2006. Askja last erupted in 1961, with a relatively small basaltic lava flow. Since 1975 the central caldera has been subsiding and there has been no indication of volcanic activity. Despite this, Askja has been one of the more seismically active volcanoes in Iceland. The majority of these events are due to an extensive geothermal area within the caldera and tectonically induced earthquakes to the northeast which are not related to the magma plumbing system. More intriguing are the less numerous deeper earthquakes at 12-24km depth, situated in three distinct areas within the volcanic system. These earthquakes often show a frequency content which is lower than the shallower activity, but they still show strong P and S wave arrivals indicative of brittle failure, despite their location being well below the brittle-ductile boundary, which, in Askja is ~7km bsl. These earthquakes indicate the presence of melt moving or degassing at depth while the volcano is not inflating, as only high strain rates or increased pore fluid pressures would cause brittle fracture in what is normally an aseismic region in the ductile zone. The lower frequency content must be the result of a slower source time function as earthquakes which are both high frequency and low frequency come from the same cluster, thereby discounting a highly attenuating lower crust. To image the plumbing system beneath Askja, local and regional earthquakes have been used as sources to solve for the velocity structure beneath the volcano. Travel-time tables were created using a finite difference technique and the residuals were used to solve simultaneously for both the earthquake locations

  13. A 400-ka tephrochronological framework for Central America from Lake Petén Itzá (Guatemala) sediments

    Science.gov (United States)

    Kutterolf, S.; Schindlbeck, J. C.; Anselmetti, F. S.; Ariztegui, D.; Brenner, M.; Curtis, J.; Schmid, D.; Hodell, D. A.; Mueller, A.; Pérez, L.; Pérez, W.; Schwalb, A.; Frische, M.; Wang, K.-L.

    2016-10-01

    Lake Petén Itzá, northern Guatemala, lies within a hydrologically closed basin in the south-central area of the Yucatán Peninsula, and was drilled under the auspices of the International Continental Scientific Drilling Program (ICDP) in 2006. At 16°55‧N latitude, the lake is ideally located for study of past climate and environmental conditions in the Neotropical lowlands. Because of its great depth (>160 m), Lake Petén Itzá has a record of continuous sediment accumulation that extends well into the late Pleistocene. A key obstacle to obtaining long climate records from the region is the difficulty of establishing a robust chronology beyond ∼40 ka, the limit of 14C dating. Tephra layers within the Lake Petén Itzá sediments, however, enable development of age/depth relations beyond 40 ka. Ash beds from large-magnitude, Pleistocene-to-Holocene silicic eruptions of caldera volcanoes along the Central American Volcanic Arc (CAVA) were found throughout drill cores collected from Lake Petén Itzá. These ash beds were used to establish a robust chronology extending back 400 ka. We used major- and trace-element glass composition to establish 12 well-constrained correlations between the lacustrine tephra layers in Lake Petén Itzá sediments and dated deposits at the CAVA source volcanoes, and with their marine equivalents in eastern Pacific Ocean sediments. The data also enabled revision of eight previous determinations of erupted volumes and masses, and initial estimates for another four eruptions, as well as the designation of source areas for 14 previously unknown eruptions. The new and revised sedimentation rates for the older sediment successions identify the interglacial of MIS5a between 84 and 72 ka, followed by a stadial between 72 and 59 ka that corresponds to MIS4. We modified the age models for the Lake Petén Itzá sediment sequences, extended the paleoclimate and paleoecological record for this Neotropical region to ∼400 ka, and determined the

  14. Genetic and morphological divergence among Cooper's Hawk (Accipiter cooperii) populations breeding in north-central and western North America

    Science.gov (United States)

    Sonsthagen, Sarah A.; Rosenfield, Robert N.; Bielefeldt, John; Murphy, Robert K.; Stewart, Andrew C.; Stout, William C.; Driscoll, Timothy G.; Bozek, Michael A.; Sloss, Brian L.; Talbot, Sandra L.

    2012-01-01

    Cooper's Hawk (Accipiter cooperii) populations breeding in the northern portion of the species' range exhibit variation in morphological traits that conforms to predictions based on differences in prey size, tree stand density, and migratory behavior. We examined genetic structure and gene flow and compared divergence at morphological traits (PST) and genetic markers (FST) to elucidate mechanisms (selection or genetic drift) that promote morphological diversification among Cooper's Hawk populations. Cooper's Hawks appear to conform to the genetic pattern of an east-west divide. Populations in British Columbia are genetically differentiated from north-central populations (Wisconsin, Minnesota, and North Dakota; pairwise microsatellite FST= 0.031-0.050; mitochondrial DNA ΦST = 0.177-0.204), which suggests that Cooper's Hawks were restricted to at least two Pleistocene glacial refugia. The strength of the Rocky Mountains—Great Plains area as a barrier to dispersal is further supported by restricted gene-flow rates between British Columbia and other sampled breeding populations. Divergence in morphological traits (PST) was also observed across study areas, but with British Columbia and North Dakota differentiated from Wisconsin and Minnesota, a pattern not predicted on the basis of FST and ΦST interpopulation estimates. Comparison of PSTand FSTestimates suggests that heterogeneous selection may be acting on Cooper's Hawks in the northern portion of their distribution, which is consistent with hypotheses that variation in prey mass and migratory behavior among populations may be influencing overall body size and wing chord. We were unable to distinguish between the effects of genetic drift and selection on tail length in the study populations.

  15. Evidence and future scenarios of a low-carbon energy transition in Central America: a case study in Nicaragua

    Science.gov (United States)

    Barido, Diego Ponce de Leon; Johnston, Josiah; Moncada, Maria V.; Callaway, Duncan; Kammen, Daniel M.

    2015-10-01

    The global carbon emissions budget over the next decades depends critically on the choices made by fast-growing emerging economies. Few studies exist, however, that develop country-specific energy system integration insights that can inform emerging economies in this decision-making process. High spatial- and temporal-resolution power system planning is central to evaluating decarbonization scenarios, but obtaining the required data and models can be cost prohibitive, especially for researchers in low, lower-middle income economies. Here, we use Nicaragua as a case study to highlight the importance of high-resolution open access data and modeling platforms to evaluate fuel-switching strategies and their resulting cost of power under realistic technology, policy, and cost scenarios (2014-2030). Our results suggest that Nicaragua could cost-effectively achieve a low-carbon grid (≥80%, based on non-large hydro renewable energy generation) by 2030 while also pursuing multiple development objectives. Regional cooperation (balancing) enables the highest wind and solar generation (18% and 3% by 2030, respectively), at the least cost (US127 MWh-1). Potentially risky resources (geothermal and hydropower) raise system costs but do not significantly hinder decarbonization. Oil price sensitivity scenarios suggest renewable energy to be a more cost-effective long-term investment than fuel oil, even under the assumption of prevailing cheap oil prices. Nicaragua’s options illustrate the opportunities and challenges of power system decarbonization for emerging economies, and the key role that open access data and modeling platforms can play in helping develop low-carbon transition pathways.

  16. Phylogeography and genetic variation of Triatoma dimidiata, the main Chagas disease vector in Central America, and its position within the genus Triatoma.

    Directory of Open Access Journals (Sweden)

    María Dolores Bargues

    Full Text Available BACKGROUND: Among Chagas disease triatomine vectors, the largest genus, Triatoma, includes species of high public health interest. Triatoma dimidiata, the main vector throughout Central America and up to Ecuador, presents extensive phenotypic, genotypic, and behavioral diversity in sylvatic, peridomestic and domestic habitats, and non-domiciliated populations acting as reinfestation sources. DNA sequence analyses, phylogenetic reconstruction methods, and genetic variation approaches are combined to investigate the haplotype profiling, genetic polymorphism, phylogeography, and evolutionary trends of T. dimidiata and its closest relatives within Triatoma. This is the largest interpopulational analysis performed on a triatomine species so far. METHODOLOGY AND FINDINGS: Triatomines from Mexico, Guatemala, Honduras, Nicaragua, Panama, Cuba, Colombia, Ecuador, and Brazil were used. Triatoma dimidiata populations follow different evolutionary divergences in which geographical isolation appears to have had an important influence. A southern Mexican-northern Guatemalan ancestral form gave rise to two main clades. One clade remained confined to the Yucatan peninsula and northern parts of Chiapas State, Guatemala, and Honduras, with extant descendants deserving specific status. Within the second clade, extant subspecies diversity was shaped by adaptive radiation derived from Guatemalan ancestral populations. Central American populations correspond to subspecies T. d. dimidiata. A southern spread into Panama and Colombia gave the T. d. capitata forms, and a northwestern spread rising from Guatemala into Mexico gave the T. d. maculipennis forms. Triatoma hegneri appears as a subspecific insular form. CONCLUSIONS: The comparison with very numerous Triatoma species allows us to reach highly supported conclusions not only about T. dimidiata, but also on different, important Triatoma species groupings and their evolution. The very large intraspecific genetic

  17. Technologies to better serve the millions of diabetic patients: a holistic, interactive and persuasive ICT model to facilitate self care, in extremely poor rural zones of Central America.

    Science.gov (United States)

    Vargas-Lombardo, Miguel; Jipsion, Armando; Vejarano, Rafael; Camargo, Ismael; Alvarez, Humberto; Mora, Elena Villalba; Ruíz, Ernestina Menasalva

    2012-04-01

    Health indicators express remarkable gaps between health systems at a world-wide level. Countries of the entire world are overflowed by the need of new strategies, methodologies and technologies to better serve the millions of patients, who demand better medical attention. The present archaic and ephemerally systematized systems widen the gap even more than the quality of medical services that should be provided for the millions of diabetic patients. It is therefore necessary to develop highly familiar environments with diabetic patients and their care needs. A Holistic, Interactive and Persuasive ICT model to facilitate self care of patients with diabetes (hIPAPD), is proposed as an innovative technological development in Panama to health optimized treatment for diabetic patients. Three health centers located in the District of Aguadulce, Province of Cocle, located on Panama's Pacific Coast, were selected to validate the model; the area presents extremely poor population, mostly with one daily meal, without any health insurance and with a high illiteracy rate. A series of experiences in the application and validation process are presented and analyzed in order to confirm the application, value and contribution of ICTs in health care in poor regions of Central America. PMID:20703674

  18. Two new species of Urocleidoides Mizelle et Price, 1964 (Monogenoidea) from the gill lamellae of profundulids and poeciliids from Central America and southern Mexico.

    Science.gov (United States)

    Mendoza-Franco, Edgar F; Caspeta-Mandujano, Juan Manuel; Salgado-Maldonado, Guillermo; Matamoros, Wilfredo Antonio

    2015-01-01

    During investigations of gill ectoparasites (Platyhelminthes) parasitising freshwater fish from Central America (Guatemala, Honduras, El Salvador and Panama) and southeastern Mexico (Guerrero, Oaxaca and Chiapas), the following dactylogyrid monogenoidean were found: Urocleidoides simonae sp. n. from Profundulus punctatus (Günther) (type host), Profundulus balsanus Ahl, Profundulus guatemalensis (Günther), Profundulus kreiseri Matamoros, Shaefer, Hernández et Chakrabarty, Profundulus labialis (Günther), Profundulus oaxacae (Meek), Profundulus sp. 1 and Profundulus sp. 2 (all Profundulidae); Urocleidoides vaginoclaustroides sp. n. from Pseudoxiphophorus bimaculata (Heckel) (type host) and Poeciliopsis retropinna (Regan) (both Poeciliidae); and Urocleidoides vaginoclaustrum Jogunoori, Kritsky et Venkatanarasaiah, 2004 from P. labialis, Profundulus portillorum Matamoros et Shaefer and Xiphophorus hellerii Heckel (Poeciliidae). Urocleidoides simonae sp. n. differs from all other congeneric species in having anchors with well-differentiated roots, curved elongate shaft and short point. Urocleidoides vaginoclaustroides sp. n. most closely resembles U. vaginoclaustrum, but differs from this species mainly in the shape of its anchors (i.e. evenly curved shaft and short point vs curved shaft and elongate point extending just past the tip of the superficial anchor root). The complexity of potential hosts for species of Urocleidoides and their effect on its distribution on profundulid and poeciliid fishes are briefly discussed. PMID:26580223

  19. Transboundary aquifers: the response of international law and legal voids in Central America; Acuiferos transfronterizos: respuestas desde el derecho internacional y vacios en Centroamerica

    Energy Technology Data Exchange (ETDEWEB)

    Boeglin, N.

    2012-11-01

    Central America is one of the regions of the world that will suffer the impact of climate change much more than others. The adoption of clear rules on the use of transboundary aquifers and on the need to preserve these groundwater reservoirs from serious pollution by the various states in the region is absolutely essential. Despite the lack of any bilateral or regional frameworks to rule on this issue, many general regulations have been adopted within the international framework of the United Nations that are applicable to shared surface and groundwater resources as well as to transboundary aquifers. The case of the Las Crucitas project in Costa Rica, halted by domestic tribunals thanks to the decisive action of its civilian society, reflects a clear lack of technical information concerning aquifers in Costa Rica, and probably in many other states in the region, despite the very valuable efforts being undertaken by the OAS and UNESCO under the aegis of the ISARM project for the Latin American region.

  20. Noninvasive individual and species identification of jaguars (Panthera onca), pumas (Puma concolor) and ocelots (Leopardus pardalis) in Belize, Central America using cross-species microsatellites and faecal DNA.

    Science.gov (United States)

    Wultsch, Claudia; Waits, Lisette P; Kelly, Marcella J

    2014-11-01

    There is a great need to develop efficient, noninvasive genetic sampling methods to study wild populations of multiple, co-occurring, threatened felids. This is especially important for molecular scatology studies occurring in challenging tropical environments where DNA degrades quickly and the quality of faecal samples varies greatly. We optimized 14 polymorphic microsatellite loci for jaguars (Panthera onca), pumas (Puma concolor) and ocelots (Leopardus pardalis) and assessed their utility for cross-species amplification. Additionally, we tested their reliability for species and individual identification using DNA from faeces of wild felids detected by a scat detector dog across Belize in Central America. All microsatellite loci were successfully amplified in the three target species, were polymorphic with average expected heterozygosities of HE = 0.60 ± 0.18 (SD) for jaguars, HE = 0.65 ± 0.21 (SD) for pumas and HE = 0.70 ± 0.13 (SD) for ocelots and had an overall PCR amplification success of 61%. We used this nuclear DNA primer set to successfully identify species and individuals from 49% of 1053 field-collected scat samples. This set of optimized microsatellite multiplexes represents a powerful tool for future efforts to conduct noninvasive studies on multiple, wild Neotropical felids. PMID:24751217

  1. Why does the convergence rate between Nazca and South America decrease since the Neogene?

    Science.gov (United States)

    Quinteros, J.; Sobolev, S. V.

    2012-12-01

    The classic example of the poorly understood rapid change of tectonic plates motion is the increase and then decrease of the convergence rate between the Nazca and South America plates during the last 25-20 Myr that has coincided with the growth of the Andes Mountains. Currently, the decrease in convergence rate is explained either by the increasing load of the Andes or by the appearance of flat slab segments beneath South America. Here, we present an alternative view derived from a thermomechanical self-consistent (gravity driven) model of Nazca plate subduction. Reconstructions of global plate velocities suggest that before some 25 Ma subduction of the Faralon/Nazca plate was almost perfectly parallel to the coastline of South America south of 20°S. After some 22 Ma direction of subduction became almost perpendicular to the trench. Based on these data as well as seismic tomographic images, we assume that the tip of the oceanic slab was still in the upper mantle under the central and southern parts of South America till 22 Ma. We run 2D thermomechanical models of gravity driven subduction starting at 22 Ma in the 1200 km deep mantle domain considering all the most important phase transformations. In all our numerical experiments we get a large increment in convergence velocity related to the penetration of the tip of the slab into the mantle transition zone. The subduction velocity is later reduced when the slab interacts with the spinel/perovskite phase transition and underlying more viscous lower mantle. Our models fit quite well the observed variations of convergence rate and are consistent with seismic tomographic images of the Nazca plate beneath South America. In a number of experiments we also added thick crust and high topography of Andes. These experiments demonstrate that presence of the Andes does not affect much the convergence rate between Nazca and South America plates. From our models we conclude that the variations in the convergence rate between

  2. A new endemic focus of Chagas disease in the northern region of Veraguas Province, Western Half Panama, Central America.

    Directory of Open Access Journals (Sweden)

    Azael Saldaña

    Full Text Available BACKGROUND: Chagas disease was originally reported in Panama in 1931. Currently, the best knowledge of this zoonosis is restricted to studies done in historically endemic regions. However, little is known about the distribution and epidemiology of Chagas disease in other rural areas of the country. METHODS AND FINDINGS: A cross-sectional descriptive study was carried out between May 2005 - July 2008 in four rural communities of the Santa Fe District, Veraguas Province. The study included an entomologic search to collect triatomines, bloodmeal type identification and infection rate with trypanosomes in collected vectors using a dot- blot and PCR analysis, genotyping of circulating Trypanosoma cruzi (mini-exon gene PCR analysis and the detection of chagasic antibodies among inhabitants. The vector Rhodnius pallescens was more frequently found in La Culaca and El Pantano communities (788 specimens, where it was a sporadic household visitor. These triatomines presented darker coloration and larger sizescompared with typical specimens collected in Central Panama. Triatoma dimidiata was more common in Sabaneta de El Macho (162 specimens. In one small sub-region (El Macho, 60% of the houses were colonized by this vector. Of the examined R. pallescens, 54.7.0% (88/161 had fed on Didelphis marsupialis, and 24.6% (34/138 of T. dimidiata specimens collected inside houses were positive for human blood. R. pallescens presented an infection index with T. cruzi of 17.7% (24/136, with T. rangeli of 12.5% (17/136 and 50.7% (69/136 were mixed infections. In 117 T. dimidiata domestic specimens the infection index with T. cruzi was 21.4%. Lineage I of T. cruzi was confirmed circulating in these vectors. A T. cruzi infection seroprevalence of 2.3% (24/1,056 was found in this population. CONCLUSIONS: This is the first report of Chagas disease endemicity in Santa Fe District, and it should be considered a neglected public health problem in this area of Panama.

  3. Soil bioengineering measures for disaster mitigation and environmental restoration in Central America: authochtonal cuttings suitability and economic efficiency

    Science.gov (United States)

    Petrone, A.; Preti, F.

    2009-04-01

    The use of Soil Bio-Engineering techniques in Developing countries is a relevant issue for Disaster mitigation, environmental restoration and poverty reduction. Research on authochtonal plants suitable for this kind of works and on economic efficiency is essential for the divulgation of this Discipline. The present paper is focused on this two issues related to the realization of various typologies of Soil Bio-engineering works in the Humid tropic of Nicaragua. In the area of Río Blanco, located in the Department of Matagalpa, Soil bio-engineering installations were built in several sites. The particular structures built were: drainages with live fascine mattress, a live palisade, a vegetated live crib wall for riverbank protection, a vegetative covering made of a metallic net and biotextile coupled with a live palisade made of bamboo. In order to evaluate the suitability of the various plants used in the works, monitorings were performed, one in the live palisade alongside an unpaved road and the other on the live crib wall along a riverbank, collecting survival rate and morphological parameters data. Concerning the economic efficiency we proceed to a financial analysis of the works and once the unit price was obtained, we converted the amount in EPP Dollars (Equal Purchasing Power) in order to compare the Nicaraguan context with the Italian one. Among the used species we found that Madero negro (Gliricidia sepium) and Roble macuelizo (Tabebuia rosea) are adequate for Soil-bioengineering measure on slopes while Helequeme (Erythrina fusca) reported a successful behaviour only in the crib wall for riverbank protection. In the comparison of the costs in Nicaragua and in Italy, the unit price reduction for the central American country ranges between 1.5 times (for the vegetative covering) and almost 4 times (for the fascine mattress) if it's used the EPP dollar exchange rate. Thus, a conclusion can be reached with regard to hydrological-risk mitigating actions

  4. Historical Glacier Variations in Southern South America since the Little Ice Age: Examples from Lago Viedma (Southern Patagonia) and Mendoza (Central Andes), Argentina

    Science.gov (United States)

    Nussbaumer, S. U.; Masiokas, M.; Pitte, P.; Berthier, E.; Guerrido, C.; Luckman, B. H.; Villalba, R.

    2013-12-01

    The evaluation of historical information can give valuable insight into past glacier dynamics, especially before the onset of modern measurements. Early photographs and maps depict changes for selected glaciers in southern South America. Within this study, written documents and pictorial historical records (drawings, sketches, engravings, photographs, chronicles, topographic maps) are analysed critically, with a particular focus on two regions: Lago Viedma (El Chaltén, southern Patagonia, 49.5°S, 73.0°W) and the Río Mendoza basin (Mendoza, central Andes, 33.1°S, 69.9°W). For the Lago Viedma area, early historical data for the end of the 19th century stem from the expedition of the Chilean-Argentinean border commission. In addition, the expedition by the German Scientific Society, conducted between 1910 and 1916, and the later photographs by Alberto M. de Agostini give an excellent depiction of the glaciers. Glaciar Viedma is a calving glacier which shows distinct retreat from 1896 until the present (though with a stationary or possibly advancing glacier front between 1930/31 and 1951/52), similar to the neighbouring glaciers. On the contrary, nearby Glaciar Perito Moreno shows an exceptional behaviour: the glacier front has been advancing during the first half of the 20th century, staying in an advanced position until the present. At the beginning of the 20th century, Robert Helbling explored the Argentinean-Chilean Andes together with his friend Friedrich Reichert. In the summer of 1909/10, they started a detailed survey of the highly glacierized Juncal-Tupungato mountains (Río Mendoza basin), leading to the first accurate topographic map of the area published in 1914. Its outstanding quality allows a comparison with contemporary satellite imagery. The area received attention in 1934, when the sudden drainage of a glacier-dammed lake in the upper Río del Plomo valley caused fatalities and considerable damage to constructions and the Transandine Railway. A

  5. South America Province Boundaries, 1999 (prv6ag)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — South America is part of Region 6 (Central and South America) for the World Energy Assessment. South America was divided into 107 geologic provinces as background...

  6. Along-strike Translation of a Fossil Slab Beneath California (Invited)

    Science.gov (United States)

    Forsyth, D. W.

    2013-12-01

    There are three places where subduction ceased before a spreading ridge was consumed at a trench, leaving behind remnant microplates that were incorporated into the non-subducting oceanic plate. In the cases of the Phoenix plate off the Antarctic peninsula and the Guadalupe and Magdalena microplates off Baja California, fossil slabs still attached to the microplates have been traced into the asthenosphere using seismological techniques. Apparently deep subducting plates can tear off from the surface plate leaving behind fossil pieces of young oceanic lithosphere extending 100 km or more into the asthenosphere. The young slab fragments may be close to neutral buoyancy with their asthenospheric surroundings. In the case of the Monterey microplate off central California, now part of the Pacific plate, oceanic crust has been traced beneath the continental margin using active source seismology. Nicholson et al. (1994) suggested that the translation of the Monterey microplate under North America dragged bits of the overriding plate with it, causing the rotation of the Transverse Ranges in southern California. They also suggested that the San Andreas initiated as a low angle fault between the overriding North American plate and the subducted Monterey plate. There is a gap in coastal, post-subduction volcanic activity opposite the microplate, perhaps because a slab window never formed. A steeply dipping seismic anomaly, the Isabella anomaly, also lies opposite the microplate, probably indicating the continuation of the Monterey slab deep into the asthenosphere. Between the Isabella anomaly and the surface remnants of the Monterey microplate lies the aseismic, creeping section of the San Andreas fault, which we speculate may be caused by the migration of fluids from the subducted plate. The Monterey case differs from the Phoenix and Guadalupe cases in that the hypothesized fossil slab lies beneath the North American plate, which is translating relative to the Pacific

  7. Convective upwelling in the mantle beneath the Gulf of California.

    Science.gov (United States)

    Wang, Yun; Forsyth, Donald W; Savage, Brian

    2009-11-26

    In the past six million years, Baja California has rifted obliquely apart from North America, opening up the Gulf of California. Between transform faults, seafloor spreading and rifting is well established in several basins. Other than hotspot-dominated Iceland, the Gulf of California is the only part of the world's seafloor-spreading system that has been surrounded by enough seismometers to provide horizontal resolution of upper-mantle structure at a scale of 100 kilometres over a distance great enough to include several spreading segments. Such resolution is needed to address the long-standing debate about the relative importance of dynamic and passive upwelling in the shallow mantle beneath spreading centres. Here we use Rayleigh-wave tomography to image the shear velocity in the upper 200 kilometres or so of the mantle. Low shear velocities similar to those beneath the East Pacific Rise oceanic spreading centre underlie the entire length of the Gulf, but there are three concentrated locations of anomalously low velocities spaced about 250 kilometres apart. These anomalies are 40 to 90 kilometres beneath the surface, at which depths petrological studies indicate that extensive melting of passively upwelling mantle should begin. We interpret these seismic velocity anomalies as indicating that partial melting triggers dynamic upwelling driven by either the buoyancy of retained melt or by the reduced density of depleted mantle. PMID:19940924

  8. Development of food crops by modern biotechnology techniques in Central America Desarrollo de cultivos y alimentos por técnicas de biotecnología moderna en Centroamérica

    OpenAIRE

    Giovanni Garro Monge

    2012-01-01

    In the last decade, the adoption of Genetically Modified Crops (GMC) has increased in stages worldwide. The worldwide total area planted with biotech crops reached 148 million hectares by 2010, also increasing the number of farmers around the world who decided to produce crops with this technology. At the regional level there are different responses of government agencies by generating rules and regu- lations according to the reality of these countries. In Central America, countries with grea...

  9. In the Shadow of the Cold War: The Caribbean and Central America in U.S. Foreign Policy. [and] Teacher's Resource Book. Revised. Choices for the 21st Century.

    Science.gov (United States)

    Brown Univ., Providence, RI. Thomas J. Watson, Jr. Inst. for International Studies.

    This unit examines the economic and military concerns that have linked the Caribbean and Central America to the United States. The first section of the first booklet reviews the history of U.S. involvement in the region from the mid-1800s to the early 1960s. Part 2 focuses on the Cuban missile crisis of 1962 and presents a day-by-day account of…

  10. Climate Impacts of Deforestation/Land-Use Changes in Central South America in the PRECIS Regional Climate Model: Mean Precipitation and Temperature Response to Present and Future Deforestation Scenarios

    OpenAIRE

    Canziani, Pablo O.; Gerardo Carbajal Benitez

    2012-01-01

    Deforestation/land-use changes are major drivers of regional climate change in central South America, impacting upon Amazonia and Gran Chaco ecoregions. Most experimental and modeling studies have focused on the resulting perturbations within Amazonia. Using the Regional Climate Model PRECIS, driven by ERA-40 reanalysis and ECHAM4 Baseline model for the period 1961–2000 (40-year runs), potential effects of deforestation/land-use changes in these and other neighboring ecoregions are evaluated....

  11. Isotopic and geochemical evolution of ground and surface waters in a karst dominated geological setting: a case study from Belize, Central America

    International Nuclear Information System (INIS)

    Analysis of stable isotopes and major ions in groundwater and surface waters in Belize, Central America was carried out to identify processes that may affect drinking water quality. Belize has a subtropical rainforest/savannah climate with a varied landscape composed predominantly of carbonate rocks and clastic sediments. Stable oxygen (δ18O) and hydrogen (δD) isotope ratios for surface and groundwater have a similar range and show high d-excess (10-40.8%o). The high d-excess in water samples suggest secondary continental vapor flux mixing with incoming vapor from the Caribbean Sea. Model calculations indicate that moisture derived from continental evaporation contributes 13% to overhead vapor load. In surface and groundwater, concentrations of dissolved inorganic carbon (DIC) ranged from 5.4 to 112.9 mg C/l and δ13CDIC ranged from -7.4 to -17.4%o. SO42, Ca2+ and Mg2+ in the water samples ranged from 2-163, 2-6593 and 2-90 mg/l, respectively. The DIC and δ13CDIC indicate both open and closed system carbonate evolution. Combined δ13CDIC and Ca2+, Mg2+, and SO42- suggest additional groundwater evolution by gypsum dissolution and calcite precipitation. The high SO42-content of some water samples indicates regional geologic control on water quality. Similarity in the range of δ18O, δD and δ13CDIC for surface waters and groundwater used for drinking water supply is probably due to high hydraulic conductivities of the karstic aquifers. The results of this study indicate rapid recharge of groundwater aquifers, groundwater influence on surface water chemistry and the potential of surface water to impact groundwater quality and vise versa

  12. Fault kinematics in northern Central America and coupling along the subduction interface of the Cocos Plate, from GPS data in Chiapas (Mexico), Guatemala and El Salvador

    Science.gov (United States)

    Franco, A.; Lasserre, C.; Lyon-Caen, H.; Kostoglodov, V.; Molina, E.; Guzman-Speziale, M.; Monterosso, D.; Robles, V.; Figueroa, C.; Amaya, W.; Barrier, E.; Chiquin, L.; Moran, S.; Flores, O.; Romero, J.; Santiago, J. A.; Manea, M.; Manea, V. C.

    2012-06-01

    New GPS measurements in Chiapas (Mexico), Guatemala and El Salvador are used to constrain the fault kinematics in the North America (NA), Caribbean (CA) and Cocos (CO) plates triple junction area. The regional GPS velocity field is first analysed in terms of strain partitioning across the major volcano-tectonic structures, using elastic half-space modelling, then inverted through a block model. We show the dominant role of the Motagua Fault with respect to the Polochic Fault in the accommodation of the present-day deformation associated with the NA and CA relative motion. The NA/CA motion decreases from 18-22 mm yr-1 in eastern Guatemala to 14-20 mm yr-1 in central Guatemala (assuming a uniform locking depth of 14-28 km), down to a few millimetres per year in western Guatemala. As a consequence, the western tip of the CA Plate deforms internally, with ≃9 mm yr-1 of east-west extension (≃5 mm yr-1 across the Guatemala city graben alone). Up to 15 mm yr-1 of dextral motion can be accommodated across the volcanic arc in El Salvador and southeastern Guatemala. The arc seems to mark the northern boundary of an independent forearc sliver (AR), pinned to the NA plate. The inversion of the velocity field shows that a four-block (NA, CA, CO and AR) model, that combines relative block rotations with elastic deformation at the block boundaries, can account for most of the GPS observations and constrain the overall kinematics of the active structures. This regional modelling also evidences lateral variations of coupling at the CO subduction interface, with a fairly high-coupling (≃0.6) offshore Chiapas and low-coupling (≃0.25) offshore Guatemala and El Salvador.

  13. Health care providers and human trafficking: what do they know, what do they need to know? Findings from the Middle East, the Caribbean and Central America.

    Directory of Open Access Journals (Sweden)

    Roderik F Viergever

    2015-01-01

    Full Text Available BackgroundHuman trafficking is a crime that commonly results in acute and chronic physical and psychological harm. To foster more informed health sector responses to human trafficking, training sessions for health care providers were developed and pilot-tested in the Middle East, Central America and the Caribbean. This study presents the results of an investigation into what health care providers knew and needed to know about human trafficking as part of that training program.MethodsParticipants attended one of seven two-day training courses in Antigua and Barbuda, Belize, Costa Rica, Egypt, El Salvador, Guyana and Jordan. We assessed participants’ knowledge about human trafficking and opinions about appropriate responses in trafficking cases via questionnaires pre-training, and considered participant feedback about the training post-training. Results178 participants attended the trainings. Pre-training questionnaires were completed by 165 participants (93% and post-training questionnaires by 156 participants (88%. Pre-training knowledge about health and human trafficking appeared generally high for topics such as the international nature of trafficking and the likelihood of poor mental health outcomes among survivors. However, many participants had misconceptions about the characteristics of trafficked persons and a provider’s role in responding to cases of trafficking. The most valued training components included the Role of the Health Provider, Basic Definitions and Concepts and Health Consequences of Trafficking. DiscussionTraining health care providers on caring for trafficked persons has the potential to improve practitioners’ knowledge about human trafficking and its health consequences, and to increase safe practices when responding in cases of trafficking. This study provides lessons for the design of training programs on human trafficking that aim to help health care providers identify and refer victims, and provide care for

  14. Description of the Oocysts of Three New Species of Eimeria (Apicomplexa: Eimeriidae from Iguanid Lizards (Sauria: Iguanidae of Central and South America

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    Daszak P

    1998-01-01

    Full Text Available Three new species of Eimeria are described from iguanid lizards of Central and South America. The oocysts of each species have no micropyles or residua and the sporocysts lack Stieda bodies, but all have a sporocyst residuum. Eimeria sanctaluciae n.sp. was found in the St. Lucia tree lizard, Anolis luciae, collected from the Maria Islands, Lesser Antilles. The oocysts are spherical to subspherical, averaging 17.3 x 16.5 µm, with a single layered colourless wall; about 60% contain polar granules. The sporocysts are ellipsoidal and average 7.7 x 5.5 µm. Eimeria liolaemi n.sp. was recovered from the blue-gold swift, Liolaemus taenius, from Chile. The oocysts are spherical to subspherical, measuring 21 x 20.1 µm with a single-layered colourless wall. The sporocysts are subspherical and average 7.4 x 6.8 µm. Eimeria caesicia n.sp. is described from the Brazilian collared iguanid, Tropidurus torquatus. The oocysts measure 27.4 x 23.7 µm, are spherical to subspherical, with a bilayered wall, the outer surface of which appears pale blue in colour, the thin, inner wall appearing brown, when viewed by direct light under the optical microscope. The sporocysts are subspherical and average 9.4 x 7.2 µm. Unnamed polysporocystid oocysts with dizoic sporocysts are reported from the faeces of the lesser St. Vincent tree lizard, Anolis trinitatis and the possibility of spurious parasitism briefly discussed. In addition, oocysts of an unnamed Isospora sp. with a smooth oocyst wall which closely resembles I. reui were recovered from A. trinitatis.

  15. Children’s Migration to the United States from Mexico and Central America: Evidence from the Mexican and Latin American Migration Projects

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    Katharine M. Donato

    2015-02-01

    Full Text Available In light of rising numbers of unaccompanied minors at the Mexico-US border in 2014, this article examines child migration from Mexico, Guatemala, El Salvador, Costa Rica, and Nicaragua. Using data from the Mexican and Latin American Migration Projects that permit us to go beyond simple descriptive analysis about children apprehended at the border, we investigate the extent to which children from these countries: (1 enter without legal authorization to do so; (2 are more likely to cross the border now than in the past; and (3 are tied to their parents’ migration. In theory, if immigration and refugee protections worked well for children and offered them legal pathways to reunify with their families, then we would expect low levels of unauthorized entry and no dramatic shifts over time. However, our examination of child migration shows that it is strongly linked to unauthorized entry, period of entry, and parents’ US experience.The findings show that the migration of children is closely linked to their parents’ migration history. Although the overall likelihood of a Mexican child making a first US trip is quite low, it is practically non-existent for children whose parents have no US experience. Thus, the increase in child migration from Central America, and the continued high levels of child migration from Mexico result from widespread migration networks and the United States’ long-standing reliance on the children’s parents as immigrant workers. The findings suggest that these children need protection in the form of family reunification and permanent legal status.

