An analysis of the intraplate earthquake (2016M5.8_GY) that occurred in the Gyeongsang Basin in the SE of the Korean Peninsula, based on 3-D modelling of the gravity and magnetic field

Choi, Sungchan; Ryu, In‐Chang; Lee, Young‐Cheol

doi:10.1093/gji/ggz001

Cited by 7 publications

(4 citation statements)

References 35 publications

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“…4B에서 (Schmidt et al, 2004;2010). 그런 기능으로 인해서 IGMAS+에 의해서 제시된 최종 모형은 신뢰성 높은 3차원 밀도 및 자기장 분포를 제시하는 것 으로 인정되고 있으며, 지질학적인 해석과 지구물리학적 인 의미 부여에 효과적으로 활용되고 있다 (Choi et al, 2013;2019;2020;2021a)…”

Section: 지질구조 및 단층unclassified

Analysis of the Causes of Clustered Scismicity Registered in Yeoncheon, the Middle Part of the Korean Peninsula through Gravity Field Interpretation and Modeling

Choi¹,

Kim²,

Choi³

et al. 2022

Econ. Environ. Geol.

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Gravity data were analyzed to identify the cause of clustered seismicity that occurred intensively in Yeoncheon, located in the central part of the Korean Peninsula. Our analysis suggests that the En echelon faults developed in the northwest-southeast direction. In addition, in the eastern part of the Dongducheon Fault, it was interpreted that high-density lower bedrock intermittently lifts close to the surface due to vertical tectonic movement accompanied by a flower structure. The fracture zone of the Dongducheon Fault is estimated that the width is about 200 m, the depth is at least 5 km, and the density is about 15% lower than the adjacent rocks. It is analyzed that the shallow earthquakes that occurred within 5 km depth was concentrated along the low-density En echelon fault fracture zone developed between the high-density rocks intruding close to the surface. Therefore, the earthquakes can be interpreted as the result that the north-south stress caused by the dextral tectonic movement of the Dongducheon Fault activated the En echelon fault in the northwest-southeast direction.

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Section: 지질구조 및 단층unclassified

Analysis of the Causes of Clustered Scismicity Registered in Yeoncheon, the Middle Part of the Korean Peninsula through Gravity Field Interpretation and Modeling

Choi¹,

Kim²,

Choi³

et al. 2022

Econ. Environ. Geol.

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“…Geol., 54(6), 743-752, 2021 http://dx.doi.org/10. 9719/EEG.2021.54.6.743 추가령단층대의 중력장 데이터 해석 (Kim et al, 2017) 이 경상분지의 평균 밀도(2.67 g/cm 3 )에 비해서 밀도가 낮은 고립된 화강암(2.60 g/cm 3 )에 응력이 작용하여 발생 한 것으로 보고되었다 (Choi et al, 2019). 2017년 11월에 발생한 포항지진의 원인에 대해서는 다양한 이견이 있지 만, 대체로 경주지진에 의해서 활성화된 포항 분지의 알 려지지 않은 단층에서 일어난 것으로 알려져 있다 (Kim et al, 2018;Choi et al, 2020).…”

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“…연이은 두 번의 지진 이후 양산단층을 중심으로 경상 분지 지역의 활성단층 연구가 국가연구사업으로 지난 5 년간 진행되었다 (Kim et al, 2017;. 연구의 주된 방 향은 중력장 해석을 통해 단층의 위치를 확인하고 3차원 적인 규모를 파악하는 작업으로 수행되었으며, 그 성과 가 매우 성공적이었다 (Choi et al, 2019;2021;Sohn et al, 2020). 한편, 전체 인구의 절반이 거주하고 있는 수 도권 지역은 양산단층에 준하는 규모의 취성전단대인 추 가령단층대(Fig.…”

