排序方式： 共有41条查询结果，搜索用时 406 毫秒
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Riko Iizuka Hiroyuki Kagi Kazuki Komatsu Daichi Ushijima Satoshi Nakano Asami Sano-Furukawa Takaya Nagai Takehiko Yagi 《Physics and Chemistry of Minerals》2011,38(10):777-785
The pressure responses of portlandite and the isotope effect on the phase transition were investigated at room temperature
from single-crystal Raman and IR spectra and from powder X-ray diffraction using diamond anvil cells under quasi-hydrostatic
conditions in a helium pressure-transmitting medium. Phase transformation and subsequent peak broadening (partial amorphization)
observed from the Raman and IR spectra of Ca(OH)2 occurred at lower pressures than those of Ca(OD)2. In contrast, no isotope effect was found on the volume and axial compressions observed from powder X-ray diffraction patterns.
X-ray diffraction lines attributable to the high-pressure phase remained up to 28.5 GPa, suggesting no total amorphization
in a helium pressure medium within the examined pressure region. These results suggest that the H–D isotope effect is engendered
in the local environment surrounding H(D) atoms. Moreover, the ratio of sample-to-methanol–ethanol pressure medium (i.e.,
packing density) in the sample chamber had a significant effect on the increase in the half widths of the diffraction lines,
even at pressures below the hydrostatic limit of the pressure medium. 相似文献
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Fine scale distribution of nitrous oxide in marine sediments 总被引：1，自引：0，他引：1
Vertical profiles of nitrous oxide and other inorganic nitrogen compounds in the sediments in Tokyo Bay and its vicinity were measured using the whole core squeezing method. Within the bay area, vertical profiles of nitrous oxide in the interstitial waters showed one or two distinctive peaks around the depth of 2–4 cm, which corresponded to the peaks of nitrite and nitrate. In situ formation of nitrous oxide through nitrification was suggested in those sediments, which was possibly activated by the presence of benthic animals. On the other hand, at the deep sediment off Tokyo Bay the profiles of nitrous oxide, nitrite and nitrate gave a monotonous single peak, indicating less bioturbated condition. Denitrification or dissimilatory nitrate reduction might be important for the formation of nitrous oxide peaks in the latter type of sediment. 相似文献
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Takashi Furumura Toshihiko Hayakawa Misao Nakamura Kazuki Koketsu Toshitaka Baba 《Pure and Applied Geophysics》2008,165(3-4):585-607
Strong ground motions recorded in central Tokyo during the 1944 Tonankai Mw8.1 earthquake occurring in the Nankai Trough demonstrate significant developments of very large (>10 cm) and prolonged (>10 min) shaking of long-period (T > 10–12 s) ground motions in the basin of Tokyo located over 400 km from the epicenter. In order to understand the process by which such long-period ground motions developed in central Tokyo and to mitigate possible future disasters arising from large earthquakes in the Nankai Trough, we analyzed waveform data from a dense nation wide strong-motion network (K-NET and KiK-net) deployed across Japan for the recent SE Off-Kii Peninsula (Mw 7.4) earthquake of 5 September 2004 that occurred in the Nankai Trough. The observational data and a corresponding computer simulation for the earthquake clearly demonstrate that such long-period ground motion is primarily developed as the wave propagating along the Nankai Trough due to the amplification and directional guidance of long-period surface waves within a thick sedimentary layer overlaid upon the shallowly descending Philippine Sea Plate below the Japanese Island. Then the significant resonance of the seismic waves within the thick cover of sedimentary rocks of the Kanto Basin developed large and prolonged long-period motions in the center of Tokyo. The simulation results and observed seismograms are in good agreement in terms of the main features of the long-period ground motions. Accordingly, we consider that the simulation model is capable of predicting the long-period ground motions that are expected to occur during future Nankai Trough M 8 earthquakes. 相似文献
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Shin'ichi Iida Kathryn I. Wheeler Kazuki Nanko Yoshinori Shinohara Xinchao Sun Naoki Sakai Delphis F. Levia 《水文研究》2021,35(8):e14294