  16. Market regulation in Central America and Bit-Energy.CEL as tool for improving the self regulating forces for a liberalised market

    International Nuclear Information System (INIS)

    establishment of regional spot and contracts market comprising 6 Central American countries; 3. the introduction of a retail market, allowing auto generation for industrial consumers; 4. the introduction of a renewable and rural electrification support scheme; 5. the introduction of the stochastic planning tool Bit-Energy.CEL for making offers for the spot market less predictable and more flexible. The proposed paper will show more details on the history of market liberalisation in Central America, summarise ongoing activities for improving market efficiency and explain in more detail which role Bit-Energy.CEL plays in this process. (author)

  17. the Caribbean, and Central America

    Directory of Open Access Journals (Sweden)

    Douglas S. Massey

    2003-01-01

    Full Text Available Se comparan datos de las encuestas Latin American Migration Project (LAMP y Mexican Migration Project (MMP para analizar patrones migratorios a los Estados Unidos desde México, Puerto Rico, República Dominicana, Nicaragua y Costa Rica. Usando muestras de 31 comunidades, se documenta la frecuencia y tiempos de migración, la fecha, duración, destino y documentación del primer y más reciente viaje a los Estados Unidos, las características laborales de los migrantes en estos viajes, y las características socieconómicas y la selectividad de los migrantes. Los resultados muestran que una proporción significativa de la migración es indocumentada. Las características distintivas de la migración mexicana con respecto a otros flujos son su concentración en el trabajo agrícola, la falta de selectividad educativa, la mayor frecuencia de los viajes y tiempos de estancia más cortos. Todos los grupos muestran una pronunciada tendencia a establecerse lejos de las áreas de destino tradicionales. El análisis sugiere patrones y procesos de migración comunes, estructurados y expresados en maneras distintas de acuerdo al contexto. Este análisis muestra que los datos del LAMP y del MMP pueden conjugarse con efectividad para llevar a cabo estudios cuantitativos comparativos

  18. Seismicity of the Earth 1900-2013, seismotectonics of South America (Nazca Plate Region)

    Science.gov (United States)

    Hayes, Gavin P.; Smoczyk, Gregory M.; Benz, Harley M.; Furlong, Kevin P.; Villaseñor, Antonio

    2015-01-01

    The South American arc extends over 7,000 kilometers (km), from the Chilean margin triple junction offshore of southern Chile, to its intersection with the Panama fracture zone, offshore of the southern coast of Panama in Central America. It marks the plate boundary between the subducting Nazca plate and the South America plate, where the oceanic crust and lithosphere of the Nazca plate begin their descent into the mantle beneath South America. The convergence associated with this subduction process is responsible for the uplift of the Andes Mountains, and for the active volcanic chain present along much of this deformation front. Relative to a fixed South America plate, the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80 millimeters/year (mm/yr) in the south, to approximately 65 mm/yr in the north. Although the rate of subduction varies little along the entire arc, there are complex changes in the geologic processes along the subduction zone that dramatically influence volcanic activity, crustal deformation, earthquake generation and occurrence all along the western edge of South America.

  19. Modelling the Crust beneath the Kashmir valley in Northwestern Himalaya

    Science.gov (United States)

    Mir, R. R.; Parvez, I. A.; Gaur, V. K.; A.; Chandra, R.; Romshoo, S. A.

    2015-12-01

    We investigate the crustal structure beneath five broadband seismic stations in the NW-SE trendingoval shaped Kashmir valley sandwiched between the Zanskar and the Pir Panjal ranges of thenorthwestern Himalaya. Three of these sites were located along the southwestern edge of the valley andthe other two adjoined the southeastern. Receiver Functions (RFs) at these sites were calculated usingthe iterative time domain deconvolution method and jointly inverted with surface wave dispersiondata to estimate the shear wave velocity structure beneath each station. To further test the results ofinversion, we applied forward modelling by dividing the crust beneath each station into 4-6homogeneous, isotropic layers. Moho depths were separately calculated at different piercing pointsfrom the inversion of only a few stacked receiver functions of high quality around each piercing point.These uncertainties were further reduced to ±2 km by trial forward modelling as Moho depths werevaried over a range of ±6 km in steps of 2 km and the synthetic receiver functions matched with theinverted ones. The final values were also found to be close to those independently estimated using theH-K stacks. The Moho depths on the eastern edge of the valley and at piercing points in itssouthwestern half are close to 55 km, but increase to about 58 km on the eastern edge, suggesting thathere, as in the central and Nepal Himalaya, the Indian plate dips northeastwards beneath the Himalaya.We also calculated the Vp/Vs ratio beneath these 5 stations which were found to lie between 1.7 and1.76, yielding a Poisson's ratio of ~0.25 which is characteristic of a felsic composition.

  20. The integripennis species group of Geocharidius Jeannel, 1963 (Carabidae, Bembidiini, Anillina from Nuclear Central America: a taxonomic review with notes about biogeography and speciation

    Directory of Open Access Journals (Sweden)

    Igor Sokolov

    2014-09-01

    Full Text Available Our review recognizes 15 species of the integripennis species group of Geocharidius from Nuclear Central America, include three species previously described (G. gimlii Erwin, G. integripennis (Bates and G. zullinii Vigna Taglianti and 12 described here as new. They are: G. andersoni sp. n. (type locality: Chiapas, Chiapas Highlands, Cerro Huitepec and G. vignatagliantii sp. n. (type locality: Chiapas, Motozintla, Sierra Madre de Chiapas, Benito Juárez from Mexico; G. antigua sp. n. (type locality: Sacatepéquez, 5 km SE of Antigua, G. balini sp. n. (type locality: Suchitepéquez, 4 km S of Volcan Atitlán, G. erwini sp. n. (type locality: Quiché Department, 7 km NE of Los Encuentros, G. jalapensis sp. n. (type locality: Jalapa Department, 4 km E of Mataquescuintla, G. longinoi, sp. n. (type locality: El Progreso Department, Cerro Pinalón, and G. minimus sp. n. (type locality: Sacatepéquez Department, 5 km SE of Antigua from Guatemala; and G. celaquensis sp. n. (type locality: Lempira Department, Celaque National Park, G. comayaguanus sp. n. (type locality: Comayagua Department, 18 km ENE of Comayagua, G. disjunctus sp. n. (type locality: Francisco Morazán, La Tigra National Park, and G. lencanus sp. n. (type locality: Lempira Department, Celaque National Park from Honduras. For all members of the group, adult structural characters, including male and female genitalia, are described, and a taxonomic key for all members of the integripennis species group is presented based on these characters. Behavioral and biogeographical aspects of speciation in the group are discussed, based on the morphological analysis. In all cases of sympatry, pairs of closely related species show greater differences in sizes than pairs of more remotely related species. Integripennis group species occupy six different montane areas at elevations above 1300m, with no species shared among them. Major faunal barriers in the region limiting present species distributions

  1. The integripennis species group of Geocharidius Jeannel, 1963 (Carabidae, Bembidiini, Anillina) from Nuclear Central America: a taxonomic review with notes about biogeography and speciation.

    Science.gov (United States)

    Sokolov, Igor M; Kavanaugh, David H

    2014-01-01

    Our review recognizes 15 species of the integripennis species group of Geocharidius from Nuclear Central America, include three species previously described (Geocharidiusgimlii Erwin, Geocharidiusintegripennis (Bates) and Geocharidiuszullinii Vigna Taglianti) and 12 described here as new. They are: Geocharidiusandersoni sp. n. (type locality: Chiapas, Chiapas Highlands, Cerro Huitepec) and Geocharidiusvignatagliantii sp. n. (type locality: Chiapas, Motozintla, Sierra Madre de Chiapas, Benito Juárez) from Mexico; Geocharidiusantigua sp. n. (type locality: Sacatepéquez, 5 km SE of Antigua), Geocharidiusbalini sp. n. (type locality: Suchitepéquez, 4 km S of Volcan Atitlán), Geocharidiuserwini sp. n. (type locality: Quiché Department, 7 km NE of Los Encuentros), Geocharidiusjalapensis sp. n. (type locality: Jalapa Department, 4 km E of Mataquescuintla), Geocharidiuslonginoi, sp. n. (type locality: El Progreso Department, Cerro Pinalón), and Geocharidiusminimus sp. n. (type locality: Sacatepéquez Department, 5 km SE of Antigua) from Guatemala; and Geocharidiuscelaquensis sp. n. (type locality: Lempira Department, Celaque National Park), Geocharidiuscomayaguanus sp. n. (type locality: Comayagua Department, 18 km ENE of Comayagua), Geocharidiusdisjunctus sp. n. (type locality: Francisco Morazán, La Tigra National Park), and Geocharidiuslencanus sp. n. (type locality: Lempira Department, Celaque National Park) from Honduras. For all members of the group, adult structural characters, including male and female genitalia, are described, and a taxonomic key for all members of the integripennis species group is presented based on these characters. Behavioral and biogeographical aspects of speciation in the group are discussed, based on the morphological analysis. In all cases of sympatry, pairs of closely related species show greater differences in sizes than pairs of more remotely related species. Integripennis group species occupy six different montane areas at

  2. A novel educational strategy targeting health care workers in underserved communities in Central America to integrate HIV into primary medical care.

    Directory of Open Access Journals (Sweden)

    Tamara Flys

    Full Text Available BACKGROUND: Current educational strategies to integrate HIV care into primary medical care in Central America have traditionally targeted managers or higher-level officials, rather than local health care workers (HCWs. We developed a complementary online and on-site interactive training program to reach local HCWs at the primary care level in underserved communities. METHODS: The training program targeted physicians, nurses, and community HCWs with limited access to traditional onsite training in Panama, Nicaragua, Dominican Republic, and Guatemala. The curriculum focused on principles of HIV care and health systems using a tutor-supported blended educational approach of an 8-week online component, a weeklong on-site problem-solving workshop, and individualized project-based interventions. RESULTS: Of 258 initially active participants, 225 (225/258=87.2% successfully completed the online component and the top 200 were invited to the on-site workshop. Of those, 170 (170/200=85% attended the on-site workshop. In total, 142 completed all three components, including the project phase. Quantitative and qualitative evaluation instruments included knowledge assessments, reflexive essays, and acceptability surveys. The mean pre and post-essay scores demonstrating understanding of social determinants, health system organization, and integration of HIV services were 70% and 87.5%, respectively, with an increase in knowledge of 17.2% (p<0.001. The mean pre- and post-test scores evaluating clinical knowledge were 70.9% and 90.3%, respectively, with an increase in knowledge of 19.4% (p<0.001. A survey of Likert scale and open-ended questions demonstrated overwhelming participant satisfaction with course content, structure, and effectiveness in improving their HIV-related knowledge and skills. CONCLUSION: This innovative curriculum utilized technology to target HCWs with limited access to educational resources. Participants benefited from technical skills

  3. Devonian Nb-enriched basalts and andesites of north-central Tibet: Evidence for the early subduction of the Paleo-Tethyan oceanic crust beneath the North Qiangtang Block

    Science.gov (United States)

    Zhang, Hongrui; Yang, Tiannan; Hou, Zengqian; Bian, Yeke

    2016-07-01

    The early evolution of the Tethyan Ocean in north-central Tibet is currently poorly constrained. A sequence of volcanic rocks ranging from basic to intermediate in composition has been identified in the Zaduo area of the North Qiangtang Block. SHRIMP U-Pb dating of zircons from a sample of Zaduo andesite suggests an eruption age of Late Devonian (~ 380 Ma). The Zaduo volcanic rocks exhibit geochemical characteristics similar to those of typical Nb-enriched basalts, with relatively high Nb, Ta, and Zr contents, resulting in high Nb/La ratios (0.70-1.08) and Nb/U ratios (10.57-34.37). The relative enrichment in high field strength elements, together with positive εNd(t) values of + 4.6 to + 5.8 and low (87Sr/86Sr)i ratios of 0.70367-0.70532, indicates the Zaduo volcanic rocks were derived from a depleted mantle source metasomatized by silicate melts of a subducted oceanic slab. The occurrence of Nb-enriched volcanic rocks in the North Qiangtang Block suggests that the subduction of Paleo-Tethyan oceanic crust was initiated in the Late Devonian. Available geochronological data from ophiolites surrounding the North Qiangtang Block suggest that the subducted slab is most likely the Longmucuo-Shuanghu Paleo-Tethyan oceanic crust.

  4. Life beneath the surface of the central Texan Balcones Escarpment: genus Anillinus Casey, 1918 (Coleoptera, Carabidae, Bembidiini: new species, a key to the Texas species, and notes about their way of life and evolution

    Directory of Open Access Journals (Sweden)

    Igor Sokolov

    2014-06-01

    Full Text Available The Texas fauna of the genus Anillinus Casey, 1918 includes three previously described species (A. affabilis (Brues, 1902, A. depressus (Jeannel, 1963 and A. sinuatus (Jeannel, 1963 and four new species here described: A. acutipennis Sokolov & Reddell sp. n. (type locality: Fort Hood area, Bell County, Texas; A. comalensis Sokolov & Kavanaugh sp. n. (type locality: 7 miles W of New Braunfels, Comal County, Texas; A. forthoodensis Sokolov & Reddell sp. n. (type locality: Fort Hood area, Bell County, Texas; A. wisemanensis Sokolov & Kavanaugh sp. n. (type locality: Wiseman Sink, Hays County, Texas. A key for identification of adults of these species is provided. The fauna includes both soil- and cave-inhabiting species restricted to the Balcones Fault Zone and Lampasas Cut Plain and adjacent areas underlain by the Edwards-Trinity Aquifer. Based on morphological and distributional data, we hypothesize that four lineages of endogean Anillinus species extended their geographical ranges from a source area in the Ouachita-Ozark Mountains to the Balconian region in central Texas. There the cavernous Edwards-Trinity aquifer system provided an excellent refugium as the regional climate in the late Tertiary and early Quaternary became increasingly drier, rendering life at the surface nearly impossible for small, litter-inhabiting arthropods. Isolated within the Edwards-Trinity aquifer system, these anilline lineages subsequently differentiated, accounting for the currently known diversity. The paucity of specimens and difficulty in collecting them suggest that additional undiscovered species remain to be found in the region.

  5. Neogene kinematic history of Nazca-Antarctic-Phoenix slab windows beneath Patagonia and the Antarctic Peninsula

    Science.gov (United States)

    Breitsprecher, Katrin; Thorkelson, Derek J.

    2009-01-01

    The Patagonian slab window is a subsurface tectonic feature resulting from subduction of the Nazca-Antarctic spreading-ridge system (Chile Rise) beneath southern South America. The geometry of the slab window had not been rigorously defined, in part because of the complex nature of the history of ridge subduction in the southeast Pacific region, which includes four interrelated spreading-ridge systems since 20 Ma: first, the Nazca-Phoenix ridge beneath South America, then simultaneous subduction of the Nazca-Antarctic and the northern Phoenix-Antarctic spreading-ridge systems beneath South America, and the southern Phoenix-Antarctic spreading-ridge system beneath Antarctica. Spreading-ridge paleo-geographies and rotation poles for all relevant plate pairs (Nazca, Phoenix, Antarctic, South America) are available from 20 Ma onward, and form the mathematical basis of our kinematic reconstruction of the geometry of the Patagonia and Antarctic slab windows through Neogene time. At approximately 18 Ma, the Nazca-Phoenix-Antarctic oceanic (ridge-ridge-ridge) triple junction enters the South American trench; we recognize this condition as an unstable quadruple junction. Heat flow at this junction and for some distance beneath the forearc would be considerably higher than is generally recognized in cases of ridge subduction. From 16 Ma onward, the geometry of the Patagonia slab window developed from the subduction of the trailing arms of the former oceanic triple junction. The majority of the slab window's areal extent and geometry is controlled by the highly oblique (near-parallel) subduction angle of the Nazca-Antarctic ridge system, and by the high contrast in relative convergence rates between these two plates relative to South America. The very slow convergence rate of the Antarctic slab is manifested by the shallow levels achieved by the slab edge (< 45 km); thus no point on the Antarctic slab is sufficiently deep to generate "normal" mantle-derived arc-type magmas

  6. Transuranic distribution beneath a retired underground disposal facility, Hanford Site

    International Nuclear Information System (INIS)

    Past liquid waste disposal practices at the Hanford Site included the discharge of solutions containing low-level concentrations of transuranics directly to the ground via structures collectively termed cribs. A study was conducted to determine the present spatial distribution of plutonium and americium beneath the retired 216-Z-1A Crib, which contains one of the highest cumulative plutonium inventories, 57 kilograms. Sixteen shallow wells were drilled in the unsaturated sediments underlying the facility using specialized, totally contained drilling techniques. Samples from each well were analyzed to obtain profiles of both sediment type and plutonium and americium concentrations as a function of depth beneath the facility. The results of the study show that the highest concentration of plutonium (>104 nCi/g of sediment) occurs within the first 3 meters of sediment beneath the central distribution pipe. The high activity at this position is tentatively attributed to the removal of solid particles from the waste stream by sediment filtration. The distributions of plutonium and americium in the sediments are similar. Peak transuranic activity in the sediment profile is generally associated with silt lenses or with major sedimentary unit interfaces (ie, sand to gravel). The maximum vertical extent of transuranic activity found is approximately 30 meters below the bottom of the crib or approximately 25 meters above the regional water table. No contamination greater than the instrumental limit of detection of 10-5 nCi/g of sediment was found from a depth of 30 to 40 meters, the maximum depth of sampling

  7. Regional geothermal effects on subglacial water routes beneath the last Cordilleran ice sheet

    OpenAIRE

    J. Seguinot; I. Rogozhina

    2016-01-01

    The Cordilleran ice sheet, which covered the mountain ranges of north-western America during the last glacial cycle, provides an ideal setting to study the effect of geothermal anomalies on subglacial water routing beneath large-scale ice masses. First, the Cordilleran ice sheet rested directly on a geologically old yet still active subduction zone, which is responsible for significant geothermal variability in the region. Second, the deep valleys and intramontane basins that char...

  8. Oceanic terranes of S-Central America - 200 Million years of accretion history recorded on the W-edge of the Caribbean Plate.

    Science.gov (United States)

    Baumgartner, P. O.; Flores, K.; Bandini, A.; Buchs, D.; Andjic, G.; Baumgartner-Mora, C.

    2012-04-01

    The W-edge of the Caribbean Plate is characterized by two major basement domains, separated today by a SW-NE trending diffuse fault zone located SE of the Nicoya Peninsula (Costa Rica) and possibly connecting with the Hess Escarpment. To the NW, in the area originally called "Chortis Block", oceanic island/arc basements range in age from Late Triassic to Early Cretaceous and form a complicated puzzle of geodynamic units. To the SE of this fault line, no age older than Turonian-Santonian (90-85 Ma) is known. This area only represents the trailing edge of the Caribbean Large Igensous Procince (CLIP). The Mesquito Composite Oceanic Terrane (MCOT) comprises the southern half of the "Chortis Block", classically considered as a continental fragment of N-America. The MCOT is defined by isolated outcrops of ultramafic, mafic oceanic/arc rocks, and radiolarites of Late Triassic, Jurassic and Early Cretaceous age: Rhaetian (latest Triassic) radiolarites found in the El Castillo Mélange (S-MCOT: S-Nicaragua/N- Costa Rica). They are associated with blocks of OIB-metabasalts. These rocks document the presence of a Late Triassic oceanic basement that must have been the substrate of the 174 -177 Ma old (Early/Middle Jurassic) Petit-Spot-like alkaline volcanics that intruded Early Jurassic radiolarites. These rocks form tectonic slivers in the middle Cretaceous Santa Rosa Accretionary Complex (relative autochthonous of the Santa Elena ultramafic unit, N-Costa Rica). The oldest rocks of the Nicoya Complex s. str. (NW-Nicoya Peninsula, Costa Rica) are Bajocian (Middle Jurassic) radiolarites, that occur as blocks magmatically engulfed in plateau-type basalts and intrusives that range in age thoughout the pre-Campanian Cretaceous (130-83 Ma). Middle and Late Jurassic metaradiolarites occur as blocks in the Siuna Serpentinite Médange (NE-Nicaragua), along with High-p, arc-related mafics. We envision an oceanic arc that collided in the latest Jurassic with the Agua Fria arc system

  9. A questão do banimento internacional das minas terrestres: novos atores na segurança internacional e os casos das Américas Central e do Sul The international ban on landmines: new actors in international security and the cases of Central America and South America

    Directory of Open Access Journals (Sweden)

    James Augusto Pires Tibúrcio

    2011-12-01

    Full Text Available O principal instrumento jurídico internacional destinado a banir o uso, a produção e as transferências internacionais de minas terrestres antipessoais é o Tratado de Ottawa, aprovado em 1997 e que, em junho de 2011, possuía 156 Estados signatários. No processo que conduziu à sua aprovação, diversas organizações da sociedade civil, em vários países, desempenharam papel de destaque por meio de uma forte pressão exercida sobre alguns governos nacionais, promovendo uma campanha de amplo impacto midiático e que obteve apoio de algumas celebridades, especialmente de Diana, princesa de Gales. O presente artigo tem como objetivo discutir a questão do banimento das minas terrestres antipessoais a partir dessa perspectiva, demonstrando que, em alguns temas com consequências humanitárias negativas muito evidentes, é possível que os governos reajam positivamente às pressões da sociedade civil. Ademais, também se analisa como o problema das minas terrestres antipessoais foi enfrentado na América Central e na América do Sul, destacando-se, ainda, o papel do Brasil no apoio às ações de desminagem nestas regiões.The main international legal instrument for banning the use, production and international transfers of antipersonnel landmines is the Ottawa Treaty, approved in 1997, which in June 2011 had 156 signatory states. In the process leading to its approval, several civil society organizations, in many countries, played a prominent role through heavy pressure on some governments, promoting a campaign of huge media impact with support from some celebrities, notably Diana, Princess of Wales. This paper shows that in some areas with very obvious negative humanitarian consequences, it is possible that governments react positively to civil society pressures. Furthermore, this paper also examines how the problem of antipersonnel landmines has been tackled in Central and South America, also touching on Brazil's role in supporting the

  10. British and Israeli Assistance to U.S. Strategies of Torture and Counter- insurgency in Central and Latin America, 1967-96: An Argument Against Complexification

    Directory of Open Access Journals (Sweden)

    Ian Almond

    2013-01-01

    Full Text Available Although the role of the U.S. in supporting the anti-democratic, counter-revolutionary movements, governments, and dictatorships that flourished in Latin America from the 1960s to the 1990s is well known, this article examines the support provided to the U.S. by other countries. Principally this support was provided by Israel and the United Kingdom, but other countries were also involved, such as South Africa, Taiwan, France, and even Saudi Arabia. The article argues that a clear material framework underlies the assistance given by these countries. It also identifies a number of cultural and historical reasons why anti-democratic governments in Latin America found particular political empathy in Israel.

  11. Use of nuclear and related techniques in studies of agroecological effects resulting from the use of persistent pesticides in Central America. Report of a final research co-ordination meeting

    International Nuclear Information System (INIS)

    The use of pesticides for the control of pests of agriculture and vectors of human and animal diseases in the countries of Central America is the highest per capita and one of the most intense in the world. There are reports of acute toxicity and chronic effects among farm workers. There are also reports that pesticide residues in food frequently exceed the Codex Alimentarius Commission's maximum residue levels (MRLs) and shipments of foodstuffs have been rejected by importing countries due to the presence of excessive residues of pesticides. Pesticides are also implicated in the contamination of continental and coastal waters. The indiscriminate use of pesticides would be expected to also aggravate pest problems by adversely affecting populations of beneficial arthropods and causing the development of resistance in pest populations. The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture initiated a co-ordinated research project in 1992 to generate information on residues of pesticides in the environment, their persistence under local conditions and effect on local species of beneficial arthropods in agricultural and adjacent areas in the countries of Central America. Such information could be used in the implementation of legislation to control the distribution and use of pesticides and the development and application of integrated pest management programmes. Scientists from Costa Rica, Guatemala, Honduras, Nicaragua, Panama and the United States of America participated in this project. This TECDOC reports on the accomplishments of the project and includes the papers presented at the final Research Co-ordination Meeting held in Panama City, Panama, 20-24 April 1998

  12. Three-dimensional attenuation structure beneath North Island, New Zealand

    Science.gov (United States)

    Satake, Kenji; Hashida, Toshihiko

    1989-03-01

    Three-dimensional attenuation structure beneath North Island, New Zealand is determined by inversion of seismic intensity data. The method developed by Hashida and Shimazaki is used; the seismic intensity is converted to the maximum acceleration of the S-wave to obtain the acceleration at a point source and the attenuation structure. Because seismic intensity data have been accumulated on a uniform scale in New Zealand since the 1950's, we were able to use more than 2000 seismic intensity data from 26 earthquakes. The results show a remarkable contrast in the attenuation structure. In the top crustal layer, a low-Q area corresponding to the Central Volcanic Region is found. This low-Q area becomes wider to the northeast of North Island, suggesting that the Central Volcanic Region continues to the Havre Trough, a young back-arc basin. The southeastern part of the upper mantle beneath North Island shows high Q while the northwestern part shows low Q. The cross section shows that the high-Q region is dipping to the northwest, with a large amount of dip in the northeast and a smaller dip in the southwestern part of North Island. A comparison of the attenuation structure with microearthquake distribution indicates that this high-Q zone is the obliquely subducting Pacific plate. A zone of abnormally low Q which has cut the high-Q slab is found at a depth range of 130 to 230 km beneath the active volcanoes in the Taupo Volcanic Zone. A tear in the Pacific plate is suggested by this discontinuity in the attenuation structure. (1984).

  13. Building America

    Energy Technology Data Exchange (ETDEWEB)

    Brad Oberg

    2010-12-31

    IBACOS researched the constructability and viability issues of using high performance windows as one component of a larger approach to building houses that achieve the Building America 70% energy savings target.

  14. Electricity in Latin America

    Energy Technology Data Exchange (ETDEWEB)

    Breeze, P.

    1998-12-01

    The report provides an overview of the Latin American power market; analyses the power generation, transmission and distribution capabilities of 20 countries in central and south America; includes detailed comparative data on current capacity, shortfall and growth; investigates the existing network infrastructures and projected demand; examines the opportunities for independent power producers resulting from deregulation; assesses indigenous and imported fuel resources; and discusses the broad financial opportunities and restraints.

  15. Coping with the “coffee crisis” in Central America: The Role of the Nicaraguan Red de Protección Social

    OpenAIRE

    Maluccio, John A.

    2005-01-01

    "The international and local Nicaraguan media have widely reported on the “coffee crisis” in Latin America and there is substantial evidence that there has been a downturn and that this has been more severe in the coffee-growing regions. Using household panel data from a randomized community-based intervention carried out in both coffee- and noncoffee-growing areas, I examine the role of a conditional cash transfer program, the Red de Protección Social (RPS), during this downturn. While not d...

  16. Inverse modeling of Central American lavas: old lithospheric and young asthenospheric heterogeneities

    Science.gov (United States)

    Feigenson, M.; Gazel, E.; Carr, M. J.

    2009-12-01

    In recent years, there have been a number of models proposed to account for the OIB-like geochemical characteristics of lavas from central Costa Rica. The source for most basalts of the Central American volcanic front (ranging from Guatemala to northern Costa Rica) is dominantly DM (depleted MORB-source mantle) fluxed by subduction-derived fluids. In contrast, central Costa Rican basalts display striking isotopic similarities to the Galapagos hotspot. How the Galapagos signature is introduced into the Central American source is at the heart of the conflicting theories. Several models incorporate asthenospheric flow of this enriched mantle, either around the Central American arc via South America, or through a slab window, which may have opened about 5 my ago beneath central Costa Rica. Alternatively, passage of the Caribbean plate over the Galapagos hotspot may have left veins of unerupted melt within the sub-Caribbean lithosphere. These veins may be preferentially tapped during later superimposed arc volcanism. Although these models yield identical isotopic systematics, it may be possible to distinguish between them by a geochemical technique that can indicate the presence of garnet in the source region. This method, developed by Hofmann and coworkers in the 1980s, is termed inverse modeling, and uses the variation of REEs in lavas to assess the relative importance of garnet vs. clinopyroxene during partial melting. We have applied this method to new REE data from back arc lavas throughout Central America, and preliminary results indicate that garnet is not present in their sources. In contrast, direct slab melts (adakites) from Central America, as well as volcanic front lavas and alkaline basalt (with minimal slab signature) from central Costa Rica and Panama, require a source with garnet. Therefore, enriched mantle in the back arc is likely stored in the shallow lithosphere rather than introduced through asthenospheric flow. Enriched material in the volcanic

  17. Nuclear rDNA pseudogenes in Chagas disease vectors: evolutionary implications of a new 5.8S+ITS-2 paralogous sequence marker in triatomines of North, Central and northern South America.

    Science.gov (United States)

    Bargues, M Dolores; Zuriaga, M Angeles; Mas-Coma, Santiago

    2014-01-01

    A pseudogene, paralogous to rDNA 5.8S and ITS-2, is described in Meccus dimidiata dimidiata, M. d. capitata, M. d. maculippenis, M. d. hegneri, M. sp. aff. dimidiata, M. p. phyllosoma, M. p. longipennis, M. p. pallidipennis, M. p. picturata, M. p. mazzottii, Triatoma mexicana, Triatoma nitida and Triatoma sanguisuga, covering North America, Central America and northern South America. Such a nuclear rDNA pseudogene is very rare. In the 5.8S gene, criteria for pseudogene identification included length variability, lower GC content, mutations regarding the functional uniform sequence, and relatively high base substitutions in evolutionary conserved sites. At ITS-2 level, criteria were the shorter sequence and large proportion of insertions and deletions (indels). Pseudogenic 5.8S and ITS-2 secondary structures were different from the functional foldings, different one another, showing less negative values for minimum free energy (mfe) and centroid predictions, and lower fit between mfe, partition function, and centroid structures. A complete characterization indicated a processed pseudogenic unit of the ghost type, escaping from rDNA concerted evolution and with functionality subject to constraints instead of evolving free by neutral drift. Despite a high indel number, low mutation number and an evolutionary rate similar to the functional ITS-2, that pseudogene distinguishes different taxa and furnishes coherent phylogenetic topologies with resolution similar to the functional ITS-2. The discovery of a pseudogene in many phylogenetically related species is unique in animals and allowed for an estimation of its palaeobiogeographical origin based on molecular clock data, inheritance pathways, evolutionary rate and pattern, and geographical spread. Additional to the technical risk to be considered henceforth, this relict pseudogene, designated as "ps(5.8S+ITS-2)", proves to be a valuable marker for specimen classification, phylogenetic analyses, and systematic

  18. Lithospheric Architecture Beneath Hudson Bay

    Science.gov (United States)

    Porritt, R. W.; Miller, M. S.; Darbyshire, F. A.

    2015-12-01

    Hudson Bay overlies some of the thickest Precambrian lithosphere on Earth, whose internal structures contain important clues to the earliest workings of plate formation. The terminal collision, the Trans-Hudson Orogen, brought together the Western Churchill craton to the northwest and the Superior craton to the southeast. These two Archean cratons along with the Paleo-Proterozoic Trans-Hudson internides, form the core of the North American craton. We use S to P converted wave imaging and absolute shear velocity information from a joint inversion of P to S receiver functions, new ambient noise derived phase velocities, and teleseismic phase velocities to investigate this region and determine both the thickness of the lithosphere and the presence of internal discontinuities. The lithosphere under central Hudson Bay approaches 􏰂350 km thick but is thinner (􏰂200-250 km) around the periphery of the Bay. Furthermore, the amplitude of the lithosphere-asthenosphere boundary (LAB) conversion from the S receiver functions is unusually large for a craton, suggesting a large thermal contrast across the LAB, which we interpret as direct evidence of the thermal insulation effect of continents on the asthenosphere. Within the lithosphere, midlithospheric discontinuities, significantly shallower than the base of the lithosphere, are often imaged, suggesting the mechanisms that form these layers are common. Lacking time-history information, we infer that these discontinuities reflect reactivation of formation structures during deformation of the craton.

  19. Anisotropic zonation in the lithosphere of Central North America: Influence of a strong cratonic lithosphere on the Mid-Continent Rift

    Science.gov (United States)

    Ola, O.; Frederiksen, A. W.; Bollmann, T.; van der Lee, S.; Darbyshire, F.; Wolin, E.; Revenaugh, J.; Stein, C.; Stein, S.; Wysession, M.

    2016-06-01

    We present shear-wave splitting analyses of SKS and SKKS waves recorded at sixteen Superior Province Rifting Earthscope Experiment (SPREE) seismic stations on the north shore of Lake Superior, as well as fifteen selected Earthscope Transportable Array instruments south of the lake. These instruments bracket the Mid-Continent Rift (MCR) and sample the Superior, Penokean, Yavapai and Mazatzal tectonic provinces. The data set can be explained by a single layer of anisotropic fabric, which we interpret to be dominated by a lithospheric contribution. The fast S polarization directions are consistently ENE-WSW, but the split time varies greatly across the study area, showing strong anisotropy (up to 1.48 s) in the western Superior, moderate anisotropy in the eastern Superior, and moderate to low anisotropy in the terranes south of Lake Superior. We locate two localized zones of very low split time (< 0.6 s) adjacent to the MCR: one in the Nipigon Embayment, an MCR-related magmatic feature immediately north of Lake Superior, and the other adjacent to the eastern end of the lake, at the southern end of the Kapuskasing Structural Zone (KSZ). Both low-splitting zones are adjacent to sharp bends in the MCR axis. We interpret these two zones, along with a low-velocity linear feature imaged by a previous tomographic study beneath Minnesota and the Dakotas, as failed lithospheric branches of the MCR. Given that all three of these branches failed to propagate into the Superior Province lithosphere, we propose that the sharp bend of the MCR through Lake Superior is a consequence of the high mechanical strength of the Superior lithosphere ca. 1.1 Ga.

  20. L’invention de la façade caraïbe centraméricaine : indios, negros, y piratas The Invention of the Carribean Coast of Central America: Indios, Negros, y Piratas

    Directory of Open Access Journals (Sweden)

    Camille Le Masne

    2011-12-01

    Full Text Available La façade caraïbe de l'Amérique centrale naît au 16è siècle avec la conquête espagnole et la mise en pratique des théories sanitaires héritées d’Hippocrate dans le processus de colonisation. Auparavant, aucune spécificité ne semble distinguer cet espace des autres grands ensembles centraméricains : terres tempérées de la cordillère centrale, voire minces plaines littorales bordant le Pacifique. Le procès d’implantation des Espagnols rend bien compte d’une pensée prégnante, hippocratique, qui justifie les difficultés rencontrées pour contrôler les littoraux, notamment caraïbes, des emblématiques tierras calientes centraméricaines. Le littoral, au-delà de la lluvia qui continue à le caractériser de nos jours, est alors l’infierno par excellence, celui des indios, des negros, et des piratas. L’analyse historique montre ainsi que l’invention de cet espace tient autant aux données bioclimatiques et à leurs implications écologiques qu’aux tensions géopolitiques engendrées par la crise que traverse un Empire espagnol précocement confronté au harcèlement de groupes plus ou moins liés aux autres puissances européennes… La concordance entre espace de marges et plaines caraïbes pourrait suggérer un déterminisme géographique fondé sur des prédispositions qui font de l'homme un objet du milieu environnant. Ce serait cependant négliger l’impact des représentations, des clichés, et de leurs implications territoriales.The Caribbean coast of Central America was born in the 16th century with the Spanish conquest and implementation of health theories of Hippocrates in the process of colonization. Previously, no specificity seems to distinguish this space from other large ones of Central America: temperate lands of the central cordillera verily thin coastal plains bordering the Pacific. The process of colonization of the Spaniards clearly shows a dominant thought, Hippocratic, who justifies the

  1. Latin America & the Caribbean - Urban Services Delivery and the Poor : The Case of Three Central American Cities (Vol. 1 of 2) : Service Delivery and Poverty

    OpenAIRE

    World Bank

    2002-01-01

    The present study describes, and quantifies the provision of basic urban services to the poor, in three Central American cities in El Salvador, Honduras, and, Panama. It also identifies priority areas for government intervention, using specialized household surveys to quantify current deficits, and to rank households from poor to rich, using aggregate consumption as the measure of welfare....

