Reconnaissance report on landslide disasters in northeast Japan following the M 9 T��hoku earthquake     

Toyohiko Miyagi  Daisuke Higaki  Hiroshi Yagi  Shoji Doshida  Noriyuki Chiba  Jun Umemura  Go Satoh 《Landslides》2011,8(3):339-342

An earthquake of M_w 9.0 struck the Pacific coast in northeast Japan on March 11, 2011 and was followed by a hugely damaging tsunami along 500 km of the Japanese coastline. An inland aftershock of M. 7.0 occurred on April 11; during which, surface fault ruptures appeared on land. A large variety of landslide disasters resulted from these earthquakes in various parts of northeastern Honshu, Japan. The full extent of the landslides is still being determined. This brief report introduces some of the landslide phenomena so far investigated by the Japanese Landslide Society. These are (1) failure of a water reservoir embankment dam in Sukagawa, Fukushima prefecture, (2) landslides and surface seismic fault rupture from the April 11 aftershock in Iwaki, Fukushima, (3) a concentration of surface failures at Matsushima Bay in Miyagi prefecture, and (4) small landslides on modified slopes in residential areas around Sendai city.  相似文献   

Particle tracking experiments on a model of the Okhotsk Sea: Toward oil spill simulation   总被引：2，自引：1，他引：1  

Kay I. Ohshima  Daisuke Simizu 《Journal of Oceanography》2008,64(1):103-114

Particle tracking experiments were conducted for the Sea of Okhotsk using a three-dimensional ocean circulation model, as a step toward the simulation of oil spills. The model’s reproducibility is first examined in detail. Comparison with surface drifter and moored ADCP data shows that the model successfully reproduces the velocity field over the shelves, particularly in the weak stratification period. This is because the current variability is simply determined by integration of the alongshore component of the wind stress over the coast from which arrested topographic waves propagate. Good agreement even in the ice-covered period implies that the neglect of sea ice in the model is not a problem for reproduction of the current over the shelves. Good agreement also supports the correction of ECMWF wind speed by a factor of 1.25. A series of particle tracking experiments was carried out to examine the case of particles released from the Sakhalin oil field at depths of 0 m and 15 m. Regardless of the deployment month and year, most particles at depth 15 m are transported southward along the Sakhalin coast, in accordance with the abrupt intensification of the East Sakhalin Current in October, finally arriving offshore of Hokkaido in November–January. Particles at the surface, which are affected by wind drift in addition to the ocean current, show larger yearly variability. In years when the offshoreward-wind dominates, the particles would be advected out of the mainstream of the current and would not be transported offshore of Hokkaido.  相似文献   

Simulating a white dwarf dominated Galactic halo     

Chris B. Brook  Daisuke Kawata  Brad K. Gibson 《Monthly notices of the Royal Astronomical Society》2003,343(3):913-923

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N-body simulations of the Magellanic stream   总被引：1，自引：0，他引：1  

Tim W. Connors  Daisuke Kawata  Brad K. Gibson 《Monthly notices of the Royal Astronomical Society》2006,371(1):108-120

A suite of high-resolution N -body simulations of the Magellanic Clouds–Milky Way system are presented and compared directly with newly available data from the H  i Parkes All-Sky Survey (HIPASS). We show that the interaction between Small Magellanic Clouds (SMC) and Large Magellanic Clouds results in both a spatial and kinematical bifurcation of both the stream and the leading arm. The spatial bifurcation of the stream is readily apparent in the HIPASS data, and the kinematical bifurcation is also tentatively identified. This bifurcation provides strong support for the tidal disruption origin for the Magellanic stream. A fiducial model for the Magellanic Clouds (MCs) is presented upon completion of an extensive parameter survey of the potential orbital configurations of the MCs and the viable initial boundary conditions for the disc of the SMC. The impact of the choice of these critical parameters upon the final configurations of the stream and leading arm is detailed.  相似文献   

Long-term integrations and stability of planetary orbits in our Solar system     

Takashi Ito  Kiyotaka Tanikawa 《Monthly notices of the Royal Astronomical Society》2002,336(2):483-500

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Distribution of gold and silver and its relation with hypogene ore minerals in the Esperanza porphyry deposit,Antofagasta Region,Chile     

Shoji Kojima  María Constanza San Martín  Toshiro Nagase  Daisuke Nakashima  Claudio Bisso  Andrew Menzies 《Resource Geology》2021,71(1):80-90

Modes of occurrence of Au‐ and Ag‐bearing phases and their relation with associated hypogene ore minerals were examined with the objective to elucidate Au‐Ag distribution at the Esperanza porphyry deposit in the Eocene Centinela copper belt, using ore‐microscope modal analysis, semi‐quantitative analyses by automated mineralogy, electron probe microanalysis, and secondary ion mass spectrometer. The Esperanza hypogene mineralization is characterized by early‐stage chalcopyrite‐rich veinlets in the potassic alteration zone and later polymetallic stage with tennantite and galena in the chlorite‐sericitic alteration zone. Only the early‐stage chalcopyrite contains fine‐grained electrum (Au₆₈Ag₃₂ ‐ Au₈₁Ag₁₉) and hessite (Ag₂Te), and thus yields positive correlations in Cu vs. Au and Cu vs. Ag grades that are clearly recognized in the hypogene sulfide zone. The early‐stage chalcopyrite grains frequently exhibit polysynthetic twinning suggestive of inversion from intermediate solid solution. These features suggest that the fine‐grained electrum and hessite are products exsolved in the cooling process with the intermediate solid solution to chalcopyrite inversion. In contrast, tennantite and galena of the later‐stage mineralization contain no detectable Ag, and it is thus proposed that the early‐stage inverted chalcopyrite is the principal storage of economically important precious metals.  相似文献   