An increasing number of studies have examined the effects of various biotic and abiotic factors on stemflow production. Of those that have ascribed the importance of canopy structure to stemflow production, there has been a bias towards field studies. Coupling Bayesian inference with the NIED (National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan) large-scale rainfall simulator, this study leveraged a unique opportunity to control rainfall amounts and intensities to pinpoint the canopy structural metrics that differentially influence stemflow funnelling ratios for three common tree species between leafed and leafless canopy states. For the first time, we examined whether canopy structure metrics exert a static control on stemflow funnelling ratios or whether different elements of canopy structure are more or less important under leafed or leafless states, thereby allowing us to determine if tacit assumptions about the static influence of canopy structure on stemflow production (and funnelling) are valid (or not). Rainfall simulations were conducted at 15, 20, 30, 40, 50, and 100 mm h−1 under both leafed and leafless tree conditions (12 simulations in total) to detect any differential effects on the presence or absence of foliage on stemflow funnelling ratios. For leafed conditions, the highest percentages of best-fitting models (ΔDIC ≤2) indicated that stemflow funnelling ratios were mainly controlled by total dry aboveground biomass (Ball), diameter at breast height (DBH), total dry foliar biomass (Bf), tree height (H), and woody to foliar dry biomass ratio (BR). Whilst for the leafless state, the highest percentages of best-fitting models (ΔDIC ≤2) indicated that total dry branch biomass (Bbr) was relatively dominant as was the interaction effects between crown projection area and species (CPA:species). These results compel us to reject any assumption of a static effect of different elements of canopy structure on stemflow funnelling. 相似文献
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Kusnowidjaja Megawati Tso-Chien Pan Kazuki Koketsu 《Soil Dynamics and Earthquake Engineering》2005,25(1):11-25
Singapore and Kuala Lumpur, the capital of Malaysia, may well represent the classic examples of area with low seismic hazard but with high consequence. Both cities are located in a low-seismicity region of Southeast Asia, where active seismic sources are located more than 300 km away. Seismic designs have not been implemented in this seemingly low-hazard region though distant earthquakes in Sumatra had frequently shaken high-rise structures in the two cities. Several studies have been conducted to systematically assess the seismic hazards of Singapore and the Malay Peninsula. The present research particularly addresses issues in deriving a new set of attenuation relationships of peak ground acceleration (PGA), peak ground velocity (PGV) and response spectral acceleration (RSA) for the Sumatran-subduction earthquakes. To be relevant for the seismic hazard assessment of the remote metropolises, the derived attenuation relationships cover a long distance range from 150 to 1500 km. The attenuation relationships are derived using synthetic seismograms that account for source and path effects. The uncertainties in rupture parameters, such as stress drop, strike, dip and rake angles, have been defined according to the regional geological and tectonic settings as well as the ruptures of previous earthquakes. The seismic potential of the Sumatran subduction zone are high in the region from 2°N to 5°S as there has been no recurrence of great thrust events since 1861. A large event with Mw greater than 7.8 in this particular subduction zone may be capable of generating destructive ground motions in Singapore and Kuala Lumpur, even at a distance of 700 km. 相似文献
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对1978和2005年发生在同一板块边界而震级不同的日本宫城近海地震建立了自发动力破裂模型,再现了由运动学震源模型所预测的滑动和破裂速度。对这两次地震的动力学震源参数进行比较,可使我们看到同一断层上不同震源过程的破裂动力学特征。特别是,我们比较了应力降和破裂能,在这两次地震中,二者可以进行稳定的评估。在整个断层面上和两次地震破裂的凹凸体上,两个模型中应力降的最大值和平均值几乎相同。另外,1978年地震的震级比2005年的大,它的破裂能值不仅是在整个断层面上,而且在多次破裂的凹凸体上也比2005年的大。这些结果与先前用地震矩所做的破裂能标度的研究结果一致。我们还将破裂能值与以前研究中所估算的其他内陆地震的能值进行了对比,我们得到的宫城近海地震的值较小。造成这种不一致的原因可能是内陆浅源地震和俯冲带深源地震在构造背景上的差异。 相似文献
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