• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.54-62
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• 2004

According to the Korea Tectonic Map, the Korean Peninsula can be divided into seven tectonic units and each of them shows a peculiar deformation pattern. In order to estimate an amount of crustal deformation in the Korean peninsula, we obtained the velocity vector fields of South Korea by dealing with the data set of the years 2001 and 2002, measured from the permanent GPS stations across the country To obtain a relatively precise coordinate of each station, we used GAMIT that is a comprehensive GPS analysis package developed at MIT, Then, a Kalman filter called GLOBK is used to combine the results from GAMIT and to estimate the relative velocity vector for the crustal deformations. The crustal movement of South Korea is turned out to be about 1mm per year westward and about 0.6mm per year southward. In case of Suwon and Seosan(Gyeonggi Massif), the movement occurs slightly to the north-east direction. The movement of a relative velocity field in the tectonic unit is unidirectional, yet the magnitude of the velocity is very small.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.1
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• pp.47-54
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• 2015

In this study, we developed strategies for pre-processing GNSS data for the purpose of separating geodetic factors from crustal deformation due to the earthquakes. Before interpreting GNSS data analysis results, we removed false signals from GNSS coordinate time series. Because permanent GNSS stations are located on a large tectonic plate, GNSS position estimates should be affected by the tectonic velocity of the plate. Also, stations with surrounding trees have seasonal signals in their three-dimensional coordinate estimates. Thus, we have estimated the location of an Euler pole and angular velocities to deduce the plate tectonic velocity and verified with geological models. Also, annual amplitudes and initial phases were estimated to get rid of those false annual signals showing up in the time series. By considering the two effects, truly geodetic analysis was possible and the result was used as preliminary data for analyzing post-seismic deformation of the Korean peninsula due to the Tohoku-oki earthquake.

• The Journal of the Petrological Society of Korea
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• v.21 no.3
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• pp.287-307
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• 2012

The study area, which is located in the southeastern part of the Jirisan province of the Yeongnam massif, Korea, consists mainly of the Precambrian Hadong northern anorthosite complex (HNAC) and the Jirisan metamorphic rock complex (JMRC) and the Mesozoic granitoids which intrude them. Its tectonic frame is built into NS trend, unlike the general NE-trending tectonic frame of Korean Peninsula. This paper researched the structural characteristics at each deformation phase to clarify the geological structures associated with the NS-trending tectonic frame which was built in the HNAC and JMRC. The result indicates that the geological structures of this area were formed at least through three phases of deformation. (1) The $D_1$ deformation formed the $F_1$ sheath or "A"-type folds in the HNAC and JMRC, and the $S_{0-1}$ composite foliation and the $S_1$ foliation and the $D_1$ ductile shear zone which are (sub)parallel to the axial plane of $F_1$ fold, and the $L_1$ stretching lineation which is parallel to the $F_1$ fold axis owing to the large-scale top-to-the SE shearing on the $S_0$ foliation. (2) The $D_2$ deformation (re)folded the $D_1$ structural elements under the EW-trending tectonic compression environment, and formed the NS-trending $F_2$ open, tight, isoclinal, intrafolial folds with the $S_{0-1-2}$ composite foliation and the $S_2$ foliation and the $D_2$ ductile shear zone with S-C-C' structure and the $L_2$ stretching lineation which is (sub)parallel to the axial plane of $F_2$ fold. The extensive $D_2$ ductile shear zone (Hadong shear zone) of NS trend was persistently developed along the eastern boundary of HNAC and JMRC which would be to the limb of $F_2$ fold on a geological map scale. The Hadong shear zone is no less than 1.4 km width, and was formed in the mylonitization process which produced the mylonitic structure and the stretching lineation with the reduction of grain size during the $F_2$ passive folding. (3) The $D_3$ deformation formed the EW-trending $F_3$ kink or open fold under the NS-trending tectonic compression environment and partially rearranged the NS-trending pre-$D_3$ structural elements into (E)NE or (W)NW direction. The regional trend of $D_1$ tectonic frame before the $D_2$ deformation would be NE-SW unlike the present, and the NS-trending tectonic frame in the HNAC and JMRC like the present was formed by the rearrangement of the $D_1$ tectonic frame owing to the $F_2$ active and passive folding. Based on the main intrusion age of (N)NE-trending basic dyke in the study area, these three deformation events are interpreted to have occurred before the Late Paleozoic.

