Intraplate Fault Stability Analysis using Rate-and-State Friction Simulation: Case studies on Spatially Aligned Earthquake Clusters in the Southern Korean Peninsula

Intraplate earthquakes occurring in the Korean Peninsula provide an important opportunity to investigate how pre-existing faults respond to the current background stress field in a low-seismicity region. This study shows that earthquakes often form sparse and linear clusters, suggesting a potential link between observed seismicity and pre-existing tectonic boudaries in the southern Korean Peninsula. Based on the 2024 M_L4.8 Buan earthquake sequence, this study extends the analysis to multiple linear earthquake clusters distributed across the southwestern Korean Peninsula. Using high-resolution earthquake catalogs via deep learning methods, waveform-based clustering, focal mechanism analyses, and rate-and-state friction (RSF) simulations, we examined the conditions under which these linear clusters become seismically active. The combined analyses highlight the roles of fault orientation, fault interaction, regional stress conditions, and frictional properties in controlling intraplate seismicity. Preliminary results indicate that faults favorably oriented with respect to the regional stress field are more likely to rupture, whereas unfavorably oriented faults may require additional factors (e.g., fault complexity, significantly reduced frictional conditions) to generate earthquakes. By extending RSF-based fault stability analyses to the southeastern Korean Peninsula, this study also emphasizes the importance of interactions within discrete fault networks in governing earthquake occurrence in low-strain-rate intraplate settings.