Features of Manifestation of the Chilean Tsunami on April 1, 2014, and September 16, 2015, on Russia’s Pacific Coast     

G.?V.?ShevchenkoEmail author  A.?V.?Loskutov  A.?A.?Shishkin  T.?N.?Ivel’skaya 《Oceanology》2017,57(6):870-879

As a result of mooring of autonomous seabed stations in bays of Shikotan Island, the records of two tsunamis were obtained from strong earthquakes that occurred off the coast of Chile on April 1, 2014, and September 16, 2015. In both cases, prolonged intense vibrations with a pronounced group structure were observed in various bays, mainly with periods of the main modes of resonance oscillations. The second event was more dangerous, and the wave height was 0.9 m at Malokurilskaya Bay. The increase in the energy of fluctuations in 2015 was more significant, manifesting itself in a wider range of periods. Numerical simulation of the tsunami showed that the nature of wave propagation in both earthquakes was identical in the northern part of the Pacific Ocean, approaching Russia’s Pacific coast, and was characterized by weak damping, in contrast to waves propagating to the south and southwest. This explains why expect large waves can be expected on the coasts of the Kurils from earthquakes off the coast of South America, despite the considerable distance.  相似文献   

Rapid generation of Digital Elevation Models from topographic maps     

Lars Eklundh  Ulrik Mårtensson 《International journal of geographical information science》2013,27(3):329-340

Abstract

In this article we demonstrate that substantial gains in time can be made when using point sampling rather than contour line digitising for generation of Digital Elevation Models (DEMs). A simple sampling scheme, based on regularly distributed points, was used supplemented with points near break-lines in the terrain. An evaluation of surfaces created with three different interpolation methods at three different resolutions shows that the statistical distribution was better when using points as opposed to contours, and that the accuracy was comparable despite the much smaller amount of input data.  相似文献   

The legacy of crystal-plastic deformation in olivine: high-diffusivity pathways during serpentinization   总被引：1，自引：1，他引：0  

Oliver Plümper  Helen E. King  Christian Vollmer  Quentin Ramasse  Haemyeong Jung  Håkon Austrheim 《Contributions to Mineralogy and Petrology》2012,163(4):701-724

Crystal-plastic olivine deformation to produce subgrain boundaries composed of edge dislocations is an inevitable consequence of asthenospheric mantle flow. Although crystal-plastic deformation and serpentinization are spatio-temporally decoupled, we identified compositional readjustments expressed on the micrometric level as a striped Fe-enriched ( [`(X)]<sub>\textFe</sub> \bar{X}_{\text{Fe}}  = 0.24 ± 0.02 (zones); 0.12 ± 0.02 (bulk)) or Fe-depleted ( [`(X)]_\textFe \bar{X}_{\text{Fe}}  = 0.10 ± 0.01 (zones); 0.13 ± 0.01 (bulk)) zoning in partly serpentinized olivine grains from two upper mantle sections in Norway. Focused ion beam sample preparation combined with transmission electron microscopy (TEM) and aberration-corrected scanning TEM, enabling atomic-level resolved electron energy-loss spectroscopic line profiling, reveals that every zone is immediately associated with a subgrain boundary. We infer that the zonings are a result of the environmental Fe²⁺Mg₋₁ exchange potential during antigorite serpentinization of olivine and the drive toward element exchange equilibrium. This is facilitated by enhanced solid-state diffusion along subgrain boundaries in a system, which otherwise re-equilibrates via dissolution-reprecipitation. Fe enrichment or depletion is controlled by the silica activity imposed on the system by the local olivine/orthopyroxene mass ratio, temperature and the effect of magnetite stability. The Fe-Mg exchange coefficients K_\textD^{\textAtg/\textOl} K_{\text{D}}^{{{\text{Atg}}/{\text{Ol}}}} between both types of zoning and antigorite display coalescence toward exchange equilibrium. With both types of zoning, Mn is enriched and Ni depleted compared with the unaffected bulk composition. Nanometer-sized, heterogeneously distributed antigorite precipitates along olivine subgrain boundaries suggest that water was able to ingress along them. Crystallographic orientation relationships gained via electron backscatter diffraction between olivine grain domains and different serpentine vein generations support the hypothesis that serpentinization was initiated along olivine subgrain boundaries.  相似文献   

From Fish to Jellyfish in the Eutrophicated Limfjorden (Denmark)     

Hans Ulrik Riisgård  Per Andersen  Erik Hoffmann 《Estuaries and Coasts》2012,35(3):701-713

