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JAEA Reports

Data of fractures based on the deep borehole investigations in the Horonobe Underground Research Laboratory Project (Phase 1)

Kusano, Tomohiro; Ishii, Eiichi

JAEA-Data/Code 2015-024, 6 Pages, 2016/02

JAEA-Data-Code-2015-024.zip:2.23MB
JAEA-Data-Code-2015-024.pdf:7.54MB

Japan Atomic Energy Agency (JAEA) is performing the Horonobe Underground Research Laboratory Project, which includes a scientific study of the deep geological environment as a basis of research and development for geological disposal of high level radioactive wastes (HLW), in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in the sedimentary rock. This report aims at compiling fracture data of drill core obtained from the Horonobe Underground Research Laboratory Project (Phase 1).

Journal Articles

Release of mantle and crustal helium from a fault following an inland earthquake

Umeda, Koji; Asamori, Koichi; Kusano, Tomohiro

Applied Geochemistry, 37, p.134 - 141, 2013/10

 Times Cited Count:10 Percentile:38.56(Geochemistry & Geophysics)

This study was undertaken to elucidate spatial and temporal changes of $$^{3}$$He/$$^{4}$$He ratios around a source region before and after an inland earthquake using both new and existing helium isotope data from hot spring and drinking water wells. Most gas samples near the seismic source region are characterized by increase in postseismic $$^{3}$$He/$$^{4}$$He ratios. In contrast, the postseismic ratios decrease by up to about 30% away from the seismic source region. Episodic faulting could release accumulated radiogenic helium from host rocks, or enhance the transfer of mantle volatiles through permeable fault zones, such that subsequent fluid flow proximal to the source region could then explain the spatio-temporal variations in $$^{3}$$He/$$^{4}$$He ratios.

Journal Articles

Spatial variations in $$^{3}$$He/$$^{4}$$He ratios along a high strain rate zone, central Japan

Umeda, Koji; Kusano, Tomohiro; Ninomiya, Atsushi*; Asamori, Koichi; Nakajima, Junichi*

Journal of Asian Earth Sciences, 73, p.95 - 102, 2013/09

 Times Cited Count:4 Percentile:15.24(Geosciences, Multidisciplinary)

A linear zone with high strain rates along the Japan Sea coast, the Niigata-Kobe Tectonic Zone (NKTZ), is considered to be associated with rheological heterogeneities in the lower crust and/or upper mantle. Helium isotope variations along the NKTZ reveal a close association with the geophysical evidence for rheological heterogeneities in the crust and mantle. In the northern NKTZ where two large inland earthquakes occurred recently, there appear to be many samples with $$^{3}$$He/$$^{4}$$He ratios significantly higher than those observed in the fore-arc side of northeast Japan. A plausible source of mantle helium could be attributed to upward mobilization of aqueous fluids generated by dehydration of the subducting Pacific Plate slab.

Journal Articles

Tectonic shortening and coeval volcanism during the Quaternary, northeast Japan arc

Umeda, Koji; Ban, Masao*; Hayashi, Shintaro*; Kusano, Tomohiro

Journal of Earth System Science, 122(1), p.137 - 147, 2013/02

 Times Cited Count:5 Percentile:18.84(Geosciences, Multidisciplinary)

From a compilation and analysis of stratigraphy, radiometric age and data on erupted magma volumes, 176 eruptive episodes identified from 69 volcanoes so far, indicate that notable changes in eruption style, magma discharge rates and distribution of eruptive centers occurred around 1.0 Ma. Before ca. 1.0 Ma in northeast Japan, large-volume felsic eruptions were dominant, forming large calderas in the frontal arc, a region of low crustal strain rate. After ca. 1.0 Ma to the present, the calc-alkaline andesite magma eruptions in the frontal and rear arcs, synchronous with crustal shortening characterized by reverse faulting, resulting in stratovolcano development along narrow uplifted zones.

