• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.228-234
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• 1998

To interpret the relationship between movement of the Yangsan fault and tectonics around the Korean peninsula, the six sequential paleostresses were reconstructed from 1, 033 striated small faults which were measured at 37 outcrops along the strike of the Yangsan fault. And, the relationship between these paleostresses of the Yangsan fault and the tectonic events around the Korean peninsula were compared. As compared with the tectonic history around the Korean peninsula, the movement of the Yangsan fault is interpreted as follows; The initial feature of the Yangsan fault was formed with the development of extension fractures by the NW-SE extension. The fault experienced a right-lateral strike-slip movement continuously. The movements had been continued until the Late Miocene age, which was the most active period in faulting. The left-lateral strike-slip movement was followed by subsequent tectonic events. In the last stage, the fault acted with a slight extension or right-lateral movement.

• 자원환경지질
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• 제22권3호
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• pp.285-291
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• 1989

The Okdong Fault is situated in Okdong-Hamchang area, the central part of Korea. The area consists of Precambrian gneisses and granitoids, Paleozoic clastic and carbonate rocks, and Mesozoic clastic rocks and igneous intrusives. The Okdong Fault is situated along contact boundary between the lowermost Cambrian Basal Quartzite and Precambrian basements. Mylonites occur as narrow zone which is extended over 100km and is restricted to within 10m-30m along the Okdong Fault. The main features of mylonites are quartz mylonite derived from Cambrian Basal Quartzite and mylonitic granitoids from Precambrian granitoids. Movement sense is deduced as a sinistral strike-slip movement with evidence of rotation of sheared porphyroclasts, rotation of fragments and S/C-bands. The mylonite zone has been reactivated as fault which reveals oblique-slip movement. The fault resurges as faults which reveals normal(to the NW) and reverse(to the SE) dip-slip movement. Normal faults are dominant in the northern and southern part and reverse or thrust faults are dominant in the central part of the Okdong Fault. The thrust movement can be correlated with the Daebo Orogeny of Jurassic Period. Granites and dyke rocks intruded into Paleozoic and Precambrian rocks during Cretaceous Period.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.418-421
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• 2008

Wenchuan earthquake (Mw 7.9) occurred in Sichuan province, China, May 2008 had resulted in a huge fault displacement around the Lungmenshan fault. Preliminary results of the fault displacement observed by ALOS PALSAR interferometry are presented. The surface deformation by the Wenchuan earthquake was reported up to 10m consisting of thrust- and right-slip compnents. A significant reduction in ionospheric density was also reported. Twenty differential interferograms and twenty multiple aperture SAR interferometry (MAI) pairs were produced over four ALOS tracks. It was observed from differential interferograms that i) LOS deformation decreases steadily from northnorthwest of the Longmenshan fault to the fault, ii) the LOS deformation sharply increases at areas around the fault, and iii) the decrease of the LOS deformation is observed from the Longmenshan fault to the south-southeast of the fault. Horizontal movement of the reverse fault displacement can better be observed by MAI technique, and the MAI phases show that i) the south-southeast directional reverse fault displacement (negative along-track deformation for an ascending track) of the north-northwest block gradually increases to the Longmenshan fault, ii) the reverse fault movement of the south-southeast block is sharply reversed to the north-northwest of the fault, and iii) the northnorthwest movement gradually decreases to the south-southeast of fault. Although the Lonmenshan Fault line is a center of earthquake epicenter, the boundary of surface movement exists to the north-northeast of the fault. Since the ionosphere was not stable even forty days after the mainshock, MAI phases were seriously corrupted by ionospheric effect. It is necessary to acquire more data when the ionosphere recovered to a normal state.

• 한국지형학회지
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• 제27권4호
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• pp.29-39
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• 2020

This study estimated influences of the Ulsan Fault on tectonic movement and uplift characteristics in the Eastern Block of the Ulsan Fault. The averaged uplift rate in the Northern Coast of the Eastern Block was 0.202 m/ka, while the site in Seokbyeong-ri, Guryongpo-eup, Pohang-si, showed relatively high rate of 0.249 m/ka, attributable to influences of small fault movement, called the Gangsa Fault. Higher averaged rate of 0.270 m/ka than in the Northern Coast was calculated in the Southern Coast of the Eastern Block. The site in north of Haseo-ri, Yangnam-myeon, Gyeongju-si, showed the highest rate, suggesting influences of the Eupcheon Fault. The Western Block of the Ulsan Fault indicated the averaged rate of 0.208 m/ka, similar to that of the Northern Coast. The sites approximately 10 km apart from the Ulsan Fault showed 1.3 times higher rate in the Eastern Block than in the Western Block, while similar rates were calculated in the sites >20 km apart from the Ulsan Fault. These distributions of the rate suggest that the Ulsan Fault has significantly influenced development of marine terrace and tectonic movement in the study area, while local fault movements have also played a role.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.11-18
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• 2002

