Nickel content of basaltic magmas: identification of primary magmas and a measure of the degree of olivine fractionation   总被引：4，自引：0，他引：4  

Hiroaki Sato 《Lithos》1977,10(2):113-120

Available NiO analyses of olivine in peridotites of probable mantle origin are consistent in giving values around 0.40 weight per cent. Assuming that basaltic magma forming from the mantle was in equilibrium with such peridotitic olivine, the NiO content of primary basaltic magmas is estimated to be about 0.030–0.050 weight per cent. The fractionation behaviour of nickel in basaltic magma due to the crystallization of olivine has been calculated using constant NiMg and FeMg exchange partition coefficients between olivine and magma. It is shown that the NiO content of both magma and olivine decreases by 50 per cent after fractional crystallization of 6–12 per cent of olivine. The nickel distribution in some basaltic rocks and olivines is examined in the light of these results, and it is suggested that basaltic magmas, such as some of the ocean-floor basalt and the Hawaiian tholeiite and alkali basalts, represent primary magmas from mantle peridotites.  相似文献   

Towards an integrated management framework for emerging disaster risks in Japan   总被引：2，自引：1，他引：1  

Saburo Ikeda  Teruko Sato  Teruki Fukuzono 《Natural Hazards》2008,44(2):267-280

An integrated framework for disaster risk management is presented to cope with the risk of low-probability high-consequence (LPHC) disasters in urban communities. Since the 2000 Tokai flood in Japan, there has been a shift in the management strategy from disaster prevention with a presumed zero risk to disaster reduction with an acceptable risk. The framework consists of: (i) integration of a different categories of risk reduction options in terms of structural and nonstructural measures, regulation and market-oriented measures, (ii) strengthening of the capacity of local communities to make their own management choices for LPHC-type disaster risks, and (iii) promoting the participation of stakeholders throughout the entire cycle of risk management. The interdisciplinary framework is discussed with reference to lessons learned from two recent major flood disasters (the 2000 Tokai flood and the 2004 Niigata flood). To implement the goals of the integrated framework, a participatory platform for disaster risk communication called “Pafrics” has been developed. Preliminary results of the pilot study of participation and risk communication supported by Pafrics are presented.  相似文献   

Nonlinear response of surface soil and NTT building due to soil–structure interaction during the 1995 Hyogo-ken Nanbu (Kobe) earthquake     

T. Inaba  H. Dohi  K. Okuta  T. Sato  H. Akagi 《Soil Dynamics and Earthquake Engineering》2000,20(5-8):289-300

The 1995 Hyogo-ken Nanbu (Kobe) earthquake brought about enormous damage to structures in the Hanshin and Awaji areas. In this paper the importance of investigating the relationship between ground motion and structural damage is pointed out.

Strong seismic motion was observed at the NTT (Nippon Telegraph and Telephone) Building during this earthquake. The structural damage to this building was relatively slight. In order to evaluate the relationship between ground motion and structural damage, it is necessary to assess the effects of the soil–structure interaction. In this study, the seismic response of the building and of the surface soil were evaluated by means of a nonlinear soil–structure interaction analysis using FEM.

It was found that, the nonlinearity of surface soil near the building had a great effect on the soil–structure interaction, especially the rocking of the building.  相似文献   

ASTE observations of the massive-star forming region Sgr B2: a giant impact scenario     

Tetsuo Hasegawa  Takaaki Arai  Nobuyuki Yamaguchi  Fumio Sato 《Astrophysics and Space Science》2008,313(1-3):91-94

We report mapping observations of a 35 pc × 35 pc region covering the Sgr B2 molecular cloud complex in the ¹³CO (3-2) and the CS (7-6) lines using the ASTE 10 m telescope with high angular resolution. The central region was mapped also in the C¹⁸O (3-2) line. The images not only reproduce the characteristic structures noted in the preceding millimeter observations, but also highlight the interface of the molecular clouds with a large velocity jump of a few tens of km s⁻¹. These new results further support the scenario that a cloud–cloud collision has triggered the formation of massive cloud cores, which form massive stars of Sgr B2. Prospects of exciting science enabled by ALMA are discussed in relation to these observations.  相似文献   

Activities of Parent Comets and Related Meteor Showers     

Jun-Ichi Watanabe  Mikiya Sato 《Earth, Moon, and Planets》2008,102(1-4):111-116

The activity of a meteor shower is thought to be proportional to the activities through time of the parent comet. Recent applications of the dust trail theory provide us not only with a new method to forecast the occurrences and intensities of shower activities, but it is also offers a new approach to explore the history of past activities of the parent comet by retro-tracking its associated meteor showers. We introduce the result of an effort for relating meteor shower activities to the parent comet activities for which we chose the October Draconids and comet 21P/Giacobini-Zinner in this paper.  相似文献   

Variations in stress and driving pore fluid pressure ratio using vein orientations along megasplay faults : Example from the Nobeoka Thrust,Southwest Japan          下载免费PDF全文

Makoto Otsubo  Ayumu Miyakawa  Ryoji Kawasaki  Katsushi Sato  Asuka Yamaguchi  Gaku Kimura 《Island Arc》2016,25(6):421-432

