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11.
Electromagnetic anomalies associated with 1995 Kobe earthquake 总被引：1，自引：0，他引：1
T. Nagao Y. Enomoto Y. Fujinawa M. Hata M. Hayakawa Q. Huang J. Izutsu Y. Kushida K. Maeda K. Oike S. Uyeda T. Yoshino 《Journal of Geodynamics》2002,33(4-5)
Occurrences of anomalous electro-magnetic phenomena at varied frequency ranges, covering ELF to VHF, have been reported in relation to the 17 January 1995 Kobe earthquake (M7.2), by several independent research groups. Prominent pre-seismic peaks, which could have been emitted from the focal area, were observed on 9-10 January in ELF, VLF, LF and HF ranges. Whether these changes were truly related to the earthquake is not certain, because atmospheric (thunderbolt discharge) activities also peaked on 9-10 January. The nomalous changes were markedly enhanced toward the catastrophe in agreement with many reports on unusual radio/TV noise. Anomalous transmission of man-made electromagnetic waves in VLF and VHF ranges was also detected from a few days before the earthquake, indicating the possibility that the ionosphere above the focal zone was disturbed at the final stage of the earthquake preparation process. 相似文献
12.
Michihiro Miyake Mutsumi Matsuo Mayumi Hata Shin-ichi Iwai 《Physics and Chemistry of Minerals》1981,7(2):88-90
The phase transition of K2SO4 has been investigated by measurements of the dielectric constant and electrical conductivity, correlated with the structural point of view. Using single crystals, the temperature dependences of the dielectric constants and electrical conductivities were measured at frequencies of 0.3, 1, 3, and 5 MHz in the temperature range from 20° to 640 °C. Within this range, the dielectric constant does not reach a maximum, but near the phase-transition temperature at 587° C, the dielectric constant along the c axis shows a larger discontinuity than those along the a and b axes. The temperature dependence of the dielectric constant is consistent with the disordered structure of the high temperature form. Based on the parabolic increase of the dielectric constant in the temperature range from 582° to 587° C, it is likely that the phase transition propagates through an intermediate state. The electrical conductivity coefficients of K2SO4 increase with increasing temperature, exhibiting semiconducting character above the phase-transition temperature. In the high-temperature form, the electrical conductivity along the a axis exceeds that along the c axis. Since the electrical conductivity of K2SO4 is mainly ionic in character, the migration of K+ ions makes a major contribution to the conduction process. 相似文献
13.
Accuracy assessment of QuickBird stereo imagery 总被引：2，自引：0，他引：2
Mayumi Noguchi Clive S. Fraser Takayuki Nakamura Takahiro Shimono Shoichi Oki 《The Photogrammetric Record》2004,19(106):128-137
The Geographical Survey Institute of Japan has recently carried out an evaluation of the metric performance of QuickBird stereo satellite imagery. This paper describes the accuracy assessment of the sensor orientation and geopositioning phases of the study, the aim of which was twofold. First, it was desired to confirm the metric potential of QuickBird imagery for 1:25 000 scale topographic mapping. Second, a determination was to be made of the accuracy attainable from the Basic image product. The techniques of rational functions and affine bundle adjustment were employed, the former with bias compensation. The results obtained both reassert the high precision of the rational functions approach and cast doubt upon the applicability of the 3D affine model for accurate geopositioning from QuickBird imagery. 相似文献
14.