  2. Soil mineral N dynamics beneath mixtures of leaves from legume and fruit trees in Central Amazonian multi-strata agroforests Dinâmica do nitrogênio mineral no solo em misturas de folhas de leguminosas arbóreas e de fruteiras em sistemas agroflorestais multiestratificados na Amazônia Central

    Directory of Open Access Journals (Sweden)

    Carol Melanie Schwendener

    2007-01-01

    Full Text Available Long term applications of leguminous green mulch could increase mineralizable nitrogen (N beneath cupuaçu trees produced on the infertile acidic Ultisols and Oxisols of the Amazon Basin. However, low quality standing cupuaçu litter could interfere with green mulch N release and soil N mineralization. This study compared mineral N, total N, and microbial biomass N beneath cupuaçu trees grown in two different agroforestry systems, north of Manaus, Brazil, following seven years of different green mulch application rates. To test for net interactions between green mulch and cupuaçu litter, dried gliricidia and inga leaves were mixed with senescent cupuaçu leaves, surface applied to an Oxisol soil, and incubated in a greenhouse for 162 days. Leaf decomposition, N release and soil N mineralization were periodically measured in the mixed species litter treatments and compared to single species applications. The effect of legume biomass and cupuaçu litter on soil mineral N was additive implying that recommendations for green mulch applications to cupuaçu trees can be based on N dynamics of individual green mulch species. Results demonstrated that residue quality, not quantity, was the dominant factor affecting the rate of N release from leaves and soil N mineralization in a controlled environment. In the field, complex N cycling and other factors, including soil fauna, roots, and microclimatic effects, had a stronger influence on available soil N than residue quality.Aplicações a longo prazo de leguminosas como adubo verde podem aumentar o nitrogênio (N mineralizável sob árvores de cupuaçu em solos pouco férteis e ácidos (Ultisols e Oxisols da Bacia Amazônica. Entretanto, a baixa qualidade da liteira de cupuaçu pode influênciara liberação de N do adubo verde e a mineralização deste no solo. Neste estudo foram comparados o N mineral, N total, e o N da biomassa microbiana sob árvores de cupuaçu cultivadas em dois sistemas

  3. Tectonic history of the southeastern North America

    Energy Technology Data Exchange (ETDEWEB)

    Hatcher, R.D. Jr. (Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences Oak Ridge National Lab., TN (United States))

    1993-03-01

    The present-day configuration of the crust of southeastern North America (SENA) is the product of a lengthy history traceable through more than 1 billion yr. of geologic time. The Appalachians (AP) record complete Wilson cycles of opening and closing of several oceans from ca. 690 Ma to 245 M. The final event forming the AP was the collision of SENA with Gondwana to form the supercontinent Pangaea. The Ouachitas (OA) had a somewhat different history culminating with island-arc collision during the Pennsylvanian--before the final collision began in the AP. SENA faced the open lapetos ocean no earlier than the Early Cambrian. The AP and OA were built on an earlier margin formed by rifting of the Rodonia super-continent formed by construction of the 1.2 to 1.0 Ga Grenville orogen, and farther west, a crust formed by still earlier (1.3 and 1.8 Ga) events. Recent suggestions that part of the AP platform is in Argentina raises the possibility that a fragment was rifted from between the AP and OA during the early Paleozoic. The crust beneath the Mississippi Embayment is atypical of continental crust, and would have been rifted during the Neoproterozoic and early Paleozoic. The Argentine fragment may have been removed along a transform that was reactivated several times since. Northern Pangaea was rifted during the Late Triassic and Early Jurassic and SENA once again faced open ocean-the nascent present Atlantic (AT) when spreading began. The Gulf of Mexico (GOM) also opened then forming extensive salt deposits. The AT opened partly along the old suture, but produced a failed rift in GA and FL leaving a piece of Africa forming the crust beneath the Coastal Plain as far south as central FL. The overlying sediments record recurrent uplift and decay of the AP and OA, cooling of new AT oceanic crust, eustatic sea-level changes during the Mesozoic and Cenozoic, and uplift of the Rockies providing a new source of voluminous detritus that is still being deposited in the GOM.

  4. Crustal structure beneath China from receiver function analysis

    Science.gov (United States)

    Chen, Youlin; Niu, Fenglin; Liu, Ruifeng; Huang, Zhibin; TkalčIć, Hrvoje; Sun, Li; Chan, Winston

    2010-03-01

    We collected and processed a large amount of high-quality broadband teleseismic waveform data recorded by the 48 Chinese National Digital Seismic Network stations to estimate large-scale lateral variations of crustal thickness and Vp/Vs ratio (hence Poisson's ratio) beneath China. A statistical method was used to select mutually coherent receiver functions at each station, which yielded over 200 traces for most of the stations. With the conventional H-κ (the crustal thickness and Vp/Vs ratio) approach, there is a large trade-off between H and κ. Consequently, multiple maxima are frequently observed in the H-κ domain. We introduced a weight function that measures the coherence between the P-to-S conversion and the reverberation phases at each H-κ grid to reduce the trade-off. A 4th-root stacking method was further applied to reduce uncorrelated noise relative to the linear stack. These modifications turned out to be very effective in reducing the H-κ trade-off and yielded reliable estimates of crustal thickness and Vp/Vs ratio. The crust beneath eastern China is as thin as 31-33 km and the underlying Moho is relatively flat and sharp. In the western part of China, the crust is considerably thicker and shows large variations. The Moho is observed at about 51 km depth along the Tian Shan fold system and about 84 km deep beneath the central part of the Tibetan Plateau. The transition occurs at the so-called N-S belt between about 100° and 110°E, which is featured by unusually high seismicity and large gravity anomalies. The average Vp/Vs ratio over the mainland China crust is about 1.730 (σ = 0.249), significantly lower than the global average 1.78 (σ = 0.27) of the continental crust. This lower Vp/Vs ratio may suggest a general absence of mafic lowermost crustal layer beneath China.

  5. Receiver Function Analysis of the Lithospheric Structure Beneath the Western Great Plains

    Science.gov (United States)

    Thurner, S.; Zhai, Y.; Levander, A.

    2010-12-01

    The lithosphere in the western Great Plain region of the Southwestern U.S. has been subject to tectonic deformation from the Proterozoic to present day. Proterozoic island arc terranes accreted onto the North American continent between 1.8 and 1.1 Ga, forming the original continent, and there is evidence for Proterozoic continental extension which formed basement penetrating faults between 1.5 and .6 Ga . This was followed by the uplift of the Ancestral Rockies and, most recently, the subduction of the Farallon plate beneath North America. Extension has occurred throughout the Basin and Range and formed the Rio Grand Rift (RGR). However, the relative impact that large scale tectonic forces, regional asthenospheric upwelling, and preexisting structural weaknesses have on the extension of the RGR is still undetermined. This study seeks to better understand the current tectonic system east of the Colorado Plateau beneath the RGR and western Great Plains. We use teleseismic receiver functions to investigate the nature of extension in the RGR as well as its connection to the small-scale convection thought to be occurring beneath the Colorado Plateau-RGR-Great Plains region. Our receiver function images were generated from 85 earthquake events recorded at 187 USArray Transportable Array seismic stations located throughout the western Great Plains (Latitude: 28-48, Longitude: -105-100). Previous studies have indicated crustal thickness between 39 km and 50 km beneath the Great Plains and as thin as 35 km beneath the RGR (Wilson et.al, 2005). Tomography results have shown high velocity anomalies on both sides of the RGR, extending to 600 km depth beneath the western Great Plains, and a low velocity anomaly directly beneath the RGR (Gok et. al, 2003, Wilson et. al, 2005, Gao et. al, Song and Helmberger, 2007). The western Great Plains high velocity anomaly has been interpreted to be part of the downwelling portion of an edge driven convection system induced by a lateral

  6. Illiterate America.

    Science.gov (United States)

    Kozol, Jonathan

    Intended for those involved in American social service and educational communities, this book addresses the widespread problem of illiteracy in the United States and the social consequences of this problem. Following an introduction, the chapters in the first section of the book discuss the growing crisis of illiterate America, specifically, the…

  7. Middle Miocene near trench volcanism in northern Colombia: A record of slab tearing due to the simultaneous subduction of the Caribbean Plate under South and Central America?

    Science.gov (United States)

    Lara, M.; Cardona, A.; Monsalve, G.; Yarce, J.; Montes, C.; Valencia, V.; Weber, M.; De La Parra, F.; Espitia, D.; López-Martínez, M.

    2013-08-01

    Field, geochemical, geochronological, biostratigraphical and sedimentary provenance results of basaltic and associated sediments northern Colombia reveal the existence of Middle Miocene (13-14 Ma) mafic volcanism within a continental margin setting usually considered as amagmatic. This basaltic volcanism is characterized by relatively high Al2O3 and Na2O values (>15%), a High-K calc-alkaline affinity, large ion lithophile enrichment and associated Nb, Ta and Ti negative anomalies which resemble High Al basalts formed by low degree of asthenospheric melting at shallow depths mixed with some additional slab input. The presence of pre-Cretaceous detrital zircons, tourmaline and rutile as well as biostratigraphic results suggest that the host sedimentary rocks were deposited in a platform setting within the South American margin. New results of P-wave residuals from northern Colombia reinforce the view of a Caribbean slab subducting under the South American margin. The absence of a mantle wedge, the upper plate setting, and proximity of this magmatism to the trench, together with geodynamic constraints suggest that the subducted Caribbean oceanic plate was fractured and a slab tear was formed within the oceanic plate. Oceanic plate fracturing is related to the splitting of the subducting Caribbean Plate due to simultaneous subduction under the Panama-Choco block and northwestern South America, and the fast overthrusting of the later onto the Caribbean oceanic plate.

  8. Electricity and gas regulation in Latin America

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, Peter N.

    1998-08-01

    Contains Executive Summary and Chapters on: Background Information; The Electricity Chain; The Gas Chain; The Regulatory Structure; International Activity; Argentina; Bolivia; Brazil; Chile; Colombia; Mexico; Peru; Venezuela; Central America; Other Latin American Markets; Non-Latin America Markets; The Caribbean. (Author)

  9. Prevalence and Social Determinants of Smoking in 15 Countries from North Africa, Central and Western Asia, Latin America and Caribbean: Secondary Data Analyses of Demographic and Health Surveys.

    Directory of Open Access Journals (Sweden)

    Chandrashekhar T Sreeramareddy

    Full Text Available Article 20 of the World Health Organisation Framework Convention on Tobacco Control calls for a cross-country surveillance of tobacco use through population-based surveys. We aimed to provide country-level prevalence estimates for current smoking and current smokeless tobacco use and to assess social determinants of smoking.Data from Demographic and Health Surveys done between 2005 and 2012, among men and women from nine North African, Central and West Asian countries and six Latin American and Caribbean countries were analyzed. Weighted country-level prevalence rates were estimated for 'current smoking' and 'current use of smokeless tobacco (SLT products' among men and women. In each country, social determinants of smoking among men and women were assessed by binary logistic regression analyses by including men's and women's sampling weights to account for the complex survey design.Prevalence of smoking among men was higher than 40% in Armenia (63.1%, Moldova (51.1%, Ukraine (52%, Azerbaijan (49.8 %, Kyrgyz Republic (44.3 % and Albania (42.52% but the prevalence of smoking among women was less than 10% in most countries except Ukraine (14.81% and Jordan (17.96%. The prevalence of smokeless tobacco use among men and women was less than 5% in all countries except among men in the Kyrgyz Republic (10.6 %. Smoking was associated with older age, lower education and poverty among men and higher education and higher wealth among women. Smoking among both men and women was associated with unskilled work, living in urban areas and being single.Smoking among men was very high in Central and West Asian countries. Social pattern of smoking among women that was different from men in education and wealth should be considered while formulating tobacco control policies in some Central and West Asian countries.

  10. Crustal structure beneath the Northern Transantarctic Mountains and Wilkes Subglacial Basin: Implications for tectonic origins

    Science.gov (United States)

    Hansen, Samantha E.; Kenyon, Lindsey M.; Graw, Jordan H.; Park, Yongcheol; Nyblade, Andrew A.

    2016-02-01

    The Transantarctic Mountains (TAMs) are the largest noncollisional mountain range on Earth. Their origin, as well as the origin of the Wilkes Subglacial Basin (WSB) along the inland side of the TAMs, has been widely debated, and a key constraint to distinguish between competing models is the underlying crustal structure. Previous investigations have examined this structure but have primarily focused on a small region of the central TAMs near Ross Island, providing little along-strike constraint. In this study, we use data from the new Transantarctic Mountains Northern Network and from five stations operated by the Korea Polar Research Institute to investigate the crustal structure beneath a previously unexplored portion of the TAMs. Using S wave receiver functions and Rayleigh wave phase velocities, crustal thickness and average crustal shear velocity (V>¯s) are resolved within ±4 km and ±0.1 km/s, respectively. The crust thickens from ~20 km near the Ross Sea coast to ~46 km beneath the northern TAMs, which is somewhat thicker than that imaged in previous studies beneath the central TAMs. The crust thins to ~41 km beneath the WSB. V>¯s ranges from ~3.1-3.9 km/s, with slower velocities near the coast. Our findings are consistent with a flexural origin for the TAMs and WSB, where these features result from broad flexure of the East Antarctic lithosphere and uplift along its western edge due to thermal conduction from hotter mantle beneath West Antarctica. Locally, thicker crust may explain the ~1 km of additional topography in the northern TAMs compared to the central TAMs.

  11. Raman and micro-thermometric investigation of the fluid inclusions in quartz in a gold-rich formation from Lepaguare mining district (Honduras, Central America)

    Science.gov (United States)

    Bersani, D.; Salvioli-Mariani, E.; Mattioli, M.; Menichetti, M.; Lottici, P. P.

    2009-08-01

    Fluid inclusions in the quartz crystals present in gold-rich veins from central Honduras have been studied by means of micro-thermometry and micro-Raman spectroscopy in order to provide information on the physico-chemical conditions and chemical composition of the mineralizing fluids. The use of a confocal micro-Raman apparatus allowed to obtain information on the fluid composition, in particular on the gas phase, minimizing the contributions of the host matrix to the Raman signal. The samples studied were collected from an area (Lepaguare mining district, Northern-Central Honduras) rich in ore deposits due to the Cenozoic magmatic activity, where the gold and sulphide mineralization is connected with a system of quartz veins (few decimetres thick) occurring in low-grade metamorphic rocks and produced by hydrothermal fluids. The quartz crystals present in the gold-rich veins often contain fluid inclusions. Four types of fluid inclusions have been observed, but their assemblage in the same clusters and fracture systems, as well as their comparable salinity and homogenization data, suggest that they have the same origin. Micro-thermometry and Raman spectroscopy provide a composition of the mineralizing fluids attributable to the system H 2O-NaCl-KCl-CO 2-CH 4, with temperature and pressure intervals of 210-413 °C and 1050-3850 bar, respectively. These data agree with an epigenetic origin of the gold deposit (depth < 6 km) related to granitoid or granodiorite intrusions associated to orogenic environments.

  12. Oceanographic conditions beneath Fimbul Ice Shelf, Antarctica

    OpenAIRE

    Abrahamsen, Einar Povl

    2012-01-01

    Antarctic ice shelves play a key role in the global climate system, acting as important sites for the cooling of shelf waters, thereby facilitating deep and bottom water formation. Many of the processes that take place under large ice shelves can be observed more conveniently beneath smaller ice shelves such as Fimbul Ice Shelf, an ice shelf in the eastern Weddell Sea. Fimbul Ice Shelf and nearby ice shelves might also play a significant regional role: although no bottom water is produced in ...

  13. Upper Mantle Flow Beneath the Subducted Nazca Plate: Slab Contortions and Flattening (Invited)

    Science.gov (United States)

    Russo, R. M.

    2010-12-01

    The form of asthenospheric flow beneath subducted lithospheric slabs can be discerned using splitting of shear waves emanating from earthquakes in the slabs themselves. However, the subducted Nazca plate’s abrupt changes in morphology from a planar slab dipping 30° ENE beneath the central Andes to large areas of flat-lying slab beneath Peru, to the north, and Argentina, to the south, are a potential complication to the sub-slab mantle flow. S waves from earthquakes in the Nazca slab reveal details of the upper mantle flow field below and in the vicinity of the slab. Nazca slab earthquakes large enough to be well recorded (M > 5.4, typically), and deep enough to separate S from pS and sS (30-40 km or more), are suitable for such study, and, for events between 1990 and 2010, recording stations are mostly well-distributed azimuthally about the source event. The S waves were recorded at seismic stations at teleseismic distances from the events, and were corrected for known sub-station seismic anisotropy. Thus, the shear wave splitting engendered during their passage through the asthenospheric upper mantle beneath the slab was isolated, and asthenospheric deformation fabrics resulting from plastic flow beneath the slab mapped in some detail. Shear wave splitting fast directions and upper mantle flow beneath the Nazca plate are most often trench-parallel, consistent with trench-parallel upper mantle flow beneath the slab. Fast splitting polarizations at high angle to the strike of the slab occur in the transition regions from flat to normally dipping slab. Upper mantle flow beneath the slab in these regions appears to be channeled by the slab contortion. Upper mantle flow oceanward of the Nazca slab also appears to change abruptly from trends at a high angle to the Peru-Chile trench to trench-parallel as the top of the Nazca slab attains a depth of around 75 km. Trench-parallel sub-slab flow appears to develop once the asthenosphere beneath the Nazca plate is affected

  14. Tomographically-imaged subducted slabs and magmatic history of Caribbean and Pacific subduction beneath Colombia

    Science.gov (United States)

    Bernal-Olaya, R.; Mann, P.; Vargas, C. A.; Koulakov, I.

    2013-12-01

    We define the length and geometry of eastward and southeastward-subducting slabs beneath northwestern South America in Colombia using ~100,000 earthquake events recorded by the Colombian National Seismic Network from 1993 to 2012. Methods include: hypocenter relocation, compilation of focal mechanisms, and P and S wave tomographic calculations performed using LOTOS and Seisan. The margins of Colombia include four distinct subduction zones based on slab dip: 1) in northern Colombia, 12-16-km-thick oceanic crust subducts at a modern GPS rate of 20 mm/yr in a direction of 110 degrees at a shallow angle of 8 degrees; as a result of its low dip, Pliocene-Pleistocene volcanic rocks are present 400 km from the frontal thrust; magmatic arc migration to the east records 800 km of subduction since 58 Ma ago (Paleocene) with shallow subduction of the Caribbean oceanic plateau starting ~24-33 Ma (Miocene); at depths of 90-150 km, the slab exhibits a negative velocity anomaly we associate with pervasive fracturing; 2) in the central Colombia-Panama area, we define an area of 30-km-thick crust of the Panama arc colliding/subducting at a modern 30/mm in a direction of 95 degrees; the length of this slab shows subduction/collision initiated after 20 Ma (Middle Miocene); we call this feature the Panama indenter since it has produced a V-shaped indentation of the Colombian margin and responsible for widespread crustal deformation and topographic uplift in Colombia; an incipient subduction area is forming near the Panama border with intermediate earthquakes at an eastward dip of 70 degrees to depths of ~150 km; this zone is not visible on tomographic images; 3) a 250-km-wide zone of Miocene oceanic crust of the Nazca plate flanking the Panama indenter subducts at a rate of 25 mm/yr in a direction of 55 degrees and at a normal dip of 40 degrees; the length of this slab suggests subduction began at ~5 Ma; 4) the Caldas tear defines a major dip change to the south where a 35 degrees

  15. Spina Bifida Association of America

    Science.gov (United States)

    Exceptional Parent, 1974

    1974-01-01

    The Statement of the Spina Bifida Association of America (SBAA) explains SB as a malformation of the central nervous system, reports the formation of SBAA in 1974, explains SBAA's emphasis on local chapter organization, and describes SBAA services, including a bimonthly publication, public education efforts, and research validation projects. (GW)

  16. Technology Solutions Case Study: Capillary Break Beneath a Slab: Polyethylene Sheeting over Aggregate, Southwestern Pennsylvania

    Energy Technology Data Exchange (ETDEWEB)

    None

    2014-07-01

    In this project, Building America team IBACOS worked with a builder of single- and multifamily homes in southwestern Pennsylvania (climate zone 5) to understand its methods of successfully using polyethylene sheeting over aggregate as a capillary break beneath the slab in new construction. This builder’s homes vary in terms of whether they have crawlspaces or basements. However, in both cases, the strategy protects the home from water intrusion via capillary action (e.g., water wicking into cracks and spaces in the slab), thereby helping to preserve the durability of the home.

  17. Calosota Curtis (Hymenoptera, Chalcidoidea, Eupelmidae – review of the New World and European fauna including revision of species from the West Indies and Central and North America

    Directory of Open Access Journals (Sweden)

    Gary Gibson

    2010-09-01

    Full Text Available Two of three species previously classified in Calosota Curtis (Hymenoptera: Eupelmidae from the Neotropical region are transferred to Eupelminae. Calosota eneubulus (Walker from Galapagos Islands is transferred to Eupelmus Dalman as Eupelmus (Eupelmus eneubulus (Walker, comb. n., and Calosota silvai (Brèthes from Chile is transferred to Brasema Cameron as Brasema silvai comb. n. Calosota cecidobius (Kieffer from Argentina is retained in Calosota, with reservation, as an unrecognized species. The species of Calosota from the New World excluding South America are revised. Eleven species are recognized, including the seven newly described species Calosota albipalpus sp. n. (Costa Rica, Mexico, USA, Venezuela, Calosota bicolorata sp. n. (USA, Calosota elongata sp. n. (USA, Calosota longivena sp. n. (USA, Calosota panamaensis sp. n. (Panama, Calosota setosa sp. n. (Bahamas, Dominican Republic, USA, and Calosota speculifrons sp. n. (Costa Rica, USA. The 11 regional species and the Palaearctic species Calosota vernalis Curtis are keyed and illustrated. Calosota vernalis is not known to occur in the New World but is included in the key and diagnosed because it has been intercepted in quarantine in Canada. Calosota pseudotsugae Burks is placed in synonymy under Calosota acron (Walker, syn. n., and Calosota kentra Burks, Calosota montana Burks and Calosota septentrionalis Hedqvist are placed in synonymy under Calosota aestivalis Curtis syn. n. Calosota modesta Bolívar y Pieltain is removed from synonymy under Calosota viridis Masi, stat. rev., and Calosota viridis, Calosota matritensis Bolívar y Pieltain, and Calosota coerulea Nikol’skaya are placed in synonymy under Calosota metallica (Gahan, syn. n. Calosota grylli Erdös is confirmed as a separate species from Calosota metallica based on features of both sexes. It is suggested that Calosota ariasi Bolívar y Pieltain may be a synonym of Calosota aestivalis, Calosota bolivari Askew may be a synonym

  18. Revision of Thisiomorphus Pic (Coleoptera: Mycteridae: Eurypinae) with descriptions of eleven new species from Central and South America and a key to genera of Neotropical Eurypinae.

    Science.gov (United States)

    Pollock, Darren A

    2016-01-01

    The Neotropical eurypine genus Thisiomorphus is revised, based on external structural features of adults. Twelve species are recognized, including the following eleven new species (type areas in parentheses): T. festivus (Panama, Colón Prov.), T. osaensis (Costa Rica, Puntarenas Prov.), T. davidsoni (Brazil, Chapada), T. inaequalis (Ecuador, Napo Prov.), T. caeruleus (Panama, Panamá Prov.), T. brasiliensis (Brazil, Amazonas), T. solisi (Costa Rica, Guanacaste Prov.), T. andrewsi (Panama, Chiriquí Prov.), T. bolivianus (Bolivia, Santa Cruz Dept.), T. curticornis (Ecuador, Sucumbíos Prov.), and T. convergens (Brazil, Pará). A key to the 13 described eurypine genera of Central and South American is provided, along with a key to species of Thisiomorphus. The keys are supplemented with images of habitus and selected structural features, and maps of known distributions are provided. PMID:27394498

  19. RECHERCHE SUR LES MAQUILADORAS DU SUD DU MEXIQUE ET EN AMÉRIQUE CENTRALE : TRAVAIL, GENRE ET IDENTITÉ RESEARCH ON THE MAQUILADORAS OF SOUTHERN MEXICO AND CENTRAL AMERICA: WORK, GENDER AND IDENTITY

    OpenAIRE

    Labrecque, Marie-France; Beatriz Castilla RAMOS

    2010-01-01

    Les maquiladoras de la frontière nord du Mexique ont fait couler beaucoup d’encre particulièrement en ce qui a trait à la présence des femmes dans ce type d’usine. Celles du sud et de l’Amérique centrale sont pourtant de plus en plus importantes du point de vue numérique. Leur configuration est particulière dans la mesure où, du moins dans le sud du Mexique et au Guatemala en particulier, le facteur ethnique est davantage présent dans la composition de la force de travail. Dans cet article, l...

  20. Fermilab and Latin America

    Science.gov (United States)

    Lederman, Leon M.

    2006-09-01

    As Director of Fermilab, starting in 1979, I began a series of meetings with scientists in Latin America. The motivation was to stir collaboration in the field of high energy particle physics, the central focus of Fermilab. In the next 13 years, these Pan American Symposia stirred much discussion of the use of modern physics, created several groups to do collaborative research at Fermilab, and often centralized facilities and, today, still provides the possibility for much more productive North-South collaboration in research and education. In 1992, I handed these activities over to the AAAS, as President. This would, I hoped, broaden areas of collaboration. Such collaboration is unfortunately very sensitive to political events. In a rational world, it would be the rewards, cultural and economic, of collaboration that would modulate political relations. We are not there yet.

  1. Responses of streams in central Appalachian Mountain region to reduced acidic deposition--comparisons with other regions in North America and Europe.

    Science.gov (United States)

    Chen, Yushun; Lin, Lian-Shin

    2009-03-15

    Data from 5 wet deposition stations and 21 streams during 1980-2006 were analyzed to investigate chemical responses of streams to reduced acidic deposition in the central Appalachian Mountain region of West Virginia, USA. Wet deposition of acidic anions (i.e., sulfate, nitrate, and chloride) and hydrogen ions decreased significantly during the studied time period. Stream sulfate showed a delayed response to the reduced acidic deposition, and showed a decrease in the 2000s (-5.54 microeq L(-1) yr(-1)) and the whole period (-0.49 microeq L(-1) yr(-1)). No significant trend of stream nitrate+nitrite and chloride was observed. Stream alkalinity increased in the 1990s (+23.33 microeq L(-1) yr(-1)) and the whole period (+7.26 microeq L(-1) yr(-1)). Stream hydrogen ions decreased in the 1990s (-0.002 microeq L(-1) yr(-1)), 2000s (-0.001 microeq L(-1) yr(-1)), and the whole period (-0.001 microeq L(-1) yr(-1)). Compared with most acidic streams and lakes in the United States and Europe, a lower decreasing rate of hydrogen ions and higher increasing rate of alkalinity were observed in the alkaline West Virginian streams in the 1990s. However, due to their initial negative or zero alkalinity values, those acidic streams showed a higher percent increase in alkalinity than that in the alkaline West Virginian streams (from 800 microeq L(-1) yr(-1) to 1200 microeq L(-1) yr(-1)). Total aluminum in the West Virginian streams decreased in the 1990s (-0.67 micromol L(-1) yr(-1)) and the whole period (-0.22 micromol L(-1) yr(-1)). The current study advanced our understanding of streams' responses to the reduced acidic deposition in the Mid-Appalachians since the passage of the 1970 and 1990 Amendments to the United States Clean Air Act (US CAAA).

  2. Pleurodese nos derrames pleurais malignos: um inquérito entre médicos em países da América do Sul e Central Pleurodesis for malignant pleural effusions: a survey of physicians in South and Central America

    Directory of Open Access Journals (Sweden)

    Evaldo Marchi

    2010-12-01

    Full Text Available OBJETIVO: A pleurodese é uma alternativa eficaz no controle dos derrames pleurais malignos, mas existem controvérsias a respeito de sua indicação e técnica. O objetivo deste estudo foi avaliar como é realizada a pleurodese em países da América do Sul e Central. MÉTODOS: Profissionais que realizam pleurodese responderam um questionário sobre critérios de indicação para pleurodese, técnicas utilizadas e desfechos. RESULTADOS: Nossa amostra envolveu 147 profissionais no Brasil, 49 em outros países da América do Sul e 36 em países da América Central. Mais de 50% dos participantes realizavam pleurodese somente se confirmada a malignidade no derrame pleural. Entretanto, escalas de dispneia e de status de performance eram raramente utilizadas para indicar o procedimento. Aproximadamente 75% dos participantes no Brasil e na América Central preferiam realizar a pleurodese somente no caso de recidiva do derrame, e a expansão pulmonar deveria variar de 90% a 100%. O talco slurry foi o agente mais utilizado, instilado via drenos de calibre intermediário. A toracoscopia foi realizada em menos de 25% dos casos. Febre e dor torácica foram os efeitos adversos mais comuns, e empiema ocorreu em OBJECTIVE: Pleurodesis is an effective alternative for the control of malignant pleural effusions. However, there is as yet no consensus regarding the indications for the procedure and the techniques employed therein. The objective of this study was to evaluate how pleurodesis is performed in South and Central America. METHODS: Professionals who perform pleurodesis completed a questionnaire regarding the indications for the procedure, the techniques used therein, and the outcomes obtained. RESULTS: Our sample comprised 147 respondents in Brazil, 49 in other South American countries, and 36 in Central America. More than 50% of the respondents reported performing pleurodesis only if pleural malignancy had been confirmed. However, scores on dyspnea and

  3. Pn anisotropic tomography and mantle dynamics beneath China

    Science.gov (United States)

    Zhou, Zhigang; Lei, Jianshe

    2016-08-01

    We present a new high-resolution Pn anisotropic tomographic model of the uppermost mantle beneath China inferred from 52,061 Pn arrival-time data manually picked from seismograms recorded at provincial seismic stations in China and temporary stations in Tibet and the Tienshan orogenic belt. Significant features well correlated with surface geology are revealed and provide new insights into the deep dynamics beneath China. Prominent high Pn velocities are visible under the stable cratonic blocks (e.g., the Tarim, Junngar, and Sichuan basins, and the Ordos block), whereas remarkable low Pn velocities are observed in the tectonically active areas (e.g., Pamir, the Tienshan orogenic belt, central Tibet and the Qilian fold belt). A distinct N-S trending low Pn velocity zone around 86°E is revealed under the rift running from the Himalayan block through the Lhasa block to the Qiangtang block, which indicates the hot material upwelling due to the breaking-off of the subducting Indian slab. Two N-S trending low Pn velocity belts with an approximate N-S Pn fast direction along the faults around the Chuan-Dian diamond block suggest that these faults may serve as channels of mantle flow from Tibet. The fast Pn direction changes from N-S in the north across 27°N to E-W in the south, which may reflect different types of mantle deformation. The anisotropy in the south could be caused by the asthenospheric flow resulted from the eastward subduction of the Indian plate down to the mantle transition zone beneath the Burma arc. Across the Talas-Fergana fault in the Tienshan orogenic belt, an obvious difference in velocity and anisotropy is revealed. To the west, high Pn velocities and an arc-shaped fast Pn direction are observed, implying the Indo-Asian collision, whereas to the east low Pn velocities and a range-parallel Pn fast direction are imaged, reflecting the northward underthrusting of the Tarim lithosphere and the southward underthrusting of the Kazakh lithosphere. In

  4. Analysis of groundwater flow beneath ice sheets

    Energy Technology Data Exchange (ETDEWEB)

    Boulton, G. S.; Zatsepin, S.; Maillot, B. [Univ. of Edinburgh (United Kingdom). Dept. of Geology and Geophysics

    2001-03-01

    The large-scale pattern of subglacial groundwater flow beneath European ice sheets was analysed in a previous report. It was based on a two-dimensional flowline model. In this report, the analysis is extended to three dimensions by exploring the interactions between groundwater and tunnel flow. A theory is developed which suggests that the large-scale geometry of the hydraulic system beneath an ice sheet is a coupled, self-organising system. In this system the pressure distribution along tunnels is a function of discharge derived from basal meltwater delivered to tunnels by groundwater flow, and the pressure along tunnels itself sets the base pressure which determines the geometry of catchments and flow towards the tunnel. The large-scale geometry of tunnel distribution is a product of the pattern of basal meltwater production and the transmissive properties of the bed. The tunnel discharge from the ice margin of the glacier, its seasonal fluctuation and the sedimentary characteristics of eskers are largely determined by the discharge of surface meltwater which penetrates to the bed in the terminal zone. The theory explains many of the characteristics of esker systems and can account for tunnel valleys. It is concluded that the large-scale hydraulic regime beneath ice sheets is largely a consequence of groundwater/tunnel flow interactions and that it is essential similar to non-glacial hydraulic regimes. Experimental data from an Icelandic glacier, which demonstrates measured relationships between subglacial tunnel flow and groundwater flow during the transition from summer to winter seasons for a modern glacier, and which support the general conclusions of the theory is summarised in an appendix.

  5. Early Scholars' Visits to Central America: Reports by Karl Sapper, Walter Lehmann, and Franz Termer, edited by Marilyn Beaudry-Corbett and Ellen T Hardy, Theodore E Gutman, 2000

    Directory of Open Access Journals (Sweden)

    Charles C. Kolb

    2001-05-01

    Full Text Available The Cotsen Institute's Director of Publications is archaeologist Marilyn Beaudry-Corbett, herself a specialist on the production and distribution of archaeological ceramics in Mesoamerica and Central America and a scholar of complex society economic organization. Her colleague and the co-editor of this volume, Ellen Hardy, is a Research Associate at The Cotsen Institute and an expert on mortuary customs of the Nicoya region. Theodore (Ted Gutman (1909-1997 was a longtime supporter of the Institute at UCLA worked on a number of translation projects, several of which are presented here. He was the translator of Karl Sapper's Verapaz im 16. und 17. jahrhundert, which appeared as The Verapaz in the Sixteenth and Seventeenth Centuries: A Contribution to the Historical Geography and Ethnography of Northeastern Guatemala (Los Angeles, University of California, Institute of Archae­ology, Occasional Paper 13, 1985. The contributors to the volume's narrative include, in addtion to Beaudry-Corbett and Hardy, nine other anthropologists who are recognized experts on the region and subject matter.

  6. Climate impacts of deforestation/land-use changes in Central South America in the PRECIS regional climate model: mean precipitation and temperature response to present and future deforestation scenarios.

    Science.gov (United States)

    Canziani, Pablo O; Carbajal Benitez, Gerardo

    2012-01-01

    Deforestation/land-use changes are major drivers of regional climate change in central South America, impacting upon Amazonia and Gran Chaco ecoregions. Most experimental and modeling studies have focused on the resulting perturbations within Amazonia. Using the Regional Climate Model PRECIS, driven by ERA-40 reanalysis and ECHAM4 Baseline model for the period 1961-2000 (40-year runs), potential effects of deforestation/land-use changes in these and other neighboring ecoregions are evaluated. Current 2002 and estimated 2030 land-use scenarios are used to assess PRECIS's response during 1960-2000. ERA-40 and ECHAM4 Baseline driven runs yield similar results. Precipitation changes for 2002 and 2030 land-use scenarios, while significant within deforested areas, do not result in significant regional changes. For temperature significant changes are found within deforested areas and beyond, with major temperature enhancements during winter and spring. Given the current climate, primary effects of deforestation/land-use changes remain mostly confined to the tropical latitudes of Gran Chaco, and Amazonia.

  7. Climate Impacts of Deforestation/Land-Use Changes in Central South America in the PRECIS Regional Climate Model: Mean Precipitation and Temperature Response to Present and Future Deforestation Scenarios

    Directory of Open Access Journals (Sweden)

    Pablo O. Canziani

    2012-01-01

    Full Text Available Deforestation/land-use changes are major drivers of regional climate change in central South America, impacting upon Amazonia and Gran Chaco ecoregions. Most experimental and modeling studies have focused on the resulting perturbations within Amazonia. Using the Regional Climate Model PRECIS, driven by ERA-40 reanalysis and ECHAM4 Baseline model for the period 1961–2000 (40-year runs, potential effects of deforestation/land-use changes in these and other neighboring ecoregions are evaluated. Current 2002 and estimated 2030 land-use scenarios are used to assess PRECIS's response during 1960–2000. ERA-40 and ECHAM4 Baseline driven runs yield similar results. Precipitation changes for 2002 and 2030 land-use scenarios, while significant within deforested areas, do not result in significant regional changes. For temperature significant changes are found within deforested areas and beyond, with major temperature enhancements during winter and spring. Given the current climate, primary effects of deforestation/land-use changes remain mostly confined to the tropical latitudes of Gran Chaco, and Amazonia.

  8. Climate impacts of deforestation/land-use changes in Central South America in the PRECIS regional climate model: mean precipitation and temperature response to present and future deforestation scenarios.

