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11.
Poisson's ratios of the upper and lower crust and the sub-Moho mantle beneath central Honshu, Japan, are investigated using three independent methods that are based on S to P ratios of apparent velocities, the Wadati diagrams and an inversion of P and S arrivals. Shallow earthquakes at distances of 200—500 km from the Nagoya University Telemeter Network are used for the apparent velocity ratio method. Crustal and subcrustal earth-quakes under the network are used for the other two methods. The network consists of wide-band seismometers with three components which are particularly suitable for detecting S waves. The three different methods give a consistent result for Poisson's ratio σ, that is, (1) σ = 0.23 ± 0.01 in the upper crust, (2) σ = 0.26−0.28 in both the lower crust and in the sub-Moho mantle. The result indicates a sharp contrast in σ between the upper and the lower crust rather than at the Moho. The low σ in the upper crust can only be explained by the presence of a substantial amount of free quartz, indicating granitic rocks. A higher σ in the lower crust suggests that this portion is presumably less saturated in silica and may be even undersaturated, pointing to intermediate to mafic rocks. The sub-Moho σ is almost equal to the σ averaged over the entire upper mantle that has been estimated from the Wadati diagrams of deep shocks beneath Japan but is higher than those calculated from Pn and Sn velocities in oceanic and stable continental regions. 相似文献
12.
Seven rare-earth elements (La, Ce, Sm, Eu, Tb, Yb, Lu) and Co, Cr, Sc, Ba, Hf and Th have been determined by non-destructive neutron activation analysis on the Quaternary volcanic rocks in Hokkaido, Japan. The trace-element abundances are discussed in terms of the petrological problems, particularly the origin of calc-alkali magma. On the basis of the La/Sm ratio and the contents of K, Ba, Th and La, lateral variations in the contents of trace elements exist across the Kurile and the northern Honshū arcs. The calc-alkali rocks can be classified into three types which correspond to Kuno's three basalt-magma types. There is no essential difference in the rare-earth patterns between the basaltic rocks and the associated calc-alkali rocks in each petrographic province. This suggests that the calcalkali rocks may be derived from the basaltic magmas by fractional crystallization under certain conditions. 相似文献
13.
The thermodynamic properties of the lower mantle are determined from the seismic profile, where the primary thermodynamic variables are the bulk modulus K and density ρ. It is shown that the Bullen law (K ∝ P) holds in the lower mantle with a high correlation coefficient for the seismic parametric Earth model (PEM). Using this law produces no ambiguity or trade-off between ρ0 and K0, since both K0 and K′0 are exactly determined by applying a linear K?ρ relationship to the data. On the other hand, extrapolating the velocity data to zero pressure using a Birch-Murnaghan equation of state (EOS) results in an ambiguous answer because there are three unknown adjustable parameters (ρ0, K0, K′0) in the EOS.From the PEM data, K = 232.4 + 3.19 P (GPa). The PEM yields a hot uncompressed density of 3.999 ± 0.0026 g cm?3 for material decompressed from all parts of the lower mantle. Even if the hot uncompressed density were uniform for all depths in the lower mantle, the cold uncompressed mantle would be inhomogeneous because the decompression given by the Bullen law crosses isotherms; for example, the temperature is different at different depths. To calculate the density distribution correctly, an isothermal EOS must be used along an isotherm, and temperature corrections must be placed in the thermal pressure PTH.The thermodynamic parameters of the lower mantle are found by iteration. Values of the three uncompressed anharmonic parameters are first arbitrarily selected: α0 (hot), the coefficient of thermal expansion; γ0, the Grüneisen parameter; and δ, the second Grüneisen parameter. Using γ0 and the measured ρ0 (hot) and K0 (hot), the values of θ0 (Debye temperature) and q = dlnγ/dlnρ are found from the measured seismic velocities. Then from (αKT)0 and q the thermal pressure PTH at all high temperatures is found. Correlating PTH against T to the geotherm for the lower mantle, PTH is found at all depths Z. The isothermal pressure, along the 0 K isotherm, at every Z is found by subtracting PTH from the measured P given by the seismic model. Using the isothermal pressure at depth Z, the solution for the cold uncompressed density ρ0C and the cold uncompressed bulk modulus, KT0 is found as a trace in the KT0?ρ0C plane. A narrow band of solutions is then found for ρ0C and KT0 at all depths.The thermal expansion at all T is found from [ρ0C ? ρ0 (hot)/ρ0C. From Suzuki's formula, the best fit to the thermal expansion determines γ0 and α0 (hot). When the values of these two parameters do not agree with the original assumptions, the calculation is repeated until they do agree. In this way all the important thermodynamic parameters are found as a self-consistent set subject only to the assumptions behind the equations used. 相似文献
14.
