Quasi-static slip on the plate boundary associated with the 2003 M8.0 Tokachi-oki and 2004 M7.1 off-Kushiro earthquakes, Japan     

Naoki Uchida  Satoshi Yui  Satoshi Miura  Toru Matsuzawa  Akira Hasegawa  Yoshinobu Motoya  Minoru Kasahara 《Gondwana Research》2009,16(3-4):527-533

We analyzed small repeating earthquakes recorded over a 13-year period and GPS data recorded over an 8-month period to estimate interplate quasi-static slip associated with the 2003 Tokachi-oki earthquake (M8.0) and the 2004 off-Kushiro earthquake (M7.1). The repeating-earthquake analysis revealed that the slip rate near the source region of the Tokachi-oki earthquake was relatively low (< 5 cm/year) prior to the earthquake; however, in the last 3 years leading up to the event, a minor acceleration in slip occurred upon the deeper extension of the coseismic slip area of the earthquake. Repeating-earthquake and GPS data indicate that large amounts of afterslip occurred around the rupture area following the earthquake; the afterslip mainly propagated to the east of the coseismic slip area. We also infer that the occurrence of the 2004 off-Kushiro earthquake, located about 100 km northeast of the epicenter of the Tokachi-oki earthquake, was advanced by the afterslip associated with the Tokachi-oki earthquake.  相似文献   

An empirical probabilistic approach for constraining the uncertainty of long-term solute transport predictions in fractured rock using in situ tracer experiments     

Masahiro Uchida  William Dershowitz  Glori Lee  Dawn Shuttle 《Hydrogeology Journal》2009,17(5):1093-1110

Although radionuclide tracer tests have been carried out for over 30  years, the role of tracer tests in radioactive waste repository performance assessment (PA) has been questioned due to the differences between the time scales for tracer tests and PA. The possibility of using in situ tracer tests to constrain PA time scale (over 10,000  years) solute transport has been demonstrated using a systematic “microstructural model” approach to define advective and retentive materials. A series of simulations were conducted of the “TRUE-1” sorbing solute transport experiments in a well-characterized block of fractured granite. These experiments were then used to constrain the uncertainty of long-term transport on the same pathways, using a gradient several orders of magnitude smaller. The comparison of uncertainty of this long-term transport, with and without this conditioning step, provided a measure of the ability of tracer tests to reduce PA time-scale uncertainty. Although this approach for quantifying uncertainty reduction is somewhat empirical, it does indicate the potential usefulness of tracer experiments in reducing the uncertainty of the key PA time-scale transport parameters such as the flow wetted surface, provided that immobile zone properties such as sorption (Kd), porosity and diffusivity are available.  相似文献   

Performance evaluation of a ground-source heat pump system utilizing a flowing well and estimation of suitable areas for its installation in Aizu Basin,Japan     

Gaurav Shrestha  Youhei Uchida  Satoru Kuronuma  Mutsumi Yamaya  Masahiko Katsuragi  Shohei Kaneko  Naoaki Shibasaki  Mayumi Yoshioka 《Hydrogeology Journal》2017,25(5):1437-1450

Development of a ground-source heat pump (GSHP) system with higher efficiency, and evaluation of its operating performance, is essential to expand the growth of GSHP systems in Japan. A closed-loop GSHP system was constructed utilizing a flowing (artesian) well as a ground heat exchanger (GHE). The system was demonstrated for space-heating and space-cooling of a room (area 126.7 m²) in an office building. The average coefficient of performance was found to be 4.5 for space-heating and 8.1 for space-cooling. The maximum heat exchange rate was 70.8 W/m for space-heating and 57.6 W/m for space-cooling. From these results, it was determined that a GSHP system with a flowing well as a GHE can result in higher performance. With this kind of highly efficient system, energy saving and cost reduction can be expected. In order to assess appropriate locations for the installation of similar kinds of GSHP systems in Aizu Basin, a suitability map showing the distribution of groundwater up-flowing areas was prepared based on the results of a regional-scale three-dimensional analytical model. Groundwater up-flowing areas are considered to be suitable because the flowing well can be constructed at these areas. Performance evaluation of the GSHP system utilizing the flowing well, in conjunction with the prepared suitability map for its installation, can assist in the promotion of GSHP systems in Japan.  相似文献   

减饱和砂土缓倾场地的液化性状分析     

李晶  陈育民  方志  高晗  飞田哲男  周葛 《岩土力学》2019,40(11):4352-4360

减饱和法是一种通过减小砂土地基的饱和度,从而提高地基抗液化强度的新方法。基于减饱和砂土中流体模量同步更新的改进算法对减饱和砂土离心机振动台试验进行了数值分析,并与单一流体模量的简化算法进行了对比分析。结果表明：由于改进算法中考虑了因孔压变化引起的等效流体模量的变化,其计算结果更接近试验结果,而简化算法低估了减饱和砂土的孔压积累。基于改进算法开展了不同饱和度、倾斜角度的缓倾场地上液化变形的数值模拟研究,分析发现超孔隙水压力增长的速度及其峰值随着饱和度的增加而增大,饱和度从100%降低至96.4%,同一深度处的超孔压峰值降低约20%～65%,加速度响应的峰值也有明显的降低;沿地基深度0.75 m到9.00 m,侧向位移减少约20%～50%,表明饱和度的降低对抑制倾斜场地上可液化砂土层的侧向变形有显著效果,随着地基深度的减小,饱和度对于侧向位移的影响越来越明显。  相似文献   