    Science.gov (United States)

    Canziani, Pablo O; Carbajal Benitez, Gerardo

    2012-01-01

    Deforestation/land-use changes are major drivers of regional climate change in central South America, impacting upon Amazonia and Gran Chaco ecoregions. Most experimental and modeling studies have focused on the resulting perturbations within Amazonia. Using the Regional Climate Model PRECIS, driven by ERA-40 reanalysis and ECHAM4 Baseline model for the period 1961-2000 (40-year runs), potential effects of deforestation/land-use changes in these and other neighboring ecoregions are evaluated. Current 2002 and estimated 2030 land-use scenarios are used to assess PRECIS's response during 1960-2000. ERA-40 and ECHAM4 Baseline driven runs yield similar results. Precipitation changes for 2002 and 2030 land-use scenarios, while significant within deforested areas, do not result in significant regional changes. For temperature significant changes are found within deforested areas and beyond, with major temperature enhancements during winter and spring. Given the current climate, primary effects of deforestation/land-use changes remain mostly confined to the tropical latitudes of Gran Chaco, and Amazonia. PMID:22645487

  9. Life Beneath Glacial Ice - Earth(!) Mars(?) Europa(?)

    Science.gov (United States)

    Allen, Carlton C.; Grasby, Stephen E.; Longazo, Teresa G.; Lisle, John T.; Beauchamp, Benoit

    2002-01-01

    We are investigating a set of cold springs that deposit sulfur and carbonate minerals on the surface of a Canadian arctic glacier. The spring waters and mineral deposits contain microorganisms, as well as clear evidence that biological processes mediate subglacial chemistry, mineralogy, and isotope fractionation . The formation of native sulphur and associated deposits are related to bacterially mediated reduction and oxidation of sulphur below the glacier. A non-volcanic, topography driven geothermal system, harboring a microbiological community, operates in an extremely cold environment and discharges through solid ice. Microbial life can thus exist in isolated geothermal refuges despite long-term subfreezing surface conditions. Earth history includes several periods of essentially total glaciation. lee in the near subsurface of Mars may have discharged liquid water in the recent past Cracks in the ice crust of Europa have apparently allowed the release of water to the surface. Chemolithotrophic bacteria, such as those in the Canadian springs, could have survived beneath the ice of "Snowball Earth", and life forms with similar characteristics might exist beneath the ice of Mars or Europa. Discharges of water from such refuges may have brought to the surface living microbes, as well as longlasting chemical, mineralogical, and isotopic indications of subsurface life.

  10. Shear wave anisotropy beneath the Andes from the BANJO, SEDA, and PISCO experiments

    Science.gov (United States)

    Polet, J.; Silver, P. G.; Beck, S.; Wallace, T.; Zandt, G.; Ruppert, S.; Kind, R.; Rudloff, A.

    2000-03-01

    We present the results of a detailed shear wave splitting analysis of data collected by three temporary broadband deployments located in central western South America: the Broadband Andean Joint experiment (BANJO), a 1000-km-long east-west line at 20°S, and the Projecto de Investigacion Sismologica de la Cordillera Occidental (PISCO) and Seismic Exploration of the Deep Altiplano (SEDA), deployed several hunderd kilometers north and south of this line. We determined the splitting parameters ϕ (fast polarization direction) and δt (splitting delay time) for waves that sample the above- and below-slab regions: teleseismic *KS and S, ScS waves from local deep-focus events, as well as S waves from intermediate-focus events that sample only the above-slab region. All but one of the *KS stacks for the BANJO stations show E-W fast directions with δt varying between 0.4 and 1.5 s. However, for *KS recorded at most of the SEDA and PISCO stations, and for local deep-focus S events north and south of BANJO, there is a rotation of ϕ to a more nearly trench parallel direction. The splitting parameters for above-slab paths, determined from events around 200 km deep to western stations, yield small delay times (≤0.3 s) and N-S fast polarization directions. Assuming the anisotropy is limited to the top 400 km of the mantle (olivine stability field), these data suggest the following spatial distribution of anisotropy. For the above-slab component, as one goes from east (where *KS reflects the above-slab component) to west, ϕ changes from E-W to N-S, and delay times are substantially reduced. This change may mark the transition from the Brazilian craton to actively deforming (E-W shortening) Andean mantle. We see no evidence for the strain field expected for either corner flow or shear in the mantle wedge associated with relative plate motion. The small delay times for above-slab paths in the west require the existence of significant, spatially varying below-slab anisotropy to

  11. Along-arc variation in water distribution in the upper mantle beneath Kyushu, Japan, as derived from receiver function analyses

    Science.gov (United States)

    Abe, Y.; Ohkura, T.; Hirahara, K.; Shibutani, T.

    2013-12-01

    The Kyushu district, Japan, under which the Philippine Sea (PHS) plate is subducting in a WNW direction, has several active volcanoes. On the volcanic front in Kyushu, a 110 km long gap in volcanism exists in the central part of Kyushu and volcanic rocks with various degrees of contamination by slab-derived fluid are distributed. To reveal the causes of the gap in volcanism and the chemical properties of volcanic rocks and to understand the process of magma genesis and water transportation, we should reveal along-arc variation in water distribution beneath Kyushu. We investigated the seismic velocity discontinuities in the upper mantle beneath Kyushu, with seismic waveform data from 65 stations of Hi-net, which are established by National Research Institute for Earth Science and Disaster Prevention, and 55 stations of the J-array, which are established by Japan Meteorological Agency, Kyushu University, Kagoshima University and Kyoto University. We used receiver function analyses developed especially for discontinuities with high dipping angles (Abe et al., 2011, GJI). We obtained the geometry and velocity contrasts of the continental Moho, the oceanic Moho, and the upper boundary of the PHS slab. From the geometry of these discontinuities and contrast in S wave velocities, we interpreted that the oceanic crust of the PHS slab has a low S wave velocity and is hydrated to a depth of 70 km beneath south Kyushu, to a depth of 80-90 km beneath central Kyushu, and to a depth of no more than 50 km beneath north Kyushu. We also interpreted that the fore-arc mantle beneath central Kyushu has a low velocity region (Vs < 3.2 km/s) that can contain hydrated materials and free aqueous fluid. Such a low velocity fore-arc mantle does not exist beneath north and south Kyushu. Beneath north Kyushu, the oceanic crust does not appear to convey much water in the mantle wedge. Beneath south Kyushu, water dehydrated from the slab could move to the back-arc side and cause arc volcanism

  12. La geopolítica de México en Centro América: ¿una hegemonía regional? Mexico's geopolitics in Central America: regional hegemony?

    Directory of Open Access Journals (Sweden)

    Alberto Rocha

    2006-12-01

    analizar el Mecanismo de Diálogo y Concertación de Tuxtla-Gutiérrez y sus tres ámbitos de operación: 1. El ámbito político. 2. El ámbito del desarrollo. 3. El ámbito de la cooperación técnica regional. 4. El ámbito económico, comercial y financiero.Mexico as well as Brazil (first decade of 2000 started to release geo-economic and geo-political projections about their unmediated surroundings (their region of belonging and their mediated surroundings (their neighboring region, besides playing major political roles in their far surroundings (the Latin American and Caribbean region and their remote surroundings (the American continent. As a result, we have proposed and developed the idea that such situations and realities are those of processes of constitution of States with "sub-hegemonic" roles, with their respective functions of "sub-hegemony". We therefore ask the following question: Why are both Mexico and Brazil defining "sub-hegemonic" roles? Are such roles and functions possible within a continental space where a "superpower" exerts unquestionable "supremacy" besides seeking to redefine its "hegemony" (the one now undergoing a crisis? In order to work on the theme of Mexico's geopolitical relations with Central America, we have carried out four approximations: Mexico's current stance; historical background of the relations; process of institutionalization of cooperation; and field of action of the relations. Besides, the work is concluded with some ideas about Mexico's geopolitical view. The approximation to Mexico's structural stance in the world and in the American Continent seeks to highlight realities in its condition of semiperipheral and "sub-hegemonic" country. The historical approximation leads to the 1980s and the 1990s, when the background for Mexico's cooperation with Central America is established and that cooperation is started and strengthened. The institutional approximation, focused on the 1990s and the early 2000s, approaches the field of

  13. Data Package for Past and Current Groundwater Flow and Contamination beneath Single-Shell Tank Waste Management Areas

    Energy Technology Data Exchange (ETDEWEB)

    Horton, Duane G.

    2007-03-16

    This appendix summarizes historic and recent groundwater data collected from the uppermost aquifer beneath the 200 East and 200 West Areas. Although the area of interest is the Hanford Site Central Plateau, most of the information discussed in this appendix is at the scale of individual single-shell tank waste management areas. This is because the geologic, and thus the hydraulic, properties and the geochemical properties (i.e., groundwater composition) are different in different parts of the Central Plateau.

  14. PRESSURE FLUCTUATIONS BENEATH SPATIAL HYDRAULIC JUMPS

    Institute of Scientific and Technical Information of China (English)

    YAN Zhong-min; ZHOU Chun-tian; LU Shi-qiang

    2006-01-01

    This article deals with statistical analysis of pressure fluctuations at the bottom of spatial hydraulic jumps with abrupt lateral expansions. The effects of the channel expansion ratio and inflow condition on the power spectral and dominant frequency were examined. Pressure data were recorded for different Froude numbers ranging from 3.52 to 6.86 and channel expansion ratios ranging from 1.5 to 3.0. A sampling frequency of 100 Hz was selected. The measurements were conducted in the bed of a glass-walled laboratory flume by means of pressure transducers and data acquisition systems. Power spectra as well as dominant frequency and some other statistical characteristics of fluctuating pressure beneath hydraulic jumps were obtained. Test results were compared with those of classical jump, which indicates that the peak frequencies and intensity coefficients of pressure fluctuations are higher than those of the corresponding classical jumps.

  15. Magmatic underplating beneath the Rajmahal Traps: Gravity signature and derived 3-D configuration

    Indian Academy of Sciences (India)

    A P Singh; Niraj Kumar; Bijendra Singh

    2004-12-01

    The early Cretaceous thermal perturbation beneath the eastern continental margin of the Indian shield resulted in the eruption of the Rajmahal Traps. To understand the impact of the magmatic process that originated in the deep mantle on the lower crustal level of the eastern Indian shield and adjoining Bengal basin the conspicuous gravity anomalies observed over the region have been modelled integrating with available geophysical information. The 3-D gravity modelling has delineated 10–15km thick high-density ( = 3.02 g/cm3) accreted igneous layer at the base of the crust beneath the Rajmahal Traps. Thickness of this layer varies from 16km to the west of the Rajmahal towards north to about 12km near Kharagpur towards south and about 18km to the east of the Raniganj in the central part of the region. The greater thickness of the magmatic body beneath the central part of the region presents itself as the locus of the potential feeder channel for the Rajmahal Traps. It is suggested that the crustal accretion is the imprint of the mantle thermal perturbation, over which the eastern margin of the eastern Indian shield opened around 117Ma ago. The nosing of the crustal accretion in the down south suggests the possible imprint of the subsequent magmatic intrusion along the plume path.

  16. Evidence for Active Subduction Beneath Gibraltar

    Science.gov (United States)

    Gutscher, M.; Malod, J. A.; Rehault, J.; Contrucci, I. M.; Klingelhoefer, F.; Victor, L. M.; Spakman, W.

    2002-12-01

    The Gibraltar arc encompasses the Betic - Rif mountain belts with outward directed thrusting, surrounding a zone of strong Neogene subsidence and crustal thinning in the Western Alboran Sea. The SISMAR marine seismic survey conducted in April 2001 acquired over 3000 km of 360-channel seismic data with a 4.5 km long streamer and 1000 km of wide-angle data recorded by ocean bottom seismometers (OBS), completely spanning the actively deforming region between the margins of Portugal and northwest Morocco. We report on results from this seismic survey which reveal a thick chaotic sedimentary mass west of Gibraltar to be an actively deforming accretionary wedge, with east dipping thrust faults disrupting the seafloor and soleing out to an east dipping decollement. New travel-time tomographic results image a continuous east dipping body with high seismic velocities (i.e. a cold slab of oceanic lithosphere) descending from the Atlantic domain of the Gulf of Cadiz, passing through intermediate depth (60 - 120 km) seismicity beneath the Gibraltar Arc and Western Alboran Sea, and merging with a region of deep focus earthquakes 600 - 660 km below Granada Spain. Together these provide compelling evidence for an active east dipping subduction zone. Slab rollback towards the west provides a plausible mechanism for extension and subsidence in the Alboran Sea, while the associated westward advance of the Gibraltar Arc drives compressional deformation in the accretionary wedge where active mud volcanoes have recently been discovered. Active subduction beneath Gibraltar should be considered as a possible candidate for the source of the destructive Lisbon great earthquake (M 8.5-9) and tsunami of 1755 which ravaged the coast of the Gulf of Cadiz.

  17. Major disruption of D″ beneath Alaska

    Science.gov (United States)

    Sun, Daoyuan; Helmberger, Don; Miller, Meghan S.; Jackson, Jennifer M.

    2016-05-01

    D″ represents one of the most dramatic thermal and compositional layers within our planet. In particular, global tomographic models display relatively fast patches at the base of the mantle along the circum-Pacific which are generally attributed to slab debris. Such distinct patches interact with the bridgmanite (Br) to post-bridgmanite (PBr) phase boundary to generate particularly strong heterogeneity at their edges. Most seismic observations for the D″ come from the lower mantle S wave triplication (Scd). Here we exploit the USArray waveform data to examine one of these sharp transitions in structure beneath Alaska. From west to east beneath Alaska, we observed three different characteristics in D″: (1) the western region with a strong Scd, requiring a sharp δVs = 2.5% increase; (2) the middle region with no clear Scd phases, indicating a lack of D″ (or thin Br-PBr layer); and (3) the eastern region with strong Scd phase, requiring a gradient increase in δVs. To explain such strong lateral variation in the velocity structure, chemical variations must be involved. We suggest that the western region represents relatively normal mantle. In contrast, the eastern region is influenced by a relic slab that has subducted down to the lowermost mantle. In the middle region, we infer an upwelling structure that disrupts the Br-PBr phase boundary. Such an interpretation is based upon a distinct pattern of travel time delays, waveform distortions, and amplitude patterns that reveal a circular-shaped anomaly about 5° across which can be modeled synthetically as a plume-like structure rising about 400 km high with a shear velocity reduction of ~5%, similar to geodynamic modeling predictions of upwellings.

  18. El género Hydrophilus (Coleoptera: Hydrophilidae: Hydrophilina en México y Centroamérica The genus Hydrophilus (Coleoptera: Hydrophilidae: Hydrophilina in Mexico and Central America

    Directory of Open Access Journals (Sweden)

    Roberto Arce-Pérez

    2013-03-01

    Full Text Available A partir de la revisión morfológica de 499 ejemplares adultos y datos bibliográficos se actualizó la identidad y la distribución precisa de las especies del género Hydrophilus Geoffroy, 1762 que habitan en México y Centroamérica. Se presenta a H. (Dibolocelus purpuracens Régimbart, 1901 como nuevo registro para México. Las especies más ampliamente distribuidas son H. (H. ensifer Brullé, 1837 en 5 países y las Antillas e H. (H. insularis Castelnau, 1840 en 4 países y las Antillas. Los países con mayor riqueza fueron México con 5 especies, y Nicaragua y Costa Rica con 3 especies. En México el estado con mayor riqueza es Veracruz, y en Nicaragua los departamentos de León y Río San Juan. Se presenta una clave ilustrada para el reconocimiento de las especies.The taxonomy and precise distribution of the species of the genus Hydrophilus Geoffroy, 1762 from Mexico and Central America are reviewed, based on the morphological study of499 adult specimens, descriptions and literature records. Hydrophilus (Dibolocelus purpuracens Régimbart, 1901 is recorded for the first time for Mexico. Species with widest distribution are H. (H. ensifer Brullé, 1837 cited from 5 countries and in the Antilles, and H. (H. insularis Castelnau, 1840 cited from 4 countries and the Antilles. The richest countries are Mexico with 5 species, and Costa Rica and Nicaragua with 3 species. The highest species richness is recorded for the state of Veracruz, Mexico, and from the departments of León and Río San Juan, Nicaragua. An illustrated key to the species is included.

  19. Dynamics of Caribbean and Nazca Plate Subduction Beneath Colombia from Receiver Function Analysis

    Science.gov (United States)

    Porter, R. C.; Warren, L. M.

    2014-12-01

    The tectonics of northwestern South America are controlled by the complex interactions of the South American, Nazca, and Caribbean plates. In order to better understand subduction within the region, we utilize data recorded by the Colombian National Seismic Network to calculate P-to-S receiver functions at a range of frequencies across the nation of Colombia. Where the station spacing was dense enough, receiver functions were stacked using the Common Conversion Point (CCP) method in order to better image lateral changes in crustal and upper mantle structure. Along the Pacific margin of Colombia, where the Nazca plate is subducting beneath South America, the subducting slab dips too steeply to image it with receiver functions. However, layering and strong negative arrivals are observed in the crust above the subducting slab where active volcanoes are present. The presence of these arrivals is possibly indicative of slab dehydration and the presence of partial melt within the crust. In northeastern Colombia, the Caribbean plate is subducting beneath South America at an oblique angle. Along the direction of convergence, the slab extends ~500 km inland with a relatively shallow dip before steepening. Preliminary receiver function images from this region show a shallowly-dipping negative arrival, interpreted as the top of the slab. This arrival is underlain by a positive conversion, interpreted as the down-going oceanic Moho. As the dip of the seismicity associated with the subducting slab steepens, these arrivals are no longer observed within the receiver function stacks. These cross sections of the Caribbean plate subduction are consistent with the idea that phase changes within the downgoing oceanic crust and mantle are controlling the slab buoyancy and, as a result, the angle of subduction. As the receiver functions are refined and further combined with local earthquake locations, we will better be able to understand the location of earthquakes within the subducting

  20. Constraining the crustal root geometry beneath the Rif Cordillera (North Morocco)

    Science.gov (United States)

    Diaz, Jordi; Gil, Alba; Carbonell, Ramon; Gallart, Josep; Harnafi, Mimoun

    2016-04-01

    The analyses of wide-angle reflections of controlled source experiments and receiver functions calculated from teleseismic events provide consistent constraints of an over-thickened crust beneath the Rif Cordillera (North Morocco). Regarding active source data, we investigate now offline arrivals of Moho-reflected phases recorded in RIFSIS project to get new estimations of 3D crustal thickness variations beneath North Morocco. Additional constrains on the onshore-offshore transition are derived from onland recording of marine airgun shots from the coeval Gassis-Topomed profiles. A regional crustal thickness map is computed from all these results. In parallel, we use natural seismicity data collected throughout TopoIberia and PICASSO experiments, and from a new RIFSIS deployment, to obtain teleseismic receiver functions and explore the crustal thickness variations with a H-κ grid-search approach. The use of a larger dataset including new stations covering the complex areas beneath the Rif Cordillera allow us to improve the resolution of previous contributions, revealing abrupt crustal changes beneath the region. A gridded surface is built up by interpolating the Moho depths inferred for each seismic station, then compared with the map from controlled source experiments. A remarkably consistent image is observed in both maps, derived from completely independent data and methods. Both approaches document a large modest root, exceeding 50 km depth in the central part of the Rif, in contrast with the rather small topographic elevations. This large crustal thickness, consistent with the available Bouguer anomaly data, favor models proposing that the high velocity slab imaged by seismic tomography beneath the Alboran Sea is still attached to the lithosphere beneath the Rif, hence pulling down the lithosphere and thickening the crust. The thickened area corresponds to a quiet seismic zone located between the western Morocco arcuate seismic zone, the deep seismicity area

  1. Petroleum geology of northern central America

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, W.F.

    1980-07-01

    Major reserves of oil exist in the Reforma area of Tabasco and Chiapas states and the Campeche Shelf of SE Mexico in high-energy, bank-edge, reef-derived or reef-associated carbonate rocks, ranging in age from Late Jurassic to earliest Late Cretaceous. It is the conclusion of this study that the Reforma reservoir facies does not extend into West Guatemala. However, there the potential for major reserves in bank and lagoonal carbonates of similar age is considered excellent. A variety of structures, mostly resulting from salt tectonics, is present. Known reservoir rocks include fractured carbonates with secondary porosity resulting from solution and dolomitization, and limestones with primary intergranular porosity. An indigenous source is likely for the large quantities of oil which have been tested at Rubelsanto. Seals in the form of thick intervals of Cretaceous anhydrite and, in places, of Tertiary fine-grained clastics, are abundant. The area E of Rubelsanto may have considered merit, particularly if detailed structural analysis indicates that similar salt-tectonic features are present. The less deeply-buried areas of Cretaceous carbonates are not highly regarded because: (1) salt is absent; (2) temperatures sufficient for maturation of hydrocarbons may be lacking; and (3) a considerable number of dry holes with no significant shows have been drilled. North Guatemala is somewhat attractive, because the proper combination of unmetamorphosed Paleozoic organic shale on basement highs, well-developed Todos Santos sandstone reservoirs, and the overlying thick evaporite seal could trap sizable hydrocarbon accumulations. However, as degree of metamorphism decreases, presumably basinward, distance from source terrain for detritus increases and reservoirs may be inadequate. 13 figures, 1 table.

  2. Proterozoic history of the midcontinent region of North America

    Science.gov (United States)

    Bickford, M. E.; van, W. R.; Zietz, Isidore

    1986-06-01

    Age and petrographic data from the buried basement of the midcontinent region of North America, integrated with information from exposed rocks and magnetic- and gravity-anomaly maps, allow much of the Proterozoic history of the region to be assembled. The Superior craton may be traced into the subsurface on the basis of characteristic magnetic patterns and limited age data. The region between the Superior craton and the Wyoming craton to the west is evidently underlain by southerly extension of the Trans-Hudson orogen of Canada. The Penokean orogen formed on the southern margin of the Superior craton 1890 1830 Ma, but is not inferred west of northwestern Iowa in the subsurface. Between 1780 and 1720 Ma, a major orogen developed along the southern margin of the continent and is exposed in Arizona and Colorado. These rocks are volcanogenic and, for the most part, juvenile additions to the crust; they can be traced beneath the plains as far as eastern Kansas and Nebraska. Another orogen formed farther to the south about 1700 1630 Ma and is exposed in southern Arizona and New Mexico; rocks of this age and type have beer, traced as far east as central Missouri but may extend as far as central Michigan. A major geophysical feature of the midcontinent is a system of northwest-trending magnetic and gravity anomalies in Missouri, Kansas, and Nebraska; the origin of these is not currently understood. The tectonic history of the midcontinent between 1480 and 1340 Ma was dominated by extensional formation of two widespread granite-rhyolite terranes that evidently were formed from, and overlie, the orogenic provinces. The older, formed 1450 1480 Ma, underlies the eastern midcontinent, whereas the younger, formed 1340 1400 Ma, underlies the southwestern midcontinent. The latest Proterozoic events were the formation of the midcontinent rift system and the collisional Grenville and Llano provinces about 1100 Ma.

  3. Identifying biogeochemical processes beneath stormwater infiltration ponds in support of a new best management practice for groundwater protection

    Science.gov (United States)

    O'Reilly, Andrew M.; Chang, Ni-Bin; Wanielista, Martin P.; Xuan, Zhemin

    2011-01-01

     When applying a stormwater infiltration pond best management practice (BMP) for protecting the quality of underlying groundwater, a common constituent of concern is nitrate. Two stormwater infiltration ponds, the SO and HT ponds, in central Florida, USA, were monitored. A temporal succession of biogeochemical processes was identified beneath the SO pond, including oxygen reduction, denitrification, manganese and iron reduction, and methanogenesis. In contrast, aerobic conditions persisted beneath the HT pond, resulting in nitrate leaching into groundwater. Biogeochemical differences likely are related to soil textural and hydraulic properties that control surface/subsurface oxygen exchange. A new infiltration BMP was developed and a full-scale application was implemented for the HT pond. Preliminary results indicate reductions in nitrate concentration exceeding 50% in soil water and shallow groundwater beneath the HT pond.

  4. Investigation of upper crustal structure beneath eastern Java

    Science.gov (United States)

    Martha, Agustya Adi; Widiyantoro, Sri; Cummnins, Phil; Saygin, Erdinc; Masturyono

    2016-05-01

    The complexity of geology structure in eastern Java causes this region has many potential resources as much as the disasters. Therefore, the East Java province represents an interesting area to be explored, especially regarding its upper crustal structure. To investigate this structure, we employ the Ambient Noise Tomography (ANT) method. We have used seismic waveform data from 25 Meteorological, Climatological and Geophysical Agency (BMKG) stationary seismographic stations and 26 portable seismographs installed for 2 to 8 weeks. Inter-station cross-correlation produces more than 800 Rayleigh wave components, which depict the structure beneath eastern Java. Based on the checkerboard resolution test, we found that the optimal grid size is 0.25ox0.25o. Our inversion results for the periods of 1 to 10 s indicate a good agreement with geological and Bouguer anomaly maps. Rembang high depression, most of the southern mountains zone, the northern part of Rembang zone and the central part of the Madura Island, the area of high gravity anomaly and areas dominated with igneous rocks are associated with high velocity zones. On the other hand, Kendeng zone and most of the basin in the Rembang zone are associated with low velocity zones.

  5. Investigating Late Cenozoic Mantle Dynamics beneath Yellowstone

    Science.gov (United States)

    Zhou, Q.; Liu, L.

    2015-12-01

    Recent tomography models (Sigloch, 2011; Schmandt & Lin, 2014) reveal unprecedented details of the mantle structure beneath the United States (U.S.). Prominent slow seismic anomalies below Yellowstone, traditionally interpreted as due to a mantle plume, are restricted to depths either shallower than 200 km or between 500 and 1000 km, but a continuation to greater depth is missing. Compared to fast seismic anomalies, which are usually interpreted as slabs or delaminated lithosphere, origin of deep slow seismic anomalies, especially those in the vicinity of subduction zones, is more enigmatic. As a consequence, both the dynamics and evolution of these slow anomalies remain poorly understood. To investigate the origin and evolution of the Yellowstone slow anomaly during the past 20 Myr, we construct a 4D inverse mantle convection model with a hybrid data assimilation scheme. On the one hand, we use the adjoint method to recover the past evolution of mantle seismic structures beyond the subduction zones. On the other hand, we use a high-resolution forward model to simulate the subduction of the oceanic (i.e., Farallon) plate. During the adjoint iterations, features from these two approaches are blended together at a depth of ~200 km below the subduction zone. In practice, we convert fast and slow seismic anomalies to effective positive and negative density heterogeneities. Our preliminary results indicate that at 20 Ma, the present-day shallow slow anomalies beneath the western U.S. were located inside the oceanic asthenosphere, which subsequently entered the mantle wedge, through the segmented Farallon slab. The eastward encroachment of the slow anomaly largely followed the Yellowstone hotspot track migration. The present deep mantle Yellowstone slow anomaly originated at shallower depths (i.e. transition zone), and was then translated down to the lower mantle accompanying the sinking fast anomalies. The temporal evolution of the slow anomalies suggests that the deep

  6. Channelization of plumes beneath ice shelves

    KAUST Repository

    Dallaston, M. C.

    2015-11-11

    © 2015 Cambridge University Press. We study a simplified model of ice-ocean interaction beneath a floating ice shelf, and investigate the possibility for channels to form in the ice shelf base due to spatial variations in conditions at the grounding line. The model combines an extensional thin-film description of viscous ice flow in the shelf, with melting at its base driven by a turbulent ocean plume. Small transverse perturbations to the one-dimensional steady state are considered, driven either by ice thickness or subglacial discharge variations across the grounding line. Either forcing leads to the growth of channels downstream, with melting driven by locally enhanced ocean velocities, and thus heat transfer. Narrow channels are smoothed out due to turbulent mixing in the ocean plume, leading to a preferred wavelength for channel growth. In the absence of perturbations at the grounding line, linear stability analysis suggests that the one-dimensional state is stable to initial perturbations, chiefly due to the background ice advection.

  7. Turbulence beneath finite amplitude water waves

    Energy Technology Data Exchange (ETDEWEB)

    Beya, J.F. [Universidad de Valparaiso, Escuela de Ingenieria Civil Oceanica, Facultad de Ingenieria, Valparaiso (Chile); The University of New South Wales, Water Research Laboratory, School of Civil and Environmental Engineering, Sydney, NSW (Australia); Peirson, W.L. [The University of New South Wales, Water Research Laboratory, School of Civil and Environmental Engineering, Sydney, NSW (Australia); Banner, M.L. [The University of New South Wales, School of Mathematics and Statistics, Sydney, NSW (Australia)

    2012-05-15

    Babanin and Haus (J Phys Oceanogr 39:2675-2679, 2009) recently presented evidence of near-surface turbulence generated below steep non-breaking deep-water waves. They proposed a threshold wave parameter a {sup 2}{omega}/{nu} = 3,000 for the spontaneous occurrence of turbulence beneath surface waves. This is in contrast to conventional understanding that irrotational wave theories provide a good approximation of non-wind-forced wave behaviour as validated by classical experiments. Many laboratory wave experiments were carried out in the early 1960s (e.g. Wiegel 1964). In those experiments, no evidence of turbulence was reported, and steep waves behaved as predicted by the high-order irrotational wave theories within the accuracy of the theories and experimental techniques at the time. This contribution describes flow visualisation experiments for steep non-breaking waves using conventional dye techniques in the wave boundary layer extending above the wave trough level. The measurements showed no evidence of turbulent mixing up to a value of a {sup 2}{omega}/{nu} = 7,000 at which breaking commenced in these experiments. These present findings are in accord with the conventional understandings of wave behaviour. (orig.)

  8. Ecological Society of America meeting. Global warming, insects take the stage at Snowbird.

    Science.gov (United States)

    Kaiser, J

    2000-09-22

    Despite the turmoil of not-so-distant forest fires and United Airlines troubles that threw off travel schedules, some 2600 ecologists made their way to this sun-soaked canyon last month for the Ecological Society of America's 85th annual meeting. Topics ranged from ancient droughts to photosynthesis beneath snow and how trees resist insects.

  9. Crustal structure beneath discovery bank in the South Scotia Sea from group velocity tomography and seismic reflection data

    International Nuclear Information System (INIS)

    Bruce, Discovery, Herdman and Jane Banks, all located along the central-eastern part of the South Scotia Ridge (i.e., the Antarctica-Scotia plate boundary), represent isolated topographic reliefs surrounded by relatively young oceanic crust, whose petrological and structural nature is still the subject of speculations due to the lack of resolving data. In the Scotia Sea and surrounding regions negative anomalies of about 34% are reported in large-scale group velocity tomography maps. The spatial resolution (∼500 km) of these maps does not warrant any reliable interpretation of such anomalies. A recent surface wave tomography in the same area, performed using broad band seismic stations and 300 regional events, shows that in the period range from 15 s to 50 s the central-eastern part of the South Scotia Ridge is characterized by negative anomalies of the group velocities as large as 6. The resolution of our data set (∼300 km) makes it possible to distinguish an area (centered at 61 deg S and 36 deg W) with a crust thicker than 25 km, and a shear wave velocity vs. depth profile similar to that found beneath the northern tip of the Antarctic Peninsula and southern South America. Rayleigh and Love wave dispersion curves are inverted in the period range from 15 s to 80 s to obtain shear wave velocity profiles that suggest a continental nature of Discovery Bank. The continental-type crust of this topographic relief is in agreement with the interpretation of a multi-channel seismic reflection profile acquired across this rise. Peculiar acoustic facies are observed in this profile and are interpreted as thinned and faulted continental plateau. The boundaries of the negative group velocity anomalies are marked by a high seismicity rate. Historical normal faulting earthquakes with magnitude around 7 are localised between the low velocity anomaly region in the eastern South Scotia Ridge and the high velocity anomaly region associated with the surrounding oceanic crust

  10. Active Subduction Beneath The Gibraltar Arc

    Science.gov (United States)

    Gutscher, M.-A.; Malod, J.; Rehault, J.-P.; Contrucci, I.; Klingelhoefer, F.; Spakman, W.; Sismar Scientific Team

    The Gibraltar region features the arcuate Betic - Rif mountain belt with outward di- rected thrusting, surrounding a zone of strong Neogene subsidence and crustal thin- ning in the Western Alboran Sea. Until now its geodynamic interpretation has re- mained controversial. The Gibraltar Arc is located at the eastern end of the Azores- Gibraltar transform, a diffuse transpressional plate boundary between the Iberian and African Plates. Attention has recently been focussed on this plate boundary, while seeking the likely source of the destructive Lisbon great earthquake (M 8.5 - 9) and tsunami of 1755. The SISMAR marine seismic survey conducted in April 2001 ac- quired over 3000 km of 360-channel seismic data with a 4.5 km long streamer and 1000 km of wide-angle data recorded by ocean bottom seismometers (OBS), com- pletely spanning the actively deforming region between the margins of Portugal and northwest Morocco. Results from this seismic survey reveal a thick chaotic sedimen- tary mass west of Gibraltar to be an actively deforming accretionary wedge, with east dipping thrust faults disrupting the seafloor and soleing out to an east dipping decolle- ment. New travel-time tomographic results image a continuous east dipping body with high seismic velocities (i.e. a cold slab of oceanic lithosphere) descending from the Atlantic domain of the Gulf of Cadiz, passing through intermediate depth (60 - 120 km) seismicity beneath the Gibraltar Arc and Western Alboran Sea, and merging with a region of deep focus earthquakes 600 - 660 km below Granada Spain. Together these provide compelling evidence for an active east dipping subduction zone. Slab rollback towards the west provides a plausible mechanism for extension and subsidence in the Alboran Sea, while the associated westward advance of the Gibraltar Arc drives com- pressional deformation in the accretionary wedge where active mud volcanoes have recently been discovered.

  11. Groundwater Mounding Beneath Stormwater Infiltration Basins

    Science.gov (United States)

    Nimmer, M.; Thompson, A. M.; Misra, D.

    2007-12-01

    An accurate understanding of groundwater mound formation is important in the proper design of stormwater infiltration basins since these basins are often required to recharge a portion of pre-development infiltration volume. Mound formation due to localized recharge may reduce the infiltration rate of the basin and the ability of the soil to filter pollutants. The goal of this research was to understand groundwater mounding and the potential for contaminant transport resulting from recharge beneath stormwater infiltration basins. A 0.10 ha infiltration basin serving a 9.4 ha residential subdivision in Oconomowoc, Wisconsin was used in this study. Subsurface conditions included sand and gravel material and a groundwater table at 2.3 m below grade. Three storm events, 4.9 cm, 2.8 cm, and 4.3 cm, between August 2006 and April 2007 were modeled using the two-dimensional numerical model HYDRUS. The calibrated model was used to evaluate hypothetical basin operation scenarios for various basin sizes, soil types, ponding depths, and water table depths. The groundwater mound intersected the basin floor in most scenarios with loamy sand and sandy loam soils, an unsaturated thickness of 1.52 m, and a ponding depth of 0.61 m. No groundwater table response was observed with ponding depths less than 0.31 m with an unsaturated zone thickness of 6.09 m. The mound height was most sensitive to hydraulic conductivity and unsaturated zone thickness. A 7.6 cm sediment layer delayed the time to reach maximum mound height, but had a minimal effect on the magnitude of the mound. Mound heights increased as infiltration basin size increased.

  12. Subduction system and flat slab beneath the Eastern Cordillera of Colombia

    Science.gov (United States)

    Chiarabba, Claudio; De Gori, Pasquale; Faccenna, Claudio; Speranza, Fabio; Seccia, Danilo; Dionicio, Viviana; Prieto, Germán. A.

    2016-01-01

    Seismicity at the northern terminus of the Nazca subduction is diffused over a wide area containing the puzzling seismic feature known as the Bucaramanga nest. We relocate about 5000 earthquakes recorded by the Colombian national seismic network and produce the first 3-D velocity model of the area to define the geometry of the lithosphere subducting below the Colombian Andes. We found lateral velocity heterogeneities and an abrupt offset of the Wadati-Benioff zone at 5°N indicating that the Nazca plate is segmented by an E-W slab tear, that separates a steeper Nazca segment to the south from a flat subduction to the north. The flat Nazca slab extends eastward for about 400 km, before dip increases to ˜50° beneath the Eastern Cordillera, where it yields the Bucaramanga nest. We explain this puzzling locus of intermediate-depth seismicity located beneath the Eastern Cordillera of Colombia as due to a massive dehydration and eclogitization of a thickened oceanic crust. We relate the flat subducting geometry to the entrance at the trench at ca. 10 Ma of a thick - buoyant oceanic crust, likely a volcanic ridge, producing a high coupling with the overriding plate. Sub-horizontal plate subduction is consistent with the abrupt disappearance of volcanism in the Andes of South America at latitudes > 5°N.