• Journal of the Korean earth science society
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• v.27 no.6
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• pp.620-642
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• 2006

The Moho structure and its deformation in the southern part of the Korean Peninsula were estimated using gravity and topography data. Gravity signals from the upper and lower crust were separated using a filter that was computed from isostacy and elastic thickness. The result of this study shows three characteristic features of the Moho deformation. First, the Moho folding structure is parallel to SKTL (the South Korean Tectonic Line), which indicates positive association with the collision of the Yeongnam and Gyeonggi Massifs and repeated compression afterwards. In contrast, noticeable deformation of the Moho was not observed along the Imjingang Belt, which is interpreted as another continental collisional belt in the Korean Peninsula. Second, the Moho beneath the Gyeongsang Basin has remarkably risen; this seems to be the result from both the collisional compression and buoyancy caused by magmatic underplating. Third, the Moho deformation is shallowest in the east of the Taebaek Mountains and deepens toward the west, consistent with the topographic characteristic of the Korean Peninsula of "high east and low west". It can be interpreted as the results of the opening of the East Sea and Ulleung Basin. A tectonic explanation for this could be the ascent of the mantle induced by continental rifting and horizontal extension at the early stage of the opening of the East Sea. The Moho deformation model computed in this study correlates well with the earthquake distribution and crustal movement measured by GPS. We suggest that the compression along the SKTL is still exerted, consequently, the Moho deformation is active, although it may be weak.

• 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.

• Journal of the Korean Geophysical Society
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• v.5 no.4
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• pp.283-292
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• 2002

The Korean peninsula is located at the edge of the East Asian active margin. The seismic activity in the Korean Peninsula is relatively low compared with the neighboring countries China and Japan. According to the available Seismic information, the Korean Peninsula is not totally safe from the Earthquake disaster. Moreover, the area is surrounded by varies tectonic forces which is resulted from the relative movements of the surrounding tectonic plates "Pacific, Philippine Sea, Eurasian and South China". Nowadays South Korea has 65 GPS stations belong to 5 governmental organizations "each organization figure out its own GPS stations for different requirements" In order to minimize the seismic hazard in the Korean Peninsula a program for monitoring the recent crustal movement has been designed considering the uses of the available GPS station "some selected stations from the previously mentioned stations" and the tectonic settings in and around the Korean Peninsula. This program is composed of two main parts, the first part to monitor the crustal deformation around the Korean Peninsula with the collaboration of the surrounding countries "China and Japan" this part is composed of two phases "East Sea Phase and Yellow Sea Phase". These phases will be helpful in determining the deformation parameters in the East Sea and the Yellow Sea respectively While the Second part of this program, is designed to determine the deformation parameters id and around the main faults in the Korean Peninsula and the relative movement between the Korean Peninsula and the Cheju Island. Through out this study the needs of crustal movement center rose up to collect the data from the previously mentioned stations and Organizations in order to use such reliable data in different geodynamical application.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.239-255
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• 2021

Kinematic analyses of magmatic intrusions and faults can provide useful information on stress conditions and chronological relationships between dike emplacement and brittle deformation events. We studied structures in rocks exposed on a coastal platform in Geoje Island off the southern Korean Peninsula because of its well-developed dikes and faults. The geology of the study area includes the Cretaceous Seongpo-ri Formation, which is composed mostly of shale, sandstone, and hornfels intruded by magmatic dikes. Most of the dikes are developed along pre-existing structural features (faults and fractures), indicating that their emplacements were structurally controlled. Because dikes commonly open along the direction of the minimum principal stress, the direction of this stress can be obtained from dike geometry and orientation through the matching of piercing points on either side of a dike. In addition, the deformed dikes can give information regarding later deformation. On the basis of the kinematic analyses, we identified five deformation events in the study area, which are kinematically related to changes of the regional maximum principal stress. Results indicate that the structures in the study area have been controlled predominantly by episodes of reactivation of the NNE-trending Yangsan strike-slip fault, located to the northeast of the study area, under different stress regimes. In a wider tectonic context, the brittle deformation of the rocks of Geoje Island was probably induced by interactions among the Philippine Sea, Pacific, and Eurasian plates, including changes in subduction parameters with respect to the latter two plates over time.

• Journal of the Korean Geographical Society
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• v.42 no.4
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• pp.488-505
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• 2007

