• Title/Summary/Keyword: Dongrae fault

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Application of geophysical methods to determine the extent of the Dongrae Fault in the Oedong-eup area, Gyeongju City (경주시 외동읍 구어리 일대 동래단층 연장성 확인을 위한 물리탐사 적용)

  • Hwang, Hak-Soo;Hamm, Se-Yeong;Lee, Cheol-Woo;Lee, Chung-Mo;Kim, Sung Wook
    • The Journal of Engineering Geology
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    • v.27 no.3
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    • pp.207-215
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    • 2017
  • The northern extension of the Dongrae Fault is inferred to transect the Ulsan Fault in the Gueo-ri area, Oedong-eup, ~15 km SE of Gyeongju City, Gyeongbuk province, S Korea. We conducted geological and geophysical (magnetic, electrical resistivity, and frequency domain electromagnetic) surveys to identify the extent and orientation of the Dongrae Fault in this region. Through joint interpretation of the geological and geophysical data sets, we confirm the presence of the Dongrae Fault and determine its strike ($N14^{\circ}E$). The Dongrae Fault is thought to cross the Ulsan Fault near Ipsil Bridge in the Gwangeo-ri area. Geophysical surveying revealed a fault damage zone that widens to the south, with a typical width of >200 m. Geological field surveys did not delineate the geometry of the Dongrae Fault because alluvial deposits overlie the fault in this area.

Fault-related Landforms and Geomorphological Processes Around Ungchon-Ungsang Areas in the Middle Part of the Dongrae Fault (동래 단층 중부 지역 웅촌-웅상 일대의 단층 지형과 지형 발달)

  • Lee, Gwang-Ryul;Park, Chung-Sun;Shin, Jae Ryul
    • Journal of The Geomorphological Association of Korea
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    • v.26 no.1
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    • pp.79-91
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    • 2019
  • This study analyzed the distribution of fluvial landforms, fault-related geomorphic features and lineaments around the area of Ungchon-Ungsang in the Dongrae Fault, and discusses the charateristics of geomorphic development based on those. As a result, the NE-SW lineaments are predominantly developed in many numbers within the study area, and the NW-SE or N-S secondary lineaments are developed induced by multiple deformation with the Yangsan Fault. Geomorphologically, the early tectonic history of the Ungchon-Ungsang basin is largely divided into three stages ; 1) the Tertiary fault activity and formation of fracture zone, 2) development of erosional basin, 3) local crustal movements and development of fault-related topography. It is assumed that alluvial fans, deflected channel and stream piracy were formed by local tectonic movements related to faultings during the Quaternary.

Tracing of Active Fault Using Geomorphic Markers (지형 분석을 통한 활성 단층 추적 연구)

  • Shin, Jae-Ryul;Hong, Yeong-Min;Kim, Hyung-Soo;Lee, Gwang-Ryul
    • Journal of The Geomorphological Association of Korea
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    • v.26 no.4
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    • pp.107-121
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    • 2019
  • This study documents the distribution of (active) faults around the southern part of the Yangsan Fault and the Moryang Fault and the middle part of the Dongrae Fault. For this objective, we extracted lineaments and fault-related landforms by analyzing aerial photos and digital elevation models and with the result of fieldwork on fault-relating features of the Quaternary landforms. Geomorphological techniques for active fault study are not only preliminary but also essential methods because, in general, an active fault can be defined only with fault-deformed Quaternary sediments when there is no way to detect precise timing of faulting. Therefore, geomorphological interpretation in active fault research is necessary to determine the extent, direction, termination and timing of fault. This study addresses the results of such geomorphological analysis and geomorphic markers for tracing the active faults in the study area. It is plan to investigate with geophysical and geological techniques the sites referred in this study.

