Abstract The 2017 ML 5.4 Pohang Earthquake in southeastern Korea, which was induced by fluid injection from an enhanced geothermal system, and its foreshock–aftershock sequence has been recorded by a dense and portable temporary seismic array. The hypocentral distribution of the earthquake sequence reveals the reactivation of a complex subsurface fault system that was previously unmapped. Aftershock seismicity propagated to the southwest and revealed previously unknown fault segments. The aftershocks tend to concentrate along the tips of the main rupture, with a lack of aftershocks around the mainshock hypocenter. This pattern suggests that the stress in the mainshock area was almost completely released during the mainshock and early aftershock phase, and that the recurrence of moderate to large earthquakes in the hypocentral area is unlikely compared with the marginal areas. A new rupture occurred along the southwestern margin of the main rupture after the largest aftershock (ML 4.6).

中文翻译：

---

2017 年 ML 5.4 韩国浦项地震序列，由密集地震台网记录

摘要 韩国东南部 2017 年 ML 5.4 浦项地震是由增强型地热系统注入流体诱发的，其前震-余震序列已被密集便携式临时地震台阵记录。地震序列的震源分布揭示了以前未绘制的复杂地下断层系统的重新激活。余震地震活动传播到西南并揭示了以前未知的断层段。余震往往集中在主破裂的尖端，主震震源周围没有余震。这种模式表明主震区域的应力在主震和早期余震阶段几乎完全释放，与边缘地区相比，震源区不太可能再次发生中到大地震。在最大余震（ML 4.6）之后，主破裂的西南边缘发生了新的破裂。