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Journal Articles

Dating of buried wood logs and fragments for high resolution reconstruction of landslide histories; Case studies in the Japanese Alps region in the historical times

Yamada, Ryuji*; Kimura, Takashi*; Kariya, Yoshihiko*; Sano, Masaki*; Tsushima, Akane*; Li, Z.*; Nakatsuka, Takeshi*; Kokubu, Yoko; Inoue, Kimio*

Sabo Gakkai-Shi, 73(5), p.3 - 14, 2021/01

We discuss the applicability of dating methods for determining landslide chronologies in relation to the type of samples and the sampling location. Case studies are carried out with fossil wood samples buried in the colluvial soil of large-scale landslides occurred in two areas of the Japanese Alps region. Ages are determined by accelerator mass spectrometry radiocarbon dating and dendrochronological analysis using the oxygen isotope composition of tree ring cellulose. Most of ages for Dondokosawa rock avalanche are concordant with the period of AD 887 Ninna (Goki-Shichido) earthquake. Ages for Ohtsukigawa debris avalanche are not concentrated in a specific period. In order to obtain accurate age of large-scale landslide, utilizing buried large diameter tree trunk or branches with the good preservation condition has a lot of advantages because it allows us to compare the landslide chronology with historical records of heavy rainfall and large earthquakes.

Journal Articles

Synchronized gravitational slope deformation and active faulting; A Case study on and around the Neodani fault, central Japan

Komura, Keitaro*; Kaneda, Heitaro*; Tanaka, Tomoki*; Kojima, Satoru*; Inoue, Tsutomu*; Nishio, Tomohiro

Geomorphology, 365, p.107214_1 - 107214_22, 2020/09

 Times Cited Count:1 Percentile:18.57(Geography, Physical)

On the basis of pit excavations and sediment cores at an off-fault deep-seated gravitational slope deformation (DGSD) site and a trench excavation across the active Neodani fault at a nearby site, we examined the records of DGSD and surface-rupturing paleoearthquakes of the Neodani fault. We found the four most recent DGSD events and the four most recent surface-rupturing earthquakes, respectively and conclude that the ages of events are overlapped each other. We infer that static crustal strain from repeated seismogenic faulting plays an important role in the occurrence of DGSD events, at least in the immediate vicinity of active faults, although coseismic severe shaking would have at least some effect on them. Our case study suggests that off-fault DGSDs can be used to reconstruct or refine the paleoseismic history of a nearby active fault.

Journal Articles

Radiocarbon dating of a shrine pavilion and offerings at Abushina shrine in Gifu prefecture, Japan

Kokubu, Yoko; Nishio, Tomohiro; Fujita, Natsuko; Matsubara, Akihiro

Proceedings of the 8th East Asia Accelerator Mass Spectrometry Symposium and the 22nd Japan Accelerator Mass Spectrometry symposium (EA-AMS 8 & JAMS-22), p.91 - 93, 2020/00

no abstracts in English

Journal Articles

Lahar record during the last 2500 years, Chokai Volcano, northeast Japan; Flow behavior, sourced volcanic activity, and hazard implications

Minami, Yusuke*; Oba, Tsukasa*; Hayashi, Shintaro*; Kokubu, Yoko; Kataoka, Kyoko S.*

Journal of Volcanology and Geothermal Research, 387, p.106661_1 - 106661_17, 2019/12

 Times Cited Count:3 Percentile:24.83(Geosciences, Multidisciplinary)

The study focuses on volcanic-fan deposits at Chokai Volcano in northeast Japan. The authors conducted sedimentary facies analysis, radiocarbon dating, and historical document analysis to understand the flow characteristics and history of far-reaching lahars. The volcanic fan is composed mainly of a series of lahar deposits formed by at least five large lahar events at: the 2nd - 5th century BC; 2nd to 4th century BC; AD 5th to 7th century; AD 871; and AD 1801 during last 2500 years. These lahar events can be classified into three types: (1) a cohesive debris flow sourced by the debris avalanche deposit; (2) a non-cohesive lahar by a magmatic eruption; and (3) a cohesive debris flow by a phreatic eruption. The lahar, incorporating debris avalanche deposit, flowed as hazardous cohesive debris flow; lahars after magmatic eruptions tends to be streamflow through the flow transformation of sandy debris flow; and a cohesive lahar by a phreatic eruption tends to be of small scale.

