著者

Masaki Takahashi Maya Yasui Tatsuo Kanamaru Mitsuhiro Nakagawa

出版者

Fuji Technology Press Ltd.

雑誌

Journal of Disaster Research (ISSN:18812473)

巻号頁・発行日

vol.17, no.6, pp.1080-1089, 2022-10-01 (Released:2022-10-01)

参考文献数

30

被引用文献数

1

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The eruptive volumes and ages of the large-scale pumice eruptions of the Asama-Maekake volcano were obtained from extensive trench-based surveys. The calibrated radiocarbon age unit (CRAU) was adopted instead of each calibrated radiocarbon age. From the high-resolution tephro-stratigraphy of large-scale pumice eruptions and CRAU dating, the eruptive history of the Asama-Maekake volcano is divided into three active and two moderately active stages as follows: active stage I (9430 to 7260 ycalBP), moderately active stage 1 (7261 to 6446 ycalBP), active stage II (6447 to 3160 ycalBP), moderately active stage 2 (3161 to 1819 ycalBP), and active stage III (1820 ycalBP to present). The eruptions of the Asama-Maekake volcano consists of small-scale (phreatic to phreato-magmatic), intermediate-scale (Vulcanian), and large-scale pumice eruptions (sub-Plinian). The active stages were characterized by the occurrence of large-scale pumice eruptions. In the moderately active stages, pumice producing eruptions were lacking but instead Vulcanian eruptions dominated. A step diagram showing the relationship between eruption volumes (DRE) and ages (CRAU) is proposed, which indicates that active stage III is not time-predictable but is volume-predictable; if the large-scale pumice eruption occurs in 2022 AD, the forecasted eruptive volume is approximately 0.21 km3. The eruption rate is not constant and changes in each stage, and the average eruption rate of active stage III (0.0011 km3/year) is larger than those of active stage I (0.00006 km3/year) and II (0.0001 km3/year).

著者

Chihiro ISHII Yoshinori IKENAKA Shouta M.M. NAKAYAMA Takeshi KURITANI Mitsuhiro NAKAGAWA Keisuke SAITO Yukiko WATANABE Kohei OGASAWARA Manabu ONUMA Atsushi HAGA Mayumi ISHIZUKA

出版者

JAPANESE SOCIETY OF VETERINARY SCIENCE

雑誌

Journal of Veterinary Medical Science (ISSN:09167250)

巻号頁・発行日

vol.82, no.8, pp.1118-1123, 2020 (Released:2020-08-19)

参考文献数

31

被引用文献数

5

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Birds of a number of species have died as a result of lead (Pb) poisoning, including many Steller’s sea eagles (Haliaeetus pelagicus) and white-tailed sea eagles (Haliaeetus albicilla) in Hokkaido, the northernmost island of Japan. To address this issue, the use of any type of Pb ammunition for hunting of large animals was prohibited in Hokkaido in 2004. However, Pb poisoning is still being reported in this area, and there are few regulations regarding the use of Pb ammunition in other parts of Japan, where it has been reported that eagles and water birds have been exposed to Pb. This study was performed to accurately determine the current level of Pb exposure of birds found dead in the field or dead in the wild bird centers in Japan (June 2015–May 2018) and to identify the sources of Pb. Pb exposure was found to still be occurring in raptors and water birds in various parts of Japan. Twenty-six point five % and 5.9% of the recorded deaths of Steller’s sea eagles and white-tailed sea eagles, respectively, were found to have been poisoned by Pb. In addition, Pb isotope ratio analysis showed that both Pb rifle bullets and Pb shot pellets cause Pb exposure in birds, and these endangered eagles are also exposed to Pb in Hokkaido due to the illegal use of Pb ammunition. Changing to Pb-free ammunition, such as copper (Cu) rifle bullets, steel shot pellets, or bismuth shot pellets, will be essential for the conservation of avian species in Japan.