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Träfflista för sökning "WFRF:(van Wyk K.) srt2:(2010-2014)"

Search: WFRF:(van Wyk K.) > (2010-2014)

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2.
  • Byrne, P. K., et al. (author)
  • A sagging-spreading continuum of large volcano structure
  • 2013
  • In: Geology. - 0091-7613 .- 1943-2682. ; 41:3, s. 339-342
  • Journal article (peer-reviewed)abstract
    • Gravitational deformation strongly influences the structure and eruptive behavior of large volcanoes. Using scaled analog models, we characterize a range of structural architectures produced by volcano sagging and volcano spreading. These arise from the interplay of variable basement rigidity and volcano-basement (de-)coupling. From comparison to volcanoes on Earth (La Reunion and Hawaii) and Mars (Elysium and Olympus Montes), the models highlight a structural continuum in which large volcanoes throughout the Solar System lie.
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3.
  • Byrne, P.K., et al. (author)
  • A Volcanotectonic Survey of Ascraeus Mons, Mars
  • 2011
  • In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 117
  • Journal article (peer-reviewed)abstract
    • Ascraeus Mons is one of the largest volcanoes on Mars. It is replete with well-preserved features that can be used to understand its volcanotectonic evolution. Previous studies of this volcano focused on specific features, and were limited by the quality and coverage of contemporary data. Our objective is to review and enhance the existing developmental model for Ascraeus by considering all endogenic surface features on the volcano. We surveyed the volcano's caldera complex, flank terraces, pit structures, sinuous rilles, arcuate grabens, and small vents. We report the spatial and temporal distributions of these features, appraise their proposed formation mechanisms in light of our mapping results, and propose a detailed geological history for Ascraeus Mons. An initial shield-building phase was followed by the formation of a summit caldera complex and small parasitic cones, while compression due to flexure of the supporting basement led to extensive terracing of the shield flanks. An eruptive hiatus followed, ending with the construction of expansive rift aprons to the northeast and southwest. Against later, extensive flank resurfacing in the late Amazonian, continued flexure formed arcuate grabens concentric to the edifice. Localized eruption and surface flow of a fluid agent (lava and/or water) from within the volcano then produced a population of rilles on the lower flanks. Finally, in a change of flank tectonic regime from compression to extension, pit crater chains and troughs developed on the main shield and rift aprons, eventually coalescing to form large embayments at the northeast and southwest base of the volcano.
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4.
  • Troll, Valentin, et al. (author)
  • Pre-Teide Volcanic Activity on the Northeast Volcanic Rift Zone
  • 2013
  • In: Teide Volcano. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642258923 - 9783642258930 ; , s. 75-92
  • Book chapter (peer-reviewed)abstract
    • The northeast rift zone of Tenerife (NERZ) presents a partially eroded volcanic rift that offers a superb opportunity to study the structure and evolution of oceanic rift zones. Field data, structural observations, isotopic dating, magnetic stratigraphy, and isotope geochemistry have recently become available for this rift and provide a reliable temporal framework for understanding the structural and petrological evolution of the entire rift zone. The NERZ appears to have formed in several major pulses of activity with a particularly high production rate in the Pleistocene (ca. 0.99 and 0.56 Ma). The rift underwent several episodes of flank creep and eventual catastrophic collapses driven by intense intrusive activity and gravitational adjustment. Petrologically, a variety of mafic rock types, including crystal-rich ankaramites, have been documented, with most samples isotopically typical of the “Tenerife signal”. Some of the NERZ magmas also bear witness to contamination by hydrothermally altered components of the island edifice and/or sediments. Isotope geochemistry furthermore points to the generation of the NERZ magmas from an upwelling column of mantle plume material mixed with upper asthenospheric mantle. Finally, persistent isotopic similarity through time between the NERZ and the older central edifices on Tenerife provides strong evidence for a genetic link between Tenerife’s principal volcanic episodes.
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5.
  • Wang, Haidong, et al. (author)
  • Global, regional, and national levels of neonatal, infant, and under-5 mortality during 1990-2013 : a systematic analysis for the Global Burden of Disease Study 2013
  • 2014
  • In: The Lancet. - 0140-6736 .- 1474-547X. ; 384:9947, s. 957-979
  • Journal article (peer-reviewed)abstract
    • BACKGROUND: Remarkable financial and political efforts have been focused on the reduction of child mortality during the past few decades. Timely measurements of levels and trends in under-5 mortality are important to assess progress towards the Millennium Development Goal 4 (MDG 4) target of reduction of child mortality by two thirds from 1990 to 2015, and to identify models of success.METHODS: We generated updated estimates of child mortality in early neonatal (age 0-6 days), late neonatal (7-28 days), postneonatal (29-364 days), childhood (1-4 years), and under-5 (0-4 years) age groups for 188 countries from 1970 to 2013, with more than 29 000 survey, census, vital registration, and sample registration datapoints. We used Gaussian process regression with adjustments for bias and non-sampling error to synthesise the data for under-5 mortality for each country, and a separate model to estimate mortality for more detailed age groups. We used explanatory mixed effects regression models to assess the association between under-5 mortality and income per person, maternal education, HIV child death rates, secular shifts, and other factors. To quantify the contribution of these different factors and birth numbers to the change in numbers of deaths in under-5 age groups from 1990 to 2013, we used Shapley decomposition. We used estimated rates of change between 2000 and 2013 to construct under-5 mortality rate scenarios out to 2030.FINDINGS: We estimated that 6·3 million (95% UI 6·0-6·6) children under-5 died in 2013, a 64% reduction from 17·6 million (17·1-18·1) in 1970. In 2013, child mortality rates ranged from 152·5 per 1000 livebirths (130·6-177·4) in Guinea-Bissau to 2·3 (1·8-2·9) per 1000 in Singapore. The annualised rates of change from 1990 to 2013 ranged from -6·8% to 0·1%. 99 of 188 countries, including 43 of 48 countries in sub-Saharan Africa, had faster decreases in child mortality during 2000-13 than during 1990-2000. In 2013, neonatal deaths accounted for 41·6% of under-5 deaths compared with 37·4% in 1990. Compared with 1990, in 2013, rising numbers of births, especially in sub-Saharan Africa, led to 1·4 million more child deaths, and rising income per person and maternal education led to 0·9 million and 2·2 million fewer deaths, respectively. Changes in secular trends led to 4·2 million fewer deaths. Unexplained factors accounted for only -1% of the change in child deaths. In 30 developing countries, decreases since 2000 have been faster than predicted attributable to income, education, and secular shift alone.INTERPRETATION: Only 27 developing countries are expected to achieve MDG 4. Decreases since 2000 in under-5 mortality rates are accelerating in many developing countries, especially in sub-Saharan Africa. The Millennium Declaration and increased development assistance for health might have been a factor in faster decreases in some developing countries. Without further accelerated progress, many countries in west and central Africa will still have high levels of under-5 mortality in 2030.
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