1,2,4,5,6- 1The Institute of Basic Science, Korea University, Seoul, Korea, Republic of (hdb4812@gmail.com)
- 2Institute of Sustainable Earth and Environmental Dynamics, Pukyong National University, Busan, Korea, Republic of
- 3Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources, Daejeon, Korea, Republic of
- 4Division of Earth Environmental System Science, Pukyong National University, Busan, Korea, Republic of
- 5Department of Earth and Environmental Sciences, Korea University, Seoul, Korea, Republic of
- 6School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea, Republic of
The Miryang Fault is an inferred fault located in the southeastern Korean Peninsula and is a part of the Yangsan Fault System, which trends NNE-SSW. Although the Miryang Fault appears as a distinct topographic lineament, its activity and characteristics remain poorly constrained due to a scarcity of direct geological and seismological evidence. We investigated seismic activity along the Miryang Fault to delineate subsurface fault structures using earthquake detection, high-precision hypocenter relocation, and focal mechanism analysis. We employed energy-ratio-based automatic detection and determined relative hypocenter locations using the double-difference method. Focal mechanism solutions were derived using P-wave first-motion polarities. Epicenters are concentrated to the west of the surface trace of the Miryang Fault and generally align with its strike. The hypocenters exhibit a strongly linear spatial distribution, distinctively separated into northern and southern clusters. The seismicity tends to become more spatially scattered northward, particularly beyond the northern termination of the surface trace of the Miryang Fault. The southern cluster is characterized by a higher frequency of larger earthquakes and a lower Gutenberg–Richter b-value compared to the northern cluster. Focal depths range from 5 to 20 km, with the southern region showing a narrower range and a concentration at greater depths. Principal Component Analysis of the hypocentral distribution reveals that the fault geometries for both clusters trend NNE-SSW and dip nearly vertically. Both clusters extend approximately 30 km along the strike. Focal mechanisms indicate predominantly dextral strike-slip motion, with strike and dip consistent with the geometry inferred from the spatial distribution. These findings provide new insights into the seismotectonic characteristics of the Miryang Fault and underscore its potential role in the active tectonics of the southeastern Korean Peninsula.
How to cite: Heo, D., Han, J., Kang, T.-S., Kim, S., and Rhie, J.: Subsurface geometry of the Miryang Fault, southeastern Korean Peninsula, inferred from high-precision earthquake relocation and focal mechanism analysis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16016, https://doi.org/10.5194/egusphere-egu26-16016, 2026.
