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31.
Since 1976 groundwater-levels and the temperature of thermal water have been monitored in 100 wells distributed mostly in the southern Kanto and Tokai districts of Japan in order to predict earthquakes. Good examples of groundwater precursors were recognized prior to the following destructive earthquakes: the 1978 West Off Izu-Oshima Earthquake (M 7.0), the 1978 Off Miyagi Earthquakes (M 7.4), and the 1980 East Off Izu Peninsula Earthquake (M 6.7). In the 1978 West Off Izu-Oshima Earthquake, groundwater levels and the Japan Meteorological Agency (JMA) volume strainmeters, installed in the Izu peninsula, showed precursory changes at about the same time. In the other cases, however, precursory behavior was observed only in water level and temperature monitoring. Empirical relations are given between earthquake magnitude and the epicentral distance of the farthest groundwater anomaly, and between earthquake magnitude and the precursor time of groundwater. 相似文献
32.
Geometric modelling and object-oriented software concepts applied to a heterogeneous fractured network from the Grimsel rock laboratory 总被引:2,自引:0,他引:2
Thomas Kalbacher Ralph Mettier Chris McDermott Wenqing Wang Georg Kosakowski Takeo Taniguchi Olaf Kolditz 《Computational Geosciences》2007,11(1):9-26
Discrete fracture network simulations are computationally intensive and usually time-consuming to construct and configure.
This paper presents a case study with techniques for building a 3D finite element model of an inhomogeneous fracture network
for modelling flow and tracer transport, combining deterministic and stochastic information on fracture aperture distributions.
The complex intersected fractures represent a challenge for geometrical model design, mesh quality requirements and property
allocations. For the integrated and holistic modelling approach, including the application of numerical and analytical simulation
techniques, new object-oriented concepts in software engineering are implemented to ensure a resourceful and practicable software
environment. 相似文献
33.
Sohiko Kameyama Urumu Tsunogai Fumiko Nakagawa Motoki Sasakawa Daisuke D. Komatsu Akira Ijiri Junko Yamaguchi Takeo Horiguchi Hiroshi Kawamura Aika Yamaguchi Atsushi Tsuda 《Marine Chemistry》2009,115(1-2):92-101
During the Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study ΙΙ (SEEDS-II), we monitored variations in the concentrations of non-methane hydrocarbons (NMHCs), CH3Cl, N2O, and CH4 within a phytoplankton bloom. Stable isotopic compositions were also determined to evaluate the sources of the variations. Although there was little variation in either the concentrations or the stable isotopic compositions of alkenes, CH3Cl, N2O, and CH4 during the 23-day observation period, alkane concentrations increased substantially as the phytoplankton bloomed. The column-integrated quantities of alkanes increased to 3 times pre-bloom levels for C2H6, 5 times for C3H8, and 20 times for n-C4H10. The δ13C values of both C2H6 and C3H8 remained almost constant while concentrations increased, whereas that of n-C4H10 increased by about 12‰. To evaluate the sources of the alkanes produced during the bloom, we compared their δ13C values with those of alkanes produced in axenic phytoplankton cultures in our laboratory. We concluded that during the SEEDS-ΙΙ experiment the major portions of C2H6 and C3H8 were produced during the autolysis of diatoms cells, whereas n-C4H10 was produced during autolysis of other phytoplankton cells such as cryptophytes and dinoflagellates. 相似文献
34.
Yumi Yoshioka Kimihito Nakamura Hiroshi Takimoto Shinji Sakurai Takao Nakagiri Haruhiko Horino Takeo Tsuchihara 《水文研究》2020,34(16):3539-3554
The large volume of groundwater stored in the Tedori River alluvial fan, Ishikawa Prefecture, Japan, is an important source of local drinking and industrial water. The Tedori River was observed to be highly turbid from the beginning of May 2015 to at least November 2017 due to a landslide in the upper reach of the river. After the landslide, the groundwater level was drawn down by several to 10 m near the middle river section during paddy irrigation periods in 2015 and 2016. This study addresses the impacts of the highly turbid water on groundwater recharge from the river and paddy fields. In 2016, we sampled groundwater, river water, paddy irrigation water, paddy ponding water, and precipitation five times at 2-month intervals. We analysed the H, O, and Sr stable isotopic compositions and major dissolved ion (and Sr) concentrations and compared our data to previous data obtained in June 2011. Ca, Sr, Cl, SO4, and TN concentrations and δ18O values were higher in June 2016 than in June 2011; these increases were more extreme along the left bank of the Tedori River than along the right bank. We explored the mixing of Tedori River water with groundwater using a two-endmember mixing model based on their Sr concentrations and isotopic compositions. Compared to June 2011, mixing ratios were decreased near the Tedori River in 2016, and larger decreases were observed along the left bank and in the middle stream area. These results confirm that the contribution to groundwater recharge from the river decreased during the turbidity event, particularly along the left bank. 相似文献
35.
36.
