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Yoshida, Hidekazu*; Kojima, Keiji*; Onishi, Yuzo*; Tochiyama, Osamu*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Sugihara, Kozo; Ogata, Nobuhisa
no journal, ,
no abstracts in English
Sueoka, Shigeru; Yasue, Kenichi; Niwa, Masakazu; Shimada, Koji; Ishimaru, Tsuneari; Umeda, Koji; Yamada, Ryuji*; Danhara, Toru*; Iwano, Hideki*; Gozu, Chitaro*
no journal, ,
We introduce an attempt to date a fault distributed in the Kojyaku granite, Tsuruga area, by reconstructing its cooling history based on multi-system thermochronology. The U-Pb ages, zircon fission-track ages, and zircon fission-track length distributions of the fault gauge and host granitic rock indicate a common cooling history at higher temperature, whereas apatite fission-track may imply later reheating in the fault gauge. We are planning to provide more definitive discussions based on apatite fission-track length data.
Sueoka, Shigeru; Tsutsumi, Hiroyuki*; Tagami, Takahiro*; Hasebe, Noriko*; Tamura, Akihiro*; Arai, Shoji*; Shibata, Kenji
no journal, ,
We are attempting to reveal uplift and denudation history of the Yoro-Suzuka-Nunobiki mountains, southwest Japan, by using apatite fission-track thermochronology. The mountains are distributed along the tectonic boundary of the reverse-fault dominant Kinki district and strike-slip fault dominant Chubu district, being an important region to understand the Quaternary tectonics of the southwest Japan inner zone. We are planning to reconstruct uplift and denudation history of the mountains in the past few million years and discuss its geomorphological and tectonic implications.
Ishibashi, Masayuki; Sasao, Eiji; Nakajima, Makoto*; Atsumi, Hiroyuki*; Onoe, Hironori; Saegusa, Hiromitsu; Kawabata, Junichi*; Masumoto, Kazuhiko*; Seno, Shoji*; Iwano, Keita*
no journal, ,
no abstracts in English
Ishimaru, Tsuneari; Shimada, Koji; Sasaki, Akimichi; Tanaka, Yukumo; Miyazaki, Masashi; Yasue, Kenichi; Niwa, Masakazu; Sueoka, Shigeru; Umeda, Koji; Ikeda, Makinori
no journal, ,
The Nuclear Regulation Authority instructed to develop a further additional research plan regarding the crushed zones on the Monju site against the JAEA on September 25. The JAEA developed a research plan in response to this instruction, and, the stripping investigation with expansion of the area, the additional detailed geographical and geological surveys around the mountains/terrace boundary, and the marine seismic surveys in the coastal waters, were conducted. The fracture zones were grouped into 2 systems called 
-system and 
-system in the on-site investigation. We examined the cross-cutting relationships and displacements of the fracture zones and confirmed that the -system was formed after the -system. From the investigation results so far, similar to the results of the compilation report of April 31, 2010, no clear evidence was observed to support that on-site crushed zones are active faults.
Hayano, Akira; Matsuoka, Toshiyuki; Ishii, Eiichi
no journal, ,
no abstracts in English
Umeda, Koji; Asamori, Koichi; Makuuchi, Ayumu; Kobori, Kazuo
no journal, ,
An E-W trending discontinuity along 32 N latitude in GPS velocities across southern Kyushu Island is clearly defined, indicating a highly active left-lateral shear zone. However, there was no obvious prefaulting indication at surface in relation to the shear zone. The geophysical and geochemical observations provide significant evidence that the invasion of mantle fluids into the crust, driven by upwelling asthenosphere from the Okinawa trough, triggers off the notable left-lateral shear zone in the present-day subduction system.
Sasao, Eiji; Ishibashi, Masayuki
no journal, ,
In order to evaluate deep geological environment for geological disposal of high level radioactive waste, understanding of the geometry of water conducting features such as fractures is essential. The fracture zones have been divided based on the fracture intensity that has been obtained deep boreholes. But fracture intensity could be changeable in different portion of the rock body. The method to divide the fracture zones based on fracture spacing is studied. In this study, cumulative frequency curve of fracture spacing based on fifteen deep borehole with the total length of ca.12,000 meters was used. Cumulative frequency curve shows that half of fracture spacing is lower than 1m. Thus, fracture could exist in fracture zones. The fractures with the dip of middle to high angle are needed to divide into fracture zones based on the fracture spacing. In the future, we will establish the methodology to divides the fracture zones coupled with spatial distribution of fracture spaces.