The heavily eutrophicated Limfjorden (Denmark) provides a good illustration of the value of long-term monitoring, especially if this is combined with an experimental, interdisciplinary research approach. Here, we first give a short overview of the environmental status of Limfjorden, including the historical development of nutrient overloading and subsequent oxygen depletion in near-bottom water, and how the annual landings of edible bottom-dwelling fish species (plaice, flounder, eel and others) caught in Limfjorden have decreased from about 2,500 t in the early 1920s to only about 20 t in recent years where the fish have been replaced by an increasing number of especially the moon jellyfish, Aurelia aurita, which mainly preys on zooplankton. Next, we evaluate the ecological consequences of the present high number of jellyfish, based on data from recent years’ research on the abundance of jellyfish, their population dynamics and predation impact. In Limfjorden, the benthic polyp stage of A. aurita ensures a large number of small ephyrae in the early spring and subsequently a large population of adult medusae that control the zooplankton during summer and autumn. The holopelagic invasive ctenophore Mnemiopsis leidyi, which was observed in Limfjorden for the first time in 2007, is a second carnivore adding additional predation pressure of the indigenous A. aurita so that copepods and other mesozooplankton organisms may be virtually absent, as observed in 2008 and 2009 where ciliates made up a substantial part of the zooplankton biomass. Marine environmental management programmes should be aware of the increasing importance of both indigenous and new invasive jellyfish species that may show mass occurrence in especially eutrophicated and over-fished areas.  相似文献   

A new Ordovician eurypterid (Arthropoda: Chelicerata) from southeast Turkey: Evidence for a cryptic Ordovician record of Eurypterida     

James C. Lamsdell  İzzet Hoşgör  Paul A. Selden 《Gondwana Research》2013,23(1):354-366

A new species of eurypterid, Paraeurypterus anatoliensis gen. et sp. nov., is described from the Upper Ordovician (Katian) ?ort Tepe Formation of southeast Turkey. The single specimen, preserving the carapace, mesosoma and fragments of appendages, appears morphologically intermediate between the eurypteroid families Dolichopteridae and Eurypteridae. P. anatoliensis retains the plesiomorphic conditions of crescentic eyes with enlarged palpebral lobes and a quadrate carapace with ornamentation consisting of small pustules but also displaying the derived characteristics of genal facets and a row of large acicular scales across the posterior of each tergite. Phylogenetic analysis incorporating each of the major eurypterine clades and all Eurypterina having a three-segmented genital operculum (the triploperculate condition) resolves eurypteroids to be an unnatural group, with Dolichopteridae and Eurypteridae forming part of a grade leading to diploperculate Eurypterina. P. anatoliensis is intermediate between the two eurypteroid families, as is ‘Eurypterus’ minor from the Pentland Hills of Scotland, which is shown to be a distinct genus and assigned to Pentlandopterus gen. nov. Using the phylogenetic topology to infer ghost ranges for each of the major eurypterid clades reveals that the majority of eurypterid superfamilies must have originated by the Katian, indicating a largely unsampled record of Ordovician eurypterids. The occurrence of poor dispersers such as Paraeurypterus in the Ordovician of Gondwana is puzzling, and it has been suggested that they dispersed to the continent during periods of sea level lowstand in the Sandbian and Hirnantian, however this does not explain the lack of Ordovician species in North America and Europe, given the well-sampled nature of these continents, and an alternative is proposed whereby eurypterids originated in Gondwana and radiated out to Laurentia and Baltica in the late Ordovician and early Silurian, thus explaining their sudden appearance in the European and North American rock record.  相似文献   

Metal dynamics in an Antarctic food chain     

Nygård T  Lie E  Røv N  Steinnes E 《Marine pollution bulletin》2001,42(7):598-602

The concentrations of copper, zinc, cadmium, selenium and mercury were determined in eggs, muscle, liver, kidney and stomach content of nestilings and adults of the Antarctic petrel, Thalassoica antarctica, and its predator, the south polar skua, Chataracta maccormicki, from Svarthamaren, Dronning Maud Land, Antarctica. The dominant food of the petrels is krill, Euphausia superba. The results show relatively high levels of cadmium in krill, which is assumed to be the main reason for the high levels of cadmium in petrels and skuas. Cadmium is almost absent in eggs, but accumulates very rapidly with age in nestlings. The copper concentrations in livers of nestling petrels reach very high levels during growth. This may be seen in connection with physiological development processes. Mercury seems to be accumulated with age and between trophic levels. Among the nestlings, the mercury levels decrease with increasing age, which may be accomplished by the excretion of mercury through the growth of feathers and as a dilution effect during growth. Selenium and mercury are inversely correlated in nestlings. The levels of zinc were similar for different nestling stages and between nestlings and adults in skuas and petrels.  相似文献   

