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Yamamoto, Yusuke*; Watanabe, Takahiro; Niwa, Masakazu; Shimada, Koji
JAEA-Testing 2023-003, 67 Pages, 2024/02
JAEA-Testing-2023-003.pdf:4.63MB
A long-term geosphere stability for geological disposal is evaluated by the past geological environmental changes and modern conditions. Stable hydrogen and oxygen isotope ratios (
D, 
O) of geological samples are useful information to estimate the past environmental changes and modern conditions. Recently, the thermal conversion elemental analyzer and isotope ratio mass spectrometer (TC-EA/IRMS) were installed in the Tono Geoscience Center for D and O measurements of geological samples. In this study, we reported analytical methods of D and O using international standard reference materials. In addition, evaluation tests of uncertainty by repeated analyses of the standards were performed using the TC-EA/IRMS. Furthermore, the D and O analyses by the TC- EA/IRMS were also applied to fault rock samples.
Zwingmann, H.*; Niwa, Masakazu; Todd, A.*; Saunders, M.*
Earth, Planets and Space (Internet), 76, p.27_1 - 27_16, 2024/02
Times Cited Count：0 Percentile：0.03(Geosciences, Multidisciplinary)Atera fault zone clay gouges were collected for age dating from a river section near Kawaue, Nakatsugawa city, central Japan and the results integrated within its complex geological history. The results from the Atera Fault form an internally consistent data set with constraints from existing geochronological data (AFTA, ZFTA, CHIME) and demonstrate the application of gouge dating in providing new data to constrain timing of brittle deformation in Central Japan.
Niwa, Masakazu; Shimada, Koji; Terusawa, Shuji*; Goto, Akira*; Nishiyama, Nariaki; Nakajima, Toru; Ishihara, Takanori; Hakoiwa, Hiroaki
Island Arc, 33(1), p.e12516_1 - e12516_16, 2024/02
Times Cited Count：0To investigate the geological evidence of near-surface crustal deformations in a high-strain shear zone that has been geodetically identified but not associated with clear tectonic landforms, a fieldwork was conducted in E-W trending southern Kyushu high-strain shear zone, Japan. According to our study, an investigation based on the slip data from minor faults and the occurrences of fracture zones could help to identify a concealed fault that is small in terms of size to record tectonic landforms but can trigger large earthquakes.
Sueoka, Shigeru; Iwano, Hideki*; Danhara, Toru*; Niwa, Masakazu; Kanno, Mizuho; Kohn, B. P.*; Kawamura, Makoto; Yokoyama, Tatsunori; Kagami, Saya; Ogita, Yasuhiro; et al.
Earth, Planets and Space (Internet), 75(1), p.177_1 - 177_24, 2023/12
Times Cited Count：0 Percentile：0(Geosciences, Multidisciplinary)Fluid-inclusion and thermochronometric analyses have been applied to hydrothermal alteration zones and their host rocks outcropping in the Hongu area of the Kii Peninsula, southwestern Japan in an attempt to detect thermal anomalies related to hydrothermal events and quantify the thermal effects on the host rocks. Hydrothermal events at ca 150 deg. C and ca 200 deg. C were identified by fluid-inclusion microthermometry of quartz veins in the alteration zones. For the host rocks and alteration zones, in the youngest population zircon yielded U-Pb dates ranging between ca 74.7-59.2 Ma, fission-track dates of ca 27.2-16.6 Ma, and (U-Th)/He single-grain dates of ca 23.6-8.7 Ma. Apatite yielded pooled fission-track ages of ca 14.9-9.0 Ma. The zircon U-Pb dates constrain the maximum depositional ages of the sedimentary samples. However, the fission-track and (U-Th)/He dates show no clear trend as a function of distance from the alteration zones. Hence, no thermal anomaly was detected in the surrounding host rocks based on the thermochronometric data patterns. The fission-track and (U-Th)/He dates are rather thought to record regional thermal and exhumation histories rather than a direct thermal imprint of fluid flow, probably because the duration of such activity was too short or because fluid flow occurred before regional cooling events and were later thermally overprinted. Apatite fission-track ages of ca 10 Ma may reflect regional mountain uplift and exhumation related to the obduction of the SW Japan lithospheric sliver onto the Shikoku Basin, or the rapid subduction of the Philippine Sea slab associated with the clockwise rotation of the Southwest Japan Arc.