Engineering Geological Geotechnical Characteristics of Newly Constructed Road between the Yangsan Fault and the Dongrae Fault (양산단층과 동래단층 사이를 통과하는 지방도의 지질공학적 특성 연구)

  • 이병주;선우춘
    • The Journal of Engineering Geology
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    • v.13 no.2
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    • pp.193-205
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    • 2003
  • Fine grained granite, porphyritic granite and biotite granite together with intruded and extruded andesitic rocks are distributed in the study area which is bounded by the Yangsan and Dongrae faults. A new domestic road is being constructed along the area between the two major faults. The NNE trending Bupki fault and NE trending Myungkog fault are also developed within the area cross the road. The sheeting joints with dips of less than 30 degrees are only developed in the area of granite outcrop. High angle joints can be divided into 3 sets, such as, NE trending, NW trending and nearly EW trending joints. The joint space is mostly more than 20cm and the joint compressive strength is more than 100 MPa. These data show that even though the study area is situated between large faults, the ground condition is good because the damage zone of the Yangsan and Dongrae faults is relatively narrow.

Analysis of Subsurface Geological Structures and Geohazard Pertinent to Fault-damage in the Busan Metropolitan City (부산시 도심지의 지하 지질구조와 단층손상과 관련된 지질위험도 분석)

  • Son, Moon;Lee, Son-Kap;Kim, Jong-Sun;Kim, In-Soo;Lee, Kun
    • Economic and Environmental Geology
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    • v.40 no.1 s.182
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    • pp.87-101
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    • 2007
  • A variety of informations obtained from satellite image, digital elevation relief map (DEM), borehole logging, televiewer, geophysical prospecting, etc were synthetically analyzed to investigate subsurface geological and structural characteristics and to evaluate geohazard pertinent to fault-damage in the Busan metropolitan city. It is revealed that the geology is composed of the Cretaceous andesitic$\sim$dacitic volcanics, gabbro, and granitoid and that at least three major faults including the Dongrae fault are developed in the study area. Based on characteristics of topography, fault-fractured zone, and isobath maps of the Quaternary sediments and weathered residuals of the basement, the Dongrae fault is decreased in its width and fracturing intensity of damaged zone from south toward north, and the fault is segmented around the area between the Seomyeon and Yangieong junctions. Meanwhile, we drew a geohazard sectional map using the five major parameters that significantly suggest damage intensity of basement by fault, i.e. distance from fault core, TCR, RQD, uniaxial rock strength, and seismic velocity of S wave. The map is evaluated as a suitable method to express the geological and structural characteristics and fault-damaged intensity of basement in the study area. It is, thus, concluded that the proposed method can contribute to complement and amplify the capability of the present evaluation system of rock mass.

Consideration for the Highest Temperature Point Movement of the Dongrae Thermal Water in the Pusan Area. (Poster)

  • Kim Tong-Kwon;Lee Jin-Soo;Lee Seung-Gu;Song Yoon-Ho;Kim Tack-Hyun
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2005.10a
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    • pp.158-159
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    • 2005
  • This study showed that the highest temperature point of the Dongrae thermal spring in Pusan was moved to the north direction of the Dongrae fault as times goes by. The Br concentration(1.5mg/L) in Dongrae thermal waters indicated the influence of 2% seawater mixing. If the simple mixing without hydrochemical reaction occurs between seawater and thermal water, the concentration of Mg will be about 20mg/L. But the low concentration(0.1 mg/L) of Mg, contrary to high concentration(10 mg/L) of surrounding groundwater not affected by thermal water, suggested the thermal water, seawater and rock interactions. The calculation of saturation index(SI) by using the geochemical code of EQ3NR showed that the Mg in thermal groundwater, which was introduced by seawater, was removed by the precipitation of Antigorite (SI: log Q/K =71.753, $Mg_{48}Si_{24}O_{85}(OH)_{62}$) and Tremolite (SI: 8.463, $Ca_2Mg_5Si_8O_{22}(OH)_2$), Talc (SI: 6.409, $Mg_3Si_4O_{10}(OH)_2$), Dolomite (SI: 2.014, $CaMg(CO_3)_2$), Chrysotile (SI: 3.698, $Mg_3Si_2O_5(OH)_4$) in the crack of fault zone. The highest temperature point in the study area will move to north direction and stop in the Jangjun area without the input of seawater.

