Landslide inventory using image fusion techniques in Brazil

The present work aims to assess the accuracy of six fusion techniques (Brovey, IHS, HSV, PCA, WTYO and WTVE) in order to compile landslide inventories using orbital images (ETM+ and PAN HRV). The study area is characterized by steep terrain and dense forest in Caraguatatuba, São Paulo State, Brazil. In terms of spatial quality, the Wavelet Transform technique provided the best results, presenting correlations above 90%. As for spectral quality, the best results were obtained with the IHS fusion. Based on the results, it may be concluded that the IHS is the best technique for preserving spatial and spectral information from the original images, so as to more clearly identify landslide scars. However, it was still not possible to typify the landslides from remote sensing data. Nonetheless, it is believed that image fusion techniques adequately met expectations in terms of their capacity to identify landslide for the creation of an inventory for the studied area.     

越南红河水下三角洲北区表层沉积物类型及分布特征初探

对2007年采自越南红河水下三角洲北区24个表层沉积物样品进行了粒度分析和粒度参数计算,初步探讨了该区沉积物的主要类型及分布特征。结果表明,越南红河水下三角洲北区的表层沉积物主要由粉砂组成(体积平均含量为54.35%),平均粒径为6φ。按Link沉积物命名法,该区沉积物主要类型有砂、砂质粉砂和黏土质粉砂。水平分布上,由西部的砂向东逐渐变为黏土质粉砂,呈现出由近岸三角洲前缘相的粗粒级沉积物逐渐向前三角洲-浅海相的细粒级沉积物变化的趋势。与前人研究成果对比发现,红河水下三角洲北区沉积物黏土的比例较1996年的比例明显增大,可能与海岸线近10a来总体上呈向陆迁移、水下三角洲沉积向岸蚀退以及纵向上水动力逐渐变弱有关。     

Deep slab subduction and dehydration and their geodynamic consequences: Evidence from seismology and mineral physics

We present new pieces of evidence from seismology and mineral physics for the existence of low-velocity zones in the deep part of the upper mantle wedge and the mantle transition zone that are caused by fluids from the deep subduction and deep dehydration of the Pacific and Philippine Sea slabs under western Pacific and East Asia. The Pacific slab is subducting beneath the Japan Islands and Japan Sea with intermediate-depth and deep earthquakes down to 600 km depth under the East Asia margin, and the slab becomes stagnant in the mantle transition zone under East China. The western edge of the stagnant Pacific slab is roughly coincident with the NE–SW Daxing'Anling-Taihangshan gravity lineament located west of Beijing, approximately 2000 km away from the Japan Trench. The upper mantle above the stagnant slab under East Asia forms a big mantle wedge (BMW). Corner flow in the BMW and deep slab dehydration may have caused asthenospheric upwelling, lithospheric thinning, continental rift systems, and intraplate volcanism in Northeast Asia. The Philippine Sea slab has subducted down to the mantle transition zone depth under Western Japan and Ryukyu back-arc, though the seismicity within the slab occurs only down to 200–300 km depths. Combining with the corner flow in the mantle wedge, deep dehydration of the subducting Pacific slab has affected the morphology of the subducting Philippine Sea slab and its seismicity under Southwest Japan. Slow anomalies are also found in the mantle under the subducting Pacific slab, which may represent small mantle plumes, or hot upwelling associated with the deep slab subduction. Slab dehydration may also take place after a continental plate subducts into the mantle.     

A Study Of The Atmospheric Boundary Layer Using Radon And Air Pollutants As Tracers

Concentrations of radon ²²²Rn andair pollutants, meteorological parametersnear the surface and vertical profiles of meteorological elements were measured atUchio (Okayama City, Okayama Prefecture, Japan) 12 km north from the coast ofthe Inland Sea of Japan. In the nighttime, the ²²²Rn concentration increased in the case of weak winds, but did not increase as much in the case of moderate or strong winds, as had been expected. In the daytime, the ²²²Rn concentrationheld at a slightly higher than average level for the period from sunrise to about 1100 JST. It is considered that this phenomenon is due to a period of morning calm, that is, a transition period from land breeze to sea breeze.NO, which is sensitive to traffic volume,brought information concerning advection.Oxidant concentrations,which reflect the availability of sunlight,acted in the reverse manner to ²²²Rnconcentrations. Thus, a set of ²²²Rn and air pollutants could provide useful information regarding the local conditions of the atmospheric boundary layer.     

