Internal architecture and earthquake rupture behavior of a long-lived intraplate strike–slip fault: A case study from the Southern Yangsan Fault, Korea

Long‐Term Weakening Processes and Short‐Term Seismic Slip Behavior of an Intraplate Mature Fault Zone: A Case Study of the Yangsan Fault, SE Korea

“…On the basis of our outcrop and microscale observations (Figures 2b and 3), together with previous map‐scale results for the Yangsan Fault (Cheon, Choi, Choi, et al., 2020; C.‐M. Kim et al., 2020; N. Kim et al., 2021; C.‐M. Kim et al., 2016), we consider that the strands observed in the boreholes are anastomosing, with the damaged host rocks that are distributed between the strands being interpreted as enclosed lenses.…”

“…Recent paleoseismic studies have reported that some sections of the fault have recorded surface rupture during the Quaternary and that the most recent faulting events occurred after the Late Pleistocene (e.g., Cheon, Choi, Kim, et al, 2020;Kyung, 2003;Kyung & Chang, 2001;Kim et al, 2011;Lee et al, 2015;Song et al, 2020). The long-term and repeated movements of the fault and the nature of transected host rocks have led to the formation of variable and complex architectures within the fault core (comprising cataclastic rocks; most of the displacement accommodated) and damage zone (comprising abundant subsidiary structures; relatively little movement accommodated), and along fault traces Cheon et al, 2019;Choi et al, 2009; C.-M. N. Kim et al, 2021; C.-M. .…”

“…The widths of the main fault core and damage zone measure several decameters and a few kilometers, respectively, although variations in the width of the fault zone and its internal structures are commonly observed along fault traces (e.g., Cheon, Choi, Choi, et al., 2020; Cheon et al., 2017, 2019; Choi et al., 2009; C.‐M. Kim et al., 2020; N. Kim et al., 2021; C.‐M. Kim et al., 2016).…”

“…Kim et al., 2016). The internal geometry of the fault zone shows a major single core as well as multiple cores represented as several anastomosing core strands along the entire fault trace (Cheon, Choi, Choi, et al., 2020; Cheon et al., 2019; N. Kim et al., 2021). These features are observed mainly at outcrop scale but have also been reported at map scale (see the northern part of the northern Yangsan Fault in Figure 1b; Kang et al., 2018).…”

“…The Yangsan Fault, the most prominent fault of the system, can be traced for ∼200 km on land and shows over 20-30 km dextral offset (e.g., Chang et al, 1990;Hwang, Lee, et al, 2007;. The widths of the main fault core and damage zone measure several decameters and a few kilometers, respectively, although variations in the width of the fault zone and its internal structures are commonly observed along fault traces (e.g., Cheon et al, 2017Cheon et al, , 2019Choi et al, 2009;C.-M. Kim et al, 2020;N. Kim et al, 2021;.…”