Journal Articles

Relationship between $$^{3}$$He/$$^{4}$$He ratios and subduction of the Philippine Sea plate beneath southwest Japan

Umeda, Koji; Kusano, Tomohiro; Asamori, Koichi; McCrank, G. F.*

Journal of Geophysical Research; Solid Earth, 117(B10), p.B10204_1 - B10204_13, 2012/10

 Times Cited Count:3 Percentile:14.04(Geochemistry & Geophysics)

In order to elucidate the geographic distribution of $$^{3}$$He/$$^{4}$$He ratios in Southwest Japan, the data from a total of 924 sites were compiled and synthesized. There appears to be good correlation between variations in mantle helium and the geophysical evidence indicating the configuration of the subducting Philippine Sea plate. The helium isotopes observed on the Earth's surface may be efficient geochemical indicators of the configuration of a relatively younger, warm aseismic slab, especially useful in seismically inactive areas.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal years 2011

Asamori, Koichi; Niwa, Masakazu; Hanamuro, Takahiro; Yamada, Kunimi; Kusano, Tomohiro; Makuuchi, Ayumu; Takatori, Ryoichi; Kokubu, Yoko; Matsubara, Akihiro; Ishimaru, Tsuneari; et al.

JAEA-Research 2012-024, 132 Pages, 2012/09

JAEA-Research-2012-024.pdf:15.68MB

This annual report documents the progress of R&D in the 2nd fiscal year during the JAEA 2nd Midterm Plan (FY 2010 - 2014) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planed framework is structured into the following categories: (1) development and systematization of investigation techniques for selecting suitable sites in geosphere stability, (2) development, application and verification of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

JAEA Reports

Development of helium isotopic database in Japan

Kusano, Tomohiro; Asamori, Koichi; Umeda, Koji

JAEA-Data/Code 2012-017, 19 Pages, 2012/09

JAEA-Data-Code-2012-017.pdf:1.73MB
JAEA-Data-Code-2012-017-appendix(CD-ROM).zip:0.29MB

We constructed "Helium Isotopic Database in Japan", which includes isotope ratios of noble gases and chemical compositions of gas samples collected from hot springs and water wells. The helium isotopes are excellent natural tracers for indicating the presence of mantle derived volatiles, because they are chemically inert and thus conserved in crustal rock-water systems. It is common knowledge that mantle degassing does not occur homogeneously over the Earth's surface. The $$^{3}$$He/$$^{4}$$He ratios higher than the typical crustal values are interpreted to indicate that transfer of mantle volatiles into the crust by processes or mechanisms such as magmatic intrusion, faulting. In particular the spatial variation of helium isotope ratios could provide a valuable information to identify volcanic regions and tectonically active areas. The database was compiled geochemical data of groundwater from 108 published papers. As a result of the data compiling, the database has 1728 Helium isotopic data.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2012

Asamori, Koichi; Niwa, Masakazu; Hanamuro, Takahiro; Yamada, Kunimi; Kusano, Tomohiro; Makuuchi, Ayumu; Takatori, Ryoichi; Kokubu, Yoko; Ishimaru, Tsuneari; Umeda, Koji

JAEA-Review 2012-024, 44 Pages, 2012/07

JAEA-Review-2012-024.pdf:1.29MB

The concept of geological disposal of HLW in Japan is based on a multi-barrier system which combines a stable geological environment with a robust barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in a tectonically active zone. This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2012. The objectives and contents in fiscal year 2012 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). In addition, the planed framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal years 2010

Yasue, Kenichi; Asamori, Koichi; Tanikawa, Shinichi; Yamada, Kunimi; Yamasaki, Seiko; Kokubu, Yoko; Niwa, Masakazu; Doke, Ryosuke; Kusano, Tomohiro; Hanamuro, Takahiro; et al.

