Lead-210 in the North Pacific and the transport of terrestrial material through the atmosphere     

Yoshiyuki Nozaki  Shizuo Tsunogai 《Earth and Planetary Science Letters》1973,20(1):88-92

²¹⁰Pb in the surface water of the North Pacific was extensively determined. The results showed that the highest concentrations of²¹⁰Pb of 19 ± 3dpm/100kg were found in the northern mid-latitudes around 30°N, but longitudinal variation across the North Pacific was not observed. The mean residence time of²¹⁰Pb in the surface water up to 100 m in depth is calculated to be 230 days. In the mid-latitudes of the northern hemisphere,²¹⁰Pb may be transported by the prevailing westerly wind of a higher speed than 15 m/sec, likely the jet stream.  相似文献   

Underground storage of carbon dioxide in depleted natural gas reservoirs and in useless aquifers     

Hitoshi Koide  Yoshiyuki Tazaki  Yoshikazu Noguchi  Masaki Iijima  Kazuitsu Ito  Yuji Shindo 《Engineering Geology》1993,34(3-4):175-179

Depleted reservoirs of natural gas and petroleum can provide excellent traps for carbon dioxide. Deep aquifers, which are not used due to high salinity, can host larger amount of the carbon dioxide under their high formation pressure than natural gas and oir reservoirs. Small fraction of aquifers in sedimentary basins in the world are enough to host about 87 gigaton-C of carbon dioxide.

A preliminary technical and economical survey on the carbon dioxide injection system suggests that the energy requirement for carbon dioxide injection into subterranean aquifers is about 269 kWh/ton-C and that the investment and operation costs for system are 79 $/ton-C. By our preliminary cost estimation in Japan, the CO₂-emission-free electricity generation may become possible with a cost increase of 35% for natural-gas-fired power station, and of 60% for coal-fired-power station.  相似文献   

Composition and pressure dependence of lattice thermal conductivity of (Mg,Fe)O solid solutions     

Akira Hasegawa  Kenji Ohta  Takashi Yagi  Kei Hirose  Yoshiyuki Okuda  Tadashi Kondo 《Comptes Rendus Geoscience》2019,351(2-3):229-235

We measured the lattice thermal conductivities of Fe_0.98O wüstite and iron-rich (Mg,Fe)O magnesiowüstite using the pulsed light heating thermoreflectance technique with a diamond anvil cell up to 61 GPa at 300 K. We found that the thermal conductivity of wüstite does not show a monotonic increase as a function of pressure, contrary to that of MgO periclase. Rocksalt (B1) to rhombohedral B1 transition is likely to induce an abnormal pressure response in the conductivity of wüstite. Our results also show that magnesiowüstite has a lower conductivity than that of MgO and FeO endmembers due to a strong iron impurity effect, which is well reproduced by a model considering phonon-impurity scattering in a binary solid solution.  相似文献   

Seismic Wavefields in the Deep Seafloor Area from a Submarine Landslide Source     

Takeshi Nakamura  Hiroshi Takenaka  Taro Okamoto  Yoshiyuki Kaneda 《Pure and Applied Geophysics》2014,171(7):1153-1167

We use the finite difference method to simulate seismic wavefields at broadband land and seafloor stations for a given terrestrial landslide source, where the seafloor stations are located at water depths of 1,900–4,300 m. Our simulation results for the landslide source explain observations well at the seafloor stations for a frequency range of 0.05–0.1 Hz. Assuming the epicenter to be located in the vicinity of a large submarine slump, we also model wavefields at the stations for a submarine landslide source. We detect propagation of the Airy phase with an apparent velocity of 0.7 km/s in association with the seawater layer and an accretionary prism for the vertical component of waveforms at the seafloor stations. This later phase is not detected when the structural model does not consider seawater. For the model incorporating the seawater, the amplitude of the vertical component at seafloor stations can be up to four times that for the model that excludes seawater; we attribute this to the effects of the seawater layer on the wavefields. We also find that the amplification of the waveform depends not only on the presence of the seawater layer but also on the thickness of the accretionary prism, indicating low amplitudes at the land stations and at seafloor stations located near the trough but high amplitudes at other stations, particularly those located above the thick prism off the trough. Ignoring these characteristic structures in the oceanic area and simply calculating the wavefields using the same structural model used for land areas would result in erroneous estimates of the size of the submarine landslide and the mechanisms underlying its generation. Our results highlight the importance of adopting a structural model that incorporates the 3D accretionary prism and seawater layer into the simulation in order to precisely evaluate seismic wavefields in seafloor areas.  相似文献   

Fragility curves for expressway embankments based on damage datasets after recent earthquakes in Japan     

Yoshihisa Maruyama  Fumio Yamazaki  Kiku Mizuno  Yoshiyuki Tsuchiya  Hiroyuki Yogai 《Soil Dynamics and Earthquake Engineering》2010