The Ulsan fault with NNW-SSE strike is a very wide and long lineament about 50km along Gyeungju-Ulsan line in the southeastern part of Korea. According to previous studies the Ulsan fault was not considered as a fault but only long lineament since no displacement was found along the lineament. Recently several Quaternary faults were reported in the northeastern part of lineament, which implies the neotectonic movement in this area. We analysed drainage pattern and stream gradient using the DEM (Digital Elevation Model) data for both side of Ulsan fault line to check the recent topographic changes which indicate neotectonic movement. The result shows that stream index in the eastern part of Ulsan fault is higher than the one in the western part. This means that recent tectonic movement is more active in the eastern part of Ulsan fault.

• 암석학회지
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• 제18권1호
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• pp.19-30
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• 2009

울산시 울주군 언양읍 북부 신흥마을 입구에 북서-남동 방향으로 트렌치된 단면에서 양산단층대의 주단층과 제4기 단층이 관찰되었다. 본 논문은 신흥마을 입구의 트렌치 단면에서 조사된 양산단층대의 기반암 단층(신흥단층)과 제4기 단층(제4기 신흥단층)의 기하학적 운동학적 특성연구로부터 양산단층대 남부의 단층 운동사를 해석하였다 신흥마을 입구 트렌치 단면에서는 단층접촉으로 반복되어 산출하는 백악기 하양층군의 퇴적암류와 유천층군의 화산암류 그리고 이들 기반암류를 부정 합으로 피복하는 제4기 퇴적층 등이 산출하고, 본 연구결과 양산단층대의 형성과 관련된 적어도 2회의 주향-이동 단층운동 (D1, D2)과 이후 적어도 2회의 역-이동 단층운동(D3, D4)이 인지된다 (1) D1 단층운동: 양산단층대의 주 단층을 향하여 퇴적암류의 층리를 고각화시키는 주향-이동 단층운동. (2) D2 단층운동: 고각화된 층리를 단층면으로 하는 우수 주향-이동 단층운동 주요 특징적인 구조요소로서는 북북동 방향의 준 수평적인 우세한 단층조선과 준 수직적인 우세한 단층엽리 등이 있다. 양산단층대의 주요 단층암류는 D2 단층운동에 의해 형성되었다. (3) D3 단층운동: (동) 북동 주향에 (남)남동 내지 (북)북서 방향으로 중각 경사하는 단층면을 갖는 공역성 역-이동 단층운동 주요 특징적인 구조요소로서는 주향 방향의 단층조선을 중첩하는 경사 방향의 단층조선, D2 단층비지에 발달하는 S-C 구조 엽리, 비탈과 평탄 기하의 단층면, 단층운동에 수반된 비대칭 및 끌림 습곡과 붕괴구조 등이 있다. 양산단층대 주 단층면의 방향성은 주로 D3 단층운동에 의해 분산되었다. (4) D4 단층운동: 제4기 퇴적층내에 5-C 구조 엽리의 발달과 함께 제4기 퇴적층을 수 cm 변위시키는 제4기 역-이동 단층운동 양산단층대의 다른 제4기 단층과 같이 D4 단층면은 기반암의 D3 역-이동 단층면의 연장선상에 놓이고, 이들 단층은 동일한(북)북서-(남)남동 방향의 압축응력에 의해 형성되었다.

• 자원환경지질
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• 제26권2호
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• pp.227-237
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• 1993

Lineaments in the Kyungsang basin most intensely develop in the East coast domain including the Yangsan fault, which dominantly run in NNE direction. The geometry of small fault population near or along the Yangsan fault represents the dominant strikes of N35E, high angle dips and shallowly plunging rakes with dextral movement sense. Stereographic solution on the Yangsan fault geometry gives the dip of 88SE, the slip direction of 17,024 and the slip rake of 18, which were determined from the strike (N23E) of the fault measured on map, and the average attitude (N35E, 84SE) and fault striation (16, 037) of small fault population considered as Riedel shears. It is judged from the geometry of small fault population to the main Yangsan fault and dragging features of bedding attitude near the fault that the Yangsan fault was produced from dextrally strike-slip movement. The movement of the Yangsan and the adjacent parallel faults is thought to be taken place much later than the other fault sets in the Kyungsang basin. It might occur during the geologic age from Eocence to early Miocene according to the consideration of K-Ar ages of the igneous rocks near the fault. The estimated paleostress state indicates ENE shortening and NNW extension. The displacement of the Yangsan fault in the study area is not constant along the fault but decreases from the south to the north. Taking the northern end of the study area as a separating point the whole extension of the Yangsan fault may be divided into southern and northern segments.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.78-85
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• 2006

The Ulsan Fault System continues from north of Gyeongju to Ulsan city, trending NNW-SSE and is about 50 km. Many Quaternary faults have been reported and investigated with outcrop observation. Lineaments have been extracted with aerial photograph interpretation and classified by their ranks. Trench excavations on the lineaments along Ulsan Fault System have been carried out to clarify the neotectonic movements and fault parameters such as the latest movement age, fault displacement, slip rate and recurrence interval. We have compiled data from previous studies on criteria of segment type such as lineament rank, seismicity, slip rate, and the latest fault movement. Based on these data, we tried to devide the Ulsan Fault System into several segments. The results of segmentation with each types of segment along the Ulsan Fault System did not show singular division point but overlapped or different length and location.

• 지질공학
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• 제32권4호
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• pp.467-482
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• 2022

The Yeonghae basin is located at the northeastern part of the Yangsan fault (YSF; a potentially active fault). The study of the architecture of the Yeonghae basin is important to understand the activity of the Yangsan fault system (YSFS) as well as the basin formation mechanism and the activity of the YSFS. For this study, Digital Elevation Model (DEM) was used to highlight the marginal faults, and structural fieldwork was performed to understand the geometry of the intra-basinal structures and the nature of the bounding faults. DEM analysis reveals that the eastern margin is bounded by the northern extension of the YSF whereas the western margin is bounded by two curvilinear sub-parallel faults; Baekseokri fault (BSF) and Gakri fault (GF). The field data indicate that the YSF is striking in the N-S direction, steeply dipping to the east, and experienced both sinistral and dextral strike-slip movements. Both the BSF and GF are characterized dominantly by an oblique right-lateral strike-slip movement. The stress indicators show that the maximum horizontal compressional stress was in NNE to NE and NNW-SSE, which is consistent with right-lateral and left-lateral movements of the YSFS, respectively. The plotted structural data show that the NE-SW is the predominant direction of the structural elements. This indicates that the basin and marginal faults are mainly controlled by the right-lateral strike-slip movements of the YSFS. Based on the structural architecture of the Yeonghae basin, the study area represents a contractional zone rather than an extensional zone in the present time. We proposed two models to explain the opening and developing mechanism of the Yeonghae basin. The first model is that the basin developed as an extensional pull-apart basin during the left-lateral movement of the YSF, which has been reactivated by tectonic inversion. In the second model, the basin was developed as an extensional zone at a dilational quadrant of an old tip zone of the northern segment of the YSF during the right-lateral movement stage. Later on, the basin has undergone a shortening stage due to the closing of the East Sea. The second model is supported by the major trend of the collected structural data, indicating predominant right-lateral movement. This study enables us to classify the Yeonghae basin as an inverted strike-slip basin. Moreover, two opposite strike-slip movement senses along the eastern marginal fault indicate multiple deformation stages along the Yangsan fault system developed along the eastern margin of the Korean peninsula.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.33-40
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• 2000

The assessment of earthquake hazards involved consideration of earthquake magnitude, frequency, last movement and probability of occurrence. The appraisal of earthquake potential is feasible because historical data show a good correlation between earthquake size and the fault rupture parameters of length, displacement, and area. Additionally, the characteristics of fault behavior should be considered to evaluate the earthquake potential magnitude. In this study, in order to evaluate the earth quake potential by the fault behavioral patterns, based on the experimental background which the geometric characteristics of the individual domains, such as strike, width, fault tip patterns, and orientation of secondary shears reflect sliding behavioral patterns in each section, the straight sections of A, D and E domains were examined to the creeping section of stably sliding. In contrast, the curved section of B domain was examined to the locked section of stick-slip movement. These results of studies can be applied to evaluate the earthquake potential magnitude from the fault structural parameters.