Katsuta, Nagayoshi*; Umemura, Ayako*; Naito, Sayuri*; Masuki, Yuma*; Itayama, Yui*; Niwa, Masakazu; Shirono, Shinichi*; Yoshida, Hidekazu*; Kawakami, Shinichi*
Spectrochimica Acta, Part B, 210, p.106817_1 - 106817_11, 2023/12
Times Cited Count：0 Percentile：0.02(Spectroscopy)X-ray fluorescence (XRF) scanning of lacustrine sediments has been used to extend the approach to a wider range of elemental records in both ages and timescales of variations in past environments and climates. However, one of severe problems with effects of the XRF intensity by grain size and mineralogical composition known as "heterogeneity effects" have been pointed out. This study investigated the heterogeneity effect of Fe intensities on X-ray beam using several binary powder mixtures and lacustrine sediment cores.
Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Fujita, Natsuko; Yokoyama, Tatsunori; Ogita, Yasuhiro; Fukuda, Shoma; Nakajima, Toru; Kagami, Saya; Ogata, Manabu; et al.
JAEA-Review 2023-017, 27 Pages, 2023/10
JAEA-Review-2023-017.pdf:0.94MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2023. The objectives and contents in fiscal year 2023 are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. 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.
Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Ishihara, Takanori; Ogawa, Hiroki; Hakoiwa, Hiroaki; Watanabe, Tsuyoshi; Nishiyama, Nariaki; Yokoyama, Tatsunori; Ogata, Manabu; et al.
JAEA-Research 2023-005, 78 Pages, 2023/10
JAEA-Research-2023-005.pdf:6.51MB
This annual report documents the progress of research and development (R&D) in the 1st fiscal year of the Japan Atomic Energy Agency 4th Medium- and Long-term Plan (fiscal years 2022-2028) to provide the scientific base for assessing geosphere stability for long-term isolation of high-level radioactive waste. 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. The current status of R&D activities with previous scientific and technological progress is summarized.
Watanabe, Takahiro; Kagami, Saya; Yokoyama, Tatsunori; Niwa, Masakazu
Chigaku Zasshi, 132(4), p.353 - 361, 2023/08
U-Pb dating of detrital zircons in paleotsunami deposits from the 1662 CE Kanbun-Hyuganada sea earthquake, Miyazaki plain on the Pacific coast of southwest Japan, was performed by a laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-ICPMS) system at Tono Geoscience Center, Japan Atomic Energy Agency. Twenty-five zircon grains were separated from the paleotsunami deposits by chemical abrasion and analyzed by the LA-ICPMS. U-Pb ages of the detrital zircons showed from ca. 14 Ma to 2405 Ma, and the age spectrum revealed high relative probability values around ca. 100 Ma and 2000 Ma. Detrital zircons with the age of ca. 100 Ma in the 1662 CE paleotsunami deposits could be partly originated from the Shimanto supergroup in southwest Japan. Moreover, the age spectrum of detrital zircons with Precambrian grains from the paleotsunami deposits was similar with those of fore-arc sandstones from central Kyushu Island.
Nishiyama, Nariaki; Kawamura, Makoto; Umeda, Koji*; Niwa, Masakazu
Oyo Chishitsu, 64(3), p.98 - 111, 2023/08
It is important to accumulate research examples on the spatial distribution of dikes under volcanic edifices for risk assessment in volcanic disaster prevention and site selection and safety assessment for the geological disposal of high-level radioactive waste. The topography of volcanoes is considered to represent the location of magma intrusion associated with volcanic activity and its history. In this study, we attempted to determine the predominant orientation of radial dikes and evaluate the central conduit stability based on the distribution, centroid, and area of contour lines comprising the volcanic edifices using GIS-based topographic analysis. As a result of the topographic analysis, the predominant orientation of the dikes was successfully shown for the volcanoes with stable conduits. On the other hand, this analysis was not suitable for determine the predominant orientation of dikes in volcanoes with unstable conduits, thus the applicable range of this analysis is considered to be determined by the conduit stability. In addition, the conduit stability can be evaluated by using the area data of contour polygons, which represents the scope of application to the method for determination of the predominant orientation of dikes. This means that the conduit stability during volcanic activity can be evaluated even for volcanoes of which activity history is not yet known, and that topographic analysis is a useful tool for this purpose. The use of topographic analysis in this study will be expected to provide a new scale for the history of volcanic activity.