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“…의 중력값에서 음의 중력값으로 넘어가는 지점(RHO1에 서 RHO2로 넘어가는 경계면)의 곡률값은 당연히 음의 값을 갖게 되며, 이런 음의 곡률 값을 지도에서 파란색 으로 그 반대쪽 경계면(RHO2에서 RHO1로 넘어가는 경 계면) 즉 양의 곡률 값은 빨간색으로 표시할 수 있다. 즉, 지도에서 빨간색 계통과 파란색 계통의 경계들은 지각 내의 밀도의 경계 부분임과 동시에 단층의 가능성이 매우 큰 곳이라는 것을 의미한다 (Choi et al, 2019;2021). 2) 왕숙천단층(Fig.…”

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Expected Segmentation of the Chugaryung Fault System Estimated by the Gravity Field Interpretation

Choi¹,

Choi²,

Kim³

et al. 2021

Econ. Environ. Geol.

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The three-dimensional distribution of the fault was evaluated using gravity field interpretation such as curvature analysis and Euler deconvolution in the Seoul-Gyeonggi region where the Chugaryeong fault zone was developed. In addition, earthquakes that occurred after 2000 and the location of faults were compared. In Bouguer anomaly of Chugaryeong faults, the Pocheon Fault is an approximately 100 km fault that is extended from the northern part of Gyeonggi Province to the west coast through the central part of Seoul. Considering the frequency of epicenters is high, there is a possibility of an active fault. The Wangsukcheon Fault is divided into the northeast and southwest parts of Seoul, but it shows that the fault is connected underground in the bouguer anomaly. The magnitude 3.0 earthquake that occurred in Siheung city in 2010 occurred in an anticipated fault (aF) that developed in the north-south direction. In the western region of the Dongducheon Fault (≒5,500 m), the density boundary of the rock mass is deeper than that in the eastern region (≒4,000 m), suggesting that the tectonic movements of the western and eastern regions of the Dongducheon Fault is different. The maximum depth of the fracture zone developed in the Dongducheon Fault is about 6,500 m, and it is the deepest in the research area. It is estimated that the fracture zone extends to a depth of about 6,000 m for the Pocheon Fault, about 5,000 m for the Wangsukcheon Fault, and about 6,000 m for the Gyeonggang Fault.

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Estimating the impact process of the Jeokjung-Chogye Basin in Korea from gravity field interpretation

Choi¹,

Kim²,

Choi³

et al. 2021

Geophysical Journal International

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Summary The Jeokjung-Chogye Basin (JCB) is the first impact crater discovered in the Korean peninsula. The geometric center of the exterior crater rim is demarcated by an elevation high surrounding the JCB, exceeding 200 meters. The diameter of the exterior ring is approximately 6500 meters, and its center is located about 1000 meters southwest of the basin center. Using terrestrial measured gravity field interpretations such as dip curvature and Z-derivative analysis of the residual anomaly field, we calculated the diameters of the peak ring and uplift ring to be about 4000 and 1500 meters, respectively. The center of the peak ring is located approximately 350 meters to the west of the center of the exterior ring; meanwhile, the center of the uplift ring is located about 300 meters to the east from the exterior ring's center. Application of the Euler deconvolution method indicates that the depth discrepancy between the peak and uplift rings is approximately 200 meters. This discrepancy indicates that the bedrock under the uplift ring has risen about 200 meters following the meteorite impact. The offsets of the peak- and the uplift ring's centers, relative to the diameter of the crater center, allow us to conclude that the JCB was formed by steeply-inclined impact (∼50°–60° to the horizontal) from the eastern direction.

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An analysis of the intraplate earthquake (2016M5.8_GY) that occurred in the Gyeongsang Basin in the SE of the Korean Peninsula, based on 3-D modelling of the gravity and magnetic field

Cited by 7 publications

References 35 publications

Analysis of the Causes of Clustered Scismicity Registered in Yeoncheon, the Middle Part of the Korean Peninsula through Gravity Field Interpretation and Modeling

Analysis of the Causes of Clustered Scismicity Registered in Yeoncheon, the Middle Part of the Korean Peninsula through Gravity Field Interpretation and Modeling

Expected Segmentation of the Chugaryung Fault System Estimated by the Gravity Field Interpretation

Estimating the impact process of the Jeokjung-Chogye Basin in Korea from gravity field interpretation

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