Rapid Alkalization in Lake Inawashiro, Fukushima, Japan: Implications for Future Changes in the Carbonate System of Terrestrial Waters     

Takuya Manaka  Hiroyuki Ushie  Daisuke Araoka  Akihiko Inamura  Atsushi Suzuki  Hodaka Kawahata 《Aquatic Geochemistry》2013,19(4):281-302

The global carbon cycle, one of the important biogeochemical cycles controlling the surface environment of the Earth, has been greatly affected by human activity. Anthropogenic nutrient loading from urban sewage and agricultural runoff has caused eutrophication of aquatic systems. The impact of this eutrophication and consequent photosynthetic activity on CO₂ exchange between freshwater systems and the atmosphere is unclear. In this study, we focused on how nutrient loading to lakes affects their carbonate system. Here, we report results of surveys of lakes in Japan at different stages of eutrophication. Alkalization due to photosynthetic activity and decreases in PCO₂ had occurred in eutrophic lakes (e.g., Lake Kasumigaura), whereas in an acidotrophic lake (Lake Inawashiro) that was impacted by volcanic hot springs, nutrient loading was changing the pH and carbon cycling. When the influence of volcanic activity was stronger in the past in Lake Inawashiro, precipitation of volcanic-derived iron and aluminum had removed nutrients by co-precipitation. During the last three decades, volcanic activity has weakened and the lake water has become alkalized. We inferred that this rapid alkalization did not result just from the reduction in acid inputs but was also strongly affected by increased photosynthetic activity during this period. Human activities affect many lakes in the world. These lakes may play an important part in the global carbon cycle through their influence on CO₂ exchange between freshwater and the atmosphere. Biogeochemical changes and processes in these systems have important implications for future changes in aquatic carbonate systems on land.  相似文献   

Disintegration process of hierarchical triple systems II: non-small mass third body orbiting equal-mass binary     

M. M. Saito  K. Tanikawa  V. V. Orlov 《Celestial Mechanics and Dynamical Astronomy》2013,116(1):1-10

The stability limit of coplanar hierarchical triple systems is numerically studied. Systems we investigated consist of two equal mass bodies initially on a circular orbit and third body with various masses, which at the maximum are equal to the mass of the binary. In order to estimate the stability limit, we use an empirically-found fact that the system is quasi-periodic if the initial eccentricity of the outer binary is less than some critical value, otherwise the third body eventually escapes. We make an analytical expression for the stability limit in terms of the ratio of the orbital radii and find that the expression improves the previous criteria. The resultant expression also suggests that the ratio of the orbital radii rapidly approaches to a certain value (e.g. $\sim $ 2, in an initially circular outer binary) as the mass of the third-body tends to zero.  相似文献   

Disintegration process of hierarchical triple systems. I. Small-mass planet orbiting equal-mass binary     

M. M. Saito  K. Tanikawa  V. V. Orlov 《Celestial Mechanics and Dynamical Astronomy》2012,112(3):235-251

The stability of hierarchical triple system is studied in the case of an extrasolar planet or a brown dwarf orbiting a pair of main sequence stars. The evolution of triple system is well modelled by random walk (RW) diffusion, particularly in the cases where the third body is small and tracing an orbit with a large eccentricity. A RW model neglects the fact that there are many periodic orbits accompanied by stability islands, and hence inherently overestimates the instability of the system. The present work is motivated by the hope to clarify how far the RW model is applicable. Escape time and the surface section technique are used to analyse the outcome of numerical integrations. The analysis shows that the RW-like model explains escape of the third body if the initial configuration is directly outside of the KAM tori. A small gap exists in (q ₂/a ₁, e ₂)-plane between locations of the stability limit curves based on our numerical study and on RW-model (the former is shifted by –1.4 in q ₂/a ₁ direction from the latter).  相似文献   

Sound velocity measurements in dhcp-FeH up to 70 GPa with inelastic X-ray scattering: Implications for the composition of the Earth's core     

Yuki Shibazaki  Eiji Ohtani  Hiroshi Fukui  Takeshi Sakai  Seiji Kamada  Daisuke Ishikawa  Satoshi Tsutsui  Alfred Q.R. Baron  Naoya Nishitani  Naohisa Hirao  Kenichi Takemura 《Earth and Planetary Science Letters》2012

We have determined the density evolution of the sound velocity of dhcp-FeH_x (x ≈ 1) up to 70 GPa at room temperature, by inelastic X-ray scattering and by X-ray diffraction. We find that the variation of V_P with density is different for the ferromagnetic and nonmagnetic dhcp-FeH_x, and that only nonmagnetic dhcp-FeH_x follows Birch's law. Combining our results with Birch's law for iron and assuming an ideal two-component mixing model, we obtain an upper bound of the hydrogen content in the Earth's inner core, 0.23(6) wt.% H, corresponding to FeH_0.13(3). The iron alloy with 0.23(6) wt.% H can satisfy the density, and compressional and shear sound velocities of the PREM inner core, assuming that there are no other light elements in the inner core.  相似文献