Quaternary faults run across the Seoul metropolitan area that is the highest population region in the Korean Peninsula. Active fault identification and seismic hazard potential assessment are crucial for public safety. Densely deployed permanent and temporal seismic stations enabled us to detect micro to small earthquakes, allowing us to identify earthquake-spawning faults in Seoul metropolitan area. The source parameters of 455 earthquakes in 2004–2020 are refined. The Gutenberg-Richter b value is 0.94. Dominant focal depths are 4–15 km. The focal mechanism solutions of 64 earthquakes are determined using seismic-wave polarities and amplitude ratios. Strike-slip earthquakes are dominant in the region. Earthquakes are clustered around the Chugaryeong fault system. The dominant strikes of fault planes range from N20°E to N45°E in the northern and southern Seoul metropolitan areas, suggesting branch fault development locally. The earthquakes in middle-northern Seoul present N-S directional strike-slip motions at depths ∼7.5 km along the Chugaryeong fault, suggesting seismically active near-vertical faults subparallel with Chugaryeong fault.

中文翻译：

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首尔市区的地震产生断层及其地震意义

第四纪断层横跨朝鲜半岛人口最多的首尔市区。活动断层识别和地震潜在危险评估对公共安全至关重要。密集部署的永久和临时地震台使我们能够检测到微地震，从而使我们能够识别首尔市区的地震产生断层。细化了2004-2020年455次地震的震源参数。Gutenberg-Richter b值为 0.94。主要震源深度为 4-15 公里。64次地震的震源机制解是利用地震波极性和振幅比确定的。该地区以走滑地震为主。地震集中在 Chugaryeong 断层系统周围。在首尔市区北部和南部，断层平面的主导走向范围从 N20°E 到 N45°E，表明局部有分支断层发育。首尔中北部的地震在沿 Chugaryeong 断层约 7.5 公里的深度呈现 NS 方向走滑运动，表明地震活动的近垂直断层与 Chugaryeong 断层平行。