  13. Structure of the mantle beneath the Alboran Basin from magnetotelluric soundings

    Science.gov (United States)

    Garcia, X.; Seillé, H.; Elsenbeck, J.; Evans, R. L.; Jegen, M.; Hölz, Sebastian; Ledo, J.; Lovatini, A.; Marti, A.; Marcuello, A.; Queralt, P.; Ungarelli, C.; Ranero, C. R.

    2015-12-01

    We present results of marine MT acquisition in the Alboran sea that also incorporates previously acquired land MT from southern Spain into our analysis. The marine data show complex MT response functions with strong distortion due to seafloor topography and the coastline, but inclusion of high resolution topography and bathymetry and a seismically defined sediment unit into a 3-D inversion model has allowed us to image the structure in the underlying mantle. The resulting resistivity model is broadly consistent with a geodynamic scenario that includes subduction of an eastward trending plate beneath Gibraltar, which plunges nearly vertically beneath the Alboran. Our model contains three primary features of interest: a resistive body beneath the central Alboran, which extends to a depth of ˜150 km. At this depth, the mantle resistivity decreases to values of ˜100 Ohm-m, slightly higher than those seen in typical asthenosphere at the same depth. This transition suggests a change in slab properties with depth, perhaps reflecting a change in the nature of the seafloor subducted in the past. Two conductive features in our model suggest the presence of fluids released by the subducting slab or a small amount of partial melt in the upper mantle (or both). Of these, the one in the center of the Alboran basin, in the uppermost-mantle (20-30 km depth) beneath Neogene volcanics and west of the termination of the Nekkor Fault, is consistent with geochemical models, which infer highly thinned lithosphere and shallow melting in order to explain the petrology of seafloor volcanics.

  14. Crustal Structure beneath the Rwenzori Region of the Albertine Rift using Ambient-Noise Tomography

    Science.gov (United States)

    Kaviani, A.; Paul, A.; Rumpker, G.

    2015-12-01

    In this study we investigate the crustal structure beneath the Rwenzori region by analyzing a 1-year ambient-noise data set recorded by a network of 33 broadband seismic stations that have operated between September 2009 and August 2011. The Rwenzori region, located between the Democratic Republic of Congo and Uganda, is part of the western (Albertine) branch of the East African Rift System (EARS). The region of study is situated between the Albert Rift and the Edward Rift segments and covers an area of approximately 120 km by 50 km. The main objective of the seismological experiment was to address the questions of the uplift of the Rwenzori Mountains in an extensional regime and the absence of a crustal root beneath the mountain range. Any model proposed to address these questions requires the knowledge of the structure of the Rwenzori horst and surrounding rift shoulders. Previous results from local travel-time tomography revealed the presence of low-velocity anomalies in the upper crust beneath the mountain range relative to higher velocities in the surrounding shoulders. However, since the stations used in the previous study only covered the northern part of the region, the resolution of the models proposed by the body-wave tomography was very low beneath the Rwenzori Mountains. Hence, the limits of the Rwenzori horst at depth relative to the rift shoulders are still poorly known. The main objective of our ambient-noise tomography (ANT) is to provide an explanation for the building of Rwenzori Mountains. Due to the small aperture of the seismological network, we are mainly interested in the shallow crustal structure including the boundaries between the central Rwenzori horst and the surrounding rift shoulders as well as the variations in the thickness of the sedimentary basins. We expect that the ANT images will be able to delineate the boundaries between the main tectonic features including the limits of the Rwenzori horst at depth.

  15. Moho Depth Variation Beneath Southwest Japan Revealed From Inverted Velocity Structure Based on Receiver Functions

    Science.gov (United States)

    Shiomi, K.; Obara, K.; Sato, H.

    2004-12-01

    We determine the depth variation of the Moho discontinuity beneath Chugoku-Shikoku region, southwest Japan. We apply the receiver function analysis to teleseismic waveforms from more than 250 earthquakes with magnitude 5.5 or larger recorded by the High Sensitivity Seismograph Network (Hi-net). Integrating estimated receiver functions into six groups according to the back azimuth of each station, we estimate the seismic velocity structure for every group of the receiver functions by using the improved linearized time-domain waveform inversion method. This improved method adopts a weighting function to determine the shallow structure well and estimate both S and P wave velocity, simultaneously. We detect a clear velocity discontinuity corresponding to the Moho across which the S wave velocity changes to 4.5 km/s from 3.7 km/s. The depth of the discontinuity is about 30 km beneath northern (the Japan Sea) and southern (the Pacific) coastlines and more than 40 km beneath central part of the study region. In the central part, a low velocity layer (LVL) with 10 km thickness exists under the Moho. The depth of the upper boundary of the LVL is 45 to 50 km. The Philippine Sea plate (PHS) is subducting toward the northwest from the Nankai Trough beneath the Chugoku-Shikoku region where both the continental and the oceanic Moho exist. The LVL corresponds to the subducting oceanic crust of the PHS and the oceanic Moho is the bottom of the oceanic crust. The continental Moho of the Eurasian plate lies above the low velocity oceanic crust. However, at stations in the northern and southern part of the study region, we find only one major velocity discontinuity. We read the depth of these clear discontinuities from the inverted velocity models and map the Moho depth at the conversion point. By interpolating the results, we separately draw the depth contour of the continental and the oceanic Moho beneath Chugoku-Shikoku region under the assumptions: (1) the Moho of the Pacific

  16. Mantle structure beneath the western edge of the Colorado Plateau

    Science.gov (United States)

    Sine, C.R.; Wilson, D.; Gao, W.; Grand, S.P.; Aster, R.; Ni, J.; Baldridge, W.S.

    2008-01-01

    Teleseismic traveltime data are inverted for mantle Vp and Vs variations beneath a 1400 km long line of broadband seismometers extending from eastern New Mexico to western Utah. The model spans 600 km beneath the moho with resolution of ???50 km. Inversions show a sharp, large-magnitude velocity contrast across the Colorado Plateau-Great Basin transition extending ???200 km below the crust. Also imaged is a fast anomaly 300 to 600 km beneath the NW portion of the array. Very slow velocities beneath the Great Basin imply partial melting and/or anomalously wet mantle. We propose that the sharp contrast in mantle velocities across the western edge of the Plateau corresponds to differential lithospheric modification, during and following Farallon subduction, across a boundary defining the western extent of unmodified Proterozoic mantle lithosphere. The deep fast anomaly corresponds to thickened Farallon plate or detached continental lithosphere at transition zone depths. Copyright 2008 by the American Geophysical Union.

  17. Mohorovicic discontinuity depth analysis beneath North Patagonian Massif

    Science.gov (United States)

    Gómez Dacal, M. L.; Tocho, C.; Aragón, E.

    2013-05-01

    The North Patagonian Massif is a 100000 km2, sub-rectangular plateau that stands out 500 to 700 m higher in altitude than the surrounding topography. The creation of this plateau took place during the Oligocene through a sudden uplift without noticeable internal deformation. This quite different mechanical response between the massif and the surrounding back arc, the short time in which this process took place and a regional negative Bouguer anomaly in the massif area, raise the question about the isostatic compensation state of the previously mentioned massif. In the present work, a comparison between different results about the depth of the Mohorovicic discontinuity beneath the North Patagonian Massif and a later analysis is made. It has the objective to analyze the crustal thickness in the area to contribute in the determination of the isostatic balance and the better understanding of the Cenozoic evolution of the mentioned area. The comparison is made between four models; two of these were created with seismic information (Feng et al., 2006 and Bassin et al., 2000), another model with gravity information (Barzaghi et al., 2011) and the last one with a combination of both techniques (Tassara y Etchaurren, 2011). The latter was the result of the adaptation to the work area of a three-dimensional density model made with some additional information, mainly seismic, that constrain the surfaces. The work of restriction and adaptation of this model, the later analysis and comparison with the other three models and the combination of both seismic models to cover the lack of resolution in some areas, is presented here. According the different models, the crustal thickness of the study zone would be between 36 and 45 Km. and thicker than the surrounding areas. These results talk us about a crust thicker than normal and that could behave as a rigid and independent block. Moreover, it can be observed that there are noticeable differences between gravimetric and seismic

  18. Foundering lithosphere imaged beneath the southern Sierra Nevada, California, USA.

    Science.gov (United States)

    Boyd, Oliver S; Jones, Craig H; Sheehan, Anne F

    2004-07-30

    Seismic tomography reveals garnet-rich crust and mantle lithosphere descending into the upper mantle beneath the southeastern Sierra Nevada. The descending lithosphere consists of two layers: an iron-rich eclogite above a magnesium-rich garnet peridotite. These results place descending eclogite above and east of high P wave speed material previously imaged beneath the southern Great Valley, suggesting a previously unsuspected coherence in the lithospheric removal process.

  19. Geochronology, geochemistry and tectonic evolution of the Western and Central cordilleras of Colombia

    Science.gov (United States)

    Villagómez, Diego; Spikings, Richard; Magna, Tomas; Kammer, Andreas; Winkler, Wilfried; Beltrán, Alejandro

    2011-08-01

    Autochthonous rocks of the pre-Cretaceous continental margin of NW South America (the Tahami Terrane) are juxtaposed against a series of para-autochthonous rock units that assembled during the Early Cretaceous. Allochthonous, oceanic crust of the Caribbean Large Igneous Province collided with and accreted onto the margin during the Late Cretaceous. We present the first regional-scale dataset of zircon U-Pb LA-ICP-MS ages for intrusive and metamorphic rocks of the autochthonous Tahami Terrane, Early Cretaceous igneous para-autochthonous rocks and accreted oceanic crust. The U-Pb zircon data are complemented by multiphase 40Ar/ 39Ar crystallization and cooling ages. The geochronological data are combined with whole rock major oxide, trace element and REE data acquired from the same units to constrain the tectonic origin of the rock units and terranes exposed in the Western Cordillera, Cauca-Patía Valley and the Central Cordillera of Colombia. The Tahami Terrane includes lower Paleozoic orthogneisses (~ 440 Ma) that may have erupted during the active margin stage of the Rheic Ocean. Basement gneisses were intruded by Permian, continental arc granites during the final assembly of Pangea. Triassic sedimentary rocks were subsequently deposited in rift basins and partially melted during high-T metamorphism associated with rifting of western Pangea during 240-220 Ma. Continental arc magmatism during 180-145 Ma is preserved along the whole length of the Central Cordillera and was followed by an Early Cretaceous out-board step of the arc axis and the inception of the Quebradagrande Arc that fringed the continental margin. Back-stepping of the arc axis may have been caused by the collision of buoyant seamounts, which were coeval with plateau rocks exposed in the Nicoya Peninsular of Costa Rica. Rapid westward drift of South America closed the Quebradagrande basin in the late Aptian and caused medium-high P-T metamorphic rocks of the Arquía Complex to exhume and obduct onto

  20. Fine structure of Pn velocity beneath Sichuan-Yunnan region

    Institute of Scientific and Technical Information of China (English)

    黄金莉; 宋晓东; 汪素云

    2003-01-01

    We use 23298 Pn arrival-time data from Chinese national and provincial earthquake bulletins to invert fine structure of Pn velocity and anisotropy at the top of the mantle beneath the Sichuan-Yunnan and its adjacent region. The results suggest that the Pn velocity in this region shows significant lateral variation; the Pn velocity varies from 7.7 to 8.3 km/s. The Pn-velocity variation correlates well with the tectonic activity and heat flow of the region. Low Pn velocity is observed in southwest Yunnan , Tengchong volcano area, and the Panxi tectonic area. These areas have very active seismicity and tectonic activity with high surface heat flow. On the other hand, high Pn velocity is observed in some stable regions, such as the central region of the Yangtze Platform; the most pronounced high velocity area is located in the Sichuan Basin, south of Chengdu. Pn anisotropy shows a complex pattern of regional deformation. The Pn fast direction shows a prominent clockwise rotation pattern from east of the Tibetan block to the Sichuan-Yunnan diamond block to southwest Yunnan, which may be related to southeastward escape of the Tibetan Plateau material due to the collision of the Indian Plate to the Eurasia Plate. Thus there appears to be strong correlation between the crustal deformation and the upper mantle structure in the region. The delay times of events and stations show that the crust thickness decreases from the Tibetan Plateau to eastern China, which is consistent with the results from deep seismic sounding.

  1. Adolescent Literacies in Latin America and the Caribbean

    Science.gov (United States)

    Bartlett, Lesley; Lopez, Dina; Mein, Erika; Valdiviezo, Laura A.

    2011-01-01

    In 2000, approximately 36 million youth and adults living in Latin America and the Caribbean were reported to be unable to read or write basic texts. Of these, 20 million were women. According to official statistics, some countries in Central America (Guatemala, Nicaragua, El Salvador, and Honduras) have a youth and adult literacy rate of 80% or…

  2. Building America Top Innovations 2012: Outside Air Ventilation Controller

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2013-01-01

    venThis Building America Top Innovations profile describes Building America research showing how automated night ventilation can reduce cooling energy costs up to 40% and peak demand up to 50% in California’s hot-dry central valley climates and can eliminate the need for air conditioning altogether in the coastal marine climate.

  3. [Inequities in cardiovascular diseases in Latin America].

    Science.gov (United States)

    Fleischer, Nancy L; Diez Roux, Ana V

    2013-01-01

    In high-income countries, social inequalities in cardiovascular disease (CVD) risk are well-documented. Although Latin America has a rich history of theory and conceptual discussion regarding social inequalities in health, empirical research has been more limited. In this commentary we summarize recent empirical work on social inequalities in CVD risk in Latin America, and highlight key research needs as well as implications for prevention. Although much remains unknown about the social patterning of CVD in Latin America, the limited studies to date indicate that inequalities in CVD risk vary across populations and markers of socioeconomic position, as well as disease risk marker. The strongest social inequalities are seen among women, and in urban areas, with regards to obesity, diabetes, and diet. Few studies, though, have been conducted in some parts of Latin America, including the countries of Central America and northern South America. Vital registration systems and nationally-representative risk factor surveys can be important sources of data, as long as information on socioeconomic indicators is collected. Longitudinal studies will also be important for investigating factors driving social inequalities. As policies and prevention strategies are put into place to reduce CVD in Latin America, they must also address factors generating social inequalities in CVD risk.

  4. Development of food crops by modern biotechnology techniques in Central America Desarrollo de cultivos y alimentos por técnicas de biotecnología moderna en Centroamérica

    Directory of Open Access Journals (Sweden)

    Giovanni Garro Monge

    2012-12-01

    Full Text Available In the last decade, the adoption of Genetically Modified Crops (GMC has increased in stages worldwide. The worldwide total area planted with biotech crops reached 148 million hectares by 2010, also increasing the number of farmers around the world who decided to produce crops with this technology. At the regional level there are different responses of government agencies by generating rules and regu- lations according to the reality of these countries. In Central America, countries with greater partici- pation in the development and cultivation of food biotechnology techniques are Guatemala (papa- ya, Honduras (beans and maize and Costa Rica (cotton, soybean and pineapple, placing the latter two in the 29 countries with more GMO planting crops worldwide in 2010. Some of the countries of the region have implemented governance structures for the regulation through technical committees on Biosafety. The most important characteristics in terms of trade continue to be those that confer herbicide tolerance or pest resistance. But notice the incur- sion of new products that contain changes in their content, which are emerging as an alternative with great perspectives in the region. These experiences of culture and Biosafety regula- tion at the regional level could be a successful and progressive development of agricultural and food biotechnology in the near future.En la última década, la adopción de Cultivos Genéticamente Modificados (CGM se ha incre- mentado de forma escalonada a nivel mundial. El área sembrada con cultivos biotecnológicos llegó a un total de 148 millones de hectáreas en 2010, aumentando también el número de agricultores que decidieron producir este tipo de cultivos. A nivel regional, se producen respuestas diversas de los órganos gubernamentales mediante reglamen- tos y normativas acordes con la realidad local. En Centroamérica, los países con mayor participación en el desarrollo y cultivo de alimentos utilizando t

  5. Upper mantle velocity structure beneath Italy from direct and secondary P-wave teleseismic tomography

    Directory of Open Access Journals (Sweden)

    P. De Gori

    1997-06-01

    Full Text Available High-quality teleseismic data digitally recorded by the National Seismic Network during 1988-1995 have been analysed to tomographically reconstruct the aspherical velocity structure of the upper mantle beneath the Italian region. To improve the quality and the reliability of the tomographic images, both direct (P, PKPdf and secondary (pP,sP,PcP,PP,PKPbc,PKPab travel-time data were used in the inversion. Over 7000 relative residuals were computed with respect to the IASP91 Earth velocity model and inverted using a modified version of the ACH technique. Incorporation of data of secondary phases resulted in a significant improvement of the sampling of the target volume and of the spatial resolution of the heterogeneous zones. The tomographic images show that most of the lateral variations in the velocity field are confined in the first ~250 km of depth. Strong low velocity anomalies are found beneath the Po plain, Tuscany and Eastern Sicily in the depth range between 35 and 85 km. High velocity anomalies dominate the upper mantle beneath the Central-Western Alps, Northern-Central Apennines and Southern Tyrrhenian sea at lithospheric depths between 85 and 150 km. At greater depth, positive anomalies are still observed below the northernmost part of the Apenninic chain and Southern Tyrrhenian sea. Deeper anomalies present in the 3D velocity model computed by inverting only the first arrivals dataset, generally appear less pronounced in the new tomographic reconstructions. We interpret this as the result of the ray sampling improvement on the reduction of the vertical smearing effects.

  6. Nature and extent of lava-flow aquifers beneath Pahute Mesa, Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Prothro, L.B.; Drellack, S.L. Jr.

    1997-09-01

    Work is currently underway within the Underground Test Area subproject of the US Department of Energy/Nevada Operations Office Environmental Restoration Program to develop corrective action plans in support of the overall corrective action strategy for the Nevada Test Site as established in the Federal Facility Agreement and Consent Order (FFACO, 1996). A closure plan is currently being developed for Pahute Mesa, which has been identified in the FFACO as consisting of the Western and Central Pahute Mesa Corrective Action Units. Part of this effort requires that hydrogeologic data be compiled for inclusion in a regional model that will be used to predict a contaminant boundary for these Corrective Action Units. Hydrogeologic maps have been prepared for use in the model to define the nature and extent of aquifers and confining units that might influence the flow of contaminated groundwater from underground nuclear tests conducted at Pahute Mesa. Much of the groundwater flow beneath Pahute Mesa occurs within lava-flow aquifers. An understanding of the distribution and hydraulic character of these important hydrogeologic units is necessary to accurately model groundwater flow beneath Pahute Mesa. This report summarizes the results of a study by Bechtel Nevada geologists to better define the hydrogeology of lava-flow aquifers at Pahute Mesa. The purpose of this study was twofold: (1) aid in the development of the hydrostratigraphic framework for Pahute Mesa, and (2) provide information on the distribution and hydraulic character of lava-flow aquifers beneath Pahute Mesa for more accurate computer modeling of the Western and Central Pahute Mesa Corrective Action Units.

  7. The Merida Initiative: Security-Surveillance Harmonization in Latin America

    OpenAIRE

    Nelson Arteaga Botello

    2009-01-01

    This work analyses the Merida Initiative, whose objective is to coordinate the information systems used against terrorism, organized crime, and drug and arms trafficking between the United States, Mexico and Central America. This implies the introduction of communication equipment, data bases and surveillance technology, which not only reinforces the security policies of the ‘western hemisphere’, but also consolidates and broadens the spaces of exception in Mexico and Central America, thus er...

  8. Synthesis of crustal seismic structure and implications for the concept of a slab gap beneath Coastal California

    Science.gov (United States)

    Brocher, T.M.; ten Brink, U.S.; Abramovitz, T.

    1999-01-01

    Compilation of seismic transects across the central and northern California Coast Ranges provides evidence for the widespread tectonic emplacement beneath the margin of a slab of partially subducted oceanic lithosphere. The oceanic crust of this lithosphere can be traced landward from the former convergent margin (fossil trench), beneath the Coast Ranges, to at least as far east as the Coast Range/Great Valley boundary. Comparison of measured shear and compressional wave velocities in the middle crust beneath the Hayward fault with laboratory measurements suggests that the middle crust is a diabase (oceanic crust). Both of these observations are consistent with recent models of the high heat flow and age progression of Neogene volcanism along the Coast Ranges based on tectonic emplacement (stalling) of young, hot oceanic lithosphere beneath the margin, but appear to contradict the major predictions of the slab-gap or asthenospheric-window model. Finally, the Neogene volcanism and major strike-slip faults in the Coast Ranges occur within the thickest regions (>14 km thick) of the forearc, suggesting that the locations of Cenozoic volcanism and faulting along the margin are structurally controlled by the forearc thickness rather than being determined by the location of a broad slab gap.

  9. Upper mantle structures beneath the Carpathian-Pannonian region: Implications for the geodynamics of continental collision

    Science.gov (United States)

    Ren, Y.; Stuart, G. W.; Houseman, G. A.; Dando, B.; Ionescu, C.; Hegedüs, E.; Radovanović, S.; Shen, Y.; South Carpathian Project Working Group

    2012-10-01

    The Carpathian-Pannonian system of Eastern and Central Europe represents a unique opportunity to study the interaction between surface tectonic processes involving convergence, extension and convective overturn in the upper mantle. Here, we present high-resolution images of upper mantle structure beneath the region from P-wave finite-frequency teleseismic tomography to help constrain such geodynamical interactions. We have selected earthquakes with magnitude greater than 5.5 in the distance range 30°-95°, which occurred between 2006 and 2011. The data were recorded on 54 temporary stations deployed by the South Carpathian Project (2009-2011), 56 temporary stations deployed by the Carpathian Basins Project (2005-2007), and 131 national network broadband stations. The P-wave relative arrival times are measured in two frequency bands (0.5-2.0 Hz and 0.1-0.5 Hz), and are inverted for Vp perturbation maps in the upper mantle. Our images show a sub-vertical slab of fast material beneath the eastern Alps which extends eastward across the Pannonian basin at depths below ˜300km. The fast material extends down into the mantle transition zone (MTZ), where it spreads out beneath the entire basin. Above ˜300km, the upper mantle below the Pannonian basin is dominated by relatively slow velocities, the largest of which extends down to ˜200km. We suggest that cold mantle lithospheric downwelling occurred below the Pannonian Basin before detaching in the mid-Miocene. In the Vrancea Zone of SE Romania, intermediate-depth (75-180 km) seismicity occurs at the NE end of an upper mantle high velocity structure that extends SW under the Moesian Platform, oblique to the southern edge of the South Carpathians. At greater depths (180-400 km), a sub-circular high velocity anomaly is found directly beneath the seismicity. This sub-vertical high-velocity body is bounded by slow anomalies to the NW and SE, which extend down to the top of the MTZ. No clear evidence of a residual slab is

  10. Mantle discontinuities beneath Izu-Bonin and the implications

    Institute of Scientific and Technical Information of China (English)

    臧绍先; 周元泽; 蒋志勇

    2003-01-01

    The SdP, pdP and sdP phases are picked up with the Nth root slant stack method from the digital waveform data recorded by the networks and arrays in USA, Germany and Switzerland for the earthquakes occurring beneath Izu-Bonin and Japan Sea. The mantle discontinuities and the effects of subducting slab on the 660 km and 410 km discontinuities are studied. It is found that there are mantle discontinuities existing at the depths of 170, 220, 300, 410, 660, 850 and 1150 km. Beneath Izu-Bonin, the 410 km discontinuity is elevated, while the 660 km discontinuity is depressed; for both discontinuities, there are regionalized differences. Beneath Japan Sea, however, there is no depth variation of the 410 km discontinuity, and the 660 km discontinuity is depressed without obvious effect of the subducting slab.

  11. Initiation of liquid-solid contact beneath an impacting drop

    Science.gov (United States)

    Rubinstein, Shmuel; Kolinski, John

    2015-11-01

    Before an impacting drop contacts the solid surface it must first drain the air beneath it. As a prelude to wetting, before any contact occurs, the impinging liquid confines the intervening air into a nanometers-thin film. Once liquid-solid contact initiates by the spontaneous formation of a liquid bridge, the fluid rapidly wicks through the thin film of air, permanently binding the drop to the surface. Here, we experimentally examine these initial stages in the formation of the liquid solid contact beneath the impacting drop. Fast TIR microscopy enables unprecedented spatial and temporal resolution of the wetting process beneath the impacting drop and permits 3-dimensional imaging of the real contact line as well as nanometer-resolution of the thin film of air separating the liquid from the solid.

  12. Simultaneous Inversion of Interpolated Receiver Functions, Surface-wave Dispersion, and Gravity Observations for Lithospheric Structure Beneath the Eastern United States

    Science.gov (United States)

    Chai, C.; Ammon, C. J.; Maceira, M.; Herrmann, R. B.

    2015-12-01

    The unprecedented high-quality seismic data from Earthscope's Transportable Array provide us a great opportunity to investigate the subsurface structure beneath North America. Even with such a fine network, tightly constraining the 3D lithospheric structure is a challenge. Integrating complementary geophysical observations in simultaneous inversions has produced promising results. We have developed a receiver-function wavefield interpolation/smoothing method to enhance the complementariness of receiver functions and surface-wave dispersion. Combining information from adjacent seismic stations suppresses poorly sampled and difficult-to-interpret back-azimuthal variations and allows the stable extraction of the key features in the receiver-function wavefield. The interpolated receiver functions are inverted simultaneously with Rayleigh-wave phase and group velocities and Bouguer gravity observations to produce a robust estimate of the broad 3D shear-wave speed variations beneath the eastern United States. P-wave velocities and density variations are related to shear-speed using empirical velocity ratios and relations. We constrain the 3D variations to be laterally and vertically smooth. Application of the same methods to the western conterminous United States resulted in velocity images that are consistent with published models on the first order. With the completion of the Transportable Array deployment in the northeast US, the seismic dataset beneath the eastern U.S. region is complete. Preliminary inversions contain expected near-surface low shear-wave speeds associated with large basins and coastal regions and thicker crust beneath the interior compared with the coastal regions. Speeds in the upper mantle are generally typical, but the model includes several regions of relatively slow mantle beneath the northern Mississippi Embayment, the east coast, and beneath New England.

  13. Imaging of seismic scatterers beneath the Gauribidanur (GBA) array

    International Nuclear Information System (INIS)

    A study has been conducted to image seismic scatterers beneath the Gauribidanur (GBA) array in the Precambrian shield of south India. Short period digital data from teleseisms and regional events recorded over the 20 station L shaped array was used to image seismic scatterers beneath the array employing semblance technique. The results indicate a zone of dominant scattering encompassing the crust in a region west of GBA. The inferred zone of scattering coincides with a large N-S elongated granitic intrusion believed to be Precambrian suture zone between the East and West Dharwar craton. (author). 16 refs, 7 figs, 1 tab

  14. Building America Industrialized Housing Partnership (BAIHP II)

    Energy Technology Data Exchange (ETDEWEB)

    Abernethy, Bob; Chandra, Subrato; Baden, Steven; Cummings, Jim; Cummings, Jamie; Beal, David; Chasar, David; Colon, Carlos; Dutton, Wanda; Fairey, Philip; Fonorow, Ken; Gil, Camilo; Gordon, Andrew; Hoak, David; Kerr, Ryan; Peeks, Brady; Kosar, Douglas; Hewes, Tom; Kalaghchy, Safvat; Lubliner, Mike; Martin, Eric; McIlvaine, Janet; Moyer, Neil; Liguori, Sabrina; Parker, Danny; Sherwin, John; Stroer, Dennis; Thomas-Rees, Stephanie; Daniel, Danielle; McIlvaine, Janet

    2010-11-30

    This report summarizes the work conducted by the Building America Industrialized Housing Partnership (BAIHP - www.baihp.org) during the final budget period (BP5) of our contract, January 1, 2010 to November 30, 2010. Highlights from the four previous budget periods are included for context. BAIHP is led by the Florida Solar Energy Center (FSEC) of the University of Central Florida. With over 50 Industry Partners including factory and site builders, work in BP5 was performed in six tasks areas: Building America System Research Management, Documentation and Technical Support; System Performance Evaluations; Prototype House Evaluations; Initial Community Scale Evaluations; Project Closeout, Final Review of BA Communities; and Other Research Activities.

  15. Stress in the contorted Nazca Plate beneath southern Peru from local earthquakes

    Science.gov (United States)

    Schneider, John F.; Sacks, I. Selwyn

    1987-12-01

    We study earthquake focal mechanisms in a region of highly contorted subducting lithosphere to identify dominant sources of stress in the subduction process. We observe a stress pattern in the contorted Nazca plate beneath southern Peru from an analysis of hypocentral trend and focal mechanisms of intermediate-depth earthquakes. Expanding on previous studies, we examine the hypocentral trend using 1673 of 2178 well-located local events from the nine-station Arequipa network. The dip of the plate beneath southern Peru averages 25°-30° from 25- to 100-km depth. Below this depth there is an 80- to 100-km-wide contortion between a zone of increasing dip (convex) to the southeast and a flat lying (concave) zone to the northwest. Using more than 6000 P wave first motions of events deeper than 50 km, we derive stress orientations from a moving average of composite focal mechanisms across a 200 by 350 km region including the contortion. The in-plate distribution of tension (T) and compression (P) axes reveals a coherent stress pattern. The trend is most clear beneath south-central Peru (NW section) and below 100- km depth in southernmost Peru (SE section). Both T and P axes tend to be dominantly in plate, especially below 100-km depth. T axes orient toward the contortion in a fan-shaped trend, which suggests that the deepest part of the seismic zone, within the convex SE section, is sinking and pulling the more buoyant NW section. We conclude that from 50- to 200-km depth, slab-pull forces are dominant in the observed stress. Our results suggest that a significant amount of plate extension occurs in this region of intermediate-depth subduction.

  16. Geometry of the Subducting Nazca Plate Beneath Colombia From Relocation of Intermediate-Depth Earthquakes

    Science.gov (United States)

    Chang, Y.; Warren, L. M.; Prieto, G. A.; Grigsby, I.

    2013-12-01

    In subduction zones, earthquakes help distinguish the location of the downgoing slab to hundreds of kilometers depth. However, beneath northwestern South America, the distribution of large intermediate-depth earthquakes in the Global CMT catalog has gaps along the subduction zone, so the position of the subducting Nazca plate is uncertain. In addition, the earthquake focal mechanisms, which range from along-strike compression to down-dip extension, vary over short distances, suggesting that the subducting slab may have a complicated morphology. To clarify the geometry of the subducting Nazca plate beneath Colombia, we relocate regional seismicity recorded by the Colombian National Seismic Network (RSNC). Our data set contains 1231 earthquakes with catalog locations from 0°N-6°N and 72°W-81°W at depths of 0-200 km and magnitudes from M2.5-6.5 that occurred between 1/2010-2/2013. Catalog hypocenters show an ~20 km thick slab subducting to the east, as well as vertical columns extending up from the slab. The shape, thickness, and position of the slab and other features can be refined by using differential travel times to relocate the earthquakes relative to each other. We verify and adjust the network P and S wave picks and pick arrivals at additional or temporary stations, and these arrival times are used to relocate the earthquakes. The hypocenters of the relocated earthquakes are used to generate 3D contours of the subducting plate and visualize bends and folds in the slab.

  17. Seismic interferometry of the mantle transition zone beneath the western United States

    Science.gov (United States)

    Anderson, H. R.; Thorne, M. S.; Schmerr, N. C.; Brown, S. P.

    2011-12-01

    Determination of mantle structure is critical in understanding the ongoing dynamic processes in the Earth's interior and determining how the deep interior is connected to volcanic and tectonic features at the surface. Discontinuities within the mantle originating from solid-to-solid mineralogical phase transitions of olivine are important indicators of mantle temperature and composition, and provide key clues for interpreting velocity heterogeneity imaged by seismic tomography. Here we develop a new cross-correlation interferometry technique, to image the detailed topography of discontinuity surfaces and associated phase transitions within the mantle transition zone. Our interferometric technique is applied to 185 events originating along the South American subduction zone, recorded as transverse component broadband seismograms at dense seismic arrays in North America, including EarthScope's Transportable Array, and at the Japanese F-net seismic network. To retrieve upper mantle discontinuity structure, we study underside reflections of S-wave energy from the upper mantle discontinuities, arriving as precursory energy to the seismic phase SS. Our interferometric analysis consists of migrating the direct S-wave energy transmitted through the transition zone discontinuities recorded at North American seismic arrays with SS precursor energy reflecting off the underside of the discontinuities recorded at the F-net seismic array. This approach removes uncertainties in earthquake location and seismic velocity structure on the source side of the underside reflection point, providing enhanced vertical resolution of discontinuity topography over past studies. We present newly detailed images of the mantle discontinuity structure beneath the western United States, and compare our results with tomographic imaging. Initial results indicate large variations in mantle temperature and composition across the western United States associated with the subducting Juan de Fuca slab

  18. Deep long-period earthquakes beneath Washington and Oregon volcanoes

    Science.gov (United States)

    Nichols, M.L.; Malone, S.D.; Moran, S.C.; Thelen, W.A.; Vidale, J.E.

    2011-01-01

    Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically searched the Pacific Northwest Seismic Network (PNSN) triggered earthquake catalog for DLPs occurring between 1980 (when PNSN began collecting digital data) and October 2009. Through our analysis we identified 60 DLPs beneath six Cascade volcanic centers. No DLPs were associated with volcanic activity, including the 1980-1986 and 2004-2008 eruptions at Mount St. Helens. More than half of the events occurred near Mount Baker, where the background flux of magmatic gases is greatest among Washington and Oregon volcanoes. The six volcanoes with DLPs (counts in parentheses) are Mount Baker (31), Glacier Peak (9), Mount Rainier (9), Mount St. Helens (9), Three Sisters (1), and Crater Lake (1). No DLPs were identified beneath Mount Adams, Mount Hood, Mount Jefferson, or Newberry Volcano, although (except at Hood) that may be due in part to poorer network coverage. In cases where the DLPs do not occur directly beneath the volcanic edifice, the locations coincide with large structural faults that extend into the deep crust. Our observations suggest the occurrence of DLPs in these areas could represent fluid and/or magma transport along pre-existing tectonic structures in the middle crust. ?? 2010 Elsevier B.V.

  19. Subduction of the Indian Lithospheric Slab Beneath Tibet

    Science.gov (United States)

    Zhou, H.; Murphy, M. A.

    2001-12-01

    In order to characterize the dynamics of continent-continent collisions, it is essential to define its present geometry and physical state. We report the results of a seismic tomography study of the Tibet-Himalayan collision zone, using a global data set, which indicates that the Indian lithospheric slab has been subducted subhorizontally beneath nearly the entire Tibetan plateau to depths of 165-260 km. Tibetan velocity structure is low in the crust and high in mantle lithosphere at depths between 75-120 km. An asthenospheric layer overlies the subducted Indian slab at depths between 120-165 km beneath the Tibetan plateau. There is a large low-velocity anomaly north of the Indus-Yalu suture zone between 85ºE and 93ºE that extends from the crust down to at least 310 km depth beneath the plateau. This low-velocity anomaly is indicative of mantle upwelling through a weakened zone of the subducted slab. The extent to which India has subducted beneath Tibet, as revealed by these seismic images, is comparable to estimates of crustal shortening across the Himalaya. Moreover, we hypothesize that the buoyancy due to heating of the subducted Indian slab and the existence of the asthenospheric layer contribute to the elevation and flatness of the Tibetan plateau.

  20. Large-scale depressions on the 660 seismic discontinuity beneath Europe: signature of the role of akimotoite in subducting slabs

    Science.gov (United States)

    Cottaar, S.; Deuss, A. F.