JAEA-Research 2011-023, 113 Pages, 2011/10

JAEA-Research-2011-023.pdf:10.9MB

This annual report documents the progress of R&D in the first fiscal year during the JAEA 2nd Midterm Plan (FY 2010 - 2014) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planed framework is structured into the following categories: (1) development and systematization of investigation techniques for selecting suitable sites in geosphere stability, (2) development, application and verification of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Development of methodology for the characterisation of the long-term geosphere evolution, 2; Estimation of the long-term evolution of groundwater flow conditions in a Tono area case study

Kosaka, Hiroshi; Saegusa, Hiromitsu; Yasue, Kenichi; Kusano, Tomohiro; Onoe, Hironori

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 9 Pages, 2011/10

The methodology for estimation of the long-term evolution of groundwater flow conditions are being developed using approaches on the basis of deductive and inductive methods in the case of Tono area. Based on the studies using the approach on the basis of deductive method, it has been confirmed that the method combining physical modeling of topographic change and groundwater flow simulations is useful for estimating of changes in groundwater flow conditions in the future due to topographic and climatic perturbations. Existing information for estimation of surface hydrological conditions, which are to be used for assignment of boundary conditions for the groundwater flow simulation, has been gathered from many sources and reviewed based on modern-analogue methods. In the studies using the approach on the basis of inductive method, paleo-hydrogeological studies have been carried out on several spatial and time scales. Through the study on the largest spatial scale, a methodology needed to understand changes of groundwater flow conditions due to long-term topographic change is proposed to efficiently identify the area to be carried out site characterization involving field investigations. And then, information to estimate the paleo-topography and paleo-climate has been obtained from literature surveys and field investigations. Through these studies, it has been confirmed that these two approaches are useful for estimation of the long-term evolution of deep groundwater flow conditions.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2011

Yasue, Kenichi; Asamori, Koichi; Kusano, Tomohiro; Kokubu, Yoko; Tanikawa, Shinichi; Niwa, Masakazu; Hanamuro, Takahiro; Yamasaki, Seiko; Yamada, Kunimi; Ishimaru, Tsuneari; et al.

JAEA-Review 2011-023, 43 Pages, 2011/07

JAEA-Review-2011-023.pdf:1.84MB

The concept of geological disposal of HLW in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in a tectonically active zone. This report is a plan of research and development (R&D) for geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2011. The objectives and contents in fiscal year 2011 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

JAEA Reports

Research on geosphere stability for long-term isolation of radioactive waste (Progress report for fiscal years 2005 - 2009: H22 report)

Kusano, Tomohiro; Asamori, Koichi; Kurosawa, Hideki; Kokubu, Yoko; Tanikawa, Shinichi; Negi, Tateyuki; Hanamuro, Takahiro; Yasue, Kenichi; Yamasaki, Seiko; Yamada, Kunimi; et al.

JAEA-Research 2010-044, 153 Pages, 2011/01

JAEA-Research-2010-044.pdf:12.53MB

This progress report (H22 report) documents progress made during JAEA 1st Midterm Plan (FY 2005 - 2009) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. For the current 5-year R&D programme, three major goals have been defined as follows: (1) development and synthesis of investigation techniques for selecting suitable sites in geosphere stability, (2) development, application, and evaluation of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

A Large intraplate earthquake triggered by latent magmatism

Umeda, Koji; Asamori, Koichi; Negi, Tateyuki; Kusano, Tomohiro

Journal of Geophysical Research, 116(B1), p.B01207_1 - B01207_12, 2011/01

 Times Cited Count:14 Percentile:45.14(Geochemistry & Geophysics)

