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Journal Articles

Local tephra as an age-determination tool; Example of 2.3 ka Yakedake volcano tephra in Nagano Prefecture, central Japan

Kojima, Satoru*; Kagami, Saya; Yokoyama, Tatsunori; Kariya, Yoshihiko*; Katayama, Yoshikazu*; Nishio, Gaku*

Proceedings of 5th International Workshop on Rock Mechanics and Engineering Geology in Volcanic Fields (RMEGV 2021) (Internet), 6 Pages, 2021/09

A local tephra embedded in a hand-auger boring core drilled at near-shore of Kinugasanoike Pond about 4.6 km NE of Mt.Yakedake, one of the most active volcanoes in central Japan, is composed mainly of several kinds of volcanic glass shards (microlite-bearing, blocky, fluted and micro-vesicular types) with minor amounts of crystal minerals including quartz, plagioclase, hornblende, biotite, and pyroxene. Plant remains recovered from the horizon 10 cm below the tephra layer yield $$^{14}$$C ages of 2,331-2,295 (19.2% probability distribution) and 2,270-2,155 (76.2% probability distribution) cal yrs BP. We measured major element compositions of 241 individual glass shards using Electron Probe Micro Analyzer. They are plotted on the SiO$$_{2}$$-K$$_{2}$$O, SiO$$_{2}$$-Na$$_{2}$$O+K$$_{2}$$O, and FeO$$^{ast}$$-K$$_{2}$$O diagrams in a region different from those of major regional tephras distributed in central Japan. The clast and chemical compositions coincide with those of a tephra embedded in the Nakao pyroclastic flow deposits distributed about 2 km NNW of Mt. Yakedake dated as around 2,300 cal yrs BP. The tephra could be used as a local marker of 2,300 cal yrs BP in the southern part of Northern Japan Alps.

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:10.05(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

Quantum dynamics of hydrogen in the iron-based superconductor LaFeAsO$$_{0.9}$$D$$_{0.1}$$ measured with inelastic neutron spectroscopy

Yamaura, Junichi*; Hiraka, Haruhiro*; Iimura, Soshi*; Muraba, Yoshinori*; Bang, J.*; Ikeuchi, Kazuhiko*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Honda, Takashi*; Hiraishi, Masatoshi*; et al.

Physical Review B, 99(22), p.220505_1 - 220505_6, 2019/06

AA2019-0126.pdf:0.9MB

 Times Cited Count:1 Percentile:10.78(Materials Science, Multidisciplinary)

Inelastic neutron scattering was performed for an iron-based superconductor, where most of D (deuterium) replaces oxygen, while a tiny amount goes into interstitial sites. By first-principle calculation, we characterize the interstitial sites for D (and for H slightly mixed) with four equivalent potential minima. Below the superconducting transition temperature Tc = 26 K, new excitations emerge in the range 5-15 meV, while they are absent in the reference system LaFeAsO$$_{0.9}$$F$$_{0.1}$$. The strong excitations at 14.5 meV and 11.1 meV broaden rapidly around 15 K and 20 K, respectively, where each energy becomes comparable to twice of the superconducting gap. The strong excitations are ascribed to a quantum rattling, or a band motion of hydrogen, which arises only if the number of potential minima is larger than two.

Journal Articles

Bipartite magnetic parent phases in the iron oxypnictide superconductor

Hiraishi, Masatoshi*; Iimura, Soshi*; Kojima, Kenji*; Yamaura, Junichi*; Hiraka, Haruhiro*; Ikeda, Kazutaka*; Miao, P.*; Ishikawa, Yoshihisa*; Torii, Shuki*; Miyazaki, Masanori*; et al.