    2015-12-01

    The upper and lower mantle are delineated by a seismic discontinuity around 660 km depth. This discontinuity is regularly associated with the dissociation of ringwoodite to bridgmanite and periclase, which has a negative Clapeyron slope, and appears to play a role in global mantle dynamics. Here we study the topography of this discontinuity and the one around 410 km, using receiver functions and investigate the effect of subducting and ponding slabs beneath Europe. We collected ~150,000 receiver functions across Europe over a time period from 2000 to 2014. After quality control, we use ~28,000 in a common conversion point stack. Corrections for lateral velocity variations are applied using the P- and S-velocity models in EU60 from Zhu et al. (2015). While northern Europe shows an average mantle transition zone, strong anomalous depressions of 30 km are seen in the topography of the 660 beneath central Europe and around the Mediterranean. There is no (anti-)correlated topographic anomaly on the 410 in these regions. The observed depressions beneath central Europe correlate with elevated seismic velocities above 660 km, and are therefore probably caused by cold subducted slab material. Temperature effects on the ringwoodite-bridgmanite transition alone cannot explain such a depression. Several wt% water deepens the 660 and increases the Clapeyron slope, but other geophysical observations, e.g. elevated Vp/Vs ratio, attenuation and electric conductivity, are not seen in these regions in various studies. Our preferred alternative hypothesis is the suggestion of Yu et al. (2011) that ringwoodite dissociates into akimotoite and periclase at temperatures beneath ~1400 K within the slab The subsequent transition of akimotoite to bridgmanite has a strong negative Clapeyron slope, which explains the deep discontinuity seen here in combination with cold temperatures, as well as providing a mechanism for slabs to pond in the mantle transition zone.

  1. Crustal structure beneath northeast India inferred from receiver function modeling

    Science.gov (United States)

    Borah, Kajaljyoti; Bora, Dipok K.; Goyal, Ayush; Kumar, Raju

    2016-09-01

    We estimated crustal shear velocity structure beneath ten broadband seismic stations of northeast India, by using H-Vp/Vs stacking method and a non-linear direct search approach, Neighbourhood Algorithm (NA) technique followed by joint inversion of Rayleigh wave group velocity and receiver function, calculated from teleseismic earthquakes data. Results show significant variations of thickness, shear velocities (Vs) and Vp/Vs ratio in the crust of the study region. The inverted shear wave velocity models show crustal thickness variations of 32-36 km in Shillong Plateau (North), 36-40 in Assam Valley and ∼44 km in Lesser Himalaya (South). Average Vp/Vs ratio in Shillong Plateau is less (1.73-1.77) compared to Assam Valley and Lesser Himalaya (∼1.80). Average crustal shear velocity beneath the study region varies from 3.4 to 3.5 km/s. Sediment structure beneath Shillong Plateau and Assam Valley shows 1-2 km thick sediment layer with low Vs (2.5-2.9 km/s) and high Vp/Vs ratio (1.8-2.1), while it is observed to be of greater thickness (4 km) with similar Vs and high Vp/Vs (∼2.5) in RUP (Lesser Himalaya). Both Shillong Plateau and Assam Valley show thick upper and middle crust (10-20 km), and thin (4-9 km) lower crust. Average Vp/Vs ratio in Assam Valley and Shillong Plateau suggest that the crust is felsic-to-intermediate and intermediate-to-mafic beneath Shillong Plateau and Assam Valley, respectively. Results show that lower crust rocks beneath the Shillong Plateau and Assam Valley lies between mafic granulite and mafic garnet granulite.

  2. Hot mantle upwelling across the 660 beneath Yellowstone

    Science.gov (United States)

    Schmandt, Brandon; Dueker, Kenneth; Humphreys, Eugene; Hansen, Steven

    2012-05-01

    P-to-s receiver functions mapped to depth through P and S body-wave tomography models image continuous 410 and 660 km discontinuities beneath the area covered by USArray prior to the year 2011. Mean depths to the 410 and 660 km discontinuities of 410 and 656 km imply a mantle transition zone that is about 4 km thicker than the global average and hence has a slightly cooler mean temperature and/or enhanced water content. Compared to the mean 660 depth beneath this ~ 2000 km wide area, the 660 beneath the Yellowstone hotspot is deflected upward by 12-18 km over an area about 200 km wide. This is the most anomalous shallowing of the 660 imaged and its horizontal extent is similar to the area where P and S tomography image low-velocity mantle extending from the top of the transition zone to about 900 km depth. Together, these results indicate a high-temperature, plume-like upwelling extending across the 660. The depth of 410 km discontinuity beneath the Yellowstone region is within 5 km of the mean depth implying that the plume is vertically heterogeneous and possibly discontinuous. Tomography indicates a similar vertically heterogeneous thermal plume. The irregular plume structure may be intrinsic to the dynamics of upwelling through the transition zone, or distortion may be caused by subduction-induced mantle flow. Topography of the 410 and 660 confirms that subducted slabs beneath the western U.S. are highly segmented, as inferred from recent tomography studies. We find no evidence of regionally pervasive velocity discontinuities between 750 and 1400 km depth. The plume's depth of origin within the lower mantle remains uncertain.

  3. Animations and modeling of the 2012 slow slip event beneath southern Mexico and the accompanying 20 March 2012 Mw=7.4 Ometepec earthquake

    Science.gov (United States)

    Graham, S. E.; Cabral-Cano, E.; Kostoglodov, V.; Cotte, N.; Radiguet, M.; Walpersdorf, A.; Santiago, J.; Brudzinski, M. R.; McCaffrey, R.; DeMets, C.

    2012-12-01

    We model continuous GPS observations of a slow slip event (SSE) beneath southern Mexico, spanning late-2011 to mid-2012, to evaluate whether it had a spatial and/or temporal relationship with the 20 March 2012 Mw=7.4 subduction earthquake beneath the Oaxaca-Guerrero border. Although ~10 SSEs have been recorded beneath the southern Mexico subduction zone since the late 1990s, the 2012 SSE was the first to coincide with a large subduction thrust earthquake. Resolving the relationship between SSE and seismogenesis, if any, is critical given the vulnerability of much of southern and central Mexico, including Mexico City, to large earthquakes in the Guerrero seismic gap. Preliminary modeling of coseismic offsets measured at 22 continuous GPS sites operating during the 20 March earthquake indicates two slip patches centered at ~18 and ~ 25 km depth, spanning approximately 15-30 km depth along the plate interface, with an average slip of 1 m, maximum slip of 3.8 m, and seismic moment 1.46E20 N m (Mw=7.38). An animation of the observed SSE and earthquake will be presented, as will best-fitting slip distributions and stress change calculations to test the triggering hypothesis. Time permitting, animations of previous SSEs will also be presented to highlight the differences between shallower, larger magnitude SSEs beneath Guerrero and deeper, smaller magnitude SSEs beneath Oaxaca.

  4. Progress on the seismic anisotropy knowledge beneath Iberia and northern Morocco: the contribution of the second Topoiberia-Iberarray deployment

    Science.gov (United States)

    Diaz Cusí, J.; Gallart, J.

    2012-04-01

    In summer 2009 the dense Iberarray broad-band seismic network deployed in the framework of the large-scale TopoIberia project moved to its second footprint. Up to 55 stations covered the central part of the Iberian Peninsula for roughly 18 months, distributed in a regular grid with a nominal spacing of 60 km. 19 additional stations, active since late 2007 in the Northern part of Morocco, were moved southwards during the summer 2010 to the High Atlas, thus extending the investigated area. Continuous data from all the permanent broad-band networks covering the region have also been gathered to produce a complete database. We focus here in the results constraining the presence of anisotropy as evidenced from the analysis of splitted teleseismic phases. Few anisotropic results in the area covered by this IberArray deployment have been published till now, all of them coming from a scarce number of permanent stations. The results here presented extend the anisotropic map obtained from the first TopoIberia-Iberarray deployment in the Betics-Alboran zone (Díaz et al, 2010). The inferred fast polarization directions (FPD) clearly document a spectacular rotation along the Gibraltar arc, following the curvature of the Rif-Betic chain, from roughly N65E beneath the Betics to close to N65W beneath the Rif chain. The stations beneath the Central Iberian Massif present a small amount of anisotropy, oriented roughly E-W. Beneath SW Iberia, within the Variscan Ossa-Morena zone, the dominant orientation changes to NNE-SSW, the induced time delays are smaller and a number of good quality measurements show no evidences for anisotropy. Beneath Eastern Iberia, the NE-SW and E-W FPD observed respectively in the Betics and Central Iberia seems to converge, without any indication of an abrupt change similar to that evidenced in the southern part of the Gibraltar arc. The preliminary data of the stations located in the High Atlas show a small degree of anisotropy, with rather unconstrained

  5. Mantle transition zone thickness in the Central South-American Subduction Zone

    Science.gov (United States)

    Braunmiller, Jochen; van der Lee, Suzan; Doermann, Lindsey

    We used receiver functions to determine lateral variations in mantle transition zone thickness and sharpness of the 410- and 660-km discontinuities in the presence of subducting lithosphere. The mantle beneath the central Andes of South America provides an ideal study site owing to its long-lived subduction history and the availability of broadband seismic data from the dense BANJO/SEDA temporary networks and the permanent station LPAZ. For LPAZ, we analyzed 26 earthquakes between 1993-2003 and stacked the depth-migrated receiver functions. For temporary stations operating for only about one year (1994-1995), station stacks were not robust. We thus stacked receiver functions for close-by stations forming five groups that span the subduction zone from west to east, each containing 12 to 25 events. We found signal significant at the 2σ level for several station groups from P to S conversions that originate near 520- and 850-900 km depth, but most prominently from the 410- and 660-km discontinuities. For the latter, the P to S converted signal is clear in stacks for western groups and LPAZ, lack of coherent signal for two eastern groups is possibly due to incoherent stacking and does not necessitate the absence of converted energy. The thickness of the mantle transition zone increases progressively from a near-normal 255 km at the Pacific coast to about 295 km beneath station LPAZ in the Eastern Cordillera. Beneath LPAZ, the 410-km discontinuity appears elevated by nearly 40 km, thus thickening the transition zone. We compared signal amplitudes from receiver function stacks calculated at different low-pass frequencies to study frequency dependence and possibly associated discontinuity sharpness of the P to S converted signals. We found that both the 410- and 660-km discontinuities exhibit amplitude increase with decreasing frequency. Synthetic receiver function calculations for discontinuity topography mimicking observed topography show that the observed steep

  6. Prevent Child Abuse America

    Science.gov (United States)

    ... call the police . Crisis and support contacts For Child Abuse Reporting Numbers in your State please visit: Child ... suspected child abuse and neglect. Parent Resources Prevent Child Abuse America (800) CHILDREN A resource for tips, referrals, ...

  7. America in the Eyes of America Watchers:

    DEFF Research Database (Denmark)

    Feng, Huiyun; He, Kai

    2015-01-01

    almost half of the survey participants thought that America would remain the global hegemon in the next ten years. Meanwhile, a large majority was also optimistic that China is a rising great power, especially in the economic sense, in the world. More than half of the respondents saw Asian military...... issues, such as the South China Sea issue, as the most difficult problem between China and the US....

  8. Cohabitation in Latin America: a comparative perspective

    OpenAIRE

    Sussai Soares, Maira Covre

    2014-01-01

    The coexistence of marriage and cohabitation is an intriguing feature of Latin American nuptiality. Historically common among lower social classes in Central America and the Caribbean, the incidence of cohabitation is also increasing among higher educated groups and southern Latin American countries. This study uses census and survey data to investigate the characteristics of Latin American cohabitation.First, the countries’ socioeconomic characteristics, related to the incidence of cohabitat...

  9. Immigrant America: A Portrait

    OpenAIRE

    Rumbaut, RG; Portes, A.

    2014-01-01

    This revised, updated, and expanded fourth edition of Immigrant America: A Portrait provides readers with a comprehensive and current overview of immigration to the United States in a single volume. Updated with the latest available data, Immigrant America explores the economic, political, spatial, and linguistic aspects of immigration; the role of religion in the acculturation and social integration of foreign minorities; and the adaptation process for the second generation. This revised ed...

  10. Uppermost mantle P wavespeed structure beneath eastern China and its surroundings

    Science.gov (United States)

    Sun, Weijia; Kennett, B. L. N.

    2016-06-01

    Pn travel-time tomography provides a way of improving structural information on the uppermost mantle across eastern China exploiting recent developments of dense seismic networks with well recorded seismic events. We used waveforms from 2009 at Chinese stations, supplemented by bulletin arrival times. An initial P wave model was constructed using the crustal model from CRUST1.0 coupled to a P wave model in the mantle derived from the SL2013sv model to capture the broad-scale features. This starting model enables us to compensate for the large contrasts in crustal thickness across the region. All events were relocated using the initial 3-D P model, and after relocation, consistent patterns of travel-time residuals are obtained. We extract Pn as the first arrival in the distance range 1.8 ∘ to 12 ∘. We use the FMTOMO (Fast Marching TOMOgraphy) approach to invert the travel-time results to generate a P wavespeed structure with a resolution of 2 ∘× 2 ∘ down to 75 km. There are considerable variations in Pn wavespeed in the uppermost mantle across the region. The central portion of the North China craton is imaged with particularly slow P wavespeeds, whilst most of the neighbouring Ordos block is fast. Fast P wavespeeds extend through much of the uppermost mantle beneath eastern Central Asia Orogen, northeast China and beneath the Korean peninsula. In the south, the Sichuan Block and the western Yangtze craton show rather fast P wavespeeds. The Tanlu fault system appears to cut through the crust into the mantle with marked slow P wavespeed at its southern end.

  11. Estimation of the Crustal Bulk Properties Beneath Mainland Portugal from P-Wave Teleseismic Receiver Functions

    Science.gov (United States)

    Dündar, Süleyman; Dias, Nuno A.; Silveira, Graça; Kind, Rainer; Vinnik, Lev; Matias, Luís; Bianchi, Marcelo

    2016-06-01

    In this work, we present results from teleseismic P-wave receiver functions (PRFs) obtained in Portugal, Western Iberia. A dense seismic station deployment conducted between 2010 and 2012, in the scope of the WILAS project and covering the entire country, allowed the most spatially extensive probing on the bulk crustal seismic properties of Portugal up to date. The application of the H- κ stacking algorithm to the PRFs enabled us to estimate the crustal thickness ( H) and the average crustal ratio of the P- and S-waves velocities V p/ V s ( κ) for the region. Observations of Moho conversions indicate that this interface is relatively smooth with the crustal thickness ranging between 24 and 34 km, with an average of 30 km. The highest V p/ V s values are found on the Mesozoic-Cenozoic crust beneath the western and southern coastal domain of Portugal, whereas the lowest values correspond to Palaeozoic crust underlying the remaining part of the subject area. An average V p/ V s is found to be 1.72, ranging 1.63-1.86 across the study area, indicating a predominantly felsic composition. Overall, we systematically observe a decrease of V p/ V s with increasing crustal thickness. Taken as a whole, our results indicate a clear distinction between the geological zones of the Variscan Iberian Massif in Portugal, the overall shape of the anomalies conditioned by the shape of the Ibero-Armorican Arc, and associated Late Paleozoic suture zones, and the Meso-Cenozoic basin associated with Atlantic rifting stages. Thickened crust (30-34 km) across the studied region may be inherited from continental collision during the Paleozoic Variscan orogeny. An anomalous crustal thinning to around 28 km is observed beneath the central part of the Central Iberian Zone and the eastern part of South Portuguese Zone.

  12. Lithospheric thinning beneath rifted regions of Southern California.

    Science.gov (United States)

    Lekic, Vedran; French, Scott W; Fischer, Karen M

    2011-11-11

    The stretching and break-up of tectonic plates by rifting control the evolution of continents and oceans, but the processes by which lithosphere deforms and accommodates strain during rifting remain enigmatic. Using scattering of teleseismic shear waves beneath rifted zones and adjacent areas in Southern California, we resolve the lithosphere-asthenosphere boundary and lithospheric thickness variations to directly constrain this deformation. Substantial and laterally abrupt lithospheric thinning beneath rifted regions suggests efficient strain localization. In the Salton Trough, either the mantle lithosphere has experienced more thinning than the crust, or large volumes of new lithosphere have been created. Lack of a systematic offset between surface and deep lithospheric deformation rules out simple shear along throughgoing unidirectional shallow-dipping shear zones, but is consistent with symmetric extension of the lithosphere.

  13. Simulation of Wave-Plus-Current Scour beneath Submarine Pipelines

    DEFF Research Database (Denmark)

    Eltard-Larsen, Bjarke; Fuhrman, David R.; Sumer, B. Mutlu

    2016-01-01

    A fully coupled hydrodynamic and morphologic numerical model was utilized for the simulation of wave-plus-current scour beneath submarine pipelines. The model was based on incompressible Reynolds-averaged Navier–Stokes equations, coupled with k-ω turbulence closure, with additional bed and suspen......A fully coupled hydrodynamic and morphologic numerical model was utilized for the simulation of wave-plus-current scour beneath submarine pipelines. The model was based on incompressible Reynolds-averaged Navier–Stokes equations, coupled with k-ω turbulence closure, with additional bed....... This validation complements previously demonstrated accuracy for the same model in simulating pipeline scour processes in pure-wave environments. The model was subsequently utilized to simulate combined wave-plus-current scour over a wide range of combined Keulegan–Carpenter numbers and relative current strengths...

  14. Long Period Earthquakes Beneath California's Young and Restless Volcanoes

    Science.gov (United States)

    Pitt, A. M.; Dawson, P. B.; Shelly, D. R.; Hill, D. P.; Mangan, M.

    2013-12-01

    The newly established USGS California Volcano Observatory has the broad responsibility of monitoring and assessing hazards at California's potentially threatening volcanoes, most notably Mount Shasta, Medicine Lake, Clear Lake Volcanic Field, and Lassen Volcanic Center in northern California; and Long Valley Caldera, Mammoth Mountain, and Mono-Inyo Craters in east-central California. Volcanic eruptions occur in California about as frequently as the largest San Andreas Fault Zone earthquakes-more than ten eruptions have occurred in the last 1,000 years, most recently at Lassen Peak (1666 C.E. and 1914-1917 C.E.) and Mono-Inyo Craters (c. 1700 C.E.). The Long Valley region (Long Valley caldera and Mammoth Mountain) underwent several episodes of heightened unrest over the last three decades, including intense swarms of volcano-tectonic (VT) earthquakes, rapid caldera uplift, and hazardous CO2 emissions. Both Medicine Lake and Lassen are subsiding at appreciable rates, and along with Clear Lake, Long Valley Caldera, and Mammoth Mountain, sporadically experience long period (LP) earthquakes related to migration of magmatic or hydrothermal fluids. Worldwide, the last two decades have shown the importance of tracking LP earthquakes beneath young volcanic systems, as they often provide indication of impending unrest or eruption. Herein we document the occurrence of LP earthquakes at several of California's young volcanoes, updating a previous study published in Pitt et al., 2002, SRL. All events were detected and located using data from stations within the Northern California Seismic Network (NCSN). Event detection was spatially and temporally uneven across the NCSN in the 1980s and 1990s, but additional stations, adoption of the Earthworm processing system, and heightened vigilance by seismologists have improved the catalog over the last decade. LP earthquakes are now relatively well-recorded under Lassen (~150 events since 2000), Clear Lake (~60 events), Mammoth Mountain

  15. Kelvin-Helmholtz wave generation beneath hovercraft skirts

    Science.gov (United States)

    Sullivan, P. A.; Walsh, C.; Hinchey, M. J.

    1993-05-01

    When a hovercraft is hovering over water, the air flow beneath its skirts can interact with the water surface and generate waves. These, in turn, can cause the hovercraft to undergo violent self-excited heave motions. This note shows that the wave generation is due to the classical Kelvin-Helmholtz mechanism where, beyond a certain air flow rate, small waves at the air water interface extract energy from the air stream and grow.

  16. New interpretation of the deep mantle structure beneath eastern China

    Science.gov (United States)

    Ma, Pengfei; Liu, Shaofeng; Lin, Chengfa; Yao, Xiang

    2016-04-01

    Recent study of high resolution seismic tomography presents a large mass of high velocity abnormality beneath eastern China near the phase change depth, expanding more than 1600km-wide in East-west cross-section across the North China plate. This structure high is generally believed to be the subducted slab of Pacific plate beneath the Eurasia continent, while its origin and dynamic effect on the Cenozoic tectonic evolution of eastern China remain to be controversial. We developed a subduction-driven geodynamic mantle convection model that honors a set of global plate reconstruction data since 230Ma to help understand the formation and evolution of mantle structure beneath eastern China. The assimilation of plate kinematics, continuous evolving plate margin, asymmetric subduction zone, and paleo seafloor age data enables the spatial and temporal consistency between the geologic data and the mantle convection model, and guarantees the conservation of the buoyancy flux across the lithosphere and subducted slabs. Our model achieved a first order approximation between predictions and the observed data. Interestingly, the model suggests that the slab material stagnated above discontinuity didn't form until 15Ma, much later than previous expected, and the fast abnormality in the mid-mantle further west in the tomographic image is interpreted to be the remnants of the Mesozoic Izanagi subduction. Moreover, detailed analysis suggests that the accelerated subduction of Philippine Sea plate beneath Eurasia plate along the Ryukyu Trench and Nankai Trough since 15Ma may largely contribute to extending feature above 670km discontinuity. The long distance expansion of the slab material in the East-west direction may be an illusion caused by the approximate spatial perpendicularity between the cross-section and the subduction direction of the Philippine Sea plate. Our model emphasizes the necessity of the re-examination on the geophysical observation and its tectonic and

  17. On Irrotational Flows Beneath Periodic Traveling Equatorial Waves

    Science.gov (United States)

    Quirchmayr, Ronald

    2016-08-01

    We discuss some aspects of the velocity field and particle trajectories beneath periodic traveling equatorial surface waves over a flat bed in a flow with uniform underlying currents. The system under study consists of the governing equations for equatorial ocean waves within a non-inertial frame of reference, where Euler's equation of motion has to be suitably adjusted, in order to account for the influence of the earth's rotation.

  18. The Dumbarton Oaks Tlazolteotl: looking beneath the surface

    OpenAIRE

    MacLaren Walsh, Jane

    2014-01-01

    The Dumbarton Oaks Tlazolteotl: looking beneath the surface. Some of the earliest and most revered pre-Columbian artifacts in the world’s major museum and private collections were collected prior to the advent of systematic, scientific archaeological excavation, and have little or no reliable provenience data. They have consistently posed problems for researchers due to anomalies of theme, material, size, technical virtuosity and iconography. This paper offers a historical and scientific appr...

  19. P-wave tomographic images beneath southeastern Tibet:Investigating the mechanism of the 2008 Wenchuan earthquake

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We used 71670 P-wave arrival times from 3594 earthquakes recorded by the Sichuan and Yunnan seismic networks to determine the three-dimensional P-wave velocity structure in the crust and uppermost mantle beneath the southeastern Tibetan Plateau. Our results show that prominent low P-wave velocity (low-Vp) anomalies exist in the midto lower crust of the Song- pan-Ganze and Sichuan-Yunnan blocks. In contrast, a high P-wave velocity (high-Vp) anomaly is resolved in the middle and lower crust beneath the Sichuan Basin. Our tomographic results provide seismic evidence for a dynamic model of lower crustal flow. Ongoing lower crustal flow beneath the central and eastern Tibetan Plateau abuts against the mechanically strong Si- chuan Basin resulting in accumulated strain in the Longmen Shan region. When a critical accumulation of strain energy was reached, its sudden release led to the occurrence of 2008 Wenchuan earthquake. Pronounced low-Vp anomalies are observed in the uppermost mantle in the region south of ~26°N. Combining these results with shear-wave splitting investigations, we suggest that the flow of asthenospheric material has impacted the velocity structure of the uppermost mantle and caused the thinning of the southwestern Yangtze Craton.

  20. Flow separation and resuspension beneath shoaling nonlinear internal waves

    Science.gov (United States)

    Boegman, Leon; Ivey, Gregory N.

    2009-02-01

    Laboratory observations are presented showing the structure and dynamics of the turbulent bottom boundary layer beneath nonlinear internal waves (NLIWs) of depression shoaling upon sloping topography. The adverse pressure gradient beneath the shoaling waves causes the rear face to steepen, flow separation to occur, and wave-induced near-bottom vortices to suspend bed material. The resuspension is directly attributed to the near-bed viscous stress and to near-bed patches of elevated positive Reynolds stress generated by the vortical structures. These results are consistent with published field observations of resuspension events beneath shoaling NLIWs. Elevated near-bed viscous stresses are found throughout the domain at locations that are not correlated to the resuspension events. Near-bed viscous stress is thus required for incipient sediment motion but is not necessarily a precursor for resuspension. Resuspension is dependent on the vertical velocity field associated with positive Reynolds stress and is also found to occur where the mean (wave-averaged) vertical velocity is directed away from the bed. The results are interpreted by analogy to the eddy-stress and turbulent bursting resuspension models developed for turbulent channel flows.

  1. Recovery of datable charcoal beneath young lavas: lessons from Hawaii.

    Science.gov (United States)

    Lockwood, J.P.; Lipman, P.W.

    1980-01-01

    Field studies in Hawaii aimed at providing a radiocarbon-based chronology of prehistoric eruptive activity have led to a good understanding of the processes that govern the formation and preservation of charcoal beneath basaltic lava flows. Charcoal formation is a rate-dependent process controlled primarily by temperature and duration of heating, as well as by moisture content, density, and size of original woody material. Charcoal will form wherever wood buried by lava is raised to sufficiently high temperatures, but owing to the availability of oxygen it is commonly burned to ash soon after formation. Wherever oxygen circulation is sufficiently restricted, charcoal will be preserved, but where atmospheric oxygen circulates freely, charcoal will only be preserved at a lower temperature, below that required for charcoal ignition or catalytic oxidation. These factors cause carbonized wood, especially that derived from living roots, to be commonly preserved beneath all parts of pahoehoe flows (where oxygen circulation is restricted), but only under margins of aa. Practical guidelines are given for the recovery of datable charcoal beneath pahoehoe and aa. Although based on Hawaiian basaltic flows, the guidelines should be applicable to other areas. -Authors

  2. Nutritional situation in the Americas.

    Science.gov (United States)

    1994-09-01

    PAHO member countries maintain food and nutrition surveillance systems. The prevalence of malnutrition among children aged 0-4 in Latin American and Caribbean countries ranges from 0.8% in Chile to 38.5% in Guatemala. It is 2.9% in the US. Low height-for-age is most common among children aged 0-4 in Guatemala (57.9%), Bolivia (38.3%), Peru (35.2%), and Ecuador (34%). The interval between observations of malnutrition prevalence ranged from 22 years in Honduras to 3-4 years in Nicaragua and Panama. Overall, there was a downward trend in malnutrition rates in the Americas. Yet, malnutrition is increasing in Guatemala and Panama. Breast feeding, good weaning practices, appropriate feeding during disease episodes, nutrition education, and programs for immunization and control of diarrhea and respiratory diseases account for the downward trend. Anemia rates among pregnant women (=or 11 g Hb/dl) vary from 13% in Asuncion, Paraguay, to 61% in Misiones, Argentina. Those for preschoolers range from 22% to 45% in Brazil and 27% to 53% in Peru. The prevalence of goiter is more than 50% in Merida, Venezuela, and Chameza, Colombia. It differs greatly in different areas within the same country. Most countries have laws requiring iodination of all salt for human consumption, yet violations are common. Certain areas of the countries in the Americas have vitamin A deficiency rates ranging from 5% to 48.8%. Some countries have enacted laws for sugar enrichment with retinol palmitate to reduce vitamin A deficiency. During the 1970s, deaths from chronic diseases related to nutrition increased 105% in South America, 56% in Central America, Mexico, and Panama, and 21% in the Caribbean. Prevalence of obesity among children aged 0-6 varies from 2.2% in Nicaragua and Brazil to 10.7% in Chile. Adult obesity is most common in Uruguay (about 50%). It is more common among females than males. The highest rates among 20-29 year olds are in Chile, Costa Rica, Cuba, and Peru. The US adult obesity

  3. Zircon reveals protracted magma storage and recycling beneath Mount St. Helens

    Science.gov (United States)

    Claiborne, L.L.; Miller, C.F.; Flanagan, D.M.; Clynne, M.A.; Wooden, J.L.

    2010-01-01

    Current data and models for Mount St. Helens volcano (Washington, United States) suggest relatively rapid transport from magma genesis to eruption, with no evidence for protracted storage or recycling of magmas. However, we show here that complex zircon age populations extending back hundreds of thousands of years from eruption age indicate that magmas regularly stall in the crust, cool and crystallize beneath the volcano, and are then rejuvenated and incorporated by hotter, young magmas on their way to the surface. Estimated dissolution times suggest that entrained zircon generally resided in rejuvenating magmas for no more than about a century. Zircon elemental compositions reflect the increasing influence of mafic input into the system through time, recording growth from hotter, less evolved magmas tens of thousands of years prior to the appearance of mafic magmas at the surface, or changes in whole-rock geochemistry and petrology, and providing a new, time-correlated record of this evolution independent of the eruption history. Zircon data thus reveal the history of the hidden, long-lived intrusive portion of the Mount St. Helens system, where melt and crystals are stored for as long as hundreds of thousands of years and interact with fresh influxes of magmas that traverse the intrusive reservoir before erupting. ?? 2010 Geological Society of America.

  4. The ribbon continent of northwestern South America

    Science.gov (United States)

    Altamira-Areyan, Armando

    The tectonic structure of the Plate Boundary Zone (PBZ) between the Caribbean Plate (CARIB) and the South American Plate (SOAM) is interpreted using models that require CARIB motion from the Pacific into the Atlantic. Those models can be subdivided into: (1) those in which the island arc rocks that are now in the CARIB-SOAM PBZ have collided with the northern South America margin, either obliquely or directly during the Cretaceous or during the Cenozoic, and (2) those in which the island arc rocks now in the CARIB-SOAM PBZ collided with the west coast of South America during the Cretaceous and were transferred to the northern margin by transform motion during the Cenozoic. Magnetic anomalies were first rotated in the Central and South Atlantic, holding Africa fixed to establish how much NOAM had converged on SOAM during the Cenozoic. WSW convergence was discovered to have been accommodated in the northern boundary of the CARIB. There is no evidence of convergence in the form of Cenozoic island arc igneous rocks on the north coast of South America. Those results are consistent only with models of Class (2) that call for transform movement of material that had collided with the west coast of South America along the CARIB-SOAM PBZ on the northern margin of South America. 40Ar/39Ar ages of island arc rocks from northern Venezuela were found to be older than ca 70 Ma, which is consistent with a requirement of models of Class (2) that those rocks are from an island arc which collided with the west coast of South America during Cretaceous times. Testing that conclusion using data from Ecuador, Colombia, Venezuela, the Netherlands Antilles, Trinidad and Tobago has led to the construction of a new ribbon continent model of the northwestern Cordillera of South America. Because the part of the ribbon continent on the north coast of South America has been experiencing substantial deformation in the Maracaibo block during the past 10 m.y., structures in that body have had to be

  5. Understanding the nature of mantle upwelling beneath East-Africa

    Science.gov (United States)

    Civiero, Chiara; Hammond, James; Goes, Saskia; Ahmed, Abdulhakim; Ayele, Atalay; Doubre, Cecile; Goitom, Berhe; Keir, Derek; Kendall, Mike; Leroy, Sylvie; Ogubazghi, Ghebrebrhan; Rumpker, Georg; Stuart, Graham

    2014-05-01

    The concept of hot upwelling material - otherwise known as mantle plumes - has long been accepted as a possible mechanism to explain hotspots occurring at Earth's surface and it is recognized as a way of removing heat from the deep Earth. Nevertheless, this theory remains controversial since no one has definitively imaged a plume and over the last decades several other potential mechanisms that do not require a deep mantle source have been invoked to explain this phenomenon, for example small-scale convection at rifted margins, meteorite impacts or lithospheric delamination. One of the best locations to study the potential connection between hotspot volcanism at the surface and deep mantle plumes on land is the East African Rift (EAR). We image seismic velocity structure of the mantle below EAR with higher resolution than has been available to date by including seismic data recorded by stations from many regional networks ranging from Saudi Arabia to Tanzania. We use relative travel-time tomography to produce P- velocity models from the surface down into the lower mantle incorporating 9250 ray-paths in our model from 495 events and 402 stations. We add smaller earthquakes (4.5 poorly sampled regions in order to have a more uniform data coverage. The tomographic results allow us to image structures of ~ 100-km length scales to ~ 1000 km depth beneath the northern East-Africa rift (Ethiopia, Eritrea, Djibouti, Yemen) with good resolution also in the transition zone and uppermost lower mantle. Our observations provide evidence that the shallow mantle slow seismic velocities continue trough the transition zone and into the lower mantle. In particular, the relatively slow velocity anomaly beneath the Afar Depression extends up to depths of at least 1000 km depth while another low-velocity anomaly beneath the Main Ethiopian Rift seems to be present in the upper mantle only. These features in the lower mantle are isolated with a diameter of about 400 km indicating deep

  6. Progress on the Seismic Anisotropy Parameters Knowledge Beneath Iberia and Morocco: New Results from the Second Topoiberia-Iberarray Deployment

    Science.gov (United States)

    Diaz, J.; Gallart, J.; TopoIberia Seismic Working Group

    2011-12-01

    In summer 2009 the dense Iberarray broad-band seismic network deployed in the framework of the large-scale TopoIberia project moved to its second footprint. Up to 55 stations covered the central part of the Iberian Peninsula until end 2010, distributed in a regular grid with a nominal spacing of 60 km. Up to 19 additional stations, active since late 2007, have remained operative in the Northern part of Morocco till summer 2010 and then moved southwards, to cover the Atlas belt. Continuous data from permanent broad-band stations have also been gathered to produce a complete database. We focus here in the results constraining the presence of anisotropy as evidenced from the analysis of splitted teleseismic phases. Few anisotropic results in the area covered by this IberArray deployment have been published till now, all of them coming from a scarce number of permanent stations. Beneath Iberia, this second deployment encompasses mainly the Variscan units of the Central Iberian Massif. To the East, the investigated area includes also the southern part of the Celtiberian Chain and reaches the Valencia Gulf, affected by a significant extensional episode in Neogene times. Beneath Morocco, the newly installed stations cover the Atlas belt, and area that seems to be associated with a significant lithospheric thinning, even if its geodynamic features are still poorly constrained. The results would extend the anisotropic map obtained from the first TopoIberia-Iberarray deployment in the Betics-Alboran zone (Díaz et al, 2010). The inferred fast polarization directions (FPD) have clearly documented a spectacular rotation along the Gibraltar arc, following the curvature of the Rif-Betic chain, from roughly N65E beneath the Betics to close to N65W beneath the Rif chain. The stations of that first deployment located in the Iberian Massif tent to present a relatively small amount of anisotropy and suggested complex anisotropy features, probably including two anisotropic layers. The

  7. 美国CWU课堂教学评价理念对我国高校现行课堂教学评价创新的启示%Enlightenment of Classroom Teaching Evaluation Idea of Central Washington University in America on the Innovation of Current Evaluation of Classroom Teaching in Chinese Universities

    Institute of Scientific and Technical Information of China (English)

    李贵安; 刘婵玉; 赵志鹏

    2012-01-01

    基于我国高校现行课堂教学评价的现状,通过分析美国中央华盛顿大学(CentralWashington University:CWU)课堂教学评价之学生评价的理念,提出创新我国高校课堂教学评价的四大理念,即新评价应能体现"以人为本"、"简约而不简单"、"整体性基本评价制度化"以及"公开、公平和坦诚"的理念,以为我国高校课堂教学质量稳步提升奠定扎实基础。%Based on the current situation of classroom teaching evaluation in Chinese universities,four ideas for the innovation of classroom teaching evaluation in Chinese universities are put forward by analyzing the ideas of student evaluation of classroom teaching of Central Washington University(CWU) in America.The new ideas of classroom teaching evaluation are "people first","simple,but not brief,"institutionalized overall basic evaluation" and "Open,fair and frank".We expect that it will lay solid foundation for the improvement of the qualities of classroom teaching in Chinese universities.

  8. Fossil Overlapping Spreading Centre in the Central Pacific at the Trace of the Pacific-Cocos-Nazca Triple Point

    Science.gov (United States)

    Meschede, M.; Barckhausen, U.; Weinrebe, W.; Engels, M.

    2005-12-01

    The Central Pacific region between 125° W/5° N and 110° W/10° S which contains the "plate tectonic mirror image" to the region of the Cocos plate currently being subducted beneath Central America has been the target of an investigation using multibeam bathymetry, magnetics and gravity. One of the main points of interest was the formation of the triple junction of Pacific, Cocos and Nacza plates in the Late Oligocene/Early Miocene (around 24 Myrs). This event indicates the breakup of the Farallon plate on the eastern side of the East-Pacific-Rise into Cocos and Nazca plates. At this time the first Cocos-Nazca spreading centre (CNS-1) a precursor of the currently active spreading centre (CNS-3) between Cocos and Nazca plates was initiated. The breakup process is a result of changing spreading directions caused by global changes in plate movement directions. This is documented in the area of investigation in the Central Pacific in changes in the strike direction of magnetic lineations from north to south and morphological structures of the seafloor. Irregularities in the magnetic lineation pattern in a small area in the centre of the investigation area and curved morphological structures on the oceanic seafloor are interpreted in terms of remnants of a fossil overlapping spreading centre. The overlapping spreading centre was formed as a consequence of shiftings in the spreading axis which subsequently are straightened out by processes like the one described.

