Effect of basal guided waves on landslides   总被引：1，自引：0，他引：1  

Yoshimasa Kobayashi 《Pure and Applied Geophysics》1994,142(2):329-346

A landslide model riding on basal guided waves is investigated to explain lower net frictions at high slide velocities from the wave-theoretical point of view. It is shown that there is a wave propagated along the basal layer at the phase velocity equal to the slide velocity, as well as a guided wave with considerably higher phase velocities propagated likewise along the basal layer as a leaking mode at low slide velocities. With increasing slide velocity the phase velocity of the guided wave decreases until it is equal to that of the slide mass. Over this threshold slide velocity, a sonic boom is generated around the basal layer, and the shock contributes to a loosening of the slide mass into a fluidized state. Landslides on long slide-ways are more liable to exceed this threshold velocity since their slide velocities tend to be higher than those on short slide-ways of a similar shape. Hence, the reduction of net friction of landslides can possibly be better correlated with the lengths of slide-ways than with the volumes of landslides as is widely maintained.  相似文献   

A case study of the application of a microcomputer-based favorability evaluation system: Uranium exploration in the Alligator Rivers Uranium Field, Northern Territory, Australia     

T. Kobayashi  T. Semba  Y. Yamada  S. Williams  Y. Kato 《Mathematical Geology》1994,26(8):937-960

We have attempted to develop an expert system to evaluate the favorability of uranium exploration projects using the Data-directed Numerical Method (DdM). We developed the system for the Macintosh personal computer, so as to facilitate the iterative processes of trial and error inherent in the DdM. In a detailed case study, we use the above system to evaluate the favorability of the Alligator Rivers Uranium Field, Northern Territory, Australia. The favorability of the target area is evaluated by considering several exploration parameters related to the geological factors controlling ore formation. The selection of appropriate exploration parameters is important to the success of the method. We then selected 15 model cells to validate each exploration parameter and also to design the exploration model by the application of the chi-square test. The result of the favorability evaluation, as displayed by the developed system, indicates that our designed exploration model is acceptable. By employing the above processes we conclude that the system using the DdM is applicable as an exploration tool and is useful in establishing an exploration model.  相似文献   

日本内陆地震活动的迁移与扩散          下载免费PDF全文

吉田明夫  细野耕司 《地震工程学报》1989,11(4):105-116

本文研究了日本内陆及其外围海域发生大地震后的地震活动迁移现象。在所研究的6个震例中,一个共同的特点是,地震活动的迁移总是沿着地壳内的活动地质构造带发生。有时可以根据地震活动的迁移来进一步确定活动构造带的存在。把板块边缘地区的地震活动类比为沿着力学偶合平面迁移和扩散,我们可以认为,岛上的活动构造带对应着地壳块体的力学相互作用边界。地震迁移的形式可能不只一种。在我们所研究的震例中发现了以下特征:地震迁移速度约为几km/年;大地震震源区之间存在着地震空区;在每一条地震带上有一定的地震活动周期。地震迁移的一种可能机制是:由于地壳块体的相对运动,在其边界上的凹凸不平区造成了构造应力集中,这些凹凸不平区相继地发生破裂,形成了地震迁移。  相似文献   

利用TDR对土壤含水量及土壤溶液电导率的同步连续测量   总被引：1，自引：0，他引：1  

王维真  小林哲夫 《冰川冻土》2008,30(3):488-493

土壤含水量和可溶解的土壤盐分浓度的测定, 对了解土壤盐分的分布及移动具有重要的意义. 在内蒙古黄河流域灌溉玉米田的一个野外实验中, 利用TDR对土壤含水量及土壤溶液电导率进行了同时连续测量. 结果表明: 在降雨量较少的时期内, 当土壤水分从地下含水层向地表面移动的同时, 地下水中含有的盐分也通过作物根区层向地表移动;当灌溉或有强降雨存在时, 土壤表面蓄积的盐分在未能完全溶解于灌溉水及雨水之前, 大量的灌溉水及降雨通过土壤内的大空隙快速渗入土壤下层;余下的水分在完全溶解了土壤表面的盐分之后, 缓慢通过土壤小空隙下渗.  相似文献   

Swift observations of GRB 050712     

Massimiliano De Pasquale  Dirk Grupe  T. S. Poole  A. A. Breeveld  S. Zane  S. R. Rosen  M. J. Page  K. O. Mason  D. N. Burrows  H. A. Krimm  N. Gehrels  J. A. Nousek  P. W. A. Roming  S. Kobayashi  B. Zhang 《Monthly notices of the Royal Astronomical Society》2006,370(4):1859-1866

