Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
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：8 Percentile：40.25(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 The authors conducted sedimentary facies analysis, radiocarbon dating, and historical document analysis to understand the flow characteristics and history of far-reaching lahars.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.
Umeda, Koji; Ban, Masao*; Hayashi, Shintaro*; Kusano, Tomohiro
Journal of Earth System Science, 122(1), p.137 - 147, 2013/02
Times Cited Count：6 Percentile：18.11(Geosciences, Multidisciplinary)From a compilation and analysis of stratigraphy, radiometric age and data on erupted magma volumes, 176 eruptive episodes identified from 69 volcanoes so far, indicate that notable changes in eruption style, magma discharge rates and distribution of eruptive centers occurred around 1.0 Ma. Before ca. 1.0 Ma in northeast Japan, large-volume felsic eruptions were dominant, forming large calderas in the frontal arc, a region of low crustal strain rate. After ca. 1.0 Ma to the present, the calc-alkaline andesite magma eruptions in the frontal and rear arcs, synchronous with crustal shortening characterized by reverse faulting, resulting in stratovolcano development along narrow uplifted zones.
Tomiyama, Shingo*; Umeda, Koji; Hanamuro, Takahiro; Takashima, Isao*; Hayashi, Shintaro*; Negishi, Yoshimitsu*; Masudome, Yukiko*
Ganseki Kobutsu Kagaku, 36(4), p.111 - 121, 2007/07
To clarify a progress history of the alteration accompanied by Mutsu-Hiuchidake volcanic activities, the study on distribution and characteristics of alteration zones and alteration dating at the Mutsu-Hiuchidake Volcano. The results of alteration zoning and alteration dating suggest that alteration zones generated by hydrothermal activities accompanied by Mutsu-Hiuchidake volcanic activities are distributed along the fracture zones and enlarged by fractures or highly permeable zones in the body of volcano and basement. The result of measurement of homogeneous temperatures of fluid inclusion suggests that the highest temperature of these hydrothermal alterations is about 200 to 250
C.
Tanase, Atsushi*; Oikawa, Teruki*; Ninomiya, Atsushi; Hayashi, Shintaro*; Umeda, Koji
Kazan, 52(1), p.39 - 61, 2007/02
Temporal and spatial variations on Plio-Pleistocene volcanism in the Ryohaku Mountains, central Japan, have been investigated by newly obtained K-Ar ages on 38 groundmass samples separated from volcanic rocks. The volcanoes in the Ryohaku Mountains form two volcanic rows of the Kuzuryu and hakusan Volcanic Chains which have ESE-WNW and N-S alignments, respectively. Early volcanic activity occurred intermittently from 3.6 Ma to 1.5 Ma, and the volcanoes near the junction of the two volcanic chains were active. The volcanic activity in the ESE-WNW trending Kuzuryu Volcanic Chain was restricted in the age range from 1.2 Ma to 0.7 Ma with migration from Eboshi-Washigatake Volcano (ESE end) to Hoonji Volcano (WNW end). The N-S trending Hakusan Volcanic Chain was active from 0.4 Ma to the present.
Miyamoto, Yoshiaki; Ogawa, Masuro; Akino, Norio; Shiina, Yasuaki; Inagaki, Yoshiyuki; Shimizu, Saburo; Onuki, Kaoru; Ishiyama, Shintaro; Katanishi, Shoji; Takeda, Tetsuaki; et al.
JAERI-Review 2001-006, 147 Pages, 2001/03
JAERI-Review-2001-006.pdf:9.2MB
no abstracts in English
Ban, Masao*; Oba, Tsukasa*; Hayashi, Shintaro*; Umeda, Koji
Ganko, 92(5), p.181 - 188, 1997/00
None
Minami, Yusuke*; Oba, Tsukasa*; Hayashi, Shintaro*; Kokubu, Yoko; Kataoka, Kyoko S.*
no journal, ,
A volcanic-fan developed at the northern base of Chokai Volcano in northeast Japan. To understand the flow characteristics and history of far-reaching lahars occurring in the volcanic fan, we carried out excavation survey at the distal part of the volcanic fan, sedimentary facies analysis, and radiocarbon dating. Geological observation revealed that at least five large lahar events occurred. The 
C ages of the lahar deposits and their correlation with historical documents indicate that the large lahars travelled down the volcanic fan at: the 2nd - 5th century BC; 2nd to 4th century BC; AD 5th to 7th century; AD 871; and AD 1801 after the Kisakata debris avalanche (2.5 ka). These 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.