Boron substitution in diopside evaluated through 11B nuclear reaction analysis     

U. Hålenius  P. Kristiansson  H. Skogby 《Physics and Chemistry of Minerals》2000,27(10):681-688

 Nuclear reaction analyses on boron in flux-grown Me³⁺- and Na⁺-doped diopside crystals utilising the ¹¹B(p,2α)⁴He reaction in conjunction with EMP analyses for major elements and optical absorption spectroscopy for determination of Me-valence state distributions show that appreciable amounts of B may enter the diopside lattice in crystals produced in Na₂B₄O₇ fluxes. The results indicate that the substitution ^[6]Me^3+[4]B^3+[6]Mg²⁺ ₋₁ ^[4]Si⁴⁺ ₋₁ operates in the present diopside samples in addition to the coupled substitution ^[6]Me^3+[8]Na^+[6]Mg²⁺ ₋₁ ^[8]Ca²⁺ ₋₁. The specific NRA technique applied allows for quantitative, high resolution (ca. 5 μm) B analyses at ppm level as well as high-resolution and high-contrast imaging of B-concentration patterns in minerals. The estimated detection limit and relative error of the B analyses are 10 ppm and 5–10%, respectively. Received: 20 September 1999 / Accepted: 6 June 2000  相似文献   

A review of various factors influencing the stable carbon isotope ratio of organic lake sediments by the change from glacial to post-glacial environmental conditions     

Sören Håkansson 《Quaternary Science Reviews》1985,4(2):135-146

A survey is made of various factors influencing the ${}^{13}\text{C}{}^{12}\text{C}$ ratio of the organic component in lake sediments, focusing on the behaviour at the change from glacial to post-glacial environmental conditions.Increase in the ¹³C content of the organic sediment is caused by increase in temperature and the corresponding decrease of the supply of molecular CO₂ in the water of the lakes. An increase in the rate of organic production in the lakes may also, perhaps, cause a corresponding ¹³C increase. An increase of the fermentation of organic mud in the lakes may also have an effect in the same direction.Decrease in the ¹³C content of the organic sediment is caused by the change of the relative amounts of production of plankton and submersed macrophytes in the lakes from mainly submersed macrophytes to mainly plankton. A decrease towards almost complete absence of bicarbonate and CO₂ originating from carbonate rocks will also lead to a ¹³C decrease in the organic sediments. The same effect has the change of the terrestrial vegetation cover from almost complete absence to complete cover. A possible decrease of the ¹³C content in the atmospheric CO₂ has an effect in the same direction.  相似文献   

西藏柯月锌多金属矿床地质特征及成矿时代初步研究   总被引：2，自引：1，他引：1  

林彬  唐菊兴  郑文宝  王艺云  高一鸣  林鑫  杨欢欢  冷秋锋  李晓童  唐晓倩  付燕刚 《矿床地质》2016,35(1):33-50

柯月锌多金属矿床是北喜马拉雅锑金多金属成矿带上新发现的重要矿床。矿体主要呈脉状、透镜状产于近南北向张扭性断裂中,金属矿物主要有方铅矿、闪锌矿、辉锑矿、脆硫锑铅矿、硫锑铅矿、黄铁矿、毒砂、黄铜矿等,非金属矿物主要有石英、铁锰碳酸盐、方解石等。矿石组构以热液充填交代成因为主。流体包裹体初步研究表明,包裹体以液体包裹体为主,还有少量纯气体和纯液体包裹体。成矿流体为中低温、中低盐度、低密度H2O-Na Cl体系。流体中气液成分以H2O为主,液相中局部含有少量的HCO-3、CO2-3和CO2,气相中局部有少量CO2、CH4、N2。根据含矿石英脉中绢云母40Ar-39Ar定年,准确限定柯月矿床成矿热液活动的时限为21.3 Ma。矿床地质特征表明,柯月为中低温热液脉状锌多金属矿床,是后碰撞造山成矿作用的产物。  相似文献   

Detecting climate adaptation with mobile network data in Bangladesh: anomalies in communication,mobility and consumption patterns during cyclone Mahasen     

Xin Lu  David J. Wrathall  Pål Roe Sundsøy  Md. Nadiruzzaman  Erik Wetter  Asif Iqbal  Taimur Qureshi  Andrew J. Tatem  Geoffrey S. Canright  Kenth Engø-Monsen  Linus Bengtsson 《Climatic change》2016,138(3-4):505-519

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