In given active faults, to explore the location, timing, and size of large paleo-earthquakes is the most essential work to examine characteristics of future large earthquakes, which can be facilitated for seismic hazard assessment and loss mitigation. During the last 20 years, many studies have been conducted for mapping of earthquake surface ruptures and/or active faults, which is greatly indebted to the advances in remote sensing techniques. In particular, based on fault geometry and slip distribution, many studies have tried to understand the effects of fault inheritances on coseismic rupture dynamics as well as temporal and spatial rupture history over multiple earthquake cycle. These studies commonly indicate that seismogenic-scale fault segmentation plays a key role in earthquake rupture behavior and fault evolution. This implies that paleoseismological investigations should be carried out based on fault segmentation in order to infer earthquake recurrence characteristics in a given active fault. Here, after brief reviewing of general concepts, materials/methods, and history/trend of the study on earthquake surface ruptures and active faults, we introduce major results of the most recent studies. Finally, we suggest a possible segmentation system of the Yangsan fault in southeast Korea based on previous paleoseismological studies, and discuss research strategies for further active fault researches in Korea and its associated seismic hazard assessment.