In situ strength measurements on natural upper-mantle minerals   总被引：1，自引：0，他引：1  

Junji Yamamoto  Jun-ichi Ando  Hiroyuki Kagi  Toru Inoue  Akihiro Yamada  Daisuke Yamazaki  Tetsuo Irifune 《Physics and Chemistry of Minerals》2008,35(5):249-257

Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700°C, we examined rheological properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential stress of 4–6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600°C. Neither orthopyroxene nor spinel shows complete stress relaxation, but both retain some stress even at 700°C. The strength of the minerals decreases in the order of chromian-spinel ≈ orthopyroxene > olivine for these conditions. This order of strength is consistent with the residual pressure of fluid inclusions in mantle xenoliths.  相似文献   

Addendum to the paper “Preferential concentration of marine particles in isotropic turbulence”     

Kyle D. Squires  Hidekatsu Yamazaki 《Deep Sea Research Part I: Oceanographic Research Papers》1996,43(11-12)

  相似文献   

Convection induced by cooling at one side wall in two-dimensional non-rotating fluid —applicability to the deep Pacific circulation—     

Ichiro Ishikawa  Shigeaki Aoki  Ryo Furue  Nobuo Suginohara 《Journal of Oceanography》1996,52(5):617-632

In recognition that similarity in the density balance leads to resemblance in circulation between the two-dimensional non-rotating and three-dimensional rotating systems which have similar density stratification, we investigate convection induced by cooling at one side wall and heating at the sea surface by using a two-dimensional non-rotating model as idealized representation for the deep Pacific circulation. In the model, various vertical profiles are taken for the side wall cooling, which are assumed to correspond to the density structure of the Anatarctic Circumpolar Current. In a small diffusivity range, two important features are found to be robust against change in the vertical profile of the side wall cooling. One is that the density stratification is horizontally almost uniform. The other is that the balance in the density equation between the vertical advection and the vertical diffusion holds in the interior. Consequently, the vertical density balance, together with the equation of continuity, determines the circulation pattern for the prescribed vertical profile of the side wall cooling. The multi-layered meridional flow, which is expected to exist in the deep Pacific, is shown to form for certain vertical profiles of the side wall cooling.  相似文献   

Preferential concentration of marine particles in isotropic turbulence     

Kyle D. Squires  Hidekatsu Yamazaki   《Deep Sea Research Part I: Oceanographic Research Papers》1995,42(11-12)

The effect of small-scale turbulence on marine and aquatic particle transport has traditionally been to act as a means for creating homogeneous distributions. However, previous numerical simulations of heavy particle transport in turbulent flows have shown that particles are preferentially concentrated by turbulence and that effects of preferential concentration are most pronounced for particle parameters comparable to the Kolmogorov scales. Therefore, the focus of the present work is examination of the preferential concentration of marine particles. Application of Kolmogorov scaling indicates that effects of preferential concentration may be important for marine particles with diameters of order 1 mm in the upper mixed layer. Numerical simulations of unstratified isotropic turbulence are then used to support the notion that preferential concentration of particles possessing material characteristics representative of those encountered in marine environments can occur. In the simulations, particles of order 1 mm diameter are idealized as rigid spheres with a density ratio of 1.005. Simulation results demonstrate preferential concentration with peak particle number densities ranging from 10 to 60 times the global mean value. Implications of preferential concentration are also discussed, together with the limitations of the approach employed in the present study.  相似文献   

Controlled experiment in the ionosphere with a rocket-borne plasma gun     

Nobuki Kawashima  Susumu Sasaki  Osamu Kaneko  Akira Yamori  Ryo Okamura  Shoichi Okamura 《Planetary and Space Science》1978,26(4):367-373

A controlled active experiment was performed by a plasma gun on-board a rocket to study the plasma stream across the magnetic field in space. A mother and daughter system was employed. An 8 kV 0.8 μF (25 J) capacitor bank on the daughter rocket was discharged every 12 s and about 10¹⁶ ion and electron pairs were ejected. A plasma signal was detected on the electron temperature probe. The propagation speed of the plasma stream is estimated to be 10⁶ cm/s, considerably lower than that obtained in the prelaunch test. The amplitude of the plasma signal decays as the inverse square of the mutual distance between the mother and daughter rockets and this decay is much slower than the free streaming. The importance of the geomagnetic field on the plasma propagation in space is discussed.  相似文献   

Internal deformation of Sikhote Alin volcanic belt, far eastern Russia: Paleocene paleomagnetic results     

Yo-ichiro Otofuji  Takaaki Matsuda  Ryo Enami  Koji Uno  Katsuhiko Nishihama  Li Su  Ruslan G. Kulinich  Petr S. Zimin  Anatoly P. Matunin  Vladimir G. Sakhno 《Tectonophysics》2002,350(3)

