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Gravity Field Interpretation and Underground Structure Modelling as a Method of Setting Horizontal and Vertical Zoning of a Active Fault Core
활성단층의 3차원적인 규모를 결정하기 위한 중력장 데이터의 해석 및 지각구조 모델링: 양산단층에서의 예
Econ. Environ. Geol. 2021 Feb;54(1):91-103
Published online February 28, 2021;  https://doi.org/10.9719/EEG.2021.54.1.91
Copyright © 2021 the Korean society of economic and environmental gelology.

Sungchan Choi1, Sung-Wook Kim1,*, Eun-Kyeong Choi1, Young-Cheol Lee2, Sangmin Ha3
최승찬1 · 김성욱1,* · 최은경1 · 이영철2 · 하상민3

1Geo-information Institute, GI Co. Ltd., Busan 47598, Korea
2Research Institute of Geologic Hazard and Industrial Resources, Pusan National University, Busan 46241, Korea
3Department of Geological Sciences, Pusan National University, Busan 46241, Korea
1지아이 지반정보연구소 2부산대학교 지질재해·산업자원연구소 3부산대학교 지질환경과학과
Received November 25, 2020; Revised February 1, 2021; Accepted February 5, 2021.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
In order to estimate the vertical and horizontal structural in the Yangsan fault core line (Naengsuri area, Pohang), we carried out gravity field measurements and interpretation procedures such as Euler deconvolution method and curvature analysis in addition to the forward modelling technique (i.e. IGMAS+). We found a prominent gravity difference of more than 1.5 mGal across the fault core. This indicates a distinct density difference between the western and eastern crustal area across the Yangsan fault line. Comparing this gravity field interpretation with other existent geologic and geophysical survey data (e.g. LiDAR, trenching, electric resistivity measurements), It is concluded that (1) the prominent gravity difference is caused by the density difference of about 0.1 g/cm3 between the Bulguksa Granite in the west and the Cretaceous Sandstone in the east side, (2) the fault core is elongated vertically into a depth of about 2,000 meters and extended horizontally 3,000 meters to the NNE direction from Naengsuri area. Our results present that the gravity field method is a very effective tool to estimate a three -dimensional image of the active fault core.
Keywords : gravity field interpretation, Euler deconvolution method, Yangsan fault, curvature analysis

 

February 2021, 54 (1)