Yasue, Kenichi; Hirouchi, Daisuke*; Kokubu, Yoko; Matsubara, Akihiro; Furusawa, Akira*
no journal, ,
In order to clarify the stratigraphic correlation around the fault and the timing of faulting event, we carried out radiocarbon dating of the black soil sampled from the trench wall of the Atera Fault. The dating results show that the soil ages varies from 4,000 to 2,000 years with depth. Black soil was deposited at approximately constant rate each at both sides of the fault in 4,000-2,000 years ago. This indicates that the fault wasn't displaced during this period. In the upper part, there is no variation in ages of black soils with depth. This suggests that sedimentation rate was faster. One of the causes that the sedimentation rate around the fault suddenly changes is fault displacement. It is thought that the faulting was about 2,000 years ago. About this timing, it is necessary to consider in behavioral segments of Atera fault zone in detail.
Ikuta, Masafumi; Sato, Yoshiki; Niwa, Masakazu; Kamataki, Takanobu*; Kurosawa, Hideki*; Takatori, Ryoichi*
no journal, ,
A lot of great earthquakes have caused in the Hyuganada and the Nankai trough. According to historical records of documents, the 1662 Kanbun Hyuganada earthquake, had caused serious damage and natural calamity. Around the estuary of the Kaeda-gawa River, the tsunami had reached to about 4 to 5meter height, and ground subsided about 1meter.Shimayama region which is located in the estuary of the Kaeda-gawa River, was formed an intrusive arm of the sea occurred by this subside event. Some historical records of documents and landscape pictures show that the 1662 Kanbun Hyuganada earthquake changed topography and depositional environment in this area extremely. However, there is no case study of this evidence. So, we did multiple borings in the abandoned lagoon sediments and tried to restore depositional environment around the subsided area by some analysis methods such as microfossils and chemistry to use boring cores. These results will be presented in this session.
Shimemoto, Hidenori; Wakasugi, Keiichiro; Shibata, Masahiro; Yamaguchi, Masaaki
no journal, ,
In the safety assessment of radioactive waste disposal, consideration of evolution of geological environment is requested. The disposal facility can be expected to come close to ground surface, when continuous uplift and erosion for long-term is assumed. In general, geological conditions in near-surface underground is different from those in deep-underground due to weathering. Preparing for such scenario and nuclides migration analysis, information regarding weathered zone are surveyed and arranged. As a result, 37data of depth (thickness) of weathered zone were extracted. Then the data distribution and characteristics of thick weathered case was discussed. The relation between weathered zone and landform was also discussed. Categorization into four patterns of the relation are proposed, and factors which contribute to the difference of the patterns are discussed. Regarding the geological property/condition in the weathered zone, quantitative information on hydraulic and chemical conditions is limited, to the contrary data on uniaxial strength and porosity are available. For the sake of condition setting for near-surface underground in the long-term safety assessment, continuous survey of information is important.
Dohi, Terumi; Omura, Yoshihito*; Kashiwadani, Hiroyuki; Fujiwara, Kenso; Iijima, Kazuki
no journal, ,
no abstracts in English
Martin, A.*; Ishimaru, Tsuneari; Umeda, Koji; Asamori, Koichi
no journal, ,
In Japan, numerous studies have been carried out to assess the stability of the geological environment including in particular, the spatio-temporal distribution of active faulting in the context of site selection of a radioactive waste repository and/or assessing the safety of current nuclear facilities etc. One key concern is the existance of active faults that do not show any surface rupture. High He-3/He-4 ratios which tend to be found in volcanic regions have also been measured in non-volcanic regions. This has been attributed to degassing from the mantle with faults potentially acting as conduits. Studies carried out in the western Tottori district have shown the potential of using 
He/
He ratios as a means of providing indirect evidence of the existence of source fault(s) that caused the 6 Oct 2000 Tottori earthquake (Mw 6.8), but which had no apparent surface indication prior to the earthquake.
Sato, Tatsuhiko; Kataoka, Ryuho*; Nagamatsu, Aiko*
no journal, ,
Forecast of radiation doses for astronauts as well as aircrews due to the exposure to solar energetic particles (SEP) is one of the greatest challenges in space weather research. In last 3 years, we have developed a warning system of aviation exposure to solar energetic particles: WASAVIES, which can predict the SEP doses at any flight conditions within 2.5 hours after the onset of ground level enhancements (GLE). In this system, the SEP fluxes incident to the atmosphere are calculated by physics based models, and they are converted to radiation doses using a database developed on the basis of air-shower simulation. In this study, we applied the same physics-based models to the estimate of the SEP fluxes on the orbit of International Space Station, and converted the fluxes to radiation doses for astronauts staying inside the Kibo module.