Journal Articles

A Suitable procedure for preparing of water samples used in radiocarbon intercomparison

Takahashi, Hiroshi*; Minami, Masayo*; Aramaki, Takafumi*; Handa, Hiroko*; Kokubu, Yoko; Ito, Shigeru*; Kumamoto, Yuichiro*

Radiocarbon, 61(6), p.1879 - 1887, 2019/12

 Times Cited Count:1 Percentile:9.33(Geochemistry & Geophysics)

Water sample for interlaboratory comparison (here after "comparison water") must have inalterable $$^{14}$$C concentration during the comparison campaign and inter-batches homogeneity. In this study, the procedure for preparing of comparison water was discussed. We employed that comparison waters were artificially made by mixing chemical reagents, controlling $$^{14}$$C concentration and chemical composition. We could prepare six comparison waters, having 1, 14, 37, 56, 72 and 100 pMC, respectively. The stable carbon isotopic values and chemical compositions of some batches were measured to exanimate the inter- batches homogeneity. The $$^{14}$$C discrepancies among the batches were negligible for the inter-laboratory comparison. Finally, the results of trial comparison in Japan will be presented. Most of $$^{14}$$C results of CO$$_{2}$$ extracted by six laboratories showed good agreements each other.

Journal Articles

Preliminary test of the EA-AGE3 system for $$^{14}$$C measurement of CaCO$$_{3}$$ samples and coral-based estimation of marine reservoir correction in the Ogasawara Islands, Northwestern Subtropical Pacific

Kokubu, Yoko; Mitsuguchi, Takehiro*; Watanabe, Takahiro; Yamada, Tsutomu*; Asami, Ryuji*; Iryu, Yasufumi*

Radiocarbon, 61(5), p.1593 - 1601, 2019/10

 Times Cited Count:0 Percentile:0.01(Geochemistry & Geophysics)

We performed $$^{14}$$C measurements of two fossil and one modern corals using a combined system of an elemental analyzer and an automated graphitization equipment AGE3 (EA-AGE3 system) and JAEA-AMS-TONO. The $$^{14}$$C concentrations (pMC values) of mid-Holocene Okinawa corals obtained by our EA-AGE3 system appear to be slightly higher than those obtained by the conventional graphitization method using phosphoric acid. The pMC increase in our EA-AGE3 system may result in significant underestimation of $$^{14}$$C age especially for older samples (e.g., 10,000 BP); however, the pMC increase is negligible in $$^{14}$$C measurements of modern or recent samples. We applied the EA-AGE3 method to the pre- and post-bomb annual-band samples from the modern Ogasawara coral for $$^{14}$$C measurements. On the basis of the pre-bomb coral $$^{14}$$C data, we estimated marine reservoir correction ($$Delta$$R) around Ogasawara Islands and its stability between $$sim$$1900 and 1950 AD.

Journal Articles

$$^{14}$$C ages and calendar years of Japanese nails measured with accelerator mass spectrometry

Nagata, Kazahiro*; Furunushi, Yasuko*; Matsubara, Akihiro*; Kokubu, Yoko; Nakamura, Toshio*

Tetsu To Hagane, 105(4), p.488 - 491, 2019/04

 Times Cited Count:1 Percentile:9.85(Metallurgy & Metallurgical Engineering)

The Japanese nails had been produced by the traditional ironmaking way of Tatara until the Edo period since the late of 6 Century. The quality of the Japanese nails is affected from steel produced by Tatara in each age. The $$^{14}$$C ages of 3 Japanese nails collected at shrines and temples at their repair were measured with accelerator mass spectrometry and calibrated to calendar years. Each $$^{14}$$C age provided plural calendar year periods with definite probabilities, and one of the periods determined in comparison with the history of temples and their repair records. The production ages of nails used in the Daibutuden of the Todaiji temple, the living quarters of the Manjuin temple and the Zaoudo of the Yoshino-Kongoji temple are before 1692, the 12 Century and before 1592, respectively, when they were repaired or reconstructed.

Journal Articles

Hydrological and climate changes in southeast Siberia over the last 33 kyr

Katsuta, Nagayoshi*; Ikeda, Hisashi*; Shibata, Kenji*; Kokubu, Yoko; Murakami, Takuma*; Tani, Yukinori*; Takano, Masao*; Nakamura, Toshio*; Tanaka, Atsushi*; Naito, Sayuri*; et al.

Global and Planetary Change, 164, p.11 - 26, 2018/05

 Times Cited Count:8 Percentile:48.18(Geography, Physical)

Paleoenvironmental and paleoclimate changes in Siberia were reconstructed by continuous, high-resolution records of chemical compositions from a sediment core retrieved from the Buguldeika Saddle, Lake Baikal, dating back to the last 33 cal. ka BP. The Holocene climate followed by a shift at ca. 6.5 cal. ka BP toward warm and dry, suggesting that the climate system transition from the glacial to interglacial state occurred. In the last glacial period, the deposition of carbonate mud from the Primorsky Range was associated with Heinrich events (H3 and H1) and the Selenga River inflow was caused by meltwater of mountain glaciers in the Khamar-Daban Range. The anoxic bottom-water during Allerod-Younger Dryas was probably a result of weakened ventilation associated with reduced Selenga River inflow and microbial decomposition of organic matters from the Primorsky Range. The rapid decline in precipitation during the early Holocene may have been a response to the 8.2 ka cooling event.

