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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.

JAEA Reports

R&D on seismic emergency information system

Seismic Emergency Information System Research Team

JAERI-Tech 2001-036, 294 Pages, 2001/06

JAERI-Tech-2001-036.pdf:23.23MB

no abstracts in English

JAEA Reports

None

*; Ito, Kiyoshi*

PNC TJ1673 95-001, 50 Pages, 1995/03

PNC-TJ1673-95-001.pdf:1.33MB

None

Oral presentation

Report of the (U-Th)/He dating system at Tono Geoscientific Research Unit, Japan Atomic Energy Agency

Yamada, Kunimi; Hanamuro, Takahiro; Tagami, Takahiro*; Yamada, Ryuji*; Umeda, Koji

no journal, , 

Japan Atomic Energy Agency have jointly set up the lab of the (U-Th)/He dating in cooperation with Kyoto University. At the present stage, samples are apatite and zircon. Infrared laser heating in vacuum chamber extracts helium. The helium is quantified using the MM5400 rare gas mass spectrometer and the sensitivity method. The sensitivity of the mass spectrometer is calibrated using standard air, a volume-known pipette, and a capacitance manometer. The ICP quadrupole mass spectrometer quantifies uranium and thorium using standard addition method after dissolution of the gas-extracted sample. Apatite is dissolved using HNO$$_{3}$$ and zircon is decomposed by the alkali-fusion method using XRF bead sampler and LiBO$$_{3}$$. We are performing the calibration of MM5400 and testing dissolution procedures for ICP at present, and will report detailed views of dating systems in addition to them.

Oral presentation

Results from the (U-Th)/He dating systems in Japan Atomic Energy Agency

Yamada, Kunimi; Hanamuro, Takahiro; Tagami, Takahiro*; Yamada, Ryuji*; Umeda, Koji

no journal, , 

no abstracts in English

Oral presentation

Evaluation of influence on the radiocarbon dating by the difference in chemical pretreatment protocols

Yamada, Ryuji*; Kokubu, Yoko; Wakatsuki, Tsuyoshi*; Yasue, Kenichi

no journal, , 

Mass movements and fault movements are natural phenomena to change the local topography. Reconstruction of the movement histories and evaluation of long-term stability of topographies are crucial to assess the geological environment in future. History reconstruction based on radiocabon dating of plant material recovered from sediment deposited by the past movements requires the compilation and the comparison of existing data measured by different analysts with different methods. We compared the results of radiocarbon ages measured at different laboratories with various chemical pretreatments, using plant material samples. For older samples (about 45000 BP), dispersion in ages is greater than measurement uncertainty. However the order of weighted mean ages for each sample agrees well with stratigraphic sequence at the sampling site. It is therefore thought that the influence of the systematic error due to a specific experimental conditions is small.

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