Department of Geology, Kangwon National University, Chuncheon 24341, Republic of Korea.
Department of Geology, Kangwon National University, Chuncheon 24341, Republic of Korea.
Sci Total Environ. 2022 Mar 1;810:152305. doi: 10.1016/j.scitotenv.2021.152305. Epub 2021 Dec 11.
In this study, two geothermal wells (PX-1 and PX-2) exhibiting abnormal groundwater levels and microbial communities were examined at the Enhanced Geothermal System site before and after the Pohang earthquake (November 2017). Furthermore, the EXP-1 well level, water temperature, microbial communities and their association with earthquakes, as well as the possibility of future earthquakes were explored. The primary objectives of this research were to: (1) perform correlation and cluster analyses of hydrophysical parameters for earthquakes using next-generation sequencing; (2) analyze pre-, co-, and post-seismic changes in groundwater levels, temperatures, and microbial communities; and (3) further assess the analyzed results of the post-earthquake changes in the groundwater levels and temperatures to interpret their implications. Although the pre-earthquake water levels in the three wells were unknown, their depth-to-water levels post-earthquake ranged from 50.33-98.20 m, 570.91-735.00 m, and 47.70-56.04 m for wells PX-1 (depth 4362 m), PX-2 (4348 m), and EXP-1 (180 m), respectively. In particular, the water levels of PX-2 were abnormally low compared with the surrounding area. Moreover, the geothermal wells demonstrated unstable microbial communities prior to the earthquake. However, while the microbial communities of PX-1 recovered relatively quickly post-earthquake, those of PX-2 failed to stabilize even within two years after the earthquake. Thus, it was inferred here that the PX-2 well is more closely related to seismic activity, the effects of which can still be seen. Accordingly, it is important that PX-2 is continuously monitored until June 2024, the minimum period predicted for the water levels to reach stability.
在这项研究中，对浦项地震（2017 年 11 月）前后增强型地热系统中两个出现异常地下水位和微生物群落的地热井（PX-1 和 PX-2）进行了检查。此外，还研究了 EXP-1 井水位、水温、微生物群落及其与地震的关系，以及未来发生地震的可能性。本研究的主要目的是：（1）使用下一代测序对地震的水文物理参数进行相关和聚类分析；（2）分析地震前后地下水位、温度和微生物群落的变化；（3）进一步评估地震后地下水位和温度变化的分析结果，以解释其含义。尽管三个井的地震前水位未知，但它们的地震后水位深度范围分别为 PX-1 井（深度 4362 米）的 50.33-98.20 米、PX-2 井（4348 米）的 570.91-735.00 米和 EXP-1 井（180 米）的 47.70-56.04 米。特别是，与周围地区相比，PX-2 的水位异常低。此外，地热井在地震前表现出不稳定的微生物群落。然而，尽管 PX-1 井的微生物群落地震后相对较快地恢复，但 PX-2 井的微生物群落甚至在地震两年后仍未稳定。因此，这里推断 PX-2 井与地震活动的关系更为密切，其影响仍然可见。因此，重要的是，在 2024 年 6 月之前，即预测地下水位达到稳定的最短时间内，需要继续监测 PX-2 井。