  9. Central Andean crustal structure from receiver function analysis

    Science.gov (United States)

    Ryan, Jamie; Beck, Susan; Zandt, George; Wagner, Lara; Minaya, Estela; Tavera, Hernado

    2016-07-01

    The Central Andean Plateau (15°-27°S) is a high plateau in excess of 3 km elevation, associated with thickened crust along the western edge of the South America plate, in the convergent margin between the subducting Nazca plate and the Brazilian craton. We have calculated receiver functions using seismic data from a recent portable deployment of broadband seismometers in the Bolivian orocline (12°-21°S) region and combined them with waveforms from 38 other stations in the region to investigate crustal thickness and crust and mantle structures. Results from the receiver functions provide a more detailed map of crustal thickness than previously existed, and highlight mid-crustal features that match well with prior studies. The active volcanic arc and Altiplano have thick crust with Moho depths increasing from the central Altiplano (65 km) to the northern Altiplano (75 km). The Eastern Cordillera shows large along strike variations in crustal thickness. Along a densely sampled SW-NE profile through the Bolivian orocline there is a small region of thin crust beneath the high peaks of the Cordillera Real where the average elevations are near 4 km, and the Moho depth varies from 55 to 60 km, implying the crust is undercompensated by ~ 5 km. In comparison, a broader region of high elevations in the Eastern Cordillera to the southeast near ~ 20°S has a deeper Moho at ~ 65-70 km and appears close to isostatic equilibrium at the Moho. Assuming the modern-day pattern of high precipitation on the flanks of the Andean plateau has existed since the late Miocene, we suggest that climate induced exhumation can explain some of the variations in present day crustal structure across the Bolivian orocline. We also suggest that south of the orocline at ~ 20°S, the thicker and isostatically compensated crust is due to the absence of erosional exhumation and the occurrence of lithospheric delamination.

  10. The nature of orogenic crust in the central Andes

    Science.gov (United States)

    Beck, Susan L.; Zandt, George

    2002-10-01

    The central Andes (16°-22°S) are part of an active continental margin mountain belt and the result of shortening of the weak western edge of South America between the strong lithospheres of the subducting Nazca plate and the underthrusting Brazilian shield. We have combined receiver function and surface wave dispersion results from the BANJO-SEDA project with other geophysical studies to characterize the nature of the continental crust and mantle lithospheric structure. The major results are as follows: (1) The crust supporting the high elevations is thick and has a felsic to intermediate bulk composition. (2) The relatively strong Brazilian lithosphere is underthrusting as far west (65.5°W) as the high elevations of the western part of the Eastern Cordillera (EC) but does not underthrust the entire Altiplano. (3) The subcrustal lithosphere is delaminating piecemeal under the Altiplano-EC boundary but is not completely removed beneath the central Altiplano. The Altiplano crust is characterized by a brittle upper crust decoupled from a very weak lower crust that is dominated by ductile deformation, leading to lower crustal flow and flat topography. In contrast, in the high-relief, inland-sloping regions of the EC and sub-Andean zone, the upper crust is still strongly coupled across the basal thrust of the fold-thrust belt to the underthrusting Brazilian Shield lithosphere. Subcrustal shortening between the Altiplano and Brazilian lithosphere appears to be accommodated by delamination near the Altiplano-EC boundary. Our study suggests that orogenic reworking may be an important part of the "felsification" of continental crust.

  11. Integración regional centroamericana de la Educación Superior Pública: escenarios y desafíos / Central america regional integration of the public higher education: challenges and scenarios

    Directory of Open Access Journals (Sweden)

    Muñoz Varela, Luis

    2008-12-01

    Full Text Available Resumen: Se aborda aquí un breve análisis acerca de la globalización y de la sociedad del conocimiento, en su relación con las iniciativas de articulación académica interinstitucional y de integración regional impulsadas por las instituciones de educación superior pública de Centroamérica, a partir de 1995 y en el escenario asociativo del Consejo Superior Universitario Centroamericano (CSUCA. El propósito consiste en identificar elementos que permitan discernir el carácter y los niveles de reconfiguración académica e institucional que, de manera general, las nuevas realidades estructurales en curso acarrean para la educación superior pública de Centroamérica.Abstract:This article develops a brief analysis about globalization and the society of knowledge in terms of the attempts of inter-institutional and regional academic articulation proposed –since 1995- by the Central American institutions of higher education through Consejo Superior Universitario Centroamericano (CSUCA. The principal aim is to identify those elements that could clarify the character and the levels of the academic and institutional reconfiguration that, in a general way, the new ongoing structural realities demand from Central American public higher education.

  12. Lower crustal relaxation beneath the Tibetan Plateau and Qaidam Basin following the 2001 Kokoxili earthquake

    Science.gov (United States)

    Ryder, I.; Burgmann, R.; Pollitz, F.

    2011-01-01

    In 2001 November a magnitude 7.8 earthquake ruptured a 400 km long portion of the Kunlun fault, northeastern Tibet. In this study, we analyse over five years of post-seismic geodetic data and interpret the observed surface deformation in terms of stress relaxation in the thick Tibetan lower crust. We model GPS time-series (first year) and InSAR line of sight measurements (years two to five) and infer that the most likely mechanism of post-seismic stress relaxation is time-dependent distributed creep of viscoelastic material in the lower crust. Since a single relaxation time is not sufficient to model the observed deformation, viscous flow is modelled by a lower crustal Burgers rheology, which has two material relaxation times. The optimum model has a transient viscosity 9 ?? 1017 Pa s, steady-state viscosity 1 ?? 1019 Pa s and a ratio of long term to Maxwell shear modulus of 2:3. This model gives a good fit to GPS stations south of the Kunlun Fault, while displacements at stations north of the fault are over-predicted. We attribute this asymmetry in the GPS residual to lateral heterogeneity in rheological structure across the southern margin of the Qaidam Basin, with thinner crust/higher viscosities beneath the basin than beneath the Tibetan Plateau. Deep afterslip localized in a shear zone beneath the fault rupture gives a reasonable match to the observed InSAR data, but the slip model does not fit the earlier GPS data well. We conclude that while some localized afterslip likely occurred during the early post-seismic phase, the bulk of the observed deformation signal is due to viscous flow in the lower crust. To investigate regional variability in rheological structure, we also analyse post-seismic displacements following the 1997 Manyi earthquake that occurred 250 km west of the Kokoxili rupture. We find that viscoelastic properties are the same as for the Kokoxili area except for the transient viscosity, which is 5 ?? 1017 Pa s. The viscosities estimated for the

  13. Evidence for dike emplacement beneath Iliamna Volcano, Alaska in 1996

    Science.gov (United States)

    Roman, D.C.; Power, J.A.; Moran, S.C.; Cashman, K.V.; Doukas, M.P.; Neal, C.A.; Gerlach, T.M.

    2004-01-01

    Two earthquake swarms, comprising 88 and 2833 locatable events, occurred beneath Iliamna Volcano, Alaska, in May and August of 1996. Swarm earthquakes ranged in magnitude from -0.9 to 3.3. Increases in SO2 and CO2 emissions detected during the fall of 1996 were coincident with the second swarm. No other physical changes were observed in or around the volcano during this time period. No eruption occurred, and seismicity and measured gas emissions have remained at background levels since mid-1997. Earthquake hypocenters recorded during the swarms form a cluster in a previously aseismic volume of crust located to the south of Iliamna's summit at a depth of -1 to 4 km below sea level. This cluster is elongated to the NNW-SSE, parallel to the trend of the summit and southern vents at Iliamna and to the regional axis of maximum compressive stress determined through inversion of fault-plane solutions for regional earthquakes. Fault-plane solutions calculated for 24 swarm earthquakes located at the top of the new cluster suggest a heterogeneous stress field acting during the second swarm, characterized by normal faulting and strike-slip faulting with p-axes parallel to the axis of regional maximum compressive stress. The increase in earthquake rates, the appearance of a new seismic volume, and the elevated gas emissions at Iliamna Volcano indicate that new magma intruded beneath the volcano in 1996. The elongation of the 1996-1997 earthquake cluster parallel to the direction of regional maximum compressive stress and the accelerated occurrence of both normal and strike-slip faulting in a small volume of crust at the top of the new seismic volume may be explained by the emplacement and inflation of a subvertical planar dike beneath the summit of Iliamna and its southern satellite vents. ?? 2003 Elsevier B.V. All rights reserved.

  14. Crustal Thickness and Lower Crustal Velocity Structure Beneath the Endeavour Segment of the Juan de Fuca Ridge

    Science.gov (United States)

    Hill, R.; Soule, D. C.; Wilcock, W. S. D.; Toomey, D. R.; Hooft, E. E. E.; Weekly, R. T.

    2014-12-01

    In 2009, a multi-scale seismic tomography experiment was conducted on the Endeavour segment of the Juan de Fuca Ridge aboard the R/V Marcus G. Langseth. Ocean bottom seismometers were deployed at 64 sites and recorded 5567 shots of a 36-element, 6600 in.3 airgun array. The experiment extended 100 km along-axis and 60 km cross-axis. Two crustal tomographic analyses have previously been completed using data from the experiment. First, 93,000 manually picked crustal refraction arrivals (Pg) were used to develop a three-dimensional model of crustal velocity and thickness in the upper crust (Weekly et al. 2014). Second, this model was used as the starting model in an analysis that incorporated ~19,000 Moho reflection arrivals (PmP) for non-ridge crossing paths to image lower crustal velocity structure and crustal thickness off-axis. A key feature of this model is a ~0.5-1 km increase in crustal thickness beneath a bathymetric plateau that extends to either side of the central portion of the Endeavour segment. We present a tomographic inversions that incorporates ridge-crossing paths to examine spatial variations in lower crustal velocity and crustal thickness beneath the ridge axis. The preliminary results from an inversion that incorporates ~8700 manually picked ridge-crossing PmP arrival times reveals a ~10-km-wide low velocity zone extending throughout the lower crust with a velocity anomaly of -0.3 to -0.5 km/s at ≥4 km depth. This low velocity zone extends both to the north and south of the axial magma chamber reflector imaged previously beneath the central Endeavour. The inversion also shows significant variations in apparent crustal thickness along axis but additional analysis is required to understand whether these variations are well resolved.

  15. The flow beneath a periodic travelling surface water wave

    International Nuclear Information System (INIS)

    We discuss some recent results on the behaviour of the velocity field, pressure and particle trajectories beneath a periodic travelling wave propagating at the surface of water with a flat bed, in a flow without underlying currents. By analysing the governing equations we avoid approximations, thus ensuring the validity of the results without restrictions on the wave amplitude. In particular, the presented approach applies to waves of large amplitude. We also formulate some open problems, venturing into the relatively unexplored field of wave–current interactions. (topical review)

  16. The ionospheric heating beneath the magnetospheric cleft revisited

    Directory of Open Access Journals (Sweden)

    G. W. Prölss

    2005-03-01

    Full Text Available A prominent peak in the electron temperature of the topside ionosphere is observed beneath the magnetospheric cleft. The present study uses DE-2 data obtained in the Northern Winter Hemisphere to investigate this phenomenon. First, the dependence of the location and magnitude of the temperature peak on the magnetic activity is determined. Next, using a superposed epoch analysis, the mean latitudinal profile of the temperature enhancement is derived. The results of the present study are compared primarily with those obtained by Titheridge (1976, but also with more recent observations and theoretical predictions.

  17. On the Turbulence Beneath Finite Amplitude Water Waves

    CERN Document Server

    Babanin, Alexander V

    2015-01-01

    The paper by Beya et al. (2012, hereinafter BPB) has a general title of Turbulence Beneath Finite Amplitude Water Waves, but is solely dedicated to discussing the experiment by Babanin and Haus (2009, hereinafter BH) who conducted measurements of wave-induced non-breaking turbulence by particle image velocimetry (PIV). The authors of BPB conclude that their observations contradict those of BH. Here we argue that the outcomes of BPB do not contradict BH. In addition, although the main conclusion of BPB is that there is no turbulence observed in their experiment, it actually is observed.

  18. The preliminary results: Internal seismic velocity structure imaging beneath Mount Lokon

    International Nuclear Information System (INIS)

    Historical records that before the 17th century, Mount Lokon had been dormant for approximately 400 years. In the years between 1350 and 1400, eruption ever recorded in Empung, came from Mount Lokon’s central crater. Subsequently, in 1750 to 1800, Mount Lokon continued to erupt again and caused soil damage and fall victim. After 1949, Mount Lokon dramatically increased in its frequency: the eruption interval varies between 1 – 5 years, with an average interval of 3 years and a rest interval ranged from 8 – 64 years. Then, on June 26th, 2011, standby alert set by the Center for Volcanology and Geological Hazard Mitigation. Peak activity happened on July 4th, 2011 that Mount Lokon erupted continuously until August 28th, 2011. In this study, we carefully analyzed micro-earthquakes waveform and determined hypocenter location of those events. We then conducted travel time seismic tomographic inversion using SIMULPS12 method to detemine Vp, Vs and Vp/Vs ratio structures beneath Lokon volcano in order to enhance our subsurface geological structure. During the tomographic inversion, we started from 1-D seismic velocities model obtained from VELEST33 method. Our preliminary results show low Vp, low Vs, and high Vp/Vs are observed beneath Mount Lokon-Empung which are may be associated with weak zone or hot material zones. However, in this study we used few station for recording of micro-earthquake events. So, we suggest in the future tomography study, the adding of some seismometers in order to improve ray coverage in the region is profoundly justified

  19. The preliminary results: Internal seismic velocity structure imaging beneath Mount Lokon

    Energy Technology Data Exchange (ETDEWEB)

    Firmansyah, Rizky, E-mail: rizkyfirmansyah@hotmail.com [Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Kristianto, E-mail: kris@vsi.esdm.go.id [Center for Volcanology and Geological Hazard Mitigation (CVGHM), Geological Agency, Bandung, 40122 (Indonesia)

    2015-04-24

    Historical records that before the 17{sup th} century, Mount Lokon had been dormant for approximately 400 years. In the years between 1350 and 1400, eruption ever recorded in Empung, came from Mount Lokon’s central crater. Subsequently, in 1750 to 1800, Mount Lokon continued to erupt again and caused soil damage and fall victim. After 1949, Mount Lokon dramatically increased in its frequency: the eruption interval varies between 1 – 5 years, with an average interval of 3 years and a rest interval ranged from 8 – 64 years. Then, on June 26{sup th}, 2011, standby alert set by the Center for Volcanology and Geological Hazard Mitigation. Peak activity happened on July 4{sup th}, 2011 that Mount Lokon erupted continuously until August 28{sup th}, 2011. In this study, we carefully analyzed micro-earthquakes waveform and determined hypocenter location of those events. We then conducted travel time seismic tomographic inversion using SIMULPS12 method to detemine Vp, Vs and Vp/Vs ratio structures beneath Lokon volcano in order to enhance our subsurface geological structure. During the tomographic inversion, we started from 1-D seismic velocities model obtained from VELEST33 method. Our preliminary results show low Vp, low Vs, and high Vp/Vs are observed beneath Mount Lokon-Empung which are may be associated with weak zone or hot material zones. However, in this study we used few station for recording of micro-earthquake events. So, we suggest in the future tomography study, the adding of some seismometers in order to improve ray coverage in the region is profoundly justified.

  20. Determination of Nazca slab geometry and state of stress beneath the southern Peru and northern Bolivia

    Science.gov (United States)

    Kumar, A.; Wagner, L. S.; Beck, S. L.; Young, B. E.; Zandt, G.; Long, M. D.; Tavera, H.; Minaya, E.

    2013-12-01

    Subduction of the Nazca plate in the north central Andes beneath southern Peru and northern Bolivia is of prime importance because of the role it plays in the evolution of topographic features since the late Eocene (~40 Ma). Previous studies based on slab event locations constrained only with teleseismic data defined a broad area of flat slab subduction in central and southern Peru, which transitions to a normally dipping slab beneath the northernmost Altiplano Plateau. We present earthquake locations and focal mechanisms using data from two temporary arrays: the network of 50 broadband seismic stations that were part of the NSF-Continental Dynamics-funded project 'CAUGHT' (Central Andean Uplift and the Geodynamics of High Topography) and the 40 station NSF- Geophysics funded 'PULSE' array (PerU Lithosphere and Slab Experiment). Our earthquake locations provide new information about the geometry of subducting Nazca slab between 13°S to 18°S. A significant clustering of intermediate depth earthquakes at ~15.5°S and 18°S suggests strong and localized release of tectonic stress in the slab perhaps due to bending and unbending. There are not enough intra-slab events at depth greater than 100 km to constrain the flat slab width north of 14°S. Our analyses indicate that the flat slab is at least 10 to 12 km shallower than the previous estimates (e.g. Cahill and Isacks, 1992; Ramos, 2009). Focal mechanisms and stress axis orientation of slab events at ~15.5°S indicate down-dip extension, where the dip changes from subhorizontal to steeply dipping slab. The continuity in the trend of stress suggests that the slab is deformed but not torn where it transitions from flat to steeply dipping. Data from local slab events will eventually be incorporated into a local tomographic body wave inversion to better constrain the velocity structure of the mantle lithosphere and asthenosphere below the Altiplano. This in turn will provide the valuable information on the process

  1. Regional geothermal effects on subglacial water routes beneath the last Cordilleran ice sheet

    Science.gov (United States)

    Seguinot, Julien; Rogozhina, Irina

    2016-04-01

    The Cordilleran ice sheet, which covered the mountain ranges of north-western America during the last glacial cycle, provides an ideal setting to study the effect of geothermal anomalies on subglacial water routing beneath large-scale ice masses. First, the Cordilleran ice sheet rested directly on a geologically old yet still active subduction zone, which is responsible for significant geothermal variability in the region. Second, the deep valleys and intramontane basins that characterize the Cordilleran topography tend to act as flux wells to further enhance the heterogeneity of this geothermal distribution. Third, compared to the currently ice covered areas such as Greenland and Antarctica where direct observations of the geothermal distribution are exceedingly rare, the region of the North American Cordillera offers insights into geothermal variability from numerous borehole measurements taken across western territories of the US and Canada. Fourth and last, the subglacial water system left ample evidence on the landscape, including vast esker systems, deep canyons and subglacial lake sediments, allowing for an interpretation of the modeled hydrological networks and their comparison with geological data. Here we use the Parallel Ice Sheet Model (PISM) to simulate ice dynamics and simplified subglacial hydrology of the Cordilleran ice sheet through the last 120 000 years. We test several existing reconstructions of the geothermal flux from direct and indirect observations versus a uniform distribution of heat flux to isolate the effects of regional geothermal variability on thermo-hydrological conditions at the base of the last Cordilleran ice sheet. We find that the uncertainties in the geothermal flux distribution as well as regional geothermal anomalies present in the reconstructions have little effect on the modelled ice extent and thickness, but they affect the distribution of melt rate and water routes beneath the ice sheet. All but one of the

  2. Boys & Girls Clubs of America

    Science.gov (United States)

    ... National BGC Week Join Our Cause Donate Now Boys & Girls Clubs of America and the UPS Foundation ... the Dangers Faced When Behind-the-Wheel MORE» Boys & Girls Clubs of America Names Jocelyn Woods National ...

  3. America's Children and the Environment

    Science.gov (United States)

    ... Protection Agency Search Search America's Children and the Environment Share Facebook Twitter Google+ Pinterest Contact Us America's Children and the Environment is an EPA report that presents key information ...

  4. Economic integration in the Americas

    OpenAIRE

    1997-01-01

    This pioneering study shows that economic integration in the Americas is not simply a matter of removing trade barriers. Economic Integration in the Americas addresses the pervasive effects of economic integration on the economy as a whole.

  5. Americas at Odds

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Despite lingering disputes,the United States keeps a firm grip on Latin America During his presidential campaign,Evo Morales said his election would be a "nightmare" for the United States.The Bolivian president honored his words. On September 10, Morales declared U.S.

  6. Literacy in South America.

    Science.gov (United States)

    Hornberger, Nancy H.

    1991-01-01

    Literacy in South America must be understood in terms of the linguistic diversity there, where only 2 of 14 nations and territories are monolingual. Oral traditions, standardization of indigenous languages, nonstandard varieties of colonial languages, bilingual education and mother tongue literacy, literacy teaching, and politics are discussed.…

  7. Still Teaching for America

    Science.gov (United States)

    Kronholz, June

    2013-01-01

    In this article, June Kronholz talks to co-chief executives of Teach For America (TFA), Elisa Villanueva Beard and Matt Kramer about how TFA has managed to keep its forward momentum for almost 24 years. Four primary reasons are discussed: (1) Common Vision, Regional Innovation; (2) Data-Driven Improvement; (3) Global Reach; and (4) Stoking the…

  8. Two Visions of America

    Science.gov (United States)

    Capaldi, Nicholas

    2012-01-01

    Since the seventeenth century, there have been two narratives about modernity in general and America in particular. The author uses the term "narrative" to include (a) facts, (b) arguments, and most important, (c) a larger vision of how one sees the world and chooses to engage the world. The first and originalist narrative is the Lockean Liberty…

  9. Only "In America"

    Science.gov (United States)

    Miranda, Maria Eugenia

    2011-01-01

    As the daughter of an interracial couple growing up in a middle-class town on Long Island in the 1970s, Soledad O'Brien learned not to let inappropriate or racist comments throw her. Now as the anchorwoman of CNN's "In America" documentary unit, she says she asks those uncomfortable questions about race all the time. She shines spotlight on…

  10. An Idea Called America

    Science.gov (United States)

    Hartoonian, Michael; Van Scotter, Richard; White, William E.

    2007-01-01

    America evolved out of the principles of the eighteenth-century Enlightenment, suggesting that individuals could govern themselves and that people were "endowed" with "unalienable rights" such as life, liberty, and the pursuit of happiness. To secure these principles, Americans would continue to work on forming a more perfect Union, by…

  11. Anaglyph, North America

    Science.gov (United States)

    2003-01-01

    This anaglyph (stereoscopic view) of North America was generated with data from the Shuttle Radar Topography Mission (SRTM). It is best viewed at or near full resolution with anaglyph glasses. For this broad view the resolution of the data was first reduced to 30 arcseconds (about 928 meters north-south and 736 meters east-west in central North America), matching the best previously existing global digital topographic data set called GTOPO30. The data were then resampled to a Mercator projection with approximately square pixels (about one kilometer, or 0.6 miles, on each side). Even at this decreased resolution the variety of landforms comprising the North American continent is readily apparent.Active tectonics (structural deformation of the Earth's crust) along and near the Pacific North American plate boundary creates the great topographic relief seen along the Pacific coast. Earth's crustal plates converge in southern Mexico and in the northwest United States, melting the crust and producing volcanic cones. Along the California coast, the plates are sliding laterally past each other, producing a pattern of slices within the San Andreas fault system. And, where the plates are diverging, the crust appears torn apart as one huge tear along the Gulf of California (northwest Mexico), and as the several fractures comprising the Basin and Range province (in and around Nevada).Across the Great Plains, erosional patterns dominate, with stream channels surrounding and penetrating the remnants of older smooth slopes east of the Rocky Mountains. This same erosion process is exposing the bedrock structural patterns of the Black Hills in South Dakota and the Ozark Mountains in Arkansas. Lateral erosion and sediment deposition by the Mississippi River has produced the flatlands of the lower Mississippi Valley and the Mississippi Delta.To the north, evidence of the glaciers of the last ice age is widely found, particularly east of the Canadian Rocky Mountains and around the

  12. Lateinamerika oder -amerikas? Latin America or Americas?

    Directory of Open Access Journals (Sweden)

    Ana Belén García Timón

    2008-07-01

    Full Text Available Anhand interdisziplinärer und empirischer Studien wird Lateinamerika als Bühne für die Entwicklung transkultureller Phänomene präsentiert. Geschlechterverhältnisse in unterschiedlichen Kontexten stehen im Mittelpunkt der Untersuchung. Begriffe wie Macht, Rasse oder Raum werden mit dem Ziel, weg von der bisherigen Vorstellung von homogenen kulturellen Einheiten zu kommen, revidiert.Latin America is presented as a stage for the development of transcultural phenomena through the use of interdisciplinary and empirical studies. Gender relations in different contexts lie at the heart of this study. Terms such as power, race, or space are revised with the goal of moving away from current perceptions of homogenous cultural unities.

  13. S-P wave travel time residuals and lateral inhomogeneity in the mantle beneath Tibet and the Himalaya

    Science.gov (United States)

    Molnar, P.; Chen, W.-P.

    1984-01-01

    S-P wave travel time residuals were measured in earthquakes in Tibet and the Himalaya in order to study lateral inhomogeneities in the earth's mantle. Average S-P residuals, measured with respect to Jeffrey-Bullen (J-B) tables for 11 earthquakes in the Himalaya are less than +1 second. Average J-B S-P from 10 of 11 earthquakes in Tibet, however, are greater than +1 second even when corrected for local crustal thickness. The largest values, ranging between 2.5 and 4.9 seconds are for five events in central and northern Tibet, and they imply that the average velocities in the crust and upper mantle in this part of Tibet are 4 to 10 percent lower than those beneath the Himalaya. On the basis of the data, it is concluded that it is unlikely that a shield structure lies beneath north central Tibet unless the S-P residuals are due to structural variations occurring deeper than 250 km.

  14. Thermal constraints on the emerald ash borer invasion of North America

    Science.gov (United States)

    DeSantis, R.; Moser, W. K.; Gormanson, D. D.; Bartlett, M. G.

    2012-12-01

    Emerald ash borer (Agrilus planipennis Fairmaire; EAB), a non-native invasive beetle, has caused substantial damage to green (Fraxinus pennsylvanica Marsh.), white (Fraxinus americana L.), and black ash (Fraxinus nigra Marsh.), the major ash species of North America. In the absence of effective methods for controlling or eradicating the beetle, EAB continues to spread unimpeded across North America. Evidence indicates the mortality rate for EAB-infested trees near the epicenter of the infestation in southeast Michigan exceeds 99 percent for the major ash species. One possible climatic limitation on the spread of the infestation is suggested by recent work indicating that beetles cannot survive exposure to temperatures below -35.3 degrees Celsius. We considered whether this thermal constraint will limit the spread and distribution of EAB in North America. Historical climatic data for the United States and Canada were employed along with thermal models of the conditions beneath likely winter snowpack and beneath tree bark to predict the potential geographic distribution of the invasion. Results suggested the thermal mortality constraint will not lead to the protection of ash stands across most of North America. However, recent work indicates the majority of beetles cannot survive exposure to temperatures below -30 degrees Celsius. Along with our results, this suggests thermal constraints near the northern and western edges of the ranges of ash might limit EAB survival to some extent, thereby reducing the EAB population, the likelihood of EAB infestation, and subsequent ash mortality.

  15. Shear Wave Splitting Observations Beneath Uturuncu Volcano, Bolivia

    Science.gov (United States)

    Sims, N. E.; Christensen, D. H.; Moore-Driskell, M. M.

    2015-12-01

    Anisotropy in the upper mantle is often associated with mantle flow direction through the lattice preferred orientation of anisotropic minerals such as olivine in the upper mantle material. The flow of the mantle around subduction zones can be particularly complex, and thus difficult to explain. Because of its relationship to anisotropy, analysis of shear wave splitting measurements can help to answer questions regarding the upper mantle flow that surrounds subducting slabs. Here we present SK(K)S shear wave splitting measurements from a temporary broadband network (PLUTONS) of 33 stations deployed from April 2009 to October 2012 on the Altiplano plateau around Uturuncu volcano in Bolivia. The stations are spaced 10-20 km apart, providing a high spatial resolution of the region of the mantle directly below Uturuncu volcano. Despite the lack of numerous splitting results to analyze, preliminary measurements indicate a relatively consistent pattern of fast-polarization directions in a NW-SE orientation of about N80ºW. We think that it is likely that these observations come from anisotropy in the mantle wedge above the subducting Nazca plate indicating a direction of flow in the mantle wedge that is sub-parallel to the subduction direction of the Nazca plate. Although W-E flow beneath the subducting Nazca plate cannot be completely ruled out, these results appear to be consistent with the simple model of two-dimensional corner flow in the mantle wedge and slab-entrained mantle flow beneath the slab.

  16. Isotopic discontinuities in ground water beneath Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Analytical data for stable isotopes in ground water from beneath Yucca Mountain, when examined in map view, show areal patterns of heterogeneity that can be interpreted in terms of mixing of at least three end members. One end member must be isotopically heavy in terms of hydrogen and oxygen and have a young apparent 14C age such as water found at the north end of Yucca Mountain beneath Fortymile Wash. A second end member must contain isotopically heavy carbon and have an old apparent 14C age such as water from the Paleozoic aquifer. The third end member cannot be tightly defined. It must be isotopically lighter than the first with respect of hydrogen and oxygen and be intermediate to the first and second end members with respect to both apparent 14C age and δ13C. The variable isotopic compositions of hydrogen and oxygen indicate that two of the end members are waters, but the variable carbon isotopic composition could represent either a third water end member or reaction of water with a carbon-bearing solids such as calcite. 15 refs., 4 figs., 1 tab

  17. Shear wave anisotropy in D" region beneath the western Pacific

    Institute of Scientific and Technical Information of China (English)

    DAI Zhi-yang; LIU Bin; WANG Xiao-xiang; ZHA Xian-jie; ZHANG Hu; YANG Feng-qin

    2007-01-01

    Using seismic shear phases from 47 Tonga-Fiji and its adjacent region events recorded by the CENC and IRIS, and from 26 northeast Asia and north Pacific events recorded by IRIS, we studied the shear wave anisotropy in D" region beneath the western Pacific utilizing the ScS-S differential travel time method and obtained the splitting time values between the radial and transverse components of each ScS wave corresponding to each core-mantle boundary (CMB) reflection point. We found that most shear waves involved horizontally polarized shear wave components traveling faster than vertically polarized shear wave components through the D" region. The splitting time values of ScS wave range from (0.91 s to 3.21 s with an average value of 1.1 s. The strength of anisotropy varies from (0.45% to 1.56% with an average value of 0.52%. The observations and analyses show that in the D" region beneath the western Pacific the lateral flow is expected to be dominant and the vertical transverse isotropy may be the main anisotropic structure. This structure feature may be explained by the shape preferred orientation of the CMB chemical reaction products or partial melt and the lattice preferred orientation of the lower mantle materials caused by the lateral flow at lowermost mantle.

  18. 2. The Central American gang phenomenon

    OpenAIRE

    Does, Antonia

    2013-01-01

    2.1. Differentiating between pandillas and maras Youth gangs have existed since the 1960s and 1970s in Central America. However, there are different types of Central American gangs and thus one has to distinguish between pandillas and maras. The former are localized, homegrown gangs, which are “direct inheritors” (Jütersonke, Rodgers & Muggah 2009: 379) of the gangs that have historically characterized Central American societies, while the latter are a more recent phenomenon with transnationa...

  19. 1.6 Million Child-Bearing Women in Latin America Could Get Zika

    Science.gov (United States)

    ... news/fullstory_160059.html 1.6 Million Child-Bearing Women in Latin America Could Get Zika: Study ... HealthDay News) -- Up to 1.6 million child-bearing women in Central and South America may be ...

  20. Precambrian crust beneath the Mesozoic northern Canadian Cordillera discovered by Lithoprobe seismic reflection profiling

    Science.gov (United States)

    Cook, Frederick A.; Clowes, Ronald M.; Snyder, David B.; van der Velden, Arie J.; Hall, Kevin W.; Erdmer, Philippe; Evenchick, Carol A.

    2004-04-01

    -British Columbia border, a reflection dips eastward from ˜14.0 s to ˜21.0 s (˜45 to 73 km depth) beneath exposed Eocene magmatic rocks. It is interpreted as a relict subduction surface of the Kula plate. Our interpretation of Proterozoic layered rocks beneath most of the northern Cordillera suggests a much different crustal structure than previously considered: (1) Ancient North American crust comprising up to 25 km of metamorphosed Proterozoic to Paleozoic sediments plus 5-10 km of pre-1.8 Ga crystalline basement projects westward beneath most of the northern Canadian Cordillera. (2) The lateral (500 km by at least 1000 km) and vertical (up to 25 km) extent of the Proterozoic layers and their internal deformation are consistent with a long-lived margin for northwestern North America with alternating episodes of extension and contraction. (3) The detachments that carry deformed rocks of the Mackenzie Mountains and northern Rocky Mountains are largely confined to the upper crustal region above the layering. (4) Accreted terranes include thin klippen that were thrust over North American pericratonic strata (e.g., Yukon-Tanana), and terranes such as Nisling and Stikinia that thicken westward as the underlying Proterozoic layers taper and disappear. (5) The ages of exposed rocks are not necessarily indicative of the ages of underlying crust, a frequent observation in Lithoprobe interpretations, so that estimates of crustal growth based on surface geology may not be representative.

  1. Slab melting and magma formation beneath the southern Cascade arc

    Science.gov (United States)

    Walowski, K. J.; Wallace, P. J.; Clynne, M. A.; Rasmussen, D. J.; Weis, D.

    2016-07-01

    The processes that drive magma formation beneath the Cascade arc and other warm-slab subduction zones have been debated because young oceanic crust is predicted to largely dehydrate beneath the forearc during subduction. In addition, geochemical variability along strike in the Cascades has led to contrasting interpretations about the role of volatiles in magma generation. Here, we focus on the Lassen segment of the Cascade arc, where previous work has demonstrated across-arc geochemical variations related to subduction enrichment, and H-isotope data suggest that H2O in basaltic magmas is derived from the final breakdown of chlorite in the mantle portion of the slab. We use naturally glassy, olivine-hosted melt inclusions (MI) from the tephra deposits of eight primitive (MgO > 7 wt%) basaltic cinder cones to quantify the pre-eruptive volatile contents of mantle-derived melts in this region. The melt inclusions have B concentrations and isotope ratios that are similar to mid-ocean ridge basalt (MORB), suggesting extensive dehydration of the downgoing plate prior to reaching sub-arc depths and little input of slab-derived B into the mantle wedge. However, correlations of volatile and trace element ratios (H2O/Ce, Cl/Nb, Sr/Nd) in the melt inclusions demonstrate that geochemical variability is the result of variable addition of a hydrous subduction component to the mantle wedge. Furthermore, correlations between subduction component tracers and radiogenic isotope ratios show that the subduction component has less radiogenic Sr and Pb than the Lassen sub-arc mantle, which can be explained by melting of subducted Gorda MORB beneath the arc. Agreement between pMELTS melting models and melt inclusion volatile, major, and trace element data suggests that hydrous slab melt addition to the mantle wedge can produce the range in primitive compositions erupted in the Lassen region. Our results provide further evidence that chlorite-derived fluids from the mantle portion of the

  2. Driving in America

    Institute of Scientific and Technical Information of China (English)

    刘世一

    2005-01-01

    Mitsuaki recently arrived in the United States to enter university. He wants to do well in his studies and adjust to the new culture. But Mitsuaki has a problem. It's not his roommates. It's not his school fees. It's not even his English ability. Mitsuaki's problem is that he doesn't have a car. And in America, that really makes him a foreigner. Mitsuaki has already discovered a basic fact of American culture : Driving is a way of life.

  3. Making America Great Again?

    OpenAIRE

    Leth, Aksel N.; Lykke, Lærke G.; Dyrbye, Zachary R.; Jordahn, Sally E.; Egholm, Marcus

    2016-01-01

    This study aims at uncovering the discourses in Donald Trump’s announcement speech and their relation to his campaign slogan Make America Great Again. Through a thorough analysis of his speech, we have identified thematic categories and used critical discourse studies (CDS), to denaturalise the discourses he produces and reproduces in a socio-cultural and socio-political context. Our method of Critical Discourse Analysis is based on Fairclough, complemented by Wodak, Richardson and van Dijk, ...

