This study provides information about fault motion by statistically presenting shape and orientation information for tens of thousands of grains. The recently developed shape preferred orientation (SPO) measurement method using synchrotron micro-computed tomography was used. In addition, various factors that were not considered in previous SPO analysis were analyzed in-depth. The study area included the Yangsan and Ulsan fault zones, which are the largest fault zones in the southeastern part of the Korean Peninsula. Samples were collected from five outcrops in two regions. According to the field observation results, the samples in the area were largely divided into fault gouge and cataclasite, and as a result of SPO analysis, we succeeded in restoring the three-dimensional fault motion direction for each outcrop and identified the fault type. In addition, the analysis results of the fault gouge and cataclasite samples collected from the thin fault zone were interpreted using the focal mechanism solution. As a result, the statistical SPO analysis approach supplements the shortcomings of previous research methods on two-dimensional planes and can quantitatively infer the three-dimensional fault motion for various fault rock samples in the same sequence, thus, presenting useful evidence for structural analysis.
Bibliographical noteFunding Information:
Funding: This study was funded by the Korea Meteorological Administration Research and Development Program under grant KMI2018-01910.
Acknowledgments: We would like to appreciate the reviewers and editor who reviewed this paper, and also thank those who helped us with the editing process. This study was supported by the study on submarine active faults and evaluation of possibility of submarine earthquakes in the southern part of the East Sea, Korea of the Ministry of Land, Infrastructure, and Transport.
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
All Science Journal Classification (ASJC) codes
- Geotechnical Engineering and Engineering Geology