• Journal of the Korean earth science society
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• v.24 no.4
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• pp.361-368
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• 2003

We have investigated the electric resistivity structure of the fault zone located in the Hongseong area where a big earthquake with M 5.0 occurred in 1978. Usually, Electric and Electromagnetic methods are broadly operated in the field of engineering works since these methods are effective to understand the distribution of geological weak zones - fault or fracture zones. We have conducted the dipole-dipole array resistivity method and MT(magnetotelluric) method and interpreted the resistivity distribution of the fault zone with the aid of various inversion methods. An MT survey was performed at 18 points along a 2.9 km survey line perpendicular to the fault line and a magnetic dipole source was used to enhance the S/N ratio in the high frequency. A Electric dipole-dipole array resistivity survey with the dipole length of 50 meters was carried out perpendicular to the fault. In view of two survey results, the fault marks the boundary between two opposite resistivity structures, especially the low resistivity zone is exhibited deeply through the prospective fault line. The result that the low resistivity zone is located at the center of the fault zone corresponds with the fact that the fault zone of the Hongseong area is active. We expect these results to provide basic information about the physical properties of fault zones in Korea.

• Journal of the Korean earth science society
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• v.45 no.3
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• pp.224-238
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• 2024

This study analyzed lineaments and fault-related landforms in Chungcheongnam-do, central Korean Peninsula, based on historical and instrumental records, given its susceptibility to future earthquakes. We extracted 151 lineaments associated with fault-related landforms. In regions with the Dangjin and Yesan faults, lineaments with strikes matching these faults were densely distributed. Conversely, in the Hongseong Fault area, the number of lineaments was smaller, and those with strikes similar to the fault were less discernible. This is likely due to the extensive distribution of alluvium and surface deformation from long-term weathering, erosion, and cultivation, which obscures geomorphic evidence of faults. At five key fault points, we identified fault-related landforms, such as fault saddles, knickpoints in Quaternary alluvium, and linear valleys, along the lineament, which may indicate an actual fault. However, the displacements of the Quaternary layer within the lineaments appear to be influenced more by external factors, such as artificial disturbances (e.g., cultivation) or stream erosion, than by direct fault movement. The differences between the fault-related landforms in this study area and those in the southeastern Korean Peninsula suggest a specific relationship between fault types and their associated landforms.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.63-71
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• 2008

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.741-745
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• 1998

양전자방출단층촬영 영상획득시 수반되는 산란분획의 분포를 Monte-Carlo simulation을 이용하며 평가하고자 하였다. 모사계산에서는 GE Advance PET 스캐너와 NEMA 규정에 의한 팬텀을 모델화하였고 선상선원을 대상으로 평균 산란분획 10.2%와 산란방사선의 축방향 분포를 구하였다. 방사선원 F-18을 사용한 실제 측정의 평균산란 분획 9.16%와 산란방사선 분포를 비교하여 유사한 결과를 얻었다.

• Economic and Environmental Geology
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• v.52 no.5
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• pp.449-457
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• 2019

We present the K-Ar age-dating results of the bulk and the less than $0.1{\mu}m$ fraction of the fault gouges collected from some major faults in the Gyeongsang basin. We try to determine the timings of fault activation based on the mineralogical characteristics, and to interpret the spatio-temporal variability of the major fault events during the Cenozoic Era by considering together with the previous results. We propose at least the 3-times of major fault events at about 50 Ma, and just after 30 Ma and 20 Ma in the Gyeongsang basin, which were inferred from the combined approach of the K-Ar ages and the clay mineralogy of the bulk fault gouges and the <$0.1{\mu}m$ fractions. The fault activation timings of the Yangsan fault tend to be younger in the northern part than in the southern part. In particular, the inferred fault events just after 30 Ma and 20 Ma are mainly detected in the Ocheon fault and the related faults, and the fault in the Gyeongju area. The fault activation timings of the major faults can be revised accurately by using illite-age-analysis(IAA) method. These geochronological determinations of the multiple events of the major faults in the Gyeongsang basin are crucial to establish the tectonic evolution in the southeastern part of the Korean Peninsula during the Cenozoic Era.