The seismometer network of the Japanese expressway system was enhanced following the 1995 Kobe earthquake. Based on earthquake information from the instruments of the seismometer network, a traffic control is performed directly after the event because of the potential for damage to expressway structures. Expressways serve as vital trunk lines of transportation and are important for the restoration of damage-stricken areas. Therefore, earthquake-induced damage to expressway structures should be estimated as soon as possible. Expressway embankments were seriously damaged during recent earthquakes, such as the 2004 Niigata Chuetsu earthquake. The present study constructs the fragility curves of expressway embankments in Japan in order to estimate the damage distribution immediately after an earthquake. Damage datasets for expressways are compiled for the 2003 Northern-Miyagi earthquake, the 2003 Tokachi-oki earthquake, the 2004 Niigata Chuetsu earthquake, and the 2007 Niigata Chuetsu-oki earthquake. The spatial distributions of the peak ground velocity (PGV) are estimated for these four earthquakes in order to evaluate the relationship between the damage ratio of expressway embankments and the PGV. Statistical analysis is then conducted in order to draw the fragility curves for expressway embankments. Based on the fragility curves, major damage that disrupts ordinary expressway traffic may occur when the peak ground velocity exceeds approximately 35.0 cm/s. The fragility curves constructed in the present study are helpful for predicting the damage distribution on expressways soon after an earthquake, which enables efficient traffic control and rapid disaster response.  相似文献   

Element transport by dehydration of subducted sediments: Implication for arc and ocean island magmatism   总被引：5，自引：0，他引：5  

Yoshitaka Aizawa  Yoshiyuki Tatsumi  & Hirohisa Yamada 《Island Arc》1999,8(1):38-46

High-pressure experiments on a natural pelite have been conducted at 2–11-GPa pressures in order to evaluate contributions of subducted sediments to arc and ocean island magmatism. Obtained phase relations suggest that, at least in modern subduction zones, subsolidus dehydration of chlorite and phengitic muscovite in the subducted sediments, rather than partial melting, is a predominant process in overprinting sediment components onto the magma source region. Trace element compositions of sediment-derived fluids are estimated based on dehydration experiments at 5.5 GPa and 900/1300°C. Pb is effectively transported by fluids relative to other elements. This results in the Pb enrichment for arc basalts by fluids, generated by the dehydration of subducted sediments, together with altered mid-ocean ridge basalt (MORB), and complementary depletion of Pb in subducted sediments. Inferred arc magma compositions obtained by model calculations based on the present experimental results agree well with a natural primitive arc basalt composition. A large increase in the U/Pb ratio in the subducted sediments at deeper levels than major dehydration depths results in a high Pb isotopic ratio through radioactive decay after long periods of isolation. Combined with other isotopic ratios such as Sr and Nd, it is possible to produce the EM II source, one of the enriched geochemical reservoirs for ocean island basalt magmas, by mixing of a small amount of subducted sediments with depleted or primitive mantle.  相似文献   

Stream temperature,specific conductance and runoff process in mountain watersheds     

Daiji Kobayashi  Yoshiyuki Ishii  Yuji Kodama 《水文研究》1999,13(6):865-876

Stream temperature ranged from 3 to 4°C at an experimental site during snowmelt on Hokkaido Island, Japan, which provided direct evidence of major contributions of subsurface water to stream water. In contrast, stream temperatures during rainstorms in summer decreased gradually after stream flow peaked, attaining a nearly constant temperature ranging from 9 to 11°C. During storm flow recession, stream temperatures during summer or snowmelt were similar to the soil temperature at 1·8 m below the land surface, suggesting that subsurface water contributions to stream flow are derived from this depth. The hygrographs during two rainstorms, August 1987 and September 1989, were separated using temperature. The stream temperature was assumed to depend on the mixing of surface flow, having a temperature ranging from that of rainfall to that of shallow (50 cm deep) soil water, and subsurface flow, having the temperature of the soil at 1·8 m below the land surface. Subsurface flow was estimated to contribute 85–90% of the total stream flow during each rainstorm. A two‐component hydrograph separation was also evaluated using specific conductance. Runoff contributions from the two sources for the temperature and specific conductance analysis were similar. Analysis of the temperature and conductance–discharge hysteresis loop, and of individual flow components for storm hygrographs, provide a general picture of the runoff process in the experimental basin. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Stable Isotopic Information on Calcareous Pelitic Rocks in the Tizapa Volcanogenic Massive Sulfide Deposit Area, the United Mexican States     

Haruhisa Morozumi  Hideya Metsugi  Yoshiyuki Kita  Toru Suzuki 《Resource Geology》1999,49(3):169-173

Abstract: Tizapa volcanogenic massive sulfide (VMS) deposit is hosted in greenschist facies metamorphic rocks; footwall is green schist of felsic to mafic metavolcanic rocks and hanging wall is graphite schist of metasedmentary pelitic rock. Pb-Pb dating of ore samples indicates 103. 4Ma to 156. 3Ma for the age of mineralization (JICA/MMAJ, 1991).  相似文献   

Bathymetric imaging of protothrust zone along the Nankai Trough          下载免费PDF全文

Mikiya Yamashita  Seiichi Miura  Gregory F. Moore  Ayako Nakanishi  Shuichi Kodaira  Yoshiyuki Kaneda 《Island Arc》2018,27(2)

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Varieties of the Himalayan eclogites: A pictorial review of textural and petrological features   总被引：1，自引：0，他引：1       下载免费PDF全文

Hafiz U. Rehman  M. Qasim Jan  Tahseenullah Khan  Hiroshi Yamamoto  Yoshiyuki Kaneko 《Island Arc》2017,26(5)

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