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91.
92.
Manuela Uhlmann Oliver Korup Christian Huggel Luzia Fischer Jeffrey S. Kargel 《地球表面变化过程与地形》2013,38(7):675-682
The ongoing debate over the effects of global environmental change on Earth's cryosphere calls for detailed knowledge about process rates and their variability in cold environments. In this context, appraisals of the coupling between glacier dynamics and para‐glacial erosion rates in tectonically active mountains remain rare. We contribute to filling this knowledge gap and present an unprecedented regional‐scale inventory of supra‐glacial sediment flux and hillslope erosion rates inferred from an analysis of 123 large (> 0·1 km2) catastrophic bedrock landslides that fell onto glaciers in the Chugach Mountains, Alaska, as documented by satellite images obtained between 1972 to 2008. Assuming these supra‐glacial landslide deposits to be passive strain markers we infer minimum decadal‐scale sediment yields of 190 to 7400 t km–2 yr–1 for a given glacier‐surface cross‐section impacted by episodic rock–slope failure. These rates compare to reported fluvial sediment yields in many mountain rivers, but are an order of magnitude below the extreme sediment yields measured at the snouts of Alaskan glaciers, indicating that the bulk of debris discharged derives from en‐glacial, sub‐glacial or ice‐proximal sources. We estimate an average minimum para‐glacial erosion rate by large, episodic rock–slope failures at 0·5–0·7 mm yr–1 in the Chugach Mountains over a 50‐yr period, with earthquakes likely being responsible for up to 73% of this rate. Though ranking amongst the highest decadal landslide erosion rates for this size of study area worldwide, our inferred rates of hillslope erosion in the Chugach Mountains remain an order of magnitude below the pace of extremely rapid glacial sediment export and glacio‐isostatic surface uplift previously reported from the region. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
93.
We present direct observations of Mars zonal wind velocities around northern spring equinox (LS = 336°, LS = 355°, LS = 42°) during martian year 27 and 29. Data was acquired by means of infrared heterodyne spectroscopy of CO2 features at 959.3917 cm?1 (10.4232 μm) and 957.8005 cm?1 (10.4405 μm) using the Cologne Tuneable Heterodyne Infrared Spectrometer (THIS) at the McMath–Pierce telescope of the National Solar Observatory on Kitt Peak in Arizona and the NASA Infrared Telescope Facility on Mauna Kea, Hawaii between 2005 and 2008. Winds were measured on the dayside of Mars with an unprecedented spatial resolution allowing sampling of up to nine independent latitudes over the martian disk. Retrieved wind velocities depend strongly on latitude and season with values ranging from 180 m/s prograde to ?94 m/s retrograde. A comparison of the observational results to predicted values from the Mars Climate Database yield a reasonable agreement between modeling and observation. 相似文献
94.
Quantitative methods for estimating flood fatalities: towards the introduction of loss-of-life estimation in the assessment of flood risk 总被引:1,自引:0,他引:1
Risk, including flood risk, can be defined as ??the combination of the probability of an event and its consequences??. Assessing and managing the risk from flooding should explicitly include the estimation of impacts to people. Extensive research is currently ongoing looking at both quantitative and qualitative approaches for assessing flood impacts on people. Although there is some literature available on such approaches, examples of methodological and routinely applications of these methodologies as part of flood risk assessments are rare. This paper focuses on quantitative approaches for estimating impacts of flooding to people, notably on methods for assessing fatality numbers associated with flooding. Three methods for assessing losses of life are discussed in detail. The methods discussed here constitute the forefront of research in Canada, UK and The Netherlands. These methods provide an assessment of the physical consequences of flooding on people and can be used to introduce the impacts to people as quantitative metric for the assessment of flood risk. In this paper, the three methodologies are discussed and applied in a UK case study reproducing the 1953 East Coast flood event. This study aims to provide a comprehensive comparison on both the reliability and the applicability of the methods. We analyse possible added values on using of these methods in systematic analyses, aiming to provide guidelines for applying these methods for flood fatality risk assessment. 相似文献
95.
Mark A. Sephton Rachael H. James Manuela A. Fehr Philip A. Bland Matthieu Gounelle 《Meteoritics & planetary science》2013,48(5):872-878
Hydrothermal processing on planetesimals in the early solar system produced new mineral phases, including those generated by the transformation of anhydrous silicates into their hydrated counterparts. Carbonaceous chondrites represent tangible remnants of such alteration products. Lithium isotopes are known to be responsive to aqueous alteration, yet previously recognized variability within whole rock samples from the same meteorite appears to complicate the use of these isotopes as indicators of processing by water. We demonstrate a new way to use lithium isotopes that reflects aqueous alteration in carbonaceous chondrites. Temperature appears to exert a control on the production of acetic acid‐soluble phases, such as carbonates and poorly crystalline Fe‐oxyhydroxides. Temperature and degree of water‐rock interaction determines the amount of lithium isotope fractionation expressed as the difference between whole rock and acetic acid‐leachable fractions. Using these features, the type 1 chondrite Orgueil (δ7Li(whole rock) = 4.3‰; Δ7Li(acetic‐whole) = 1.2‰) can be distinguished from the type 2 chondrites Murchison (δ7Li(whole rock) = 3.8; Δ7Li(acetic‐whole) = 8.8‰) and carbonate‐poor Tagish Lake (δ7Li(whole rock) = 4.3; Δ7Li(acetic‐whole) = 9.4‰). This initial study suggests that lithium isotopes have the potential to reveal the role of liquid water in the early solar system. 相似文献
96.