We present paleomagnetic results of Paleocene welded tuffs of the 53–50 Ma Bogopol Group from the northern region (46°N, 137°E) of the Sikhote Alin volcanic belt. Characteristic paleomagnetic directions with high unblocking temperature components above 560 °C were isolated from all the sites. A tilt-corrected mean paleomagnetic direction from the northern region is D=345.8°, I=49.9°, α₉₅=14.6° (N=9). The reliability of the magnetization is ascertained through the presence of normal and reversed polarities. The mean paleomagnetic direction from the northern region of the Sikhote Alin volcanic belt reflects a counterclockwise rotation of 29° from the Paleocene mean paleomagnetic direction expected from its southern region. The counterclockwise rotation of 25° is suggested from the paleomagnetic data of the Kisin Group that underlies the Bogopol Group. These results establish that internal tectonic deformation occurred within the Sikhote Alin volcanic belt over the past 50 Ma. The northern region from 44.6° to 46.0°N in the Sikhote Alin volcanic belt was subjected to counterclockwise rotational motion through 29±17° with respect to the southern region. The tectonic rotation of the northern region is ascribable to relative motion between the Zhuravlevka terrane and the Olginsk–Taukhinsk terranes that compose the basements of the Sikhote Alin volcanic belt.  相似文献   

Quantitative reconstruction of the lake water paleotemperature of Daihai Lake, Inner Mongolia, China and its significance in paleoclimate   总被引：5，自引：2，他引：5  

沈吉  Ryo Matsumoto  王苏民  朱育新 《中国科学D辑(英文版)》2002,45(9):792-800

By measuring Sr/Ca ratios of the ostracod shells (Limnocthere cf. inopinata) in sediments of the Daihai Lake, and combined with Sr²⁺/Ca²⁺ ratios of the lake water, this paper obtained paleosalinity of the lake water. Vaporizing experiment of the lake water in laboratory showed that there was a quantitative relationship between salinity and oxygen isotope. Using this relationship, oxygen isotope values of the paleo-lake water were calculated. By measuring the oxygen isotope of the authigenic carbonate in the lake’s sediments, and in combination with the oxygen isotope values of the paleo-lake water, the paleotemperature of the lake water was calculated. Finally, based on these proxies, the paleoclimate in the lake basin was explored.  相似文献   

Soil-structure interaction analysis of the Hualien containment model     

Todor Ganev  Fumio Yamazaki  Tsuneo Katayama  Teruyuki Ueshima 《Soil Dynamics and Earthquake Engineering》1997,16(7-8):459-470

This paper presents results from forced vibration tests, microtremor observations and earthquake response analysis of a nuclear reactor containment model constructed on stiff soil in Hualien, Taiwan. The dynamic behavior of the soil-structure system is simulated successfully with two numerical models: a sway-rocking model, whose soil parameters are evaluated on the basis of the continuum formulation method, and a finite element model, using the program SASSI with the flexible volume substructuring approach. The dependences of the soil parameters of both models on the amplitudes of the different dynamic excitations are investigated in detail. An original numerical simulation of microtremor is performed. Comparison with results of a previous study involving a rigid tower on a soft soil site in Chiba, Japan is offered.  相似文献   

Fundamental study on the response characteristics of drivers during an earthquake based on driving simulator experiments     

Yoshihisa Maruyama  Fumio Yamazaki 《地震工程与结构动力学》2004,33(6):775-792

After the 1995 Kobe earthquake, the expressway structures in Japan were retrofitted and they will not now be seriously damaged under a certain level of strong earthquake motion. However, the stability of a moving vehicle has not been investigated yet. It has been reported that drivers feel seismically induced vibrations, especially in the transverse direction of vehicles. Owing to this phenomenon, drivers have some difficulty in controlling the vehicles during strong shaking. For further safety promotion of the expressway networks, it is important to understand the drivers' reactions to seismic motion. The present authors have performed a series of seismic response analyses of a moving vehicle to investigate its response characteristics based on numerical simulation. However, the responses of the driver were not considered in the simulation process. In order to investigate the drivers' reactions during an earthquake, a series of virtual tests were conducted using a driving simulator. This driving simulator has six servomotor‐powered electric actuators that control its motions. Several types of tests were carried out for different examinees to investigate drivers' responses while controlling the simulator under seismic motion. The results of this study showed that a larger response time lag to strong shaking and over turning of the steering wheel may shift the vehicle into the next lane. According to this finding, trafficaccidents could possibly occur under strong ground shaking in the case of heavy traffic. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Sequence of faulting and deformation during the 2000 eruptions of the Usu Volcano, Hokkaido, Japan—interpretation and image analyses of aerial photographs     

Hiromitsu Yamagishi  Tsukasa Watanabe  Fumiaki Yamazaki 《Geomorphology》2004,57(3-4):353-365

Significant faulting and deformation of the ground surface has been rarely known during volcanic eruptions. Usu Volcano, Hokkaido, Japan, is a unique example of deformation due to felsic magma intrusion. Usu Volcano has a history of such types of eruptions as phreatic, pumice eruption (Plinian type), pyroclastic flowing and lava doming since 1663. On March 31, 2000, phreatomagmatic to phreatic eruptions took place after 23 years of dormancy in the western piedmont, followed by explosions on the western flank of Usu Volcano. They were associated with significant deformation including faulting and uplift. The eruptions and deformation were continuing up to the end of May 2000.We identified the faulting using total nine sets of aerial photographs taken from before the eruption (March 31, 2000) to more than 1 year (April 27, 2001) after the end of the activity, and traced deformation processes through image processing using aerial photographs. We found that some of the new faults and the associated phreatic eruptions were related to old faults formed during the 1977–1981 eruptive episode.The image processing has revealed that the surface deformation is coincident with the area of faulting forming small grabens and the phreatic explosion vents. However, the faulting and main explosive eruptions did not take place in the highest uplift area, but along the margin. This suggests that the faulting and explosive activities were affected by small feeder channels diverging from the main magma body which caused the highest uplift.  相似文献