A magnitude ($$M$$$$_{j}$$) 7.3 intraplate earthquake occurred in the western Tottori area, southwest Japan, on 6 October 2000, where there was no apparent prefaulting subsurface indication of the source fault of the 2000 earthquake. Magnetotelluric soundings were taken in and around the aftershocks occurred in order to image 3D electrical resistivity structure at depths of up to 40 km, which could indicate an anomalous conductor in the crust to the upper mantle on the southwest side of the source fault. Free gas and dissolved gases collected from groundwater wells around the seismic source region are characterized by $$^{3}$$He/$$^{4}$$He ratios several times higher than the atmospheric value. Although alkali basalts of early Pleistocene age are sparsely distributed in the western Tottori area, the observed $$^{3}$$He/$$^{4}$$He ratios are higher than the calculated $$^{3}$$He/$$^{4}$$He ratio derived from the ancient magmatism, considering post-extrusive radiogenic ingrowth of $$^{4}$$He by decay of U and Th included in the magma. Therefore, it is concluded that the geophysical anomaly imaged to the southwest of the source fault is attributed to latent magmatism in the present-day subduction system. Aqueous fluids separated from the cooling crustal magma could cause deep low-frequency earthquakes around the Moho discontinuity and migrate into the brittle upper crust. In addition, the presence of aqueous fluid is expected to weaken the crustal materials. Locally anelastic deformation, implying notable compressive deformation in the E-W direction, was observed in the region where aftershocks were distributed. Under overpressure conditions, the existing fault could serve as a pathway for aqueous fluids expelled from magma with high $$^{3}$$He/$$^{4}$$He ratios, so that the upwelling of overpressurized fluids toward the Earth's surface results in the emanation of groundwaters with high $$^{3}$$He/$$^{4}$$He ratios along the trace of the source fault segments.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2010

Yasue, Kenichi; Asamori, Koichi; Yamada, Kunimi; Kokubu, Yoko; Yamasaki, Seiko; Kurosawa, Hideki; Tanikawa, Shinichi; Negi, Tateyuki; Kusano, Tomohiro; Hanamuro, Takahiro; et al.

JAEA-Review 2010-034, 42 Pages, 2010/09

JAEA-Review-2010-034.pdf:1.15MB

The concept of geological disposal of HLW in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in a tectonically active zone. This report is a plan of research and development (R&D) for geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2010. The objectives and contents in fiscal year 2010 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

JAEA Reports

Research on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2010-2014

Umeda, Koji; Ishimaru, Tsuneari; Yasue, Kenichi; Asamori, Koichi; Yamada, Kunimi; Kokubu, Yoko; Hanamuro, Takahiro; Tanikawa, Shinichi; Kusano, Tomohiro

JAEA-Review 2010-030, 48 Pages, 2010/09

JAEA-Review-2010-030.pdf:1.42MB

The concept of geological disposal of HLW in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in a tectonically active zone. This report is to outline 5 years plan (fiscal years 2010-2014) of research and development (R&D) for geosphere stability for long-term isolation of the high-level radioactive waste in JAEA. Background of this research are clarified with the necessity and the significance, and the past progresses in this report. The objectives, outline, contents and schedule during the next 5 years are described in detail. In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

JAEA Reports

Compilation of near-surface hydrological information for estimation of long-term change on groundwater flow conditions

Kusano, Tomohiro; Yasue, Kenichi; Takeuchi, Ryuji; Saegusa, Hiromitsu; Miyahara, Tomoya*

JAEA-Review 2009-079, 56 Pages, 2010/03

JAEA-Review-2009-079.pdf:4.64MB

We paid attention to near-surface hydrology which influence the change of groundwater flow characteristic to grasp generally the width of long-term change of the geological environment condition with climatic / sea-level changes, and collected the data of evapotranspiration of 84 districts shown in about 50 parts domestic and foreign documents about evapotranspiration that it was difficult in the data of near-surface hydrology and arranged information about annual evapotranspiration. We collected the data of current Japan and the world district in a high latitude area (an area resemble climate of Japan of the glacial epoch) to consider the width of the change of near-surface hydrology with the climate change because data of the warmness period chilliness period in Japan were necessary. We compiled these information to the table which showed calculation technique or quantity of position / basin characteristic / evapotranspiration / precipitation every district.

JAEA Reports

Annual report for research on long-term stability of geological environments in FY2008

Kusano, Tomohiro; Asamori, Koichi; Kurosawa, Hideki; Tanikawa, Shinichi; Ninomiya, Atsushi; Negi, Tateyuki; Hanamuro, Takahiro; Yasue, Kenichi; Yamada, Kunimi; Ishimaru, Tsuneari; et al.