Shiho Kobayashi Eisuke Hashimoto Masayuki Nagao Yoshio Takasugi 《Journal of Oceanography》2009,65(5):657-664
We observed tidal currents, turbulent energy dissipation and water column stratification at the entrance of a narrow strait
(Neko Seto) in the Seto Inland Sea, Japan, using a free-falling turbulent microstructure profiler (TurboMAP) and acoustic
Doppler current profiler (ADCP). The variation in turbulent energy dissipation at the entrance of the strait was not at quarter-diurnal
frequency but at semi-diurnal frequency; turbulent energy dissipation was enhanced during the ebb tide, although it was moderate
during the flood tide. This result is consistent with the results of Takasugi (1993), which showed the asymmetry of tidal
energy loss during a semidiurnal tidal cycle using control volume analysis. It is suggested that significant turbulent energy
dissipation is generated in the strait, which influences the properties of water outside the strait when tidal currents flow
out from the strait. 相似文献
15.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》2011,110(2):143-168
Under perturbations from outer bodies, the Earth experiences changes of its angular momentum axis, figure axis and rotational
axis. In the theory of the rigid Earth, in addition to the precession and nutation of the angular momentum axis given by the
Poisson terms, both the figure axis and the rotational axis suffer forced deviation from the angular momentum axis. This deviation
is expressed by the so-called Oppolzer terms describing separation of the averaged figure axis, called CIP (Celestial Intermediate
Pole) or CEP (Celestial Ephemeris Pole), and the mathematically defined rotational axis, from the angular momentum axis. The
CIP is the rotational axis in a frame subject to both precession and nutation, while the mathematical rotational axis is that
in the inertial (non-rotating) frame. We investigate, kinematically, the origin of the separation between these two axes—both
for the rigid Earth and an elastic Earth. In the case of an elastic Earth perturbed by the same outer bodies, there appear
further deviations of the figure and rotational axes from the angular momentum axis. These deviations, though similar to the
Oppolzer terms in the rigid Earth, are produced by quite a different physical mechanism. Analysing this mechanism, we derive
an expression for the Oppolzer-like terms in an elastic Earth. From this expression we demonstrate that, under a certain approximation
(in neglect of the motion of the perturbing outer bodies), the sum of the direct and convective perturbations of the spin
axis coincides with the direct perturbation of the figure axis. This equality, which is approximate, gets violated when the
motion of the outer bodies is taken into account. 相似文献
16.
Yoshio Fukao 《Geophysical Journal International》1977,50(3):621-642
17.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》1979,19(3):215-241
Effects of an interaction between the mantle and the core of the Earth on its rotational motion are investigated. Assuming that the Earth consists of a rigid mantle and a rigid core with a frictional coupling and a kind of inertial coupling between them, the equations of motion are derived, and they are solved in a close approximation. The solution gives the expressions for the precession, the nutation, the secular changes in the obliquity and the rotational speed, the polar motion and so on as functions of the magnitudes of these forces. A numerical estimation shows that the effect of the friction on the amplitude and phase of the nutation is small for a reasonable intensity of the friction while inertial coupling force has a decisive influence on the amplitude, and an appropriately chosen value of the latter force gives a nutation which closely agrees with observations. It is also indicated that this torque remarkably lessens the rates of the secular changes in the obliquity and the rotational speed. The possibility of a periodical change in the amplitude of the polar motion is suggested as a result of the interaction between the two consituents. 相似文献
18.