Nishiyama, Nariaki; Goto, Akira*; Tsukahara, Yuzuko; Kawamura, Makoto; Umeda, Koji*; Niwa, Masakazu
JAEA-Testing 2022-003, 51 Pages, 2022/09
JAEA-Testing-2022-003.pdf:5.24MB
JAEA-Testing-2022-003-appendix(CD-ROM).zip:1.12MB
Advancement of the evaluation technology of the magma activity range is essential as one of the technical issues related to volcanic and igneous activities in the evaluation of the long-term stability of the geological environment in the geological disposal of high-level radioactive waste. As an effective method, topographical analysis of volcanic edifices is expected to be used to determine the distribution area of dikes. In recent years, the development of computer-based topographic analysis technology has made it possible to simply perform a large volume of work that would otherwise be difficult due to the manual handling. This report describes an analysis method for the shape of contour lines that forms volcanic edifices using GIS software.
Sasao, Eiji; Ishimaru, Tsuneari; Niwa, Masakazu; Shimada, Akiomi; Shimada, Koji; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; Ogita, Yasuhiro; et al.
JAEA-Review 2022-022, 29 Pages, 2022/09
JAEA-Review-2022-022.pdf:0.97MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2022. The objectives and contents in fiscal year 2022 are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. 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
Niwa, Masakazu; Shimo, Michito*; Shimada, Koji; Goto, Akira
JAEA-Research 2022-004, 38 Pages, 2022/06
JAEA-Research-2022-004.pdf:2.86MBJAEA-Research-2022-004-appendix(CD-ROM).zip:0.41MB
Methane (CH
) seepage to the surface in the early stage of hydrocarbon exploration has attracted increasing attention. Also, detection of CH-rich fluid emission can be applied to reconnaissance surveys for safety management in geological disposal of radioactive waste because high-temperature fluids that come from slab dehydration along a subduction zone are often rich in CH. These fluids likely migrate along faults and fractures. In this study, we employed a portable analyzer that used a wavelength-scanned cavity ring-down spectroscopy (CRDS) with high accuracy (in ppb levels) and short measurement intervals (
1 s). An on-vehicle measurement that employed the CRDS system was performed in the Hongu area in southeast Kii Peninsula, Japan, which included CH-bearing hot springs (Kawayu and Yunomine). The measurement near the hot springs detected a clear CH anomaly (
2 ppm) that exceeded the background concentration. The estimation of CH diffusion in air based on the Gaussian plume model corresponded to the result of the on-vehicle measurement. This study confirmed that the method using the vehicle-mounted CRDS analyzer can help in quickly and easily identifying CH-bearing fluid emissions at the surface. Additionally, directions for use of the analyzer were summarized in this report.
Watanabe, Takahiro; Kagami, Saya; Niwa, Masakazu
Marine Geology, 444, p.106704_1 - 106704_13, 2022/02
Times Cited Count：4 Percentile：41.35(Geosciences, Multidisciplinary)Miyazaki plain on the Pacific coast of southwest Japan along the Nankai-Suruga trough was also affected by marine incursion by the past interplate earthquakes and tsunami. Notably, paleotsunami deposits were found on the area and important clues to reconstruct the past marine incursion by earthquakes and tsunami. However, geochemical and heavy mineral analyses on the area were not enough to characterize the deposits. Therefore, quantification analyses with high-time resolution by portable energy dispersive X-ray fluorescence spectrometry (portable XRF), scanning by X-ray analytical microscope (XGT), statistical analyses for chemical components, and heavy mineral analyses were performed for the paleotsunami deposits of the Kanbun Hyuganada earthquake with the age of 1662 CE from the south Miyazaki plain in this study. Based on our research, we summarized as follows: (1) increases in the titanium normalized values of S, Ca, Fe and Sr, and depletions of Si, K, and Rb were observed in the deposits, (2) Zr accumulations and heavy minerals such as zircon were found in the deposits caused by possible high energy tsunami, and (3) cluster analyses of the geochemical data from the core by portable XRF distinguished the paleotsunami deposits on the Miyazaki plain.