Sawanoike Pond, an artificial reservoir constructed ca. 150 yrs. ago, lies in an area geologically sensitive to acidification and contains water that is presently weakly acidic (pH 5.5; alkalinity 15 eq 1-1). Sediments from a core obtained from the northern part and a core from the central part of the pond were analyzed for organic matter, total organic carbon, total nitrogen, natural and artificial radionuclides, pollen, diatoms, metals and spheroidal carbonaceous particles. A peaty silt layer at the bottom of the central core was replaced by a silt layer initially rich in humic substances, but became more mineral-rich near the surface. Although most of the dominant diatoms throughout the cores were acidophilous taxa, some acidobiontic species increased moderately in abundance after the middle 1960's. Diatom-inferred pH values for the northern core are relatively low before about 1930, then increase, reaching a maximum level between the 1930's and the late 1940's. They then decrease to the surface and reach minimum level during the middle 1980's. Diatom-inferred pH declined by 0.4-0.5 units in the northern core and 0.2-0.3 units in the central core since ca. 1910, when vegetation around the shore changed to a community similar to that of recent years. An increase in labile Pb, Zn, Cd and spheroidal carbonaceous particles, indicative of atmospheric deposition of fossil fuel combustion by-products, preceded the decline in inferred pH. The inferred pH decline of the pond could be an acidification due to acidic precipitation caused by fossil fuel combustion. 相似文献
15.
Marilia Mayumi Augusto dos Santos Mirian Chieko Shinzato Juliana Gardenalli de Freitas 《Environmental Earth Sciences》2018,77(13):515
Tropical peat soils present higher ash content than those generated at temperate climate areas. Therefore, this study evaluated the characteristics of a Brazilian organic soil (OS), commercialized as peat, as well as its capacity in removing Cr(VI) from contaminated waters. The OS is composed of 35.5 wt% of organic matter and 56 wt% of inorganic fraction (ash), which is formed by minerals and phytoliths rich in silica (29.2 wt%) and alumina (23.6 wt%). The Cr(VI) removal tests were carried out in batch and column systems using OS and solutions of Cr(VI) prepared with distilled water and groundwater. Batch tests revealed that the organic substances in the OS caused the reduction of Cr(VI) to Cr(III), with an efficiency depending on solution pH. At pH 5.0 the Cr(VI) removal was 0.45 mg g?1 in 24 h; whereas at pH 2.0, this removal increased to 1.10 mg g?1. Since this redox reaction is very slow, the removal of Cr(VI) at pH 5.0 increased to around 2 mg g?1 after 5 days. The removal of Cr(VI) was more effective in the column tests than in the batch test due to the greater solid/solution ratio, and their half-lives were 4.4 and 26.2 h, respectively. Chemical analysis indicated that Cr(VI) was reduced by the humic substances of OS, followed by the precipitation and/or adsorption of Cr(III) into the organic and inorganic components, as anatase. The presence of Cr(III) increased the stability of anatase structure, avoiding its transformation into rutile, even after being heated at 800 °C/2 h. 相似文献
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17.
To estimate the groundwater flow around a borehole heat exchanger (BHE), thermal properties of geological core samples were measured and a thermal response test (TRT) was performed in the Tsukuba upland, Japan. The thermal properties were measured at 57 points along a 50-m-long geological core, consisting predominantly of sand, silt, and clay, drilled near the BHE. In this TRT, the vertical temperature in the BHE was also monitored during and after the test. Results for the thermal properties of the core samples and from the monitoring indicated that groundwater flow enhanced thermal transfers, especially at shallow depths. The groundwater velocities around the BHE were estimated using a two-dimensional numerical model with monitoring data on temperature changes. According to the results, the estimated groundwater velocity was generally consistent with hydrogeological data from previous studies, except for the data collected at shallow depths consisting of a clay layer. The reasons for this discrepancy at shallow depths were predicted to be preferential flow and the occurrence of vertical flow through the BHE grout, induced by the hydrogeological conditions. 相似文献
18.