The Nobeoka Thrust of Southwest Japan is an on‐land example of an ancient megasplay fault that provides an excellent record of deformation and fluid flow at seismogenic depths. The present study reports: (i) temporal stress changes for the seismogenic period of the Nobeoka Thrust; and (ii) spatial heterogeneities in driving pressure ratios P* obtained from mineral veins around the Nobeoka Thrust fault zone. Many quartz veins that filled mode I cracks can be observed in the hanging wall and footwall of the thrust. Inversion for stress orientation suggests that normal faulting dominated in both the hanging wall and footwall, with similar stress axis orientations in both. The orientation of σ₃ for the estimated stress regime is parallel to the slip direction of the Nobeoka Thrust. The detected normal‐faulting‐type stress regimes likely resulted from post‐seismic stress buildup after megathrust earthquakes. The hanging wall of the Nobeoka Thrust has smaller P* values than the footwall. Two possible explanations are proposed for the observed spatial variations in the driving pore fluid pressure ratio, P*: spatial variations in pore fluid pressure P_f are directly responsible for P* variations, or P* variations are controlled by differences in mechanical properties between the hanging wall and footwall.  相似文献   

Numerical model of local scour considering the unsteady sediment inflow and sediment sorting: Application to scour upstream of slit weir     

Kazuyuki Ota  Takahiro Sato  Ryosuke Arai 《国际泥沙研究》2022,37(4):469-483

The current study proposes a novel framework for the numerical model for estimating the temporal scour considering unsteady sediment inflow and the sediment sorting process. The framework was applied to local scour upstream of a slit weir. The scour model is based on an ordinary nonlinear differential equation derived from sediment continuity and scour rate equations. A one-dimensional(1-D)Boussinesq-type model coupled with nonequilibrium sediment transport was incorporated in the scour model to...  相似文献   

Interhemispheric observations of field line resonance frequencies as a continuous function of ground latitude in the auroral zones     

S. Takasaki  N. Sato  A. Kadokura  H. Yamagishi  H. Kawano  Y. Ebihara  Y.-M. Tanaka 《Polar Science》2008,2(2):73-86

In the austral summer of 2006–2007, the 48th Japanese Antarctic Research Expedition (JARE-48) installed two unmanned low-power magnetometers to form a closely spaced magnetometer network in combination with the permanent sites at Japan's Syowa Station in Antarctica. To identify field line resonances (FLRs), gradient methods are applied to the data from three adjacent sites in Antarctica and data from conjugate points in Antarctica and Iceland. By analyzing the data from the Antarctic and Icelandic sites individually, the structure of FLRs with high coherence is clearly identified. However, by analyzing the data from closely spaced Antarctic sites, it is more difficult to identify the signature of FLRs because of the inclusion of multiple signals related to the local geomagnetic pulsations over a broad frequency range. The frequency and resonance width of FLRs are determined by applying the amplitude phase gradient method (APGM) to the data from Antarctic sites. This yields the eigenfrequency as a continuous function of ground latitudes in the area surrounding Syowa Station. The mass density in the equatorial region at the L of the auroral zones is estimated from the obtained FLR frequency by numerically solving the standing Alfvén wave equation. The mass density thus obtained is consistent with observational results from previous in situ measurements by spacecraft. The results of the present study demonstrate that data from geomagnetic conjugate points are helpful in identifying FLR in cases in which the magnetometers are too close to each other to enable identification. Once FLR is identified, APGM can be applied to the identified FLR, yielding the FLR frequency as a continuous function of ground latitudes. Therefore, the magnetospheric equatorial mass density is readily estimated with high spatial resolution.  相似文献   

Synoptic distribution of dayside aurora: Multiple-wavelength all-sky observation at Yellow River Station in Ny-Ålesund,Svalbard     

Z.-J. Hu  H. Yang  D. Huang  T. Araki  N. Sato  M. Taguchi  E. Seran  H. Hu  R. Liu  B. Zhang  D. Han  Z. Chen  Q. Zhang  J. Liang  S. Liu 《Journal of Atmospheric and Solar》2009,71(8-9):794-804

Observations acquired from three-wavelength (427.8, 557.7 and 630.0 nm) all-sky imagers (ASIs) at Yellow River Station (YRS) in Ny-Ålesund, Svalbard, are used to examine the synoptic distribution of dayside aurora. The results demonstrate that the maximum emission regions (MERs) at each wavelength are all located in the postnoon sector, but have rather different magnetic local time (MLT) distributions from each other. The so-called 15 MLT “hot spot” is the overlapping region of the MERs at three wavelengths, and the prenoon “warm spot” is characterized uniquely by an increase of emissions at the 557.7 nm wavelength. The detailed dayside auroral spectra and morphology as a function of MLT are discussed.  相似文献   

Non-destructive monitoring of trace element levels in short-tailed albatrosses (Phoebastria albatrus) and black-footed albatrosses (Phoebastria nigripes) from Torishima Island, Japan using eggs and blood     

Ikemoto T  Kunito T  Tanabe S  Tsurumi M  Sato F  Oka N 《Marine pollution bulletin》2005,51(8-12):889-895

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl and Pb) were determined in abandoned eggs of short-tailed albatrosses and abandoned eggs and blood of black-footed albatrosses from Torishima Island, Japan in 2002. Mercury concentration was highest among the toxic elements in egg content of both the two species. In some egg contents of black-footed albatrosses, Hg concentrations were higher than the threshold level that may cause decreased hatchability and aberrant nesting behavior in some avian species. Concentrations of Cd in egg content and Ba in egg content and shell increased with an increase in egg breadth/length ratio, whereas Hg in egg content showed an opposite trend in black-footed albatrosses. Since egg breadth/length ratio is known to increase with the age of mother bird, this result may imply that concentrations of these elements in eggs vary with age of mother bird. In blood of black-footed albatross chicks, concentration of Hg was highest among the toxic elements and the Hg concentration showed an increase in the later growth stages. In contrast, concentration of Sr in blood decreased with growth stage. Since the behaviour of Sr is similar to that of Ca in animals, it is conceivable that Sr was used along with Ca for the formation of bone.  相似文献