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Tajikara, Masayoshi; Takada, Keita*; Furusawa, Akira*; Sugai, Toshihiko
Dai Yonki Kenkyu, 50(1), p.21 - 34, 2011/02
Three major fluvial terraces are developed well along the Kabura-gawa river, tributary of the Tone-gawa river. We detected cryptotephras in overbank and aeolian deposits covering the middle terrace gravels, and examined petrologic character. We also investigated petrologic character of the Iizuna-Kamitaru tephra (In-Kt) and the Iizuna-Nishiyama (In-Ny) tephra extracted from the outcrops near the Iizuna volcano. Based on these data, we identified possibly In-Kt and In-Ny tephra at the bottom of overbank deposits on the middle terrace of the Kabura-gawa river. This indicates that the middle terrace was formed through aggradation at glacial age of marine oxygen isotope stage 6. The Kabura-gawa river basin is located out of the previously reported distribution area of In-Kt. This fact implies that In-Kt is distributed more widely in the northern Kanto and southern Tohoku regions, and that In-Kt is useful as marker tephra of the middle Pleistocene in these regions.
Kinoshita, Hirohisa; Nohara, Tsuyoshi; Nakata, Takashi*; Ikeda, Yasutaka*; Ito, Kiyoshi*; Otsuki, Kenshiro*; Sagiya, Takeshi*; Takada, Keita*; Toda, Shinji*
Katsudanso Kenkyu, (25), p.27 - 37, 2005/06
Results of numerical analyses and field studies in the epicenter area of the 2000 Tottoriken-seibu earthquake suggest that several research techniques are effective for identifying subsurface active faults unaccompanied with remarkable surface earthquake faults. Field observation of the lineaments found in the area by detailed air-photo interpretation revealed that most of them are accompanied by faults and/or dikes, and some of them show minor slips at the time of the earthquake. Crustal deformation caused by the activity of the subsurface seismogenic faults is deduced by numerical analyses based on seismic and geodetic data. The vertical deformation assumed from the height changes of the terraces along the river across the epicenter area suggests that cumulative uplift and subsidence associated with left-lateral strike-slip has been continuing. Offsets rate of the streams and uplift rate of the river terraces surfaces show good agreement with the estimate from the parameter of the earthquake faults model. Identification of active faults without clear surface evidence before occurrence of earthquakes is a difficult issue, and the techniques adopted in this study will probably provide relevant information effective to locate subsurface active faults.
Takada, Keita*
JNC TJ7420 2005-106, 139 Pages, 2004/03
JNC-TJ7420-2005-106.pdf:59.93MB
We discuss developing the technique of extracting indistinct seismogenic faults such as a case of partly existing displacement on the ground surface and indistinct active faults. We maped active faults and possible active faults that have possibility to induce earthquakes by aerial photograph interpretation around the Chugoku district, southwestern Japan and Chubu district, central Japan. Then we make a field survey around epicentral area of the 2000 Tottori-ken Seibu earthquake. The result of the field survey shows characteristics of lineaments that faulted during 2000 earthquake. We compared results of interpretation with several datas, for example seismicity, geology, gravity, GPS, and summarize notable point for extracting indistinct seismogenic faults.
Niwa, Masakazu; Takada, Keita*; Kinoshita, Hirohisa*
no journal, ,
no abstracts in English
Tajikara, Masayoshi; Takada, Keita*; Nohara, Tsuyoshi
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Tajikara, Masayoshi; Takada, Keita*; Furusawa, Akira*; Morita, Yoshimune*; Sugai, Toshihiko*
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We investigated fluvial terraces along the Kaburakawa River, in order to clarify the model of fluvial terrace development. Based on air photo analysis, fluvial terraces in the study area were classified into four categories (Q1-Q4). Existing papers reported that Q3 was formed in Marin Oxygen Isotope Stage (MIS) 2. In this study, we found a fragment of tree which is identified as 
or 
. This fact indicates that Q3 was formed in relatively cold age. Q2 is distributed at higher level than Q3. We found Iizuna-Kamitaru Tephra (Iz-Kt) at the lowermost part of aeolian deposits or uppermost part of overbank deposits in some outcrops of Q2 deposits. Since Iz-Kt is believed to fall at boundary of MIS 5 and 6, we concluded that Q2 deposits was accumulated in MIS 6 and that Q2 was incised in MIS 5.
Tajikara, Masayoshi; Yasue, Kenichi; Sugiyama, Shinji*; Takada, Keita*; Kato, Takayuki*; Sugai, Toshihiko; Morita, Yoshimune*; Furusawa, Akira*
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no abstracts in English
Kagohara, Kyoko; Takada, Keita*; Goto, Hideaki*; Kurosawa, Hideki; Ishimaru, Tsuneari
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cameraYamagishi, Keita*; Takada, Eiji*; Sato, Yuki; Torii, Tatsuo
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cameraYamagishi, Keita*; Takada, Eiji*; Sato, Yuki; Torii, Tatsuo
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Nogami, Mitsuhiro*; Kitayama, Yoshiharu; Hitomi, Keitaro*; Takada, Eiji*; Torii, Tatsuo*; Ishii, Keizo*
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no abstracts in English
Nogami, Mitsuhiro*; Kitayama, Yoshiharu; Hitomi, Keitaro*; Takada, Eiji*; Torii, Tatsuo*; Ishii, Keizo*
no journal, ,
no abstracts in English
Nogami, Mitsuhiro*; Kitayama, Yoshiharu; Hitomi, Keitaro*; Tamura, Yusuke*; Kaneko, Shinichiro*; Takada, Eiji*; Torii, Tatsuo*
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no abstracts in English
