1994 Fiscal Year Final Research Report Summary
Recurrence Time of Large Events on Active Faults in Korea
| Project/Area Number |
06041060
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Field Research |
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| Research Institution | Kyoto University |
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Principal Investigator |
OIKE Kazuo Kyoto University, Faculty of Science, 理学部, 教授 (40027248)
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| Co-Investigator(Kenkyū-buntansha) |
JO 華龍 慶北大学校師範大学地理学教室, 教授
金 性均 全南大学校自然科学大学, 教授
慶 在福 韓国教員大学校地球科学科, 助教授
全 明純 韓国資源研究所, 研究員
OKURA Takahiro Kyoto University, Faculty of Integrated studie Humo, 総合人間学部, 助手 (40233077)
KUJE Keiko Kyoto University, Faculty of Science, 理学部, 助手 (50234414)
中西 一郎 京都大学, 理学部, 助教授 (10164229)
IRIZUKI Toshiaki Aichi University of Education, 教育学部, 助手 (60262937)
AKIMOTO Kazumi Nagoya Jiyugakuen College, 助教授 (70222536)
YAMAJI Atsushi Kyoto University, Faculty of Science, 理学部, 助教授 (40212287)
SUZUKI Yasuhiro Aichi Prefectural University, Faculty of Lit., 文学部, 講師 (70222065)
WATANABE Mitsuhisa Toyo University, Faculty of Literature, 文学部, 講師 (30222409)
OKADA Atsumasa Kyoto University, Faculty of Science, 理学部, 教授 (90086174)
KIM Sung-kyun Chonnam University, Faculty of Natural Scienc
JUN Myang-soon Korea Institute of Energy and Geology
JO Wha-ryong Kyungpok University, Faculty of Education
KYUNG Jai-bok Korean University of Education
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| Project Period (FY) |
1994
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| Keywords | Active fault / Yangsan fault / Ulsan fault / Fault topography / Trench excavation survey / Crustal movement / Large earthquake / Recurrence time |
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| Research Abstract |
The yangsan fault in the southeastern part of Korea trends about 200km with ca NNE-SSW direction and accompanies the wide shattered zone. The active fault topography and geology have investigated along this fault system and trench excavation had been carried out across this fault. It is confirmed that this fault cleary dislocates the river terrace surfaces and their deposits with the predominantly right-lateral com-ponent of vertical displacement upthrown to the east (Okada and others, 1994).
The large-scale construction for making a new town has now been conducted at the southern part of Eonyang, Ulsan County, where many trench excavation surveys have carried out to clarify the associated crustal deformation along the main fault and subordinary faults. The following results have been gotten from these investigations ; The high terrace at south of Eonyang, which has been formed by the former river flowed to the northeastward, had originally declined to northeast, but is now tilting to w
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est in the reverse direction. The gravels forming the high terrace has been deformed by the flexure movement. The vertical amount of displacement on the high terrace reaches about 5 meters. Although several faults are recognized within the trench walls, these rupturing did not extend to the surface.
The Ulsan fault system extends about 40km with N-S or NNW to SSE direction. The surface trace is remarkably sinous. The Ulsan fault is a typical reverse fault, considering from the expression on the outcrop and the style of surface deformation. As geomorphic surfaces and deposits formed during late Quatenary time are clearly dislocated, Ulsan fault is really active one. The vertical amount of displacement along this fault is 5m on the middle terrace, and 15m on the high terrace. These values indicate the cumulative offsetting in the late Quatenary.
The outcrops showing active fault were clearly observed at two localities. The shattered granite thrust over the gravel layrs with the strike of N-S direction and the dip of 25-30ﾟ E on north wall of Sagok reservoir at east of Malbang-ri settlement ; detailed structures were sketched after cleaning of this wall. Well shatterd granite is overridden on the slightly weathered gravel layrs on the river (Yeonan Stream) -side outcrop of at the northeastern part of Kaegok-ri settlement.
The silty sediments consisting of the upper part of the middle terrace at Malbang-ri were clearly disturbed by liquefaction. This phenomena indicate the occurrence of large earthquakes in this area. Recurrence time of large events in the southeast-ern part of Korea will be treated after getting the ages of the terrace surfaces and its deposits.
As the marine Miocene sediments are well distributed around Pohan basin, geological surveys have been carried out to clarify post-Miocene movements of the Yansang fault. The detailed analyzes of micro-fossils and molluscas have been investigated in the laboratory works. Less
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Research Products
(6 results)
