## 5 Conclusