• The Korean Journal of Quaternary Research
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• v.9 no.1
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• pp.61-86
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• 1995

칠레 북부해안에는 여러개의 해안 단구들이 발견되는데 이는 지구조 운동과 하께 해수면 변동과 밀접한 관련이 있다, 단구의 형성시기는 전부 밝혀지지는 않았으며 여전히 논란이 되고 있다,. 안토파가스타에서 이끼케까지 9개지역에서 발견되는 여러단구에 대한 탄 소 연대측정 전자스핀 공명법, 우라늄측정, 아미노산 연대측정 방법들을 이용하여 그 형성시 기를 측정하였다, 그결과들은 기본적으로 3∼4개의 뚜렷한 단구를 선정하여 지역간에 서로 대비하였다, 대부분의 단구들은 산소 동위연소 연대(Oxygen Isotope State) 3에서 11범주에 들어가는데 이것은 계단식 단구들이 단지 지구조 운동만으로 형성된 것이 아니라 전지구 기 후 변동과 밀접하게 관련된 전세계 해수면 변동에 의해 강한 영향을 받았음을 시사한다. 특 히 플라이스토세에 형성된 일련의 해빈 사구들은 플라이스토세 초기에서 중기사이 반복된 간빙기를 나타낸다.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.519-533
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• 2012

This study investigates a neotectonic context of the past 5 Ma for the Otway Ranges along the southern Victoria coast, SE Australia by evaluating the distribution and development of marine terraces along the mountainous coastal area. Uplift rate derived from low terrace deposits using OSL dating method is determined to evaluate the extent to which mild intraplate tectonism has the capability to influence the geomorphic evolution of continental interiors. This study also investigates the stratigraphic relationship between Quaternary marine terraces and Pliocene strandlines, which suggests a change of tectonic activity in the Late Neogene. The intensified tectonic response is well addressed in terms of an increase of the Australian intraplate stress level due to the change of relative motion and increased forces in the boundary between the Australian and Pacific plate.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.349-359
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• 2020

The Ulsan Fault Zone (UFZ) of NNW trend is developed in the Gyeongsang Basin, the southeastern part of the Korean Peninsula, and the Quaternary faults have been found around the UFZ. The faults generally thrust the Bulguksa igneous rocks of Late Cretaceous-Early Tertiary upon the Quaternary deposits or are developed within the Quaternary deposits. They mainly show the reverse-slip sense of top-to-the west movement. The lines connecting the their outcrop sites show a zigzag-form which is similar to the orientation of their fault surfaces which show the various trends, like (W)NW, N-S, (E)NE, ENE trends. The E-W trending dextral strike(-slip) fault is found in the Quaternary deposits of the Singye-ri valley. It cuts the N-S trending reverse fault and are cut by the N-S trending thrust fault again. Two types of at least two times of Quaternary tectonic movements related to the formation of neotectonic fault zone in the Singye-ri valley are considered from such the geometric and kinematic characteristics of Quaternary faults. One is the reverse faulting of N-S trend by the E-W directed 1st compression and associated the strike-slip tear faulting of E-W trend, and then the thrust faulting of N-S trend by the E-W directed 2nd compression. The other is the reverse faulting of N-S trend, and then the dextral strike-slip faulting of E-W trend by the NW-SE directed compression, and then the thrust faulting of N-S trend. In this paper is suggested the development history of Singye-ri neotectonic fault zone on the basis of the various orientations of Quaternary fault surfaces around the UFZ, and the zigzag-form connecting line of their outcrop sites, and the compressive arc-shaped lineaments which convex to the west reported recently in the Yangsan Fault Zone.

• Journal of the Korean association of regional geographers
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• v.18 no.4
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• pp.351-363
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• 2012

Although the Korean peninsula has been considered as a largely aseismic region compared with the surrounding high seismic areas such as North China and Japan, there are more than thirty Quaternary faults reported so far, which are mostly centered in the southeastern peninsula. Structural studies of active faults exposed in Yangnam-myeon of Gyeongju, SE Korea are largely interpreted to post date the late Quaternary, suggesting that the NE-trending reverse faults may result from the active stress regime in the peninsula. The prevailing present-day E-W $S_{Hmax}$ orientations in the peninsula are consistent with the nature of plate forcing stemming from the convergence between the Indo-Australian and Eurasian plates. It is clear that the Quaternary faults have been reactivated, although resolving more elaborate time intervals responsible for a future rupture remains a significant challenge. This study contributes to better assess many of potential seismic hazards in the study area, in particular, in terms of seismic stability for foundation of nuclear power plant.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.27-40
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• 2007

Stratigraphy has been renewedly set up and the evolution of tectonic events related to basin formation has been exam-ined on the basis of fault-slip data analysis in the Tertiary Eoil and Waeup basins of the southeastern part of Korea. First of all, field mapping was carried out in detail for Tertiary formations and then paleostress analysis were peformed with more than 400 fault slip data collected from 11 sites in the Tertiary formations and the Yucheon Group. It is judged that both the Eoil and Waeup basins filled up with Tertiary deposits might be simultaneously formed in separate locations. The Janggi Group in the Eoil basin is divided into following stratigraphic units in ascending order: Gampo Conglomerte, Hongdeok Basalt, Nodongri Conglomerate and Yeondang Basalt, and the Bomkori Group in the Waeup basin: Waeupri Tuff; Andongri Conglomerate, Yongdongri Tuff and Hoamri Volcanic Breccia. Paleostress analysis by using striated faults reveals five sequential tectonic events: (1) NW-SE transtension (event I), (2) NW-SE transpression (event IIl), (3) NE-SW pure extension (event III), (4) N-S transpression (event IV) and (5) E-W pure compression (event V). Therefore, five sequential tectonic movements are closely associated with the formation and evolution of the Tertiary basins in the study area: tectonic event I of NW-SE extension is related to formation of the Tertiary basins during the late Oligocene to the Early Miocene, tectonic events II, III and IV caused the termination of the Tertiary basin opening and the crustal uplift in the study area, and tectonic event V upheaved the east coast or Korean Peninsula with compressive stress due to intense subduction of the Pacific plate into Asian continent since the Early Pliocene.

• The Korean Journal of Petroleum Geology
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• v.2 no.2 s.3
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• pp.59-70
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• 1994

The Cenozoic geological structures and the tectonic evolution of the southern Ulleung Basin were studied with seismic profiles and exploration well data. Basement structure of the Korea Strait is distinctly characterized by normal faults trending northeast to southwest. The normal faults of the basement are most likely related to the initial liking and extensional tectonics of Ulleung Basin. Tsushima fault along the west coast of Tsushima islands runs northeastward to the central Ulleung Basin. The Middle Miocene and older sequences in the Tsushima Strait show folds and faults mostly trending northeast to southwest. These folds and faults may be interpreted as a result of compressional tectonics. The Late Miocene to Qauternary sequences are not much deformed, but numerous faults mostly N-S trending are dominated in the Tsushima Strait. The Ulleung Basin was in intial rifting during Oligocene, and then active extension and subsidence from Early to early Middle Miocene. Therefore SW Japan separated from Korea Peninsula and drifted toward southeast, and Ulleung Basin was formed as a pull-apart basin under dextral transtensional tectonic regime. During rifting and extensional stage, Tsushima fault as a main tectonic line separating SW Japan block from the Korean Peninsula acted as a normal faulting with right-lateral strike-slip motion as SW Japan drifted southeastward. During middle Middle Miocene to early Late Miocene, the opening of Ulleung basin stopped and uplifted due to compressional tectonics. The southwest Japan block converging on the Korean Peninsula caused compressional stress to the southern margin of Ulleung Basin, resulting in strong deformation under sinistral transpressional tectonic regime. Tsushima fault acted as thrust fault with left-lateral strike-slip motion. From middle Late Miocene to Quaternary, the southern margin of Ulleung Basin has been controlled by compressional motion. Thus the Tsushima fault still appears to be an active thrust fault by compressional tectonic regime.

• Journal of the Korean earth science society
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• v.21 no.3
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• pp.230-249
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• 2000