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Spectral Reflectivity on Geological Materials in Yangsan-Dongrae Fault Area (양산-동래 단층 지역의 암석에 대한 분광학적 연구)

  • 姜必鍾;智光薰
    • Korean Journal of Remote Sensing
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    • v.3 no.1
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    • pp.1-10
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    • 1987
  • The study was performed to recognize the most preferable spectral chennels for discriminating geological materials using the portable radiometer. The portable radiometer covers the visible and short infrared regions from approximately 0.4 to 2.5 microns which are coincided with Landsat TM, and the rock samples used for the study are pyrophylites, andesites, granite, granodiorite and silicified sedimentary rocks which are collected in Yangsan-Dongrae fault area. The analysis of the rock sample provides a preliminary basis for determining the wavelength regions showing diagnostic spectral features and for discriminating hydrothermal altered rocks from the unaltered rocks. The measurement of spectral of spectral reflectance for the rock samples was carried out in the laboratory which environment condition such as temperature, light sources, and humidity are constant. The analysis of the measured data was based on correlation between the reflectance value of the rock samples, and the follow discriptions are output of the study. 1) Pyrophyllite shows absorption at 0.83 $\mu\textrm{m}$ due to the oxidation of pyrite, and absorption at 2.22 $\mu\textrm{m}$ due to OH. 2) The altered rocks have generally higher reflectance than the unaltered rocks. 3) The ratio mesurement of pyrophyllites shows strong absorption at band 5/6 and band 6/4(in Landsat TM 5/7, 7/4). The ratio 1/5(Landsat TM 1/5) may be useful to discriminate andesite from the granite.

Feasibility Studies of DInSAR in the Northeastern Kyungsang Basin, Korea

  • Lee, C.W.;Kim, S.W.;Jung, H.C.;Won, J.S.
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.1070-1072
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    • 2003
  • This study focuses on examing the feasibility of differential SAR interferometry (DInSAR) in the Northeastern Kyungsang Basin, Korea. Major faults in the Kyungsang Basin such as Yangsan fault, Dongrae fault, and Ulsan fault had developed during Cretaceous, and the activeness of these faults is still controversial in Korean geology community. We attempt to measure displacements in the study area by applying DInSAR techniques to JERS-1 SAR data sets. Some surface displacements are recognized by DInSAR method at Young-il Bay in which the POSCO Company locates, although the displacements may not be directly associated with geologic structures. We also discuss atmospheric effects for the techniques used.

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Geology and Fracture Distribution in the Vicinities of the Cheonseong and Jeongjok Mountains (천성산과 정족산 일원의 지질과 단열 분포)

  • Son, Moon;Kim, Jong-Sun;Hwang, Byoung-Hoon;Ryoo, Chung-Ryul;Ock, Soo-Seok;Hamm, Se-Yeong;Kim, In-Soo
    • The Journal of Engineering Geology
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    • v.13 no.1
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    • pp.107-127
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    • 2003
  • After detailed geological mapping, structural and fracture-density data were collected and analyzed in the vicinity of Cheonseong and Jeongjok Mts., Gyeongsangnam-do. A extensive dextral strike-slip fault (Beopgi Fault) Parallel to Yangsan and Dongrae Faults, a dextral-transtensional-NW fault, and a few intermittent faults have been found in the study area. Based on strike and frequency, fracture system has been divided into three sets such as NNE-trending J1 ($NS-40^{\circ}E$), WNW-trending J2 ($N50^{\circ}-80^{\circ}W$), and ENE-trending J3 ($N60^{\circ}-90^{\circ}E$). According to analysis of fracture density, it is revealed as follows: (a) Jl is the combination of Y-, P-, and R-shear fractures due to the dextral strike-slip of the Beopgi Fault. (b) J2 is the preexisted fracture zone conducting the intrusion of granite. Two tensional fractures dipping to NNE and SSW respectively have been induced by intrusion of granite and followed crustal uplift. (c) J3 is the tensional fracture developed between Yangsan and Dongrae Faults having NNE trend and dextral strike-slip sense. This study aims to reduce environmental impact and insure stability of underground facilities and tunnels.