  4. Signature of slab fragmentation beneath Anatolia from full-waveform tomography

    Science.gov (United States)

    Govers, Rob; Fichtner, Andreas

    2016-09-01

    When oceanic basins close after a long period of convergence and subduction, continental collision and mountain building is a common consequence. Slab segmentation is expected to have been relatively common just prior to closure of other oceans in the geological past, and may explain some of the complexity that geologists have documented in the Tibetan plateau also. We focus on the eastern Mediterranean basin, which is the last remainder of a once hemispherical neo-Tethys ocean that has nearly disappeared due to convergence of the India and Africa/Arabia plates with the Eurasia plate. We present new results of full-waveform tomography that allow us to image both the crust and upper mantle in great detail. We show that a major discontinuity exists between western Anatolia lithosphere and the region to the east of it. Also, the correlation of geological features and the crustal velocities is substantially stronger in the west than in the east. We interpret these observations as the imprint in the overriding plate of fragmentation of the neo-Tethys slab below it. This north-dipping slab may have fragmented following the Eocene (about 35 million years ago) arrival of a continental promontory (Central Anatolian Core Complex) at the subduction contact. From the Eocene through the Miocene, slab roll-back ensued in the Aegean and west Anatolia, while the Cyprus-Bitlis slab subducted horizontally beneath central and east Anatolia. Following collision of Arabia (about 16 million years ago), the Cyprus-Bitlis slab steepened, exposing the crust of central and east Anatolia to high temperature, and resulting in the velocity structure that we image today. Slab fragmentation thus was a major driver of the evolution of the overriding plate as collision unfolded.

  5. Public Education--America's Civil Religion: A Social History

    Science.gov (United States)

    Bankston, Carl L., III; Caldas, Stephen J.

    2009-01-01

    In this provocative volume, the authors argue that public education is a central part of American civil religion and, thus, gives us an unquestioning faith in the capacity of education to solve all of our social, economic, and political problems. The book traces the development of America's faith in public education from before the Civil War up to…

  6. [Travellers to South America].

    Science.gov (United States)

    Lloveras, Susana Cristina

    2011-12-01

    The geography, tourist attractions and the multiple sites of historical and cultural interest make South America as an important destination chosen by travelers. The continent has a wide climatic variation from north to south, making exposure to risk different between the tropics and the temperate or cold regions. In the countries of tropical South America, the greatest risk is associated with the possibility of acquiring vector-borne diseases, like yellow fever, dengue, malaria and leishmaniasis. The risk of acquiring traveler's diarrhea and food-borne illness is similar across the continent, with some variations according to country and to visit urban or rural areas. Rabies, pertussis and diphtheria have appeared as epidemics in several countries and other diseases such as rickettsiosis, hantavirosis and viral encephalitis have expanded their distribution. The geographic and epidemiological diversity of South America, promotes a challenge for travel medicine specialists because during the pre-travel advice they have to take in account the kind of trip, traveller's medical history, exposure to risk and the dynamics of endemic emerging and reemerging diseases in the region.

  7. The Failure of Macroeconomics in America

    Institute of Scientific and Technical Information of China (English)

    Joseph Stiglitz

    2011-01-01

    Editor's Words On 18 March 2011, the China Association for World Economics hosted "The Presentation of the 2010 Pushan Award for Excellent Papers on International Economics " at the China Central University of Finance and Economics. Over 700 scholars and students from home and abroad attended the ceremony. Professor Joseph Stiglitz, the winner of the Nobel Prize in Economics, presented the awards and gave a speech on "The Failure of Economics in America." The following speech transcript has been approved and edited kindly by Professor Stiglitz.

  8. Ocean mixing beneath Pine Island Glacier Ice Shelf

    Science.gov (United States)

    Kimura, Satoshi; Dutrieux, Pierre; Jenkins, Adrian; Forryan, Alexander; Naveira Garabato, Alberto; Firing, Yvonne

    2016-04-01

    Ice shelves around Antarctica are vulnerable to increase in ocean-driven melting, with the melt rate depending on ocean temperature and strength of sub-ice-shelf-cavity circulations. We present repeated measurements of velocity, temperature, salinity, turbulent kinetic energy dissipation rate and thermal variance dissipation rate beneath Pine Island Glacier Ice Shelf, collected by CTD, ADCP and turbulence sensors mounted on an Autonomous Underwater Vehicle (AUV). The turbulence quantities measured by the AUV outside the ice shelf are in good agreement with ship-based measurements. The highest rate of turbulent kinetic energy dissipation is found near the grounding line, while its temporal fluctuation over seabed ridge within the cavity corresponds to the tidal fluctuation predicted in the Pine Island Bay to the west. The highest thermal variance dissipation rate is found when the AUV was 0.5 m away from the ice, and the thermal variance dissipation generally increases with decreasing distance between the AUV and ice.

  9. Similarity law of fluctuating pressure spectrum beneath hydraulic jump

    Institute of Scientific and Technical Information of China (English)

    LIAN JiJian; WANG JiMin; GU JinDe

    2008-01-01

    Similarity law is the conversion rule between model and prototype, on which a lot of research works have been done, with no agreement reached referring to the similarity law of fluctuating pressure fre-quency spectrum. Experimental data of peak frequency and dominant frequency range of fluctuating pressure spectrum beneath hydraulic jump obtained from serial models of scales 1:1, 1:2 and 1:5 are compared. As a result, similarity law of fluctuating pressure spectrum in the strongly rolling area agrees with the gravity law. As peak frequency and dominant frequencies of fluctuating pressures in hydraulic normalized spectrums of fluctuating pressures show that the similarity nearly agrees with the gravity law.

  10. Can slabs melt beneath forearcs in hot subduction zones?

    Science.gov (United States)

    Ribeiro, J.; Maury, R.; Gregoire, M.

    2015-12-01

    At subduction zones, thermal modeling predict that the shallow part of the downgoing oceanic crust (test the hypothesis that adakites are pristine slab melts. We find that adakites from Baja California and Philippines formed by two distinct petrogenetic scenarios. In Baja California, hydrous mantle melts mixed/mingled with high-pressure (HP) adakite-type, slab melts within a lower crustal (~30 km depth) magma storage region before stalling into the upper arc crust (~7-15 km depth). In contrast, in the Philippines, primitive mantle melts stalled and crystallized within lower and upper crustal magma storage regions to produce silica-rich melts with an adakitic signature. Thereby, slab melting is not required to produce an adakitic geochemical fingerprint in hot subduction zones. However, our results also suggest that the downgoing crust potentially melted beneath Baja California.

  11. Multicomponent seismic forward modeling of gas hydrates beneath the seafloor

    Institute of Scientific and Technical Information of China (English)

    Yang Jia-Jia; He Bing-Shou; Zhang Jian-Zhong

    2014-01-01

    We investigated the effect of microscopic distribution modes of hydrates in porous sediments, and the saturation of hydrates and free gas on the elastic properties of saturated sediments. We simulated the propagation of seismic waves in gas hydrate-bearing sediments beneath the seafloor, and obtained the common receiver gathers of compressional waves (P-waves) and shear waves (S-waves). The numerical results suggest that the interface between sediments containing gas hydrates and free gas produces a large-amplitude bottom-simulating reflector. The analysis of multicomponent common receiver data suggests that ocean-bottom seismometers receive the converted waves of upgoing P-and S-waves, which increases the complexity of the wavefield record.

  12. Chemical transport beneath a uranium mill tailings pile, Riverton, Wyoming

    International Nuclear Information System (INIS)

    A detailed geochemical study at the Riverton site was undertaken in order to define the nature of chemical transport between an inactive tailings pile and the relationship between the underlying shallow groundwater system. Isotopic measurements of oxygen, deuterium, and tritium showed that although both the shallow alluvial aquifer and a deeper aquifer in the Wind River Formation were derived from a similar source, the nearby river, recharge from the tailings pile is occurring only in the shallow alluvium. 34S/32S ratios are used as a conservative tracer in defining zones of tailings water contamination. Offsite, drilling has revealed the existence of a chemical plume in which calcium and sulfate concentrations are an order of magnitude or more above background. The plume is also characterized by high dissolved molybdenum concentrations. Pore waters in the tailings exhibit extremely high concentrations of Al, Fe and SO4 and low pH. The dissolution of calcite occurs in the alluvium beneath the pile which is characterized by high partial pressures of CO/sub 2(g)/ in the tailings while serving to neutralize pH. The groundwater, however remains saturated with CaCO3, suggesting that a buffering capacity is active. Beneath and downgradient from the tailings, the groundwater becomes saturated with gypsum. The chemical speciation code, PHREEQE, was used to model mixing reactions, assuming a hydrologically static system. Reaction path simulations were fit to observed trends of pH that were depressed in the contaminated groundwater. The simulations estimate one percent mixing of tailings-pore water with groundwater from the shallow alluvial aquifer

  13. Crustal and uppermost mantle structure beneath the United States

    Science.gov (United States)

    Shen, Weisen; Ritzwoller, Michael H.

    2016-06-01

    This paper presents a new model of the shear velocity structure of the crust and uppermost mantle beneath the contiguous U.S. The model is based on more than a decade of USArray Transportable Array (TA) data across the U.S. and derives from a joint Bayesian Monte Carlo inversion of Rayleigh wave group and phase speeds determined from ambient noise and earthquakes, receiver functions, and Rayleigh wave ellipticity (H/V) measurements. Within the Bayesian inverse theoretic framework, a prior distribution of models is posited and a posterior distribution is inferred beneath all of the more than 1800 TA stations across the U.S. The resulting mean and standard deviation of the mean of the posterior distribution at each station summarize the inversion results, which are then interpolated onto a regular 0.25°×0.25° grid across the U.S. to define the final 3-D model. We present arguments that show that the standard deviation of the posterior distribution overestimates the effect of nonsystematic errors in the final model by a factor of 4-5 and identify uncertainties in density and mantle Q as primary potential sources of remaining systematic error in the final model. The model presents a great many newly resolved structural features across the U.S. that require further analysis and dedicated explication. We highlight here low-velocity anomalies in the upper mantle that underlie the Appalachians with centers of anomalies in northern Georgia, western Virginia, and, most prominently, New England.

  14. Magma heating by decompression-driven crystallization beneath andesite volcanoes.

    Science.gov (United States)

    Blundy, Jon; Cashman, Kathy; Humphreys, Madeleine

    2006-09-01

    Explosive volcanic eruptions are driven by exsolution of H2O-rich vapour from silicic magma. Eruption dynamics involve a complex interplay between nucleation and growth of vapour bubbles and crystallization, generating highly nonlinear variation in the physical properties of magma as it ascends beneath a volcano. This makes explosive volcanism difficult to model and, ultimately, to predict. A key unknown is the temperature variation in magma rising through the sub-volcanic system, as it loses gas and crystallizes en route. Thermodynamic modelling of magma that degasses, but does not crystallize, indicates that both cooling and heating are possible. Hitherto it has not been possible to evaluate such alternatives because of the difficulty of tracking temperature variations in moving magma several kilometres below the surface. Here we extend recent work on glassy melt inclusions trapped in plagioclase crystals to develop a method for tracking pressure-temperature-crystallinity paths in magma beneath two active andesite volcanoes. We use dissolved H2O in melt inclusions to constrain the pressure of H2O at the time an inclusion became sealed, incompatible trace element concentrations to calculate the corresponding magma crystallinity and plagioclase-melt geothermometry to determine the temperature. These data are allied to ilmenite-magnetite geothermometry to show that the temperature of ascending magma increases by up to 100 degrees C, owing to the release of latent heat of crystallization. This heating can account for several common textural features of andesitic magmas, which might otherwise be erroneously attributed to pre-eruptive magma mixing.

  15. Flat vs. Normal subduction, Central Chile: insights from regional seismic tomography and rock type modeling

    Science.gov (United States)

    Marot, Marianne; Monfret, Tony; Gerbault, Muriel; Nolet, Guust; Ranalli, Giorgio; Pardo, Mario

    2013-04-01

    The Central Chilean subduction zone (27-35°S) is host to a multitude of unexplained phenomena, all likely linked to one another. Here, the 35 Ma oceanic Nazca plate is subducting beneath South America with a well developed, highly seismic flat slab, very well correlated with the subducting Juan Fernandez seamount Ridge (JFR) track, and also with the absence of volcanism at the surface. The upper plate, currently under compression, is composed of a series of accreted terranes of various origins and ages. Although no general consensus on the formation of this flat slab has been yet achieved, there may have been influence of overthickened oceanic crust, delayed eclogitization and consequent fluid retain within the slab, and slab suction due to the high convergence rate with the thick Rio de Plata craton. Therefore, the main questions we address are: Does the slab dehydrate along the flat subducting segment? If so, how hydrated is the slab, at what depth does slab dehydration occur, where are the fluids transported to, and where are they stored? Is magmatism still active beneath the now inactive arc? Are accreted terranes and suture zones important attributes of this subduction zone? Do they possess their own mantle entities? To answer these questions, we analyzed recorded local seismicity and performed regional 3D seismic tomography for Vp and Vs. Combining seismic tomography with 2D instantaneous thermo-mechanical modeling for the regions of flat and normal subduction, we predict rock compositions for these two regions based on published mineral and rock elastic properties. Here, we present a comparison between the normal subduction zone to the south, reflecting typical and expected features, and the flat slab region to the north, exhibiting heterogeneities. Our results agree with other studies for a dry and cold continental mantle above the flat slab. We distinguish the Cuyania terrane with overthickened crust and/or abnormal mantle beneath it. We notice that the

  16. Structure of the uppermost mantle beneath North America : Regional surface wave tomography and thermo-chemical interpretation

    NARCIS (Netherlands)

    Godey, Stéphanie

    2002-01-01

    Seismology is the primary tool to probe the interior of the Earth. The main requirement to obtain a high quality image of the Earth's structure is the achievement of an extensive dataset of seismograms. The North American and Caribbean regions offer a good opportunity in that matter. The large deplo

  17. Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina.

    Science.gov (United States)

    Booker, John R; Favetto, Alicia; Pomposiello, M Cristina

    2004-05-27

    Beneath much of the Andes, oceanic lithosphere descends eastward into the mantle at an angle of about 30 degrees (ref. 1). A partially molten region is thought to form in a wedge between this descending slab and the overlying continental lithosphere as volatiles given off by the slab lower the melting temperature of mantle material. This wedge is the ultimate source for magma erupted at the active volcanoes that characterize the Andean margin. But between 28 degrees and 33 degrees S the subducted Nazca plate appears to be anomalously buoyant, as it levels out at about 100 km depth and extends nearly horizontally under the continent. Above this 'flat slab', volcanic activity in the main Andean Cordillera terminated about 9 million years ago as the flattening slab presumably squeezed out the mantle wedge. But it is unknown where slab volatiles go once this happens, and why the flat slab finally rolls over to descend steeply into the mantle 600 km further eastward. Here we present results from a magnetotelluric profile in central Argentina, from which we infer enhanced electrical conductivity along the eastern side of the plunging slab, indicative of the presence of partial melt. This conductivity structure may imply that partial melting occurs to at least 250 km and perhaps to more than 400 km depth, or that melt is supplied from the 410 km discontinuity, consistent with the transition-zone 'water-filter' model of Bercovici and Karato.

  18. Evidence for elevated and spatially variable geothermal flux beneath the West Antarctic Ice Sheet.

    Science.gov (United States)

    Schroeder, Dustin M; Blankenship, Donald D; Young, Duncan A; Quartini, Enrica

    2014-06-24

    Heterogeneous hydrologic, lithologic, and geologic basal boundary conditions can exert strong control on the evolution, stability, and sea level contribution of marine ice sheets. Geothermal flux is one of the most dynamically critical ice sheet boundary conditions but is extremely difficult to constrain at the scale required to understand and predict the behavior of rapidly changing glaciers. This lack of observational constraint on geothermal flux is particularly problematic for the glacier catchments of the West Antarctic Ice Sheet within the low topography of the West Antarctic Rift System where geothermal fluxes are expected to be high, heterogeneous, and possibly transient. We use airborne radar sounding data with a subglacial water routing model to estimate the distribution of basal melting and geothermal flux beneath Thwaites Glacier, West Antarctica. We show that the Thwaites Glacier catchment has a minimum average geothermal flux of ∼ 114 ± 10 mW/m(2) with areas of high flux exceeding 200 mW/m(2) consistent with hypothesized rift-associated magmatic migration and volcanism. These areas of highest geothermal flux include the westernmost tributary of Thwaites Glacier adjacent to the subaerial Mount Takahe volcano and the upper reaches of the central tributary near the West Antarctic Ice Sheet Divide ice core drilling site. PMID:24927578

  19. U.S. STRATEGY AND POLICY IN CENTRAL ASIA

    OpenAIRE

    Laumulin, Murat

    2007-01-01

    It goes without saying that American geopolitics and geostrategy are of a genuinely global nature and affect practically every region and every country. And Central Asia is no exception in this respect. America's influence there is of a multi-factoral and multi-level nature in every aspect-the political, military-strategic, economic, and ideological. From the very first days of independence, the Central Asian countries have been aware of America's influence (and pressure) in essentially every...

  20. Timekeeping in the Americas

    Science.gov (United States)

    López, J. M.; Lombardi, M. A.

    2015-10-01

    Time and its measurement belong to the most fundamental core of physics, and many scientific and technological advances are directly or indirectly related to time measurements. Timekeeping is essential to everyday life, and thus is the most measured physical quantity in modern societies. Time can also be measured with less uncertainty and more resolution than any other physical quantity. The measurement of time is of the utmost importance for many applications, including: global navigation satellite systems, communications networks, electric power generation, astronomy, electronic commerce, and national defense and security. This paper discusses how time is kept, coordinated, and disseminated in the Americas.

  1. Chinese Food in America

    OpenAIRE

    Jou, Diana T.

    2011-01-01

    How did Chinese food get to look like this? With more than 41,000 Chinese restaurants in America - 3 times the number of McDonald’s restaurants - Chinese food is one of the most accepted and misunderstood cuisines in the United States. From large cities to small towns, locals can always count on an order of orange chicken in a takeout box, with a few fortune cookies thrown in the bag. But what Americans view as Chinese food is far from a traditional Chinese meal, wh...

  2. Eating in America

    Institute of Scientific and Technical Information of China (English)

    康海燕

    2007-01-01

    Americans are too busy to cook at home.They often eat outside.Eating culture is one of the important parts in America.There are many kinds of restaurants.Some are open for breakfast. Others are open twenty-four hours a day. A number of restaurants call themselves"family restaurants".They serve no alcohol~* and have fairly restricted~* menus.They serve steaks,hamburgers and sandwiches.Besides these,there are some special restaurants.They serve only or mainly steaks,seafood,etc.

  3. Mosques in North America

    Directory of Open Access Journals (Sweden)

    Omar Khalidi

    2008-12-01

    Full Text Available The following article derived from an exhibit catalogue put together by Public Affairs Germany in the U.S. Embassy in Berlin and the U.S. Consulates in Frankfurt and Düsseldorf and accompanied Dr. Omar Khalidi’s photo exhibit “Mosques in America.” There are over 2,000 mosques in the United States, mostly housed in buildings originally built for other purposes. American mosques built in the last few decades, however, in the period in which Islam has begun to feel at home in the United States, are almost universally architect-designed.

  4. Knight Capital Americas LLC

    DEFF Research Database (Denmark)

    Austin, Robert D.; Meister, Darren

    2015-01-01

    $450 million dollars in less than an hour. Although it was ultimately saved from bankruptcy when it was acquired two days later, the terms of acquisition were very unfavourable to the company's shareholders. How did this happen? Could it have been prevented? What should the staff, the chief executive......It took 19 years to build Knight Capital Americas LLC into the largest market maker on the New York Stock Exchange, but on August 1, 2012, it took only 45 minutes for the firm to be wiped out by an information technology (IT) problem: a change in the company's software caused it to lose more than...

  5. Let's Go to America!

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

      The United States and China have signed an agreement to facilitate Chinese group leisure travel to the United States. This agreement provides the necessary framework to permit group leisure travel from China to the United States. U.S. companies can now enter into business relationships with Chinese travel agencies to organize and market travel packages for group leisure travel to the United States. It also attracts more and more Chinese to go to America, as more and more convenience and comforts are coming up during the travel.……

  6. Let's Go to America!

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The United States and China have signed an agreement to facilitate Chinese group leisure travel to the United States. This agreement provides the necessary framework to permit group leisure travel from China to the United States. U.S. companies can now enter into business relationships with Chinese travel agencies to organize and market travel packages for group leisure travel to the United States. It also attracts more and more Chinese to go to America, as more and more convenience and comforts are coming up during the travel.

  7. Electrical conductivity anomaly beneath Mare Serenitatis detected by Lunokhod 2 and Apollo 16 magnetometers

    Science.gov (United States)

    Vanian, L. L.; Vnuchkova, T. A.; Egorov, I. V.; Basilevskii, A. T.; Eroshenko, E. G.; Fainberg, E. B.; Dyal, P.; Daily, W. D.

    1979-01-01

    Magnetic fluctuations measured by the Lunokhod 2 magnetometer in the Bay Le Monnier are distinctly anisotropic when compared to simultaneous Apollo 16 magnetometer data measured 1100 km away in the Descartes highlands. This anisotropy can be explained by an anomalous electrical conductivity of the upper mantle beneath Mare Serenitatis. A model is presented of anomalously lower electrical conductivity beneath Serenitatis and the simultaneous magnetic data from the Lunokhod 2 site at the mare edge and the Apollo 16 site are compared to the numerically calculated model solutions. This comparison indicates that the anisotropic fluctuations can be modeled by a nonconducting layer in the lunar lithosphere which is 150 km thick beneath the highlands and 300 km thick beneath Mare Serenitatis. A decreased electrical conductivity in the upper mantle beneath the mare may be due to a lower temperature resulting from heat carried out the magma source regions to the surface during mare flooding.

  8. IAI Training in Climate and Health in the Americas

    Science.gov (United States)

    Aron, J. L.

    2007-05-01

    The Inter-American Institute for Global Change Research (IAI) has addressed training in climate and health in the Americas in two major ways. First, IAI supports students to engage in research training. A multi-country health activity funded by IAI was the collaborative research network (CRN) on Diagnostics and Prediction of Human Health Impacts in the Tropical Americas, which focused principally on the effect of El Nino/Southern Oscillation and other aspects of climate variability on mosquito-borne diseases malaria and dengue. The CRN involved students in Brazil, Mexico, Venezuela, Colombia and Jamaica. The CRN was also linked to other climate and health projects that used a similar approach. Second, IAI organizes training institutes to expand the network of global change research scientists and facilitate the transfer of global change research into practice. The IAI Training Institute on Climate and Health in the Americas was held on November 7 - 18, 2005 at the University of the West Indies in Kingston, Jamaica, engaging participants from the CRN and other programs in the Americas. The Training Institute's central objective was to help strengthen local and regional capacity to address the impacts of climate variability and climate change on human health in the populations of the Americas, particularly Latin America and the Caribbean. The Training Institute had three core components: Science; Applications; and Proposal Development for Seed Grants. Recommendations for future Training Institutes included incorporating new technologies and communicating with policy-makers to develop more proactive societal strategies to manage risks.

  9. Labor Education in America

    Science.gov (United States)

    Carlson, Kenneth D.

    1971-01-01

    Labor education reflects the pragmaticism of American culture and supports the system. It emphasizes leadership training, loyalty building, and political education. The control of labor education is centralized in union headquarters. (VW)

  10. Upper mantle shear wave velocity structure beneath northern Victoria Land, Antarctica: Volcanism and uplift in the northern Transantarctic Mountains

    Science.gov (United States)

    Graw, Jordan H.; Adams, Aubreya N.; Hansen, Samantha E.; Wiens, Douglas A.; Hackworth, Lauren; Park, Yongcheol

    2016-09-01

    The Transantarctic Mountains (TAMs) are the largest non-compressional mountain range on Earth, and while a variety of uplift mechanisms have been proposed, the origin of the TAMs is still a matter of great debate. Most previous seismic investigations of the TAMs have focused on a central portion of the mountain range, near Ross Island, providing little along-strike constraint on the upper mantle structure, which is needed to better assess competing uplift models. Using data recorded by the recently deployed Transantarctic Mountains Northern Network, as well as data from the Transantarctic Mountains Seismic Experiment and from five stations operated by the Korea Polar Research Institute, we investigate the upper mantle structure beneath a previously unexplored portion of the mountain range. Rayleigh wave phase velocities are calculated using a two-plane wave approximation and are inverted for shear wave velocity structure. Our model shows a low velocity zone (LVZ; ∼4.24 km s-1) at ∼160 km depth offshore and adjacent to Mt. Melbourne. This LVZ extends inland and vertically upwards, with more lateral coverage above ∼100 km depth beneath the northern TAMs and Victoria Land. A prominent LVZ (∼4.16-4.24 km s-1) also exists at ∼150 km depth beneath Ross Island, which agrees with previous results in the TAMs near the McMurdo Dry Valleys, and relatively slow velocities (∼4.24-4.32 km s-1) along the Terror Rift connect the low velocity anomalies. We propose that the LVZs reflect rift-related decompression melting and provide thermally buoyant support for the TAMs uplift, consistent with proposed flexural models. We also suggest that heating, and hence uplift, along the mountain front is not uniform and that the shallower LVZ beneath northern Victoria Land provides greater thermal support, leading to higher bedrock topography in the northern TAMs. Young (0-15 Ma) volcanic rocks associated with the Hallett and the Erebus Volcanic Provinces are situated directly

  11. Structure of the Crust beneath Cameroon, West Africa, from the Joint Inversion of Rayleigh Wave Group Velocities and Receiver Functions

    Energy Technology Data Exchange (ETDEWEB)

    Tokam, A K; Tabod, C T; Nyblade, A A; Julia, J; Wiens, D A; Pasyanos, M E

    2010-02-18

    The Cameroon Volcanic Line (CVL) is a major geologic feature that cuts across Cameroon from the south west to the north east. It is a unique volcanic lineament which has both an oceanic and a continental sector and consists of a chain of Tertiary to Recent, generally alkaline volcanoes stretching from the Atlantic island of Pagalu to the interior of the African continent. The oceanic sector includes the islands of Bioko (formerly Fernando Po) and Sao Tome and Principe while the continental sector includes the Etinde, Cameroon, Manengouba, Bamboutos, Oku and Mandara mountains, as well as the Adamawa and Biu Plateaus. In addition to the CVL, three other major tectonic features characterize the region: the Benue Trough located northwest of the CVL, the Central African Shear Zone (CASZ), trending N70 degrees E, roughly parallel to the CVL, and the Congo Craton in southern Cameroon. The origin of the CVL is still the subject of considerable debate, with both plume and non-plume models invoked by many authors (e.g., Deruelle et al., 2007; Ngako et al, 2006; Ritsema and Allen, 2003; Burke, 2001; Ebinger and Sleep, 1998; Lee et al, 1994; Dorbath et al., 1986; Fairhead and Binks, 1991; King and Ritsema, 2000; Reusch et al., 2010). Crustal structure beneath Cameroon has been investigated previously using active (Stuart et al, 1985) and passive (Dorbath et al., 1986; Tabod, 1991; Tabod et al, 1992; Plomerova et al, 1993) source seismic data, revealing a crust about 33 km thick at the south-western end of the continental portion of the CVL (Tabod, 1991) and the Adamawa Plateau, and thinner crust (23 km thick) beneath the Garoua Rift in the north (Stuart et al, 1985) (Figure 1). Estimates of crustal thickness obtained using gravity data show similar variations between the Garoua rift, Adamawa Plateau, and southern part of the CVL (Poudjom et al., 1995; Nnange et al., 2000). In this study, we investigate further crustal structure beneath the CVL and the adjacent regions in

  12. Investigating the subsurface connection beneath Cerro Negro volcano and the El Hoyo Complex, Nicaragua

    Science.gov (United States)

    Venugopal, Swetha; Moune, Séverine; Williams-Jones, Glyn

    2016-10-01

    Cerro Negro, the youngest volcano along the Central American Volcanic Belt (CAVB), is a polygenetic cinder cone with relatively frequent basaltic eruptions. The neighbouring El Hoyo complex, of which Las Pilas is the dominant edifice, is a much larger and older complex with milder and less frequent eruptions. Previous studies have suggested a deep link beneath these two closely spaced volcanoes (McKnight, 1995; MacQueen, 2013). Melt inclusions were collected from various tephra samples in order to determine whether a connection exists and to delineate the features of this link. Major, volatile, and trace elemental compositions reveal a distinct geochemical continuum with Cerro Negro defining the primitive endmember and El Hoyo representing the evolved endmember. Magmatic conditions at the time of melt inclusion entrapment were estimated with major and volatile contents: 2.4 kbar and 1170 °C for Cerro Negro melts and 1.3 kbar and 1130 °C for El Hoyo melts with an overall oxygen fugacity at the NNO buffer. Trace element contents are distinct and suggest Cerro Negro magmas fractionally crystallise while El Hoyo magmas are a mix between primitive Cerro Negro melts and residual and evolved El Hoyo magma. Modelling of end member compositions with alphaMELTS confirms the unique nature of El Hoyo magmas as resulting from incremental mixing between Cerro Negro and residual evolved magma at 4 km depth. Combining all available literature data, this study presents a model of the interconnected subsurface plumbing system. This model considers the modern day analogue of the Lemptégy cinder cones in Massif Central, France and incorporates structurally controlled dykes. The main implications of this study are the classification of Cerro Negro as the newest conduit within the El Hoyo Complex as well as the potential re-activation of the El Hoyo edifice.

  13. Upper mantle discontinuity beneath the SW-Iberia peninsula: A multidisciplinary view.

    Science.gov (United States)

    Palomeras, Imma; de Lis Mancilla, Flor; Ayarza, Puy; Afonso, Juan Carlos; Diaz, Jordi; Morales, Jose; Carbonell, Ramon; Topoiberia Working Group

    2010-05-01

    Evidence for an upper mantle discontinuity located between 60 and 70 km depth have been provided by different seismic data sets acquired in the Southern Iberian peninsula. First indications of such a discontinuity were obtained by the very long offsets seismic refraction shot gathers acquired within the DSS ILIHA project in the early 90's. Clear seismic events recoded by the dense wide-angle seismic reflection shot gathers of the IBERSEIS experiment (2003) provided further constraints on the depth of the discontinuity and first-order estimates of its physical properties beneath the Ossa Morena Zone. Furthermore, the normal incidence Vibroseis deep seismic reflection images of the ALCUDIA transect (2007) extends this structure to the northeast beneath the Central Iberian Zone. This transect images deep laterally discontinuous reflections at upper mantle travel times (19 s) that roughly correspond to depths within the range of 60-70 km. Receiver function studies of the passive seismic recordings acquired by the IBERARRAY (TOPOIBERIA projects) provides additional support for the existence of this upper mantle structure and suggests that this is a relatively large scale regional feature. Two major scenarios need to be addressed when discussing the origin and nature of this deep structure. One is the tectonic scenario in which the structure maybe be related to a major tectonic event such as an old subduction process and therefore represent an ancient slab. A second hypothesis, would relate this feature to a phase change in the mantle. This latter assumption requires this feature ought to be a broader scale boundary which could be identified by different seismic techniques. Reflectivity modeling carried out over the IBERSEIS wide angle reflection data concludes that the observed phase is consistent with an heterogeneous gradient zone located at, approximately, 61-72 km depth. A layered structure with alternating velocities within ranges 8.1 to 8.3 km/s is necessary in

  14. High velocity anomaly beneath the Deccan volcanic province: Evidence from seismic tomography

    Science.gov (United States)

    Iyer, H.M.; Gaur, V.K.; Rai, S.S.; Ramesh, D.S.; Rao, C.V.R.; Srinagesh, D.; Suryaprakasam, K.

    1989-01-01

    Analysis of teleseismic P-wave residuals observed at 15 seismograph stations operated in the Deccan volcanic province (DVP) in west central India points to the existence of a large, deep anomalous region in the upper mantle where the velocity is a few per cent higher than in the surrounding region. The seismic stations were operated in three deployments together with a reference station on precambrian granite at Hyderabad and another common station at Poona. The first group of stations lay along a west-northwesterly profile from Hyderabad through Poona to Bhatsa. The second group roughly formed an L-shaped profile from Poona to Hyderabad through Dharwar and Hospet. The third group of stations lay along a northwesterly profile from Hyderabad to Dhule through Aurangabad and Latur. Relative residuals computed with respect to Hyderabad at all the stations showed two basic features: a large almost linear variation from approximately +1s for teleseisms from the north to-1s for those from the southeast at the western stations, and persistance of the pattern with diminishing magnitudes towards the east. Preliminary ray-plotting and three-dimensional inversion of the P-wave residual data delineate the presence of a 600 km long approximately N-S trending anomalous region of high velocity (1-4% contrast) from a depth of about 100 km in the upper mantle encompassing almost the whole width of the DVP. Inversion of P-wave relative residuals reveal the existence of two prominent features beneath the DVP. The first is a thick high velocity zone (1-4% faster) extending from a depth of about 100 km directly beneath most of the DVP. The second feature is a prominent low velocity region which coincides with the westernmost part of the DVP. A possible explanation for the observed coherent high velocity anomaly is that it forms the root of the lithosphere which coherently translates with the continents during plate motions, an architecture characteristic of precambrian shields. The low

  15. Geophysical investigation of seepage beneath an earthen dam.

    Science.gov (United States)

    Ikard, S J; Rittgers, J; Revil, A; Mooney, M A

    2015-01-01

    A hydrogeophysical survey is performed at small earthen dam that overlies a confined aquifer. The structure of the dam has not shown evidence of anomalous seepage internally or through the foundation prior to the survey. However, the surface topography is mounded in a localized zone 150 m downstream, and groundwater discharges from this zone periodically when the reservoir storage is maximum. We use self-potential and electrical resistivity tomography surveys with seismic refraction tomography to (1) determine what underlying hydrogeologic factors, if any, have contributed to the successful long-term operation of the dam without apparent indicators of anomalous seepage through its core and foundation; and (2) investigate the hydraulic connection between the reservoir and the seepage zone to determine whether there exists a potential for this success to be undermined. Geophysical data are informed by hydraulic and geotechnical borehole data. Seismic refraction tomography is performed to determine the geometry of the phreatic surface. The hydro-stratigraphy is mapped with the resistivity data and groundwater flow patterns are determined with self-potential data. A self-potential model is constructed to represent a perpendicular profile extending out from the maximum cross-section of the dam, and self-potential data are inverted to recover the groundwater velocity field. The groundwater flow pattern through the aquifer is controlled by the bedrock topography and a preferential flow pathway exists beneath the dam. It corresponds to a sandy-gravel layer connecting the reservoir to the downstream seepage zone.

  16. PN velocity beneath Western New Mexico and Eastern Arizona

    Science.gov (United States)

    Jaksha, L. H.

    1985-01-01

    The experiment involved observing Pn arrivals on an areal array of 7 seismic stations located in the transition zone and along the Jemez lineament. Explosions in coal and copper mines in New Mexico and Arizona were used as energy sources as well as military detonations at White Sands Missile Range, New Mexico, Yuma, Arizona, and the Nevada Test Site. Very preliminary results suggest a Pn velocity of 7.94 km/s (with a fairly large uncertainty) beneath the study area. The Pn delay times, which can be converted to estimates of crustal thickness given knowledge of the velocity structure of the crust increase both to the north and east of Springerville, Arizona. As a constraint on the velocity of Pn, researchers analyzed the reversed refraction line GNOME-HARDHAT which passes through Springerville oriented NW to SE. This analysis resulted in a Pn velocity of 7.9-8.0 km/s for the transition zone. These preliminary results suggest that a normal Pn velocity might persist even though the crust thins (from north to south) by 15 km along the length of the Arizona-New Mexico border. If the upper mantle is currently hot anywhere in western New Mexico or eastern Arizona then the dimensions of the heat source (or sources) might be small compared to the intra-station distances of the seismic arrays used to estimate the velocity of Pn.

  17. Crawling beneath the free surface: Water snail locomotion

    CERN Document Server

    Lee, Sungyon; Hosoi, A E; Lauga, Eric

    2008-01-01

    Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being generated by the undulation of the snail foot that is separated from the free surface by a thin layer of mucus. Here, a lubrication model is used to describe the mucus flow in the limit of small amplitude interfacial deforma