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http://dx.doi.org/10.9719/EEG.2021.54.1.91

Gravity Field Interpretation and Underground Structure Modelling as a Method of Setting Horizontal and Vertical Zoning of a Active Fault Core  

Choi, Sungchan (Geo-information Institute, GI Co. Ltd.)
Kim, Sung-Wook (Geo-information Institute, GI Co. Ltd.)
Choi, Eun-Kyeong (Geo-information Institute, GI Co. Ltd.)
Lee, Young-Cheol (Research Institute of Geologic Hazard and Industrial Resources, Pusan National University)
Ha, Sangmin (Department of Geological Sciences, Pusan National University)
Publication Information
Economic and Environmental Geology / v.54, no.1, 2021 , pp. 91-103 More about this Journal
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/㎤ 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;
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