Journal Articles

AMS radiocarbon age of the Kurodake pyroclastic-flow deposit in Kuju volcanic group, SW Japan

Okuno, Mitsuru*; Nagaoka, Shinji*; Kokubu, Yoko; Nakamura, Toshio*; Kobayashi, Tetsuo*

Fukuoka Daigaku Rigaku Shuho, 48(1), p.1 - 5, 2018/03

Kuju volcanic group, located in central Kyushu, Japan, consists of over twenty volcanoes (lava domes as well as small stratovolcanoes). The Kurodake is largest lava dome with a volume of 1.6 km$$^{3}$$, and generated Kurodake pyroclastic-flow (Kj-Kd) and ash-fall (Kj-KdA) deposits. To refine age of the Kurodake eruption, we conducted radiocarbon dating of a charcoal fragment in the Kj-Kd with an AMS system at Tono Geoscience Center, JAEA. The obtained $$^{14}$$C date, 1505$$pm$$40 BP, can correspond to 1310-1423 cal BP (probability= 74.6%), 1430-1442 cal BP (2.4%) and 1456-1521 cal BP (23.0%) in 2$$sigma$$ confidence level. The medium probability date, 1391 cal BP, is consistent with the stratigraphy and gives the reliable age for the Kj-Kd.

Journal Articles

AMS radiocarbon dates of pyroclastic-flow deposits on the southern slope of the Kuju Volcanic Group, Kyushu, Japan

Okuno, Mitsuru*; Nagaoka, Shinji*; Kokubu, Yoko; Nakamura, Toshio*; Kobayashi, Tetsuo*

Radiocarbon, 59(2), p.483 - 488, 2017/00

 Times Cited Count:3 Percentile:18.21(Geochemistry & Geophysics)

We present here results of AMS $$^{14}$$C dating to refine the history of the middle and western parts of the Kuju Volcanic Group, located in middle Kyushu, Japan, which consists of more than 20 lava domes and cones. $$^{14}$$C dating has conducted by AMS (JAEA-AMS-TONO) under the Common-Use Facility Program of JAEA. The Handa PF deposits, which are products of the largest eruption of the group, were dated to $$sim$$53.5 ka BP. The Shirani and Muro PF deposits, which are block-and-ash flows, were dated to 44 to $$>$$50 cal ka BP and 35$$sim$$39 cal ka BP, respectively. These ages can be correlated with the TL ages for the lava domes. Therefore, both TL and $$^{14}$$C methods can be useful tools in establishing the eruptive sequence of lava domes and pyroclastic flows. This study also demonstrates that these eruptive activities occurred after the Handa pfl, the biggest eruption during the last 150 kyrs without a significant time interval.

Journal Articles

$$^{14}$$C ages and calendar years of Japanese swords measured with accelerator mass spectrometry

Nagata, Kazahiro*; Matsubara, Akihiro*; Kokubu, Yoko; Nakamura, Toshio*

Tetsu To Hagane, 102(12), p.736 - 741, 2016/12

 Times Cited Count:2 Percentile:14.84(Metallurgy & Metallurgical Engineering)

Steel of Japanese swords has been produced with Tatara process from iron sand and charcoal. Carbon dissolved in steel was absorbed from wooden charcoal fuel at the production of the steel. From the decay of $$^{14}$$C activity in the steel, the $$^{14}$$C age of Japanese sword can be determined. The $$^{14}$$C ages of 4 Japanese swords were calibrated to a few calendar years. There are several generations of the same names of sword masters. The year of production of each sword was determined from the calendar year and the sword master's name cut in the grip of his sword after taking the age of charcoal into account. The oldest calendar year with high probability agreed with the age of sword master.

Journal Articles

Status of JAEA-AMS-MUTSU

Kuwabara, Jun; Kinoshita, Naoki; Tobinai, Kazuhito; Matsuno, Satoru; Oyokawa, Atsushi; Seki, Takeo; Yabuuchi, Noriaki

Dai-28-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.77 - 79, 2015/12

A Tandetron AMS system (JAEA-AMS-MUTSU) at Mutsu Office, Aomori Research and Development Center, Sector of Decommissioning and Radioactive Waste Management, JAEA, installed in 1997, has composed of 3 MV tandem accelerator and two beam lines (carbon and iodine). Status of the JAEA-AMS-MUTSU and trouble of ion source caused by deterioration of optical fiber cable are reported.