Combined Earth orientation parameters based on homogeneous and continuous VLBI and GPS data 总被引:1,自引:3,他引:1
Daniela Thaller Manuela Krügel Markus Rothacher Volker Tesmer Ralf Schmid Detlef Angermann 《Journal of Geodesy》2007,81(6-8):529-541
The CONT02 campaign is of great interest for studies combining very long baseline interferometry (VLBI) with other space-geodetic
techniques, because of the continuously available VLBI observations over 2 weeks in October 2002 from a homogeneous network.
Especially, the combination with the Global Positioning System (GPS) offers a broad spectrum of common parameters. We combined
station coordinates, Earth orientation parameters (EOPs) and troposphere parameters consistently in one solution using technique-
specific datum-free normal equation systems. In this paper, we focus on the analyses concerning the EOPs, whereas the comparison
and combination of the troposphere parameters and station coordinates are covered in a companion paper in Journal of Geodesy. In order to demonstrate the potential of the VLBI and GPS space-geodetic techniques, we chose a sub-daily resolution for
polar motion (PM) and universal time (UT). A consequence of this solution set-up is the presence of a one-to-one correlation
between the nutation angles and a retrograde diurnal signal in PM. The Bernese GPS Software used for the combination provides
a constraining approach to handle this singularity. Simulation studies involving both nutation offsets and rates helped to
get a deeper understanding of this singularity. With a rigorous combination of UT1–UTC and length of day (LOD) from VLBI and
GPS, we showed that such a combination works very well and does not suffer from the systematic effects present in the GPS-derived
LOD values. By means of wavelet analyses and the formal errors of the estimates, we explain this important result. The same
holds for the combination of nutation offsets and rates. The local geodetic ties between GPS and VLBI antennas play an essential
role within the inter-technique combination. Several studies already revealed non-negligible discrepancies between the terrestrial
measurements and the space-geodetic solutions. We demonstrate to what extent these discrepancies propagate into the combined
EOP solution. 相似文献
97.
Manuela Lodemann Peter Fritz Manfred Wolf Miro Ivanovich Bent T. Hansen Eckehart Nolte 《Applied Geochemistry》1997,12(6):831-849
Highly saline fluids were encountered during the German Continental Deep Drilling Project (KTB) from depths ranging between 2 and 3 km to about 9 km. The most reliable data were obtained from samples extracted during a long-term pumping test in the 4000-m deep KTB pilot hole. Some 460 m3 CaNaCl brines with about 68 g l−1 total dissolved solids (TDS) and some 270 m3 associated gases, mainly N2 and CH4 were pumped to the surface from the main fracture system situated near the bottom of the pilot hole. Geochemical and isotopic data support the hydraulic tests which suggest the presence of an open and large fluid reservoir at depth. The pumped fluids from this main fracture system were released from a deep reservoir situated at more than 5500 m depth which is hydraulically connected with the 9101 m deep KTB main hole, drilled some 250 m to the northeast of the pilot hole.While Ca and Sr contents of the extracted brines may be the result of water-rock interaction, Cl is most likely of external origin. The Cl is hypothesized to derive from geotectonic processes rather than to descending infiltration of paleo-seawater (evaporitic brines). The sampled fluids have probably migrated from a deeper reservoir to their present position since the Cretaceous-Tertiary period due to tectonic activity. However, several isotopic studies have identified an admixture of descending paleowaters down to more than 4000 m depth. The high 36ClCl ratio of the fluids sampled during the long-term pumping test point to a host rock highly enriched in UTh, unlike the sampled KTB country rocks. The fluid reservoir is believed to be in contact with the Falkenberg granite massif situated about 2 km to the E of the KTB holes capable of supplying sufficient neutron flux for considerable subsurface production of 36C1. The NaCl(K, SO4) precursor fluids of the CaNaCI brines were produced in the course of extensive tectonic processes since the Late Caledonian within the Bohemian Massif. 相似文献
98.
dos Santos Marinalva Martins da Silva Ricardo Siqueira Soares Marcus Alvarenga Lopes Érika Manuela Gonçalves Shabani Farzin 《Theoretical and Applied Climatology》2022,149(1-2):401-411
Theoretical and Applied Climatology - This study aimed to identify the global risk of invasion and establishment of Bedellia somnulentella, a pest of the sweet potato crop, for the present and... 相似文献
99.
Vincenzo Pane Diego Bellavita Manuela Cecconi Alessia Vecchietti 《Geotechnical and Geological Engineering》2017,35(2):765-780
The paper presents a methodology aimed at reducing—or even avoiding—the risk of heave and uplift failures of reinforced concrete diaphragm walls. The method is based on the simple concept of increasing the drainage capacity of the embedded portion of the retaining walls. The behaviour of a strutted excavation in a cohesionless soil below groundwater is examined by means of two distinct series of numerical analyses, respectively focused on the hydraulic and mechanical behaviour of the retaining system. It is shown that, for some frequent cases, such methodology is capable to improve the safety of the retaining system with respect to both hydraulic and geotechnical limit states. 相似文献
100.
Daniel Silva Leite Leonardo Sandrini-Neto Manuela Zeglin Camargo Micheli Cristina Thomas Paulo C. Lana 《Marine pollution bulletin》2014
This study assesses through a multiple before-after-control-impact (MBACI) design the effects of diesel oil on the structure of nematode assemblages in unvegetated tidal flats of a subtropical estuary. Oil-exposed treatments were contrasted with controls for a duration of four successive days before and after an experimental spill in three distinct areas of the Paranaguá Estuarine Complex (Southern Brazil). No significant differences were observed in nematode total density, number of taxa and the overall assemblage structure between the control and impact treatments from before to after the experimental spill. This reinforces the idea that, despite being good indicators of environmental stress, free-living marine nematodes are able to tolerate low concentrations of hydrocarbons and to survive in moderately contaminated areas. We also show that robust experimental designs are useful to avoid confounding expected natural variability with the effects of a mild impact. 相似文献