Izu-Bonin arc subduction under the Honshu island, Japan: Evidence from geological and seismological aspect   总被引：1，自引：1，他引：0  

Shinji Yamamoto  Junichi Nakajima  Akira Hasegawa  Shigenori Maruyama 《Gondwana Research》2009,16(3-4):572-580

The Izu-Bonin intra-oceanic arc with 20–35 km thick continental crust is being subducted under the Honshu, presumably since 17 Ma. Tomographic image clearly demonstrates that the whole Izu-Bonin arc is subducting under the Honshu arc. Geologic cross section and the thickness of continental crust do not support the accretion of thick crust in spite of the continued subduction over 17 Ma.  相似文献   

准噶尔板块东北缘富铌玄武岩的发现及其地质意义   总被引：4，自引：0，他引：4       下载免费PDF全文

张海祥  牛贺才  于学元  单强  HiroakiSato  JunichiIto 《地质找矿论丛》2003,18(1):71-72

富铌玄武岩是硅过饱和,富Ｎａ2Ｏ,ＴｉＯ2,Ｐ2Ｏ5,同时富集高场强元素的一类岛弧玄武岩,这类玄武岩的ｗ(Ｎｂ)>7×10-6,(ｗ(Ｌａ)/ｗ(Ｎｂ))ＭＮ<2。它是由来源于70100ｋｍ深处、受ａｄａｋｉｔｅ熔体交代过的地幔楔橄榄岩部分熔融形成的,是大洋板块俯冲作用的产物。目前发现的富铌玄武岩大多分布在环太平洋新生代岛弧环境,与洋壳俯冲作用密切相关[1 5]。本研究在准噶尔板块东北缘富蕴县的索尔库都克附近首次发现了富铌玄武岩。它产于下泥盆统托让格库都克组中、上部。该地层自下而上的岩石组合为:玄武岩 火山凝灰角砾岩 火山集块岩 含…  相似文献   

Examination of Self-reversal due to N-type Magnetization in Basalt     

Junichi Nishida  Sadao Sasajima 《Geophysical Journal International》1974,37(3):453-460

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Earthquake simulation test of circular reinforced concrete bridge column under multidirectional seismic excitation     

Junichi Sakai Shigeki Unjoh 《地震工程与工程振动(英文版)》2006,5(1):103-110

1 Introduction Since the 1971 San Fernando earthquake, a signi?cant amount of research has been conducted on the ductility capacity of reinforced concrete bridge columns, resulting in signi?cant advances in the seismic design of bridges. Since most tests have been done in static or quasistatic conditions and unidirectional loading conditions, however, no method that properly evaluates the effect of multidirectional dynamic loading has been developed, and design recommendations on this effect a…  相似文献   

Bifurcation current along the southwest coast of the Kii Peninsula   总被引：1，自引：0，他引：1  

Junichi Takeuchi  Naoto Honda  Yoshitaka Morikawa  Takashi Koike  Yutaka Nagata 《Journal of Oceanography》1998,54(1):45-52

Along the southwest coast of the Kii Peninsula, a bifurcation current is regularly observed. By using ADCP data taken on board the R/V Wakayama of the Wakayama Prefectural Fisheries Experimental Station, characteristics of this bifurcation current are analyzed. The occurrence frequency of the bifurcation current reaches about 70% in the period from 1988 to 1996. The bifurcation point appears to be changeable and occurs almost evenly between Cape Ichie and Cape Shionomisaki. The current divergence in the alongshore direction was also investigated. Positive divergence values dominated in the whole analyzed area, and an onshore current appears to be dominant along the southwest coast of the Kii Peninsula, except in 1990 when the Kuroshio flowed in a large meandering path.  相似文献   

Free-surface implementation in a mesh-free finite-difference method for elastic wave propagation in the frequency domain     