JAEA-Research 2009-072, 72 Pages, 2010/03

JAEA-Research-2009-072.pdf:11.27MB

The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment, taking into account volcanism, faulting, uplift, denudation, climatic change and sea-level change in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. In fiscal year 2008, we carried out the following researches. For studies on faulting and seismic activity, we developed investigation techniques for evolutional history and activity of fault, and carried out case studies for development of effective assessment model in the fault zones. For volcanological and geothermal studies, we provided an integrated approach for detecting crustal magma and/or geothermal fluid in deep underground using geophysical and geochemical data. For the general evaluation study on uplift/denudation and climatic/sea-level change, we arranged investigation techniques for reconstruction of paleo-topography and paleo-climate, and to establish a simulation model for landform development. For studies on the long-term stability of the geological environments, we developed simulation techniques for groundwater flow related by crustal movement.

JAEA Reports

Annual report for research on long-term stability of geological environments in FY2007

Kusano, Tomohiro; Nohara, Tsuyoshi; Umeda, Koji; Ishimaru, Tsuneari; Hanamuro, Takahiro; Saito, Tatsuo; Yasue, Kenichi; Niwa, Masakazu; Shimada, Koji; Yamada, Kunimi; et al.

JAEA-Research 2009-022, 47 Pages, 2009/09

JAEA-Research-2009-022.pdf:48.94MB

The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment, taking into account volcanism, faulting, uplift, denudation, climatic change and sea-level change in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. In fiscal year 2007, we carried out the following researches, to confirm existence of the phenomena that have influences on geological disposal system (e.g., active faulting, volcanism), and to develop the investigation techniques to reconstruct the history of these phenomena. For studies of faulting and seismic activity, we developed the investigation techniques to research distribution of crush zone, process of faulting, activity, and so on. For volcanological and geothermal studies, we developed a technique for detecting crustal magma and/or geothermal fluid in deep underground. For studies of uplift/denudation and climatic/sea-level changes, we extracted investigation techniques for landform developments and uplift rate with river terraces.

JAEA Reports

Annual report for research on long-term stability of geological environment in FY2006

Nohara, Tsuyoshi; Umeda, Koji; Sasao, Eiji; Hanamuro, Takahiro; Saito, Tatsuo; Yasue, Kenichi; Niwa, Masakazu; Mashima, Hidehisa*; Shimada, Koji; Yamada, Kunimi; et al.

JAEA-Research 2008-062, 61 Pages, 2008/07

JAEA-Research-2008-062.pdf:39.02MB

The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. During fiscal year 2006, we carried out the following researches, to confirm existence of the phenomena that have influences on geological disposal system, and to develop the research techniques to reconstruct the history of these phenomena. For studies of active faulting and seismic activity, we reviewed the existing techniques to research past activities and distribution of active faults (migration, extension, development process of a deformation zone). For volcanological and geothermal studies, we extracted a technique for detecting crustal magma and/or geothermal fluid in deep underground using geophysical and geochemical data, and models assessing the likelihood of future volcanism and its influence on geological environment. For studies of uplift/denudation and climatic/sea-level change, we constructed conceptual models such as landform development model.

Oral presentation

Study on topographic and climatic variations concerning long-term stability of geological environment; A Case study on an inland area in Japan

Yasue, Kenichi; Tajikara, Masayoshi; Saegusa, Hiromitsu; Niwa, Masakazu; Kurosawa, Hideki; Kusano, Tomohiro

no journal, , 

The stability of geological environments is influenced by natural events such as uplift, denudation, and climate variation. It is important for the geological disposal of nuclear wastes to assess the stability of geological environments. The purpose of this study is to establish the comprehensive techniques and method to evaluate the effects of topographic and climatic variations on groundwater flow condition. For this purpose, we developed the following techniques. (1) Research techniques for paleo-topography and paleo-climate (2) Modeling and simulation techniques for landform development (3) Simulation techniques of groundwater flow in consideration of the time-variation of geological environment. In this presentation, we introduce briefly the some of research results.

34 (Records 1-20 displayed on this page)