The purposes of this research are twofold; 1) to verify spatial differences of tectonic movement using the spatial distribution of earthquakes, and 2) to infer mechanisms that generate spatial accumulation patterns of earthquakes in the Korean Peninsula. The first part of this sequential paper (Park, 2007) argues that the Korean Peninsula consists of four geostructural regions in which tectonic deformation and consequent geomorphological development patterns are different from each other Since this conclusion has been made by terrain analyses alone, it is necessary to verify this suggestion using other independent geophysical data. Because earthquakes are results of movement and deformation of land masses moving in different directions, the distribution of earthquake epicenters may be used to identify the direction and rates of land mass movement. This paper first analysed the spatial distribution of earthquakes using spatial statistics, and then results were compared with the spatial arrangement of geostructural regions. The spatial distribution of earthquakes in the Korean Peninsula can be summarized as the followings; firstly, the intensity of earthquakes shows only weak spatial dependency, and shows large difference even at adjacent regions. Secondly, the epicenter distribution has a clear spatial accumulation pattern, even though the intensity of earthquake shows a random pattern. Thirdly, the high density area of earthquakes shows a clear 'L' shape, passing through Pyeongannam-do, centered at Pyeongyang, and Hwanghae-do, Seosan and Pohang. The correlation coefficient between the density of earthquakes and distance from geostructral region boundaries is much higher than those between the density of fault lines and distance from tectonic division boundaries. Since fault lines and tectonic divisions in the Korean Peninsula are the results of long-term geological development, there is an apparent scale discrepancy to find significant correlations with earthquakes. This result verifies the research hypothesis that the Korean Peninsula is divided into four geostructral regions in which each has its own moving direction and spatial deformation characteristics. The existence of geostructural regions is also supported by the movement parrerns of land masses estimated from the GPS measurements. This conclusion is expected to provide a new perspective to understand the geomorphological developments and the earthquake occurrences in the Korean Peninsula.

• Economic and Environmental Geology
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• v.39 no.2 s.177
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• pp.129-149
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• 2006

Previously published stratigraphic, sedimentologic, paleontologic, paleomagnetic and geophysical data are reviewed to make an understanding on the tectonic evolution of the Cretaceous Gyeongsang (Kyongsang) basin, southeast Korea. A stratigraphic framework and a tectonic model on the formation and deformation of the Gyeongsang Basin are newly proposed on the basis of integration these data with magmatism and mineralization ages in the basin. A newly proposed stratigraphic framework indicates that strata in the basin can be subdivided into five distinct stratigraphic units that represent pre-rifting, syn-rifting, inversion I, II, and III stages. The Gyeongsang Basin was formed initially as a pre-rifting stage due to north-south extension in the Late Jurassic prior to a syn-riftins stage that resulted from east-west extension during the Early Cretaceous. In the Late Cretaceous, the basin was deformed by three-staged sequential deformation of north-south, northwest-southeast, and east-west compressions. The tectonic history of the basin has been largely controlled by the change of motion of the Izanagi Plate from north to northwest during the Cretaceous. In the early Cretaceous, the Izanagi Plate began to subduct northward beneath the Eurasian Plate and caused the left-lateral strike-slip fault systems in the southern part of the peninsula. The left-lateral wrenching of these fault systems was causally linked to development of pull-apart basins, such as the Gyeongsang Basin in the southeastern part of the peninsula. However, northwestward movement of the Izanagi Plate during the Late Cretaceous probably led to the extensive volcanism as well as sequential deformations in the basin. The stratigraphic and tectonic model, which is newly proposed as a result of this study, may be expected to enhancing the efficiency for exploration and exploitation of useful mineral resources in the basin as well as establishing geologic history in the Cretaceous Gyeongsang Basin. Together with the spatial and temporal correlation of the Cretaceous basins in adjacent areas, this stratigraphic and tectonic model provides a new geologic paradigm to delineate the sophisticated tectonic history of East Asia turing the Cretaceous.

• The Journal of the Petrological Society of Korea
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• v.25 no.3
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• pp.169-193
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• 2016

In order to characterize the Neotectonic crustal deformation and current stress field in and around the Korean Peninsula and to interpret their tectonic implications, this paper synthetically analyzes the previous Quaternary fault and focal mechanism solution data and recent geotechnical in-situ stress data and examines the characteristics of crustal deformations and tectonic settings in and around East Asia after the Miocene. Most of the Quaternary fault outcrops in SE Korea occur along major inherited fault zones and show a NS-striking top-to-the-west thrust geometry, indicating that the faults were produced by local reactivation of appropriately oriented preexisting weaknesses under EW-trending pure compressional stress field. The focal mechanism solutions in and around the Korean Peninsula disclose that strike-slip faulting containing some reverse-slip component and reverse-slip faulting are significantly dominant on land and in sea area, respectively. The P-axes are horizontally clustered in ENE-WSW direction, whereas the T-axes are girdle-distributed in NNW direction. The geotechnical in-situ stress data in South Korea also indicate the ENE-trending maximum horizontal stress. The current crustal deformation in the Korean Peninsula is thus characterized by crustal contraction under regional ENE-WSW or E-W compression stress field. Based on the regional stress trajectories in and around East Asia, the current stress regime is interpreted to have resulted from the cooperation of westward shallow subduction of the Pacific Plate and collision of Indian and Eurasian continents, whereas the Philippine Sea plate have not a decisive effect on the stress-regime in the Korean Peninsula due to its high-angle subduction that resulted in dominant crust extension of the back-arc region. It is also interpreted that the Neotectonic crustal deformation and present-day tectonic setting of East Asia commenced with the change of the Pacific Plate motion during 5~3.2 Ma.