The budget of carbon dioxide variance in the surface layer over vegetated fields

The budget equation for carbon dioxide variance can be represented by production, dissipation and flux divergence terms. Each term is measured under near neutral to moderately unstable conditions over vegetated fields. The flux divergence term is about an order of magnitude smaller than production and dissipation terms, though it shows a loss for 0.006 < _v < 1 and a gain for 1 < - _v < 10. Here, _v is the Monin-Obukhov stability parameter including humidity effect. As expected from a closure of the budget, the nondimensional production and dissipation terms are basically identical and represented by the same functional form: (1–16 _v )^–1/2.     

Phase relations in the carbon-saturated C–Mg–Fe–Si–O system and C and Si solubility in liquid Fe at high pressure and temperature: implications for planetary interiors

The phase and melting relations of the C-saturated C–Mg–Fe–Si–O system were investigated at high pressure and temperature to understand the role of carbon in the structure of the Earth, terrestrial planets, and carbon-enriched extraterrestrial planets. The phase relations were studied using two types of experiments at 4 GPa: analyses of recovered samples and in situ X-ray diffractions. Our experiments revealed that the composition of metallic iron melts changes from a C-rich composition with up to about 5 wt.% C under oxidizing conditions (ΔIW = ?1.7 to ?1.2, where ΔIW is the deviation of the oxygen fugacity (fO₂) from an iron-wüstite (IW) buffer) to a C-depleted composition with 21 wt.% Si under reducing conditions (ΔIW < ?3.3) at 4 GPa and 1,873 K. SiC grains also coexisted with the Fe–Si melt under the most reducing conditions. The solubility of C in liquid Fe increased with increasing fO₂, whereas the solubility of Si decreased with increasing fO₂. The carbon-bearing phases were graphite, Fe₃C, SiC, and Fe alloy melt (Fe–C or Fe–Si–C melts) under the redox conditions applied at 4 GPa, but carbonate was not observed under our experimental conditions. The phase relations observed in this study can be applicable to the Earth and other planets. In hypothetical reducing carbon planets (ΔIW < ?6.2), graphite/diamond and/or SiC exist in the mantle, whereas the core would be an Fe–Si alloy containing very small amount of C even in the carbon-enriched planets. The mutually exclusive nature of C and Si may be important also for considering the light elements of the Earth’s core.     

Raman spectra and X-ray diffraction of tuite at various temperatures

High-temperature Raman spectra and thermal expansion of tuite, γ-Ca₃(PO₄)₂, have been investigated. The effect of temperature on the Raman spectra of synthetic tuite was studied in the range from 80 to 973 K at atmospheric pressure. The Raman frequencies of all observed bands for tuite continuously decrease with increasing temperature. The quantitative analysis of temperature dependence of Raman bands indicates that the changes in Raman frequencies for stretching modes (ν₃ and ν₁) are faster than those for bending modes (ν₄ and ν₂) of PO₄ in the present temperature range, which may be attributed to the structural evolution of PO₄ tetrahedron in tuite at high temperature. The thermal expansion of tuite was examined by means of in situ X-ray diffraction measurements in the temperature range from 298 to 923 K. Unit cell parameters and volume were analyzed, and the thermal expansion coefficients were obtained as 3.67 (3), 1.18 (1), and 1.32 (3) × 10^?5 K^?1 for V, a, and c, respectively. Thermal expansion of tuite shows an axial anisotropy with a larger expansion coefficient along the c-axis. The isothermal and isobaric mode Grüneisen parameters and intrinsic anharmonicity of tuite have been calculated by using present high-temperature Raman spectra and thermal expansion coefficient combined with previous results of the isothermal bulk modulus and high-pressure Raman spectra.