Nature Physics, 10(4), p.300 - 303, 2014/04

 Times Cited Count:101 Percentile:95.53(Physics, Multidisciplinary)

Journal Articles

New ORIGEN2 libraries based on JENDL-4.0 and their validation for long-lived fission products by post irradiation examination analyses of LWR spent fuels

Kojima, Kensuke; Okumura, Keisuke; Asai, Shiho; Hanzawa, Yukiko; Okamoto, Tsutomu; Toshimitsu, Masaaki; Inagawa, Jun; Kimura, Takaumi; Kaneko, Satoru*; Suzuki, Kensuke*

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12

Accurate inventory estimation of long-lived fission products (LLFPs) in LWR spent fuels is important for the quality management and for long-term safety assessment of high-level radioactive vitrified wastes. In Japan, ORIGEN2 has been widely used to estimate the fuel compositions. However, equipped library data in the original ORIGEN2 are old and are not validated enough for LLFPs, such as $$^{79}$$Se, $$^{99}$$Tc, $$^{126}$$Sn and $$^{135}$$Cs, because available post irradiation examination (PIE) data are limited for these nuclides, which have difficulties in radiochemical analyses. For more accurate the estimation, new ORIGEN2 libraries are developed from the latest nuclear data library JENDL-4.0 for cross sections and fission yields, and from other libraries for half-lives, and so on. The new libraries are validated by PIE analyses of the sample fuels irradiated in Cooper, Calvert-Cliffs-1, H. B. Robinson-2, and Ohi-1. As a result, it was found that the new library gives good results for the estimation.

Oral presentation

Fracture analysis determined from integrated analysis of core-description and BTV images; Example from the Late Cretaceous Toki Granite, central Japan

Dia, C.*; Takagi, Hisanori*; Kojima, Satoru*; Otani, Tomoyuki*; Amano, Kenji

no journal, , 

no abstracts in English

Oral presentation

Latest slip plane and mass transfer in the basement rock; An Example of the Atera fault

Otani, Tomoyuki*; Morikawa, Koichiro*; Kojima, Satoru*; Kakamu, Kazuhiko

no journal, , 

Mass transfer along the latest slip plane is examined by geological, petrological and geochemical studies in a fracture zone outcrop of the Atera Fault, which is displaced in 1586 Tensho Earthquake. Whole rock chemical composition shows that the sharp dark brownish gouge is remarkably Mn-rich compared to other gouges and host rocks. The fact indicates that Mn-oxides or -hydroxides were precipitated due to the latest slip along the dark brownish gouge.

Oral presentation

An Attempt of fault activity assessment using element transfer in fault zones of basement rocks

Otani, Tomoyuki*; Kutsuna, Ryosuke*; Kojima, Satoru*; Ohashi, Kiyokazu*; Kakamu, Kazuhiko

no journal, , 

Development of technique in order to judge the activities of fault using chemical characteristics of active faults is useful for the assessment of faults at geological disposal sites. In this study, element transfer at fault gauge was examined. MnO contents were enriched at fault gauge of the Adera and Neodani faults. Most of Mn-bearing minerals are amorphous, it is suggested that Mn-bearing minerals were precipitated from reduced groundwater at oxidized condition when fault gauge were formed.

Oral presentation

Mass transfer characteristics and evaluation of fault activity in the Neodani fault zone, central Japan

Kutsuna, Ryosuke*; Otani, Tomoyuki*; Kojima, Satoru*; Kakamu, Kazuhiko

no journal, , 

Development of technique in order to judge the activities of fault using chemical characteristics of active faults is useful for the assessment of faults at geological disposal sites. In this study, element transfer at fault gauge in Neodani fault was examined. Fault gauge were consist of khaki and dark-gray alteration of layer and brown layer. The origin of dark-gray and brown layers are mudstone, and MnO contents were enriched from the source rock to the fault gauge. It is suggested that Mn-bearing minerals were precipitated from reduced groundwater at oxidized condition when fault gauge were formed.