We present the results of X-ray and optical observations of GRB 050712 performed by Swift . The X-ray light curve of this burst exhibits episodes of flares in the first 1000 s, the same epoch at which the UVOT detected an optical counterpart. A shallow X-ray decay, with a decay slope of  α=−0.73  , followed and lasted ∼70 ks. This behaviour can be explained in terms of activity of the gamma-ray burst 'inner engine', with the possibility that the last flare is caused by the interaction of the ejecta with the surrounding medium.
We also find interesting spectral parameters for the X-ray emission. In particular, data suggest the presence of an intrinsic absorption in the first 1000 s, which can be explained if circumburst medium clouds lie along the line of sight.  相似文献   

Swift and optical observations of GRB 050401     

Massimiliano De Pasquale  y P. Beardmore  S. D. Barthelmy  P. Boyd  D. N. Burrows  R. Fink  N. Gehrels  S. Kobayashi  K. O. Mason  R. McNought  J. A. Nousek  K. L. Page  D. M. Palmer  B. A. Peterson  P. A. Price  J. Rich  P. Roming  S. R. Rosen  T. Sakamoto  B. P. Schmidt  J. Tueller  A. A. Wells  S. Zane  B. Zhang  H. Ziaeepour 《Monthly notices of the Royal Astronomical Society》2006,365(3):1031-1038

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Effects of dust scattering albedo and 2175-Å bump on ultraviolet colours of normal disc galaxies     

Akio K. Inoue  Veronique Buat  Denis Burgarella  Pasquale Panuzzo  Tsutomu T. Takeuchi †  Jorge Iglesias-Páramo 《Monthly notices of the Royal Astronomical Society》2006,370(1):380-398

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The origin of elliptical galaxies inferred from their metallicity gradients     

Chiaki Kobayashi 《Astrophysics and Space Science》2003,284(2):853-856

We simulate the chemodynamical evolution of elliptical galaxies using our GRAPE-SPH code. We succeed in reproducing the observed variety of the radial metallicity gradients, from which we discuss the origin of elliptical galaxies. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

grape-sph chemodynamical simulation of elliptical galaxies – II. Scaling relations and the fundamental plane     

Chiaki Kobayashi 《Monthly notices of the Royal Astronomical Society》2005,361(4):1216-1226

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The evidence of an early stellar encounter in Edgeworth-Kuiper belt     

Hiroshi Kobayashi  Shigeru Ida 《Icarus》2005,177(1):246-255

We investigate the influence of a stellar fly-by encounter on the Edgeworth-Kuiper belt objects through numerical orbital calculations, in order to explain both mass depletion and high orbital inclinations of the classical Edgeworth-Kuiper belt (CEKB) objects, which have semimajor axis of 42-48 AU and perihelia beyond 35 AU. The observationally inferred total mass of the CEKB is ∼1/10 Earth masses, which is only ∼0.02 of that extrapolated from the minimum-mass solar nebula model. The CEKB consists of bimodal population: “hot population” with inclinations i?0.2-0.6 radians and “cold population” with i?0.1. The observationally suggested difference in size and color of objects between the two populations may imply different origins of the two populations. We find that both the depletion of solid materials in the CEKB and the formation of the hot population are accounted for by a single close stellar encounter with pericenter distance of 80-100 AU and inclination relative to the initial protoplanetary disk ?50°-70°. Such a stellar encounter highly pumps up eccentricities of most objects in the CEKB and then their perihelia migrate within 35 AU. These objects would be removed by Neptune's perturbations after Neptune is formed at or migrates to the current position (30 AU). Less than 10% of the original objects remain in stable orbits with small eccentricities and perihelion distances larger than 35 AU, in the CEKB, which is consistent with the observation. We find that i of the remaining objects are as large as that of the observed hot population. The only problem is how to stop Neptune's migration at ∼30 AU, which is addressed in a separate paper. The depletion by the stellar encounter extends deeply into ∼30-35 AU, which provides the basis of the formation model for the cold population through Neptune's outward migration by Levison and Morbidelli (2003, Nature, 426, 419-421). The combination of our model with Levison and Morbidelli's model could consistently explain the mass depletion, truncation at 50 AU, bimodal distribution in i, and differences in size and color between the hot and the cold populations in the CEKB.  相似文献