Journal Articles

Estimation of deposition velocities of HT and $$^{14}$$CO$$_{2}$$ and their fluxes from surface environment with a development of a simultaneous sampling system for the speciation of atmospheric H-3 and C-14

Amano, Hikaru; Koarashi, Jun*; Koma, T.*; Atarashi-Andoh, Mariko; Iida, Takao*

JAERI-Conf 2003-010, p.221 - 225, 2003/09

Concerning atmospherically released tritium (T) and C-14 we have developed a new method, which can analyze their fluxes and the deposition velocities. Firstly, a simultaneous sampling system for the speciation of atmospheric tritium and C-14 has been developed. This system determines varieties of chemical forms of tritium and C-14, namely tritiated water (HTO), elemental tritium gas (HT) and tritiated methane (CH$$_{3}$$T) for tritium, $$^{14}$$CO$$_{2}$$ and 14C H4 for C-14, respectively. Secondly, a new method was developed to determine HT and $$^{14}$$CO$$_{2}$$ deposition velocities. This method can determine their fluxes and the deposition velocities without any tritium and C-14 sources.

JAEA Reports

Study on disposal method of graphite blocks and storage of spent fuel for modular gas-cooled reactor (Joint research)

Sumita, Junya; Sawa, Kazuhiro; Tsuchie, Yasuo*; Urakami, Masao*; Kunitomi, Kazuhiko

JAERI-Tech 2002-104, 23 Pages, 2003/02

JAERI-Tech-2002-104.pdf:1.15MB

This report describes the result of study on disposal method of graphite blocks in future block-type reactor. Present study was carried out within a framework of joint research, "Research of Modular High Temperature Gas-cooled Reactors (No. 3)", between Japan Atomic Energy Research Institute (JAERI) and the Japan Atomic Power Company (JAPCO), in 2000. In this study, activities in fuel and reflector graphite blocks were evaluated and were compared with the disposal limits defined as low-level of radioactive waste. As a result, it was found that the activity for only C-14 was higher than disposal limits for the low-level of radioactive waste and that the amount of air in the graphite is important to evaluate precisely of C-14 activity. In addition, spent fuels can be stored in air-cooled condition at least after two years cooling in the storage pool.

Journal Articles

Simple method for C-14 analysis in organic material and its distribution in forest and cultivated field

Atarashi-Andoh, Mariko; Amano, Hikaru

Environmental Radiochemical Analysis II, p.273 - 279, 2003/00

Because of the long radioactive half-life of C-14, fallout C-14 from former nuclear weapon-tests still remains in soil, and there is a C-14 flux from the soil surface to the atmosphere [1]. Patterns of C-14 enrichment in soil profiles provide important information for estimating carbon turnover and carbon flux from soil. A simple analytical method of C-14 measurement has been developed for measuring C-14 distribution in the terrestrial environment. C-14 specific activities in plants and soils in a forest and a cultivated field were measured by this method. The data were made available to assess the behavior of fallout C-14 in the surface environment.

Journal Articles

Development of dynamic compartment model for estimation of C-14 behavior in paddy field

Atarashi-Andoh, Mariko; Amano, Hikaru

Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.484 - 487, 2003/00

C-14 is one of the radionuclides released to the environment with routine operations of nuclear facilities. A dynamic compartment model was developed for estimation of C-14 behavior in paddy field. It calculates carbon transfer among air, rice, irrigation water and soil. The calculation was carried out using MOGRA: a generic analysis code of dynamic compartment model.

Journal Articles

The Present condition of a Tandetron AMS in JAERI-Mutsu

Kitamura, Toshikatsu; Togawa, Orihiko; Aramaki, Takafumi; Suzuki, Takashi; Mizutani, Yoshihiko*; Kabuto, Shoji*; Sudo, Kazuhiko*

JNC TN7200 2001-001, p.31 - 34, 2002/01

no abstracts in English

Journal Articles

Sorption behavior of organic carbon-14 onto cementitious materials

Matsumoto, Junko; Bamba, Tsunetaka

Proc. of 7th Int. Conf. on Radioactive Waste Management and Environmental Remediation (ICEM'99)(CD-ROM), 5 Pages, 1999/00

no abstracts in English

JAEA Reports

Development of fiber scope for JT-60 toroidal field coil cooling pipe

Arai, Takashi; ; Shimizu, Masatsugu

JAERI-Tech 97-003, 49 Pages, 1997/02

JAERI-Tech-97-003.pdf:2.29MB

no abstracts in English

Journal Articles

Synthesis of m-bromophenol-$$^{1}$$$$^{4}$$C$$_{6}$$ with high specific activity

Moriya, Takashi; ;

Radioisotopes, 27(5), p.263 - 265, 1978/05

no abstracts in English

27 (Records 1-20 displayed on this page)