Quantitative fracture analysis for individual fracture characterization: A case study in Geoje island, SE Korea

Fracture analyses have commonly been conducted qualitatively or descriptively based on field survey. However, recently, quantitative fracture analyses such as topological analysis have been popular, focusing on fracture network. Furthermore, to understand fracture network from the evolutionary aspect, it is also important to quantify the characteristics of individual fractures. In this study, therefore, we conducted aerial photograph analysis with UAV(unmanned aerial vehicle) as well as field survey for fracture digitizing and quantitative analysis. For data analysis, we used FracPaQ(MATLAB toolbox) for the L/Nsegment (Lengths/Number of segments) and NI-node/NY-node(only used end node) values. Based on the field survey, orientations of the fractures in the study area can be classified into four groups (Group A : N40-50°W faults; Group B : N10-20°E faults; Group C : N45°E shear fractures; Group D : EW joint and 2nd order fractures of Group A). Group A, B and C have higher L/Nsegment and NI-node/NY-node values, whereas group D has lower L/Nsegment and NI-node/NY-node values. Also, the group D fractures have short lengths and dominant Y nodes blocked by other fractures. These results suggest that the group D has different characteristics and origin from other fracture groups. Thus, the higher order fractures have lower L/Nsegment and NI-node/NY-node values, in contrast, the lower order fractures have higher L/Nsegment and NI-node/NY-node values. The results indicate that these quantitative analyses can contribute to the characterization of individual fractures within fracture networks.

Acknowledgment: This work was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP) and the Ministry of Trade, Industry & Energy(MOTIE) of the Republic of Korea (No.20201510100020).