• Journal of The Geomorphological Association of Korea
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• v.28 no.1
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• pp.67-81
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• 2021

Geomorphological development and distribution at the macro scale provide a clue to the geotectonic characteristics that have affected the geomorphological system. This is because the developmental characteristics and distribution of the landform at the macro scale remain spatial characteristics due to tectonic processes, such as fault activity. From the perspective of tectonic geomorphology, this study identified the developmental characteristics and distribution of the Quaternary landforms in central-southern Yangsan fault and discussed its relevance to fault activity. In this paper, we presented examples and results of morphotectonic analysis of the Yangsan fault, and will present the results of age dating, stratigraphic relationship of the Quaternary landforms, and calculation of cumulative slip rate in the next paper.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.645-654
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• 2020

We present the K-Ar age dating results of <0.1㎛ fraction of the selected fault rocks from the Yangsan fault in the Yeonghae area. Based on the mineralogical characterization, the <0.1㎛ fractions were mostly composed of 1Md illite polytype, or I-S interstratified mineral, which should be formed by fault activation. Therefore, we determined the timings of fault activation events by analyzing K-Ar age-dating for the <0.1㎛ fractions. Accordingly, the activation timings of Yangsan Fault in the Yeonghae area were determined as 45.5±1.1 Ma, 50.9±1.2 Ma, 58.2±1.3 Ma, 60.8±1.4 Ma, 65.3±1.6 Ma, 66.8±1.5 Ma, 67.1±1.5 Ma, and 75.1±1.7 Ma. These results indicate that at least 5-times of major fault events occurred in the Yangsan fault from late Mesozoic to Cenozoic Era. In the outcrop, age dating results tend to be younger age from the location of the oldest sample(75.1±1.7 Ma) toward to the both sides. From the results, it suggests that the fault activation extends from the location of oldest age saple to both sides. This geochronological research of the multiple fault activation ages for the Yangsan Fault will provide crucial information for establishing the tectonic evolution model in the southeastern part of the Korean Peninsula.

• 대한핵의학회:학술대회논문집
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• 2002.11a
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• pp.17.2-17.2
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• 2002

• 대한핵의학회:학술대회논문집
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• 1997.05a
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• pp.168-168
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• 1997

• Economic and Environmental Geology
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• v.49 no.4
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• pp.315-323
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• 2016

This study reports a gneiss dome in the Hongseong area, southwestern margin of the Gyeonggi massif. This gneiss dome, named here as 'Oseosan dome' because it is located around the Oseosan, the highest peak along the western coastal area, is composed mainly of the Neoproterozoic to Paleozoic ortho- and paragneiss, mafic metavolcanic rock, and metadolerite. Migmatization affected these rock units, in which leucocratic(granitic) materials derived from anatexis frequently occur as patch and vein parallel to or cutting through internal foliation. The Oseosan dome shows overall concentric geometry and outward-dipping internal foliation, but also partly complicatedly changeable or inward-dipping foliation. Taking available petrological and geochronological data into account, the Oseosan dome is interpreted to be exhumed quickly into the upper crustal level during the Late Triassic, accompanied in part with anatexis and granite intrusion. In addition, extensional shear zone intruded by the Late Triassic synkinematic granite and sedimentary basin have been reported around the Oseosan dome. These evidences possibly suggest that the Oseosan dome formed in closely associated with the Late Triassic extensional movement and diapiric flow. Alternatively, 1) thrust- or reverse fault-related doming or 2) interference between independent folds during structural inversion of the Late Traissic to Middle Jurassic sedimentary basin can be also considered as dome-forming process. However, considering the northern limb of the Oseosan dome, cutting by the Late Traissic granite, and the southern limb, cutting by contractional fault reactivated after the Middle Jurassic, it is likely that the domal structure formed during or prior to the Late Triassic.