Southeastern Korean Peninsula has undergone the polyphase deformations according to the changes of regional tectonic settings during the Cenozoic. Through analyses of more than 600 fault-slip data gathered in the study area, five tectonic events are revealed as the followings: (I) NW-SE transtension, (II) NW-SE transpression, (III) NE-SW pure or radial extension, (IV) NNE-SSW transpression, (V) NE or ENE-WSW transpression. Event I was induced by the pull-apart type extension of the East Sea during 24-16 Ma, which resulted in the NW-SE extension of the Tertiary Basins in SE Korea. Event II was resulted from the collision of SW Japan and Izu-Bonnin Arc (or Kuroshio Paleoland) on the Philippine Sea Plate at ${\sim}$ 15 Ma, which stopped the extension of the Tertiary Basins and originated the uplift of fault blocks in and around SE Korean Peninsula. It was continued until ${\sim}$ 10 Ma. Event III is interpreted as the post-tectonic event after the block-uplifts due to the event II, which indicates a temporal lull in activity of the Philippine Sea Plate since 10 Ma. Event IV was originated from the resumption in activity of the Philippine Sea Plate which was restarted to move toward north at ${\sim}$ 6 Ma. The event made the EW compressional structures behind SW Japan as well as in the Korea Straits, and thus the block-uplifts in SE Korea was resumed again. Lastly, event V was resulted from the gradual decrease in influence of the Philippine Sea Plate and the cooperative compression due to the subduction of the Pacific Sea Plate and the collision of the Indian Plate since 5-3.5 Ma, which generated the NS compressional structures in the offshore along the eastern coast of the Korean Peninsula and thrust up the fault-blocks toward west. This event is continuing so far, and thus is making the active faultings resulting in the present earthquakes of the Korean Peninsula.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.90-101
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• 2009

Analysis of multi-channel seismic reflection data from the Southern Ulleung Basin reveals that Plio-Quaternary section in the area consists of nine stacked sedimentary units separated by erosional unconformities. On the southern slope, these sedimentary units are acoustically characterized by chaotic seismic facies without distinct internal reflections, interpreted as debris-flow bodies. Toward the basin floor, the sedimentary units are defined by well-stratified facies with good continuity and strong amplitude, interpreted as turbidite/hemipelagic sediments. The seismic facies distribution suggests that deposition of Plio-Quaternary section in the area was controlled mainly by tectonic movement and sea-level fluctuations. During the Pliocene, sedimentation was mainly controlled by tectonic movements related to the back-arc closure of the East Sea. The back-arc closure that began in the Miocene caused compressional deformation along the southern margin of the Ulleung Basin, resulting in regional uplift which continued until the Pliocene. Large amounts of sediments, eroded from the uplifted crustal blocks, were supplied to the basin, depositing Unit 1 which consists of debris-flow deposits. During the Quaternary, sea-level fluctuations resulted in stacked sedimentary units (2-9) consisting of debris-flow deposits, formed during sea-level fall and lowstands, and thin hemipelagic/turbidite sediments, deposited during sea-level rise and highstands.

• The Journal of the Petrological Society of Korea
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• v.25 no.3
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• pp.231-240
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• 2016

Three Quaternary faults have been revealed in marine terraces nearby the Homigot and the Gurongpo in the southeastern offshore of Korean Peninsula. The Hajung fault cuts the $4^{th}$ marine terraces and the Guman fault the $2^{nd}$, respectively. The Hajung fault strikes $N55^{\circ}$ to $45^{\circ}W$ and dips $40^{\circ}$ to $45^{\circ}NE$ with reverse-displacement of 180cm vertically. There are four sets of colluvial sediment strata that would be produced by faulting and indicate four times of fault movements during MIS 7 and MIS 5c. The Guman fault site consists of three sets of reverse faults that strike $N80^{\circ}E$ to $N70^{\circ}W$ and dip $25^{\circ}{\sim}35^{\circ}SE$ to $30^{\circ}SW$ with vertical displacement of 9~18 cm. The Guman faulting occurred during 80 ka (MIS 5a) to 71 ka (MIS 4) but it extends only to the lowest bed, the pebble sand bed, lay just on the unconformity, and not to the upper. Considering the attitude of the faults, we inferred that the Hajung fault was activated under the ENE-WSW compression during MIS 7 to MIS 5c and the Guman under N-S trending compression during MIS 5a. Using the OSL age dating results, we reconfirmed that the $2^{nd}$ terrace is correlated to MIS 5a and the $4^{th}$ terraces to MIS 7.

• Economic and Environmental Geology
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• v.27 no.2
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• pp.209-212
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• 1994

Cheju Island was formed by volcanic activity probably related to the inferred geodynamics in the early Quaternary times. Paleostress analysis, in spite of a few fault slip data collected near Sanbangsan trachyte dome (dated 0.87 Ma) represents an extentional tectonic event with the direction ENE-WSW. Joint anayses in the vicinity of Seahwa reveal three extensional tectonic events of directions NW-SE, NE-SW and ENE-WSW. Especially the extensional event with the direction ENE-WSW affected the whole Cheju area during the most recent time.