Watanabe, Takayoshi; Mitachi, Katsuaki; Abe, Hironobu; Niizato, Tadafumi
no journal, ,
Radionuclides such as radioactive cesium, now the main radiological contributor, were released in the environment by the Fukushima Dai-ichi Nuclear Power Plant accident. Japan Atomic Energy Agency initiated a project entitled "Long-Term Assessment of Transport of Radioactive Contaminant in the Environment of Fukushima" (F-TRACE project) in November 2012. To understand radioactive cesium transport in forest, we have conducted forest investigation at Ogi district, Kawauchi Village and Yamakiya district, Kawamata Town, Fukushima Prefecture since December 2012. As a part of the investigation, we carried out geophysical exploration of soil structure with ground penetrating radar (GPR) with 100 MHz and 500 MHz radio wave. In this presentation, we report correlation between imaging of soil structure obtained by GPR survey and depth profile of radioactive cesium in soil.
Shimada, Koji; Tateishi, Ryo*; Ishimaru, Tsuneari; Sasaki, Akimichi; Tanaka, Yukumo; Miyazaki, Masashi; Yasue, Kenichi; Niwa, Masakazu; Sueoka, Shigeru; Umeda, Koji; et al.
no journal, ,
Activity evaluation of crush zones encountered in basement rock is an issue of the seismic safety assessment of nuclear plant and geological isolation of radioactive wastes. The selection of crush zone of which has been evaluated should be defined as the latest one by means of turn determination of crush zone activity based on stratigraphic or structural geological method. A lesson from granitic basement rock (Kojaku granite) holding the fast breeder reactor "Monju" is presented. The Kojaku Granite form the oval Tsuruga peninsula (ca. 8km in width) on the southeastern coast of the Sea of Japan and the age is 68.5 plus/minus 0.7Ma (Zircon U-Pb age).1. Stratigraphy-oriented turn determination of crush zone activity. (1.1) Turn determination using cover sediments. (1.2) Turn determination using dyke, mineral and clay vein. 2. Structural-oriented turn determination of crush zone activity.
Sasaki, Akimichi; Yasue, Kenichi; Shimada, Koji; Tateishi, Ryo*; Ishimaru, Tsuneari; Tanaka, Yukumo
no journal, ,
no abstracts in English
Niizato, Tadafumi; Ishii, Yasuo; Abe, Hironobu; Watanabe, Takayoshi; Sasaki, Yoshito
no journal, ,
Understanding the environmental dynamics of the radiocaesium (particularly Cs-134 and 137) released from the Fukushima Daiichi Nuclear Power Plant provides the firm foundation for a remediation of the Fukushima environment because it is the main radionuclide to radiological dose within the contaminated area. One of the main sources of radiocaesium under the current situation is a mountain forest, where the decontamination work has not been carried out as yet. Therefore, transport process, flux and chemical form of the radiocaesium flowing from the mountain forest are crucial issues for an evaluation of a radiation exposure, taking into a dynamics behavior of radiocaesium from the highest contaminated mountain forests down through the river to eventual deposition in the sea. This paper discusses the predominant process of the radiocaesium transport in the mountainous region, Fukushima, Japan.
Kokubu, Yoko; Matsubara, Akihiro; Hanaki, Tatsumi; Yasue, Kenichi; Umeda, Koji
no journal, ,
The JAEA-AMS-TONO facility was established in 1997 at the Tono Geoscience Center, Japan Atomic Energy Agency (JAEA). Our AMS system is a versatile system based on a 5MV tandem Pelletron type accelerator (National Electrostatic Corporation, US) and has been made available for 
C-, 
Be- and 
Al-AMSs. These multi-nuclide AMSs have been mainly applied to neotectonics and hydrogeology, in support of our research on geosphere stability applicable to the long-term isolation of high-level radioactive waste. Furthermore, the C- and Be-AMSs are used for geoscience, environmental science and archaeology by researchers of universities and other institutes under the JAEA's common-use facility program. In this presentation, we introduce dating of C and Be through our AMS to geoscience studies. Moreover we report development of Al-AMS.
Kametaka, Masao*; Okazaki, Kazuhiko*; Nakayama, Kazuhiko; Seshimo, Kazuyoshi; Aoki, Kazuhiro; Tanaka, Yoshihiro; Shimada, Koji; Suzuki, Kazushige*; Shimogama, Kota*; Inada, Noriyuki*
no journal, ,
The evaluation of an fault activity has been done by an observation of deformation of overlying strata of the fault. However, it is difficult to evaluate the activity where the fault zone appears only in a basement rock with no overlying strata. We have been carried out the observation of the fault zone to establish the method of evaluation of fault activity. We selected the outcrops through literature and surface geological survey. Examples of outcrops of active fault are outcrops of Gosukebashi Fault in the Rokko-Awaji Fault Zone and the Rokko Fault in the Arima-Takatsuki Tectonic Line, southern Hyogo Prefecture. An example of non-active fault is outcrop of the fault around the Rokko Horai-kyo in the northern Rokko Mountains. In this study, we focus on the easy evaluation method in the field, and described about suitability of observation of fault plane, in-situ experiments of hardness and color.