The Nojima fault on the northwestern coast of Awaji Island, south of Kobe, was reactivated during the January 17, 1995 Hyogoken-nanbu earthquake. This fault rupture was dominated by right-lateral offset (max. 1.7 m) along a high-angle reverse fault which has a maximum vertical displacement of 1.3 m on the southeastern side. We repeatedly measured seven profiles across the fault scarp in two areas (Hirabayashi to the northeast and Ogura to the southwest) for approximately 1 year following the earthquake. The original profile of the fault scarp was an overhanging scarp at Hirabayashi and Ogura, corresponding to the 70–80 ° dip of the fault plane. The fault scarp at Hirabayashi displaces Plio-Pleistocene siltstones of the Osaka Group and is overlain by a thin bed of unconsolidated gravel. The Ogura area is entirely underlain by the Osaka Group. Scarp degradation at Hirabayashi occurred by collapse of the gravel bed and proceeded more quickly than at Ogura, where fault scarp degradation proceeded mainly by exfoliation of the Osaka Group siltstones. The degradation occurred at a very fast rate until March at Hirabayashi, and until June or July at Ogura. Since then, the degradation has been very slow. Our data strongly indicate that the scarp profile was initially controlled mainly by the dip of the fault plane, and scarp degradation has been primarily controlled by lithological factors. The degradation of the Nojima earthquake fault scarp proceeded much more quickly than that of normal fault scarps in the western U.S.A., where many observations of the initial stages of scarp degradation have been carried out. The extremely rapid degradation of the Nojima fault scarp in weak late Neogene siltstones might, in combination with rapid cultural modification of the landscape, explain the paucity of geomorphic scarps along the numerous active faults in Japan. This observation may also have implications for tectonic geomorphology and paleoseismicity studies in other countries characterised by weak bedrock and moderate to high rainfall regimes. 相似文献
19.
Masakichi Nishimura Shigeki Konishi Katsuhiko Matsunaga Kohtaro Hata Tsuneo Kosuga 《Journal of Oceanography》1983,39(6):295-300
Seventy percent of 342 seawater samples collected in the Bering Sea, North and South Pacific, Japan Sea, East and South China Seas, and Indian Ocean had concentrations of “total” mercury ranging from 3 to 6 ng Hg l?1 with an arithmetic mean of 5.3 ng l?1 and a geometric mean of 5.0 ng l?1. In some cases, a higher concentration was observed at the surface, at the halocline or thermocline, or in the bottom water. But in general, there was no consistent correlation between mercury concentration and depth, except for a statistical tendency for mercury concentration to be slightly higher in the surface water. This tendency suggests that mercury in the ocean is supplied from the atmosphere by rain washout. The latitudinal variation of surface mercury concentrations showed that the maximum concentration at each latitude decreased from 40°N to 30°S. This variation provides evidence that atmospheric mercury is emitted mainly from continental areas naturally or anthropogenically. 相似文献
20.
Mayumi Murakami 《Journal of Oceanography》1986,42(3):224-239
The dynamical structure of a two-dimensional (depth and axial directions) estuary is studied analytically. A set of governing equations describing the time-averaged velocity and salinity in the estuary is used, where all of the external parameters (depth, width, freshwater discharge and horizontal and vertical coefficients of eddy viscosity and eddy diffusivity) are assumed to be constant along the estuary.Two dynamical relations are taken into consideration in the theory. One of them is the dependence of the longitudinal scaleL
d on the balance of longitudinal salt transport, and the other is the relation between the vertical stratification of salinity and the the Prandtl numberP
r=Av/Kv, whereA
v andK
v denote the coeffcients of the vertical eddy viscosity and diffusivity, respectively. The two relations result in an extension of the parameter range in which the linear balance of momentum holds.A linear state of motion (LM-state) is defined as the state where the momentum balance is linear. The LM-state comprises the so-called vertically homogeneous and the so-called partially mixed state. Perturbation analysis is introduced and dynamical theory is developed in the LM-state. Since the LM-state covers a fairly wide regime with respect to the balance of salt transport, the state is subdivided into three stages: the diffusive, intermediate and advective stages. In the diffusive stage the upstream salt transport is mainly attributed to the horizontal diffusion, whereas in the advective stage it is attributed to advection caused by gravitational circulation. The salinity balance is also linear in the diffusive and intermediate stages, whereas the balance is nonlinear in the advective stage. The advective stage of the LM-state is regarded as a stage bordering the salt wedge state.The longitudinal distribution of depth-mean salinity is found to take an exponential form in the diffusive stage, a nearly linear form in the advective stage and an intermediate form between them in the intermediate stage. 相似文献