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1.
Haijiang Liu Takenori Shimozono Tomohiro Takagawa Akio Okayasu Hermann M. Fritz Shinji Sato Yoshimitsu Tajima 《Pure and Applied Geophysics》2013,170(6-8):1033-1046
On 11 March 2011, a moment magnitude M w = 9.0 earthquake occurred off the Japan Tohoku coast causing catastrophic damage and loss of human lives. In the immediate aftermath of the earthquake, we conducted the reconnaissance survey in the city of Rikuzentakata, Japan. In comparison with three previous historical tsunamis impacting the same region, the 2011 event presented the largest values with respect to the tsunami height, the inundation area and the inundation distance. A representative tsunami height of 15 m was recorded in Rikuzentakata, with increased heights of 20 m around rocky headlands. In terms of the inundation area, the 2011 Tohoku tsunami exceeded by almost 2.6 times the area flooded by the 1960 Chilean tsunami, which ranks second among the four events compared. The maximum tsunami inundation distance was 8.1 km along the Kesen River, exceeding the 1933 Showa and 1960 Chilean tsunami inundations by factors of 6.2 and 2.7, respectively. The overland tsunami inundation distance was less than 2 km. The tsunami inundation height linearly decreased along the Kesen River at a rate of approximately 1 m/km. Nevertheless, the measured inland tsunami heights exhibit significant variations on local and regional scales. A designated “tsunami control forest” planted with a cross-shore width of about 200 m along a 2 km stretch of Rikuzentakata coastline was completely overrun and failed to protect the local community during this extreme event. Similarly, many designated tsunami shelters were too low and were overwashed by tsunami waves, thereby failing to provide shelter for evacuees—a risk that had been underestimated. 相似文献
2.
The forming star grows by mass inflow from the parent cloud core, mainly through the accretion disk. However, the core matter which has not yet contracted much is seriously disturbed by the activities of the forming star. We consider mass outflow and emission of ultraviolet radiation as such activities and determine the stellar mass as a function of the physical quantities of the parent cloud core. 相似文献
3.
Evaluation of the structural damage of high‐rise reinforced concrete buildings using ambient vibrations recorded before and after damage 
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下载免费PDF全文 Hirotoshi Uebayashi Masayuki Nagano Takenori Hida Takehiko Tanuma Mitoshi Yasui Shigeki Sakai 《地震工程与结构动力学》2016,45(2):213-228
Evaluation of the degrees of structural damage suffered by high‐rise residential buildings after being subjected to strong ground motions is extremely important to the development of life continuity planning for building residents. However, these evaluations cannot be based on strong‐motion records alone, because earthquake observation equipment is not installed in most such buildings in Japan. In this study, we propose simple equations for estimating the stiffness degradation rate and the peak inter‐story drift ratio (PIDR) by using ambient vibration records instead of strong‐motion records when high‐rise RC buildings are subjected to a severe earthquake. More specifically, we propose one equation that relates the square root of the stiffness degradation rate, which is the ratio of natural frequencies at the maximum response to the preliminary tremor response (elastic state), in strong‐motion records with the ratio of natural frequencies identified from ambient vibrations before and after damage was suffered. We also propose an equation that relates the PIDR with the stiffness degradation rate on the basis of the stiffness‐degrading bilinear restoring force characteristic derived from the strong‐motion records of 13 high‐rise buildings for the 1995 Hyogoken‐Nanbu Earthquake (Mw 6.9) and the 2011 Tohoku‐Oki Earthquake (Mw 9.0). Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
4.
Jin-Chun Chai Takenori Hino Shui-long Shen John P. Carter 《Geotechnical and Geological Engineering》2017,35(5):2107-2122
The Saga Plain in Japan contains a 10–30 m thick Holocene clayey soil deposit with a natural water content generally more than 100% and a liquidity index (I L ) larger than 1.0. Most of this is a marine deposit known as the Ariake clay formation. Using salinity in the pore water of this deposit as an index, the mechanism of post-depositional salinity leaching from the Ariake clay formation has been investigated. This has been achieved using current measurements of the salinity distribution in the deposit and the groundwater flow velocity in an underlying Pleistocene gravelly sand layer, together with advection–diffusion analyses. It is suggested that diffusion together with possible rainfall percolation and/or upward seepage flow from the Pleistocene gravelly sand layer was the main mechanism causing salinity leaching. Detailed analysis of the test results from four boreholes indicates that for the locations where the activity of the clay minerals was less than 1.25, salinity leaching probably accounts for the observed low undrained shear strength (<0.5 kPa) of remoulded soil samples, high values of the sensitivity (S t ), and the formation of a quick clay. 相似文献
5.
新疆阿勒泰地区发育了红柱石-矽线石型递增变质带,由绿泥石-黑云母带、黑云母-石榴石带、石榴石-十字石带、十字石-红柱石带和矽线石带组成,根据石榴石成分环带、变质与变形关系、矿物共生组合演化等特征,将变质作用分为峰前期、峰期和峰后期3个演化阶段。峰前期、峰期为连续的递增变质过程,形成典型的中-低压过渡型递增变质带,峰后期属于退变质过程。据石榴石一斜长石一黑云母-白云母-石英组合内部一致地质温压计估算出峰期温度-压力：T=580℃～670℃,P一0．4GPa～0．5GPa。变质作用演化具有顺时针的PTt轨迹,代表陆壳有一定程度的构造增厚,但幅度不大,没有大规模的陆壳俯冲或拆沉作用,这种增厚可能以陆壳的构造叠置机制为主。总体相当于地体间斜向走滑兼有一定垂直分量的拼合过程的地球动力学机制。 相似文献
6.
Rui Jia Takenori Hino Takaharu Hamada Jinchun Chai Mitsugu Yoshimura 《Ocean Dynamics》2013,63(5):507-517
The density and the undrained shear strength (s u) of bed sediments at either side of the Isahaya Bay dike in the Ariake Sea, Japan, were investigated using nuclear density cone penetration tests (ND-CPTs). The nuclear density cone penetrometer (ND-CP) was operated from a boat, conducting 71 ND-CPTs. Furthermore, 26 undisturbed samples were obtained for soil density and s u measurements to calibrate the ND-CPT data. The results show that the density and s u obtained from in situ with the ND-CPTs agree well with those from the laboratory tests on undisturbed samples, and the obtained density profiles show good repeatability. The vertical variation in density and s u of the bed sediment can be obtained from the ND-CPT results. The relations between the density and s u show that s u increases with an increase in density, but that this relation is site specific. The values of s u show an exponentially growing trend and the values of log s u show a linearly increasing trend with density. The vertical distribution of the bed sediments can be described using the density values obtained with the ND-CPT. 相似文献
7.
新疆阿尔泰冲乎尔地区蓝晶石-夕线石型变质带独居石CHIME二叠纪年龄及其地质意义 总被引：3，自引：0，他引：3
新疆冲乎尔地区的蓝晶石-夕线石型递增变质带由绿泥石-黑云母带、黑云母-石榴石带、石榴石-十字石带、十字石-蓝晶石带和夕线石带组成;递增变质作用峰期温度、压力分别为T=520～640℃,p=(4.5～5.8)×108Pa;十字石-蓝晶石带和夕线石带变质岩中含有丰富的独居石,而且Th-U-Pb含量比较高,适合电子探针独居石CHIME法定年,独居石CHIME法确定的变质时代为268±10～261±20Ma,与阿勒泰地区发育的红柱石-夕线石型(低压型)变质带形成时代(262±10～264±22Ma)一致,说明阿尔泰造山带蓝晶石-夕线石型和红柱石-夕线石型递增变质带是同一次大规模的构造热事件的产物,时代为二叠纪中期。 相似文献
8.
Abstract The chemical Th-U-total Pb isochron method (CHIME) has been applied to determine the ages of monazite grains from metasediments of greenscshist-amphibolite facies in the Altai orogen, northwest China. The area of distribution of these metamorphic rocks is divided into the Permian (261–268 Ma) central-western and Devonian (377–382 Ma) eastern units on the basis of their metamorphic ages. The Devonian CHIME ages are consistent with the Pb–Pb ages of granitoid in the eastern unit, and support the idea that emplacement of the granitoids was synchronous with regional metamorphism at deep levels. The Permian metamorphic ages (the present study) and igneous ages previously reported from the central-western unit can be interpreted in terms of subduction of crustal material and oceanic plate, and rapid exhumation. 相似文献
9.
The uplift behavior of a plate anchor in a structured clay (soft Ariake clay) is investigated through a series of laboratory tests and method of finite element analysis. The tests are adopted to identify the factors influencing the behavior of the anchor, including the thixotropic nature of Ariake clay, consolidation time, and embedment ratio of the anchor. A finite element method (FEM) is used to analyze and predict the uplift behavior of the anchor plate well in the elastic region and the yield load. The results from both the laboratory tests and the FEM analysis suggest that the embedment ratio for a deep anchor in Ariake clay is close to 4. Further increase in embedment ratio improves the capacity to a lesser extent. FEM overestimates the failure load of the uplift anchor in soft Ariake clay by about 20%. This may be ascribed to the hypothesis in the FEM analysis that there is continuous contact between the clay and the anchor until failure. Vesic’s theory for deep anchors, which may be used to predict the ultimate pullout resistance of the plate anchor in reconstituted Ariake clay, is verified to be applicable. In this paper, the plastic flow zone around the anchor is discussed using FEM which makes the behavior of anchor more understandable during the design stage. 相似文献
10.
CHIME dating of monazite, xenotime, zircon and polycrase: Protocol, pitfalls and chemical criterion of possibly discordant age data 总被引：7，自引：5，他引：2
This paper outlines the CHIME (chemical Th–U-total Pb isochron method) dating method, which is based on precise electron microprobe analyses of Th, U and Pb in Th- and U-bearing accessory minerals such as monazite, xenotime, zircon and polycrase. The age-mapping technique that is applicable to young monazite and zircon is also described. CHIME dating consists of analyzing multiple spots within homogeneous age domains that show sufficient compositional variation, and then these data are used to construct a “pseudo-isochron” from which an age can be obtained via regression. This method, when coupled with discrimination of possibly concordant age data by chemical criteria such as the (Ca + Si)/(Th + U + Pb + S) ratio for monazite and Ca and S contents for zircon, has the potential advantage of significant precision, and the ability to work with minerals that have a significant initial common Pb component. This technique can identify two or more homogeneous domains that are separated by age gaps smaller than the error on individual spot age analysis. Many features that are insignificant in major element analysis can have major impact in the acquisition of trace element data. Critical factors include the roles of collimator slit, detector gas, background estimation, accelerating voltage, probe current, X-ray interferences and count rate in affecting the accuracy, and a way to apply the Th and U interference correction without pure Th- and U-oxides or synthesized pure ThSiO4. The age-mapping procedure for young monazite and zircon includes acquiring PbMα (or PbMβ) intensity of individual pixels with multiple spectrometers, correcting background with background maps computed from a measured background intensity by the intensity relationships determined in advance of the measurement, calibrating of intensity with standards and calculating of ages from the Th, U and Pb concentrations. This technique provides age maps that show differences in age domains on the order of 20 Ma with in monazite as young as 100 Ma. The effect of sample damage by irradiation of intense and prolonged probe measurement is also described. 相似文献