Takanori Shimizu Koji Tamai Ikuhiro Hosoda Shoji Noguchi Yuji Kominami Toshio Abe Kenzo Kitamura Ushio Kurokawa Delphis F. Levia Tayoko Kubota Naoki Kabeya Shin'ichi Iida Tatsuhiko Nobuhiro Shinji Sawano Sho Iwagami Akira Shimizu Yoshio Tsuboyama 《水文研究》2021,35(10):e14376
This data note introduces a database of long-term daily total precipitation and stream discharge data for seven forested watersheds in Japan that have been continuously monitored by the Forestry and Forest Products Research Institute. Three of the watersheds started data collection in the 1930s. Forest cover across the sites ranges from cool to warm temperate regions with the latitude spanning from 31 to 44° N and annual precipitation ranging from 1200 to 3000 mm yr−1. The effects of vegetation change via clearcutting, thinning and forest fire (among other stressors) on stream discharge can be analysed from the long-term observation sites. Moreover, this multi-site dataset allows for inter- and intra-site comparisons of annual water loss (difference of annual precipitation and stream discharge). These long-term datasets can provide comprehensive insights into the effects of climate change and other stressors on forested ecosystems, not only in Japan but across a spectrum of forest types, if combined with other long-term records from other forested watersheds across the world. 相似文献
19.
Hidenori Terasaki Keisuke Nishida Satoru Urakawa Yusaku Takubo Soma Kuwabara Yuta Shimoyama Kentaro Uesugi Yoshio Kono Akihisa Takeuchi Yoshio Suzuki Yuji Higo Tadashi Kondo 《Comptes Rendus Geoscience》2019,351(2-3):163-170
A new experimental setup for simultaneous P-wave velocity (VP) and density (ρ) measurements for liquid alloys is developed using ultrasonic and X-ray absorption methods combined with X-ray tomography at high pressures and high temperatures. The new setup allows us to directly determine adiabatic bulk moduli (KS) and to discuss the correlation between the VP and ρ of the liquid sample. We measured VP and ρ of liquid Ni68S32 up to 5.6 GPa and 1045 K using this technique. The effect of pressure on the VP and ρ values of liquid Ni68S32 is similar to that of liquid Fe57S43. (Both compositions correspond to near-eutectic ones.) The obtained KS values are well fitted to the finite strain equation with a value (KS at ambient pressure) of 31.1 GPa and a dKS/dP value of 8.44. The measured VP was found to increase linearly with increasing ρ, as approximated by the relationship: VP [m/s] = 1.29 ρ [kg/m3] – 5726, suggesting that liquid Ni–S follows an empirical linear relationship, Birch's law. The dVP/dρ slope is similar between Ni68S32 and Fe57S43 liquids, while the VP–ρ plot of liquid Ni–S is markedly different from that of liquid Fe–S, which indicates that the effect of Ni on Birch's law is important for understanding the VP–ρ relation of planetary and Moon's molten cores. 相似文献
20.
Masaharu Fukue Koji Uehara Yoshio Sato Catherine Mulligan 《Marine Georesources & Geotechnology》2013,31(3):222-233
The re-suspension method consists of (1) dispersion of the sediment by air-water jets, (2) pumping of the suspension (small particles and organic matter), (3) settlement in a tank, (4) filtration and (5) disposal of solids (followed by incineration in this case). The pilot test was performed to clean up an area of 3000 m2. The dispersed depth of the bottom was approximately 50 cm. The time spent for the work was two weeks. The amount of re-suspended solid removed from the bottom was about 8 tonnes in dry mass. Since the solids contain high concentrations of chemical oxygen demand (COD), total phosphorous (T-P), total nitrogen (T-N) and sulfides, the remaining sediment was considerably improved. Quantitative analyses showed that the full-scale implementation would enable the removal of about 10% of the re-suspended solids, and reduce COD by 95%, T-P by 50%, T-N by 100% and sulfide by 75% for re-deposited sediments in comparison to the original sediments. 相似文献