Yamamoto, Yusuke; Watanabe, Takahiro; Niwa, Masakazu; Shimada, Koji
JAEA-Testing 2021-003, 58 Pages, 2022/01
JAEA-Testing-2021-003.pdf:6.82MB
A long term geosphere stability for geological disposal is evaluated by the past geological environmental changes and modern conditions. Whole-rock geochemical compositions in rocks and sediments are useful information to estimate the past environmental changes and modern conditions. Recently, the portable X-ray fluorescence (XRF) were installed in the Tono Geoscience Center for rapid and simple whole-rock geochemical analyses (original specification; 8 mm-diameter analysis). In particular, the 3 mm-diameter small spot analysis using the portable XRF was performed for quantitative analyses of small-weight geological samples. In this study, we reported a quantitative method for major and trace elements using calibration curves by standard reference materials, as well as evaluation tests of uncertainty by repeated analyses of the standards measured by the portable XRF (3 mm-diameter small spot analysis). Furthermore, the small spot quantitative analyses by the portable XRF were also applied to fault rock samples that have been analyzed in previous studies.
Saegusa, Hiromitsu*; Matsuoka, Toshiyuki*; Niwa, Masakazu; Sasao, Eiji; Hayano, Akira
Nihon Genshiryoku Gakkai-Shi ATOMO
, 64(1), p.46 - 50, 2022/01
This paper is a review article to introduce the concept of the site selection for geological disposal in geological environment of Japanese Islands, and the current status of related research and development.
Shimo, Michito*; Niwa, Masakazu; Miyakawa, Kazuya; Yasue, Kenichi*; Tonokura, Kenichi*; Tokunaga, Tomochika*
Fukada Chishitsu Kenkyujo Nempo, (23), p.21 - 34, 2022/00
no abstracts in English
Ishimaru, Tsuneari; Ogata, Nobuhisa; Kokubu, Yoko; Shimada, Koji; Niwa, Masakazu; Shimada, Akiomi; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; et al.
JAEA-Research 2021-007, 65 Pages, 2021/10
JAEA-Research-2021-007.pdf:4.21MB
This annual report documents the progress of research and development (R&D) in the 6th fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned 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. The current status of R&D activities with previous scientific and technological progress is summarized.
Shimada, Koji; Goto, Akira; Niwa, Masakazu; Shimo, Michito*
Chishitsugaku Zasshi, 127(10), p.I - II, 2021/10
Continuous leaking point of high-temperature fluid (liquid/gas) from underground can be easily grasped by infrared images. We show images confirmed by a FLIR C5 camera that can simultaneously obtain an infrared image and a visible light image at the outcrops of Kawayu Onsen that naturally spring along the river. Outcrops and river surface temperature rise due to hot springs that leaking from riverbanks and riverbeds, rock temperature rise around cracks where gas containing high-concentration methane leaks with hot springs, abandoned fluid pathway due to construction of the bank and damming river for hot spring river bath in winter can be confirmed at a glance. Infrared images may be useful for quick identification of hot fluid leaking points from underground.
Ishimaru, Tsuneari; Kokubu, Yoko; Shimada, Koji; Shimada, Akiomi; Niwa, Masakazu; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; Ogita, Yasuhiro; et al.
JAEA-Review 2021-012, 48 Pages, 2021/08
JAEA-Review-2021-012.pdf:1.64MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2021. The objectives and contents in fiscal year 2021 are described in detail based on the JAEA 3rd Medium- and Long-term Plan (fiscal years 2015-2021). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. 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.
Tateishi, Ryo*; Shimada, Koji; Shimizu, Mayuko; Ueki, Tadamasa*; Niwa, Masakazu; Sueoka, Shigeru; Ishimaru, Tsuneari
Oyo Chishitsu, 62(2), p.104 - 112, 2021/06
We attempted to discriminate between active and non-active faults by linear discriminant analysis using the chemical composition data of fault gouges in Japan, and then examined the elements that represent the difference between them and better discriminants. As a result, the multiple discriminants obtained could discriminate between them with high probability. In addition, the generalization performance of these discriminants is discussed, and the discriminants that can be expected to have high discriminant performance for unknown samples are presented. Also, from the combination of elements common to these discriminants, we narrowed down the number of elements that represent the difference between active and non-active faults to 6, and showed that the combination of TiO
and Sr contributing the most to the discrimination. The method applied in this study is an innovative one that can discriminate the activity by chemical analysis of fault rocks that are universally present in the bedrock.