A model for the hydrogen coma of a comet     

Yoshimi Kitamura  Osamu Ashihara  Tetsuo Yamamoto 《Icarus》1985,61(2):278-295

A model for the hydrogen coma of a comet on the basis of the Monte Carlo method is presented. In this model isotropic ejections of H atoms produced by photodissociation of H₂O and OH, thermalization of the H atoms due to collisions with ambient H₂O molecules, and the solar radiation pressure have been taken into account. A production spectrum of H atoms from OH is evaluated by using the predissociation rates and the level populations of OH, confirming that the spectrum has a sharp peak around 8.0 km sec^?1 with the standard deviation of 0.1 km sec^?1. Including the above effects, velocity distribution functions of the H atoms at various positions in the coma for the first time, as well as their density and outflow velocity profiles, have been calculated. It is pointed out that the collisional thermalization process in the inner coma is an important factor at small heliocentric distances in determining the density profiles and the velocity distributions. It is shown that thermalization leads to an increase in the H density in the inner coma larger than those expected from other models such as the vectorial model, in which collision is not taken into account. Lyman α isophotes and its line profiles in the optically thin region are computed by using the velocity distribution function.  相似文献   

An excitation mechanism for the free 'core nutation'   总被引：2，自引：0，他引：2  

Tetsuo Sasao  John M. Wahr 《Geophysical Journal International》1981,64(3):729-746

Summary. The Earth is believed to possess a free nutational mode due to its rotating, elliptical, fluid core, with an eigenfrequency of approximately (1 + 1/460) cycle sidereal day⁻¹ as seen from the sidereally rotating Earth. This free 'core nutation' has not yet been undisputably observed. Furthermore, there has been considerable doubt that any known mechanism could excite this mode to an observable level. We show here that diurnal atmospheric and oceanic loading of the Earth's surface provide an efficient excitation mechanism which depends critically on the physical damping of the mode. Possible effects of the mode on geodetic measurements are discussed. We also consider the effects of 'wobble' and 'nutation' on astrometric observations.  相似文献   

Spectrophotometric scan of comet 1973 XII Kohoutek     

Hisashi S. Ishii  Tetsuo Yamamoto  Shin'ichi Tamura 《Earth, Moon, and Planets》1981,25(4):437-450

Photoelectric spectrophotometric scans of Comet 1973 XII Kohoutek were made on November 25.85 and 28.85 UT, 1973. The vibrational temperature of C₂, the total numbers of CN and of C₂, and the production rates for CN and C₂ are derived from the observed fluxes. The temperature of C₂ was 4900 K on 25.85 November and 4300 K on 28.85 November. Mean abundance ratio of C₂ to CN was about 2.7. From the variation of production rates with heliocentric distance, it is shown that there was an outburst on 25.85 November in both CN and C₂ productions. For C₂, the production rates are derived by using two coma models, i.e. the Haser's parent-daughter model and the model relevant to a proposition of Yamamoto (1981b) that C₂ is formed via two-step photodissociation of its parent molecules. By comparing the production rate derived from the two models, it can be supported that C₂ is formed via two-step photodissociation rather than one-step photodissociation. In consequence, it is shown that the variation of the production rate with heliocentric distance is largely modified compared with that derived from the Haser's model.  相似文献   

Magnetodynamic phenomena in the solar and stellar outer atmospheres     

Yutaka Uchida 《Astrophysics and Space Science》1986,118(1-2):127-148

Magnetic effects causing anomalous heating and drastic flarings in the atmospheres of various types of stars are discussed. The best studied examples of these magnetic effects with spatially resolved observations are those in the case of the Sun, but no simple application of the solar knowledge to the stellar cases is allowed, since there are generally very large differences in the physical conditions between the Sun and other types of stars. We examine possible effects of the magnetic field in the respective situations of several types of stars which show X-ray and radio emissions indicating the presence of such activities, and it is concluded that the magnetic field may be playing important roles in producing anomalous heating and drastic flarings also in those stars having very different physical conditions, in ways seemingly very different from, but intrinsically closely related to, those in the case of the Sun.Invited review paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.  相似文献   

Toward coastal zone management that ensures coexistence between people and nature in the 21st century   总被引：1，自引：0，他引：1  

Yanagi T  Ducrotoy JP 《Marine pollution bulletin》2003,47(1-6):1-4

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A two-dimensional magnetotelluric inversion assuming Gaussian static shift   总被引：4，自引：0，他引：4  

Yasuo Ogawa  Toshihiro Uchida 《Geophysical Journal International》1996,126(1):69-76

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