Oral presentation

Manganese concentration in the latset slip plane of the Neodani fault

Kutsuna, Ryosuke*; Otani, Tomoyuki*; Kojima, Satoru*; Enami, Masaki*; Kakamu, Kazuhiko; Wakai, Shoji

no journal, , 

no abstracts in English

Oral presentation

Relationship of trace element concentration and latest slip plane in the Neodani fault zone

Otani, Tomoyuki*; Kutsuna, Ryosuke*; Kojima, Satoru*; Wakai, Shoji; Kakamu, Kazuhiko; Enami, Masaki*

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Relationship of the fault gouge ruptured by the earthquake in eastern Fukushima on April 11, 2011 and element mobility in the fault zone

Otani, Tomoyuki*; Yamashita, Mitsumasa*; Kojima, Satoru*; Wakai, Shoji*; Kakamu, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

Fault exploration based on the microcrack distribution pattern; The Example of the Tsukiyoshi fault, central Japan

Otani, Tomoyuki*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji; Sasao, Eiji; Tsuruta, Tadahiko

no journal, , 

no abstracts in English

Oral presentation

Fault exploration based on the microcrack distribution pattern; The Example of the Tsukiyoshi fault, central Japan

Otani, Tomoyuki*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji; Sasao, Eiji; Tsuruta, Tadahiko

no journal, , 

no abstracts in English

Oral presentation

Fault exploration based on the microcrack distribution pattern; The Example of the Tsukiyoshi fault, central Japan

Otani, Tomoyuki*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji; Tsuruta, Tadahiko; Sasao, Eiji

no journal, , 

no abstracts in English

Oral presentation

New concept of geological map of Gifu Prefecture "GEOLAND GIFU" using Web-GIS

Koido, Yoshimitsu*; Tanase, Atsushi*; Kano, Takashi*; Kojima, Satoru*; Sasao, Eiji; Shikano, Kanji*; Kizawa, Yoshikazu*

no journal, , 

In this presentation, the concept and background of newly compiled geological map of Gifu Prefecture. This new map will be published as a digital form and accessed through Web.

Oral presentation

Development of the geological map of Gifu Prefecture "GEOLAND GIFU" using Web-GIS for the material of geopark concept

Tanase, Atsushi*; Koido, Yoshimitsu*; Oba, Tetsuya*; Kano, Takashi*; Kojima, Satoru*; Sasao, Eiji; Shikano, Kanji*; Kizawa, Yoshikazu*

no journal, , 

In this presentation, the concept and background of newly compiled geological map of Gifu Prefecture. This new map is utilized on a Web-GIS form through PC network. In this presentation, this system is demonstrated.

Oral presentation

Relation of the Tsukiyoshi fault and orientation distribution of microcracks in the borehole MIU-3 core in Mizunami City, Gifu Prefecture

Otani, Tomoyuki*; Yokoi, Kosuke*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji*; Sasao, Eiji

no journal, , 

The orientation of microcracks was measured using the MIU-3 core penetrating the Tsukiyoshi fault to clarify the relation of the microcrack distribution near the fault. Attitude of microcracks in quartz grains in granite are measured under the optical microscope with the universal stage using three perpendicular thin sections. The healed microcracks was probably formed prior to the sealed microcracks. Both healed and sealed microcracks with moderate dip appears near the fault. The distribution of microcracks with moderate dip shows that the preferred orientation of microcracks near the fault is different from that far from the fault. The distribution of the sealed microcracks with moderate dip is narrower than that of the healed microcracks. This shows that the healed microcracks with moderate dip was developed in the intact granite at the earlier stage of the faulting history, and the sealed microcracks was in the weak fault zone which has repeated rupturing and healing at the later.

Oral presentation

The Relationship between sackung feature and active fault; A Case study about the northern tip of the Neodani fault

Komura, Keitaro*; Kaneda, Heitaro*; Kashihara, Shintaro*; Kojima, Satoru*; Nishio, Tomohiro*; Yasue, Kenichi

no journal, , 

no abstracts in English

23 (Records 1-20 displayed on this page)