Takeo Sakurai Jun Kobayashi Yoshitaka Imaizumi Noriyuki Suzuki 《Marine pollution bulletin》2009,58(7):1072-1077
We investigated the transfer of persistent organic pollutants (POPs) from unspiked bottom sediment to a benthic marine fish, marbled sole (Pleuronectes yokohamae), via non-food-chain pathways, i.e., via sediment particles and water column. One-year-old sole were held for 28 days in an exposure tank with bottom sediment or in a control tank. o,p′-DDE and tri- to penta-chlorobiphenyls were transferred from the sediment to the fish via non-food-chain pathways, as demonstrated by concentrations in the exposed fish at 2.5-30 times the control levels. A model analysis based on first-order kinetic equations indicated that the overall rate constant of transfer of these compounds from sediment to fish was generally lower than that from food (median of ratio, 0.48). It also suggested that relatively high concentrations of the other POPs in the food and the longer times necessary for them to reach a steady state masked any transfer of them from the sediment. 相似文献
37.
Takeo Nakagawa 《地球物理与天体物理流体动力学》2013,107(1):287-301
Abstract New periodic vortices were observed during a rotating tank experiment, to be described. The peculiarities and the formation mechanism of the present vortices are based on observations. The vortices reach the complete form in stages, viz. laminar boundary layer growth, sinuous motion and rolling oscillation. After being formed, the vortices are shed periodically and the diameter of the vortices grows as they advance. The vortices appear when the flow over the concave semicircular wall, fixed in the rotating tank, is maintained by the shear stresses at the inner surface of the rotating tank. The vortices and the flow were visualized with thymol blue dye. 相似文献
38.
In this paper, we examine the distribution of incompatible elements in Earth’s mantle based on data reported for 20 mantle
xenoliths collected from 5 localities worldwide. A structural model combined with an element partitioning model forms the
basis for our analyses. The former separates a bulk peridotite into mineral crystal lattices, interfaces (grain and interphase
boundaries), and intra- and inter-granular inclusions as sites for incompatible elements. The latter relates the distribution
of elements among these sites based on lattice strain theory. By treating both intra- and inter-granular inclusions as a melt-like
phase, the combined models successfully reproduce the relative concentrations of incompatible elements among minerals, clean
rock (reconstituted from mineral compositions and mineral mode), and whole rock. The analyses reveal common signatures in
the rocks: (1) incompatible elements in the crystal lattices of olivine, orthopyroxene and clinopyroxene achieved chemical
equilibrium. (2) Olivine, orthopyroxene and clinopyroxene grains contain similar amounts of an intra-granular, melt-like component
possibly in the form of sub-micron inclusions with weight (≈volume) fractions between 5 × 10−5 and 1 × 10−2. (3) All rocks contain an inter-granular melt-like component with a fraction between 10−4 and 10−2, well above the amount expected to be stored along interfaces. (4) Fractions of the inter- and intra-granular components
are positively correlated, indicating that they were originated from the same process. (5) The inter- and intra-granular melt-like
phases are chemically equilibrated with other structural components. Based on plausible upwelling rates for mantle xenoliths,
it is unlikely that the melt-like component formed during ascent. Instead, its ubiquitous appearance, its invisibility to
optical microscopy, and its absorption of the incompatible elements in a manner similar to a melt phase even at sub-solidus
condition, all might be explained by the presence of amorphous silica precipitates such as those observed previously in naturally
occurring and experimentally annealed mantle composites. From the mineral mode, grain size, and mineral plus whole rock concentrations
of incompatible elements, we can ascribe the chemical signatures of xenoliths to achievement of chemical equilibrium at mantle
conditions rather than to a consequence of some disequilibrium (metasomatic) effect as has been done previously. Although
it should be tested by additional analytical studies, our model will make it possible to determine whether or not a rock is
chemically equilibrated in terms of the distribution of incompatible elements or if a metasomatic (disequilibrium) event is
required. 相似文献
39.
40.
Takeo Sakurai 《Astrophysics and Space Science》1976,41(1):15-25
We give an analytic expression of the braking torque on a Jacobian ellipsoid rotating steadily in an environmental gas, based on the assumption that the ellipsoid rotates around its shortest principal axis with an angular momentum slightly larger than that at the bifurcation point of the Maclaurin spheroid. This braking torque is effected by the gravitational interaction between the ellipsoid matter and a spiral density configuration in the environmental gas. This spiral configuration, which we call a tidal acoustic wave, is caused by the zone of silence effect in a supersonic flow. With respect to a coordinates system rotating with the ellipsoid, a supersonic region appears outside a certain radius. In this supersonic region, the effect of the non-axisymmetric fluctuation in the ellipsoid potential propagates only along the downstream branches of the Mach waves. This one-sided response of the supersonic part causes the tidal acoustic wave. We restrict ourselves to the equatorial plane, and use an acoustic approximation of the basic equations under the assumption that the self-gravity effect of the environmental gas is negligible in comparison to the main gravity of the ellipsoid. The results are applied to the pre- and post-Main Sequence phases of a rotating star, and relating astrophysical problems are discussed. 相似文献