Junichi Takekawa  Hitoshi Mikada 《Geophysical Prospecting》2019,67(8):2104-2114

We present an original implementation of the free-surface boundary condition in a mesh-free finite-difference method for simulating elastic wave propagation in the frequency domain. For elastic wave modelling in the frequency domain, the treatment of free surfaces is a key issue which requires special consideration. In the present study, the free-surface boundary condition is directly implemented at node positions located on the free-surface. Flexible nature of the mesh-free method for nodal distribution enables us to introduce topography into numerical models in an efficient manner. We investigate the accuracy of the proposed implementation by comparing numerical results with an analytical solution. The results show that the proposed method can calculate surface wave propagation even for an inclined free surface with substantial accuracy. Next, we calculate surface wave propagation in a model with a topographic surface using our method, and compare the numerical result with that using the finite-element method. The comparison shows the excellent agreement with each other. Finally, we apply our method to the SEG foothill model to investigate the effectiveness of the proposed method. Since the mesh-free method has high flexibility of nodal distribution, the proposed implementation would deal with models of topographic surface with sufficient accuracy and efficiency.  相似文献   

Region-based automatic mapping of tsunami-damaged buildings using multi-temporal aerial images     

Junichi Susaki 《Natural Hazards》2015,76(1):397-420

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Role of end-use technologies in long-term GHG reduction scenarios developed with the BET model     

Hiromi Yamamoto  Masahiro Sugiyama  Junichi Tsutsui 《Climatic change》2014,123(3-4):583-596

In this study, we develop a new integrated assessment model called the BET model (Basic Energy systems, Economy, Environment, and End-use Technology Model). It is a multi-regional, global model based on Ramsey’s optimal growth theory and includes not only traditional end-use technologies but also advanced end-use technologies such as heat-pump water heaters and electric vehicles. Using the BET model, we conduct simulations and obtain the following results. (1) Advanced end-use technologies have an important role in containing carbon prices as well as GDP losses when GHG (greenhouse gas) constraints are stringent. (2) Electrification based on energy services progresses rapidly in scenarios with stringent GHG constraints. This is because electricity can be supplied by various methods of non-fossil power generation, and advanced end-use technologies can drastically improve energy-to-service efficiencies. The BET’s results indicate the importance of analyses that systematically combine environmental constraints, end-use technologies, supply energy technologies, and economic development.  相似文献   

The 2011 Draconids: The First European Airborne Meteor Observation Campaign     

Jeremie Vaubaillon  Pavel Koten  Anastasios Margonis  Juraj Toth  Regina Rudawska  Maria Gritsevich  Joe Zender  Jonathan McAuliffe  Pierre-Dominique Pautet  Peter Jenniskens  Detlef Koschny  Francois Colas  Sylvain Bouley  Lucie Maquet  Arnaud Leroy  Jean Lecacheux  Jiri Borovicka  Junichi Watanabe  Jürgen Oberst 《Earth, Moon, and Planets》2015,114(3-4):137-157

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Long-term climate response to stabilized and overshoot anthropogenic forcings beyond the twenty-first century     

Junichi Tsutsui  Yoshikatsu Yoshida  Dong-Hoon Kim  Hideyuki Kitabata  Keiichi Nishizawa  Norikazu Nakashiki  Koki Maruyama 《Climate Dynamics》2007,28(2-3):199-214

From multi-ensembles of climate simulations using the Community Climate System Model version 3, global climate changes have been investigated focusing on long-term responses to stabilized anthropogenic forcings. In addition to the standard forcing scenarios for the current international assessment, an overshoot scenario, where radiative forcings are decreased from one stabilized level to another, is also considered. The globally-averaged annual surface air temperature increases during the twenty-first century by 2.58 and 1.56°C for increased forcings under two future scenarios denoted by A1B and B1, respectively. These changes continue but at much slower rates in later centuries under forcings stabilized at year 2100. The overshoot scenario provides a different pathway to the lower B1 level by way of the greater A1B level. This scenario results in a surface climate similar to that in the B1 scenario within 100 years after the forcing reaches the B1 level. Contrasting to the surface changes, responses in the ocean are significantly delayed. It is estimated from the linear response theory that temperature changes under stabilized forcings to a final equilibrium state in the A1B (B1) scenario are factors of 0.3–0.4, 0.9, and 17 (0.3, 0.6, and 11) to changes during the twenty-first century, respectively, for three ocean layers of the surface to 100, 100–500, and 500 m to the bottom. Although responses in the lower ocean layers imply a nonlinear behavior, the ocean temperatures in the overshoot and B1 scenarios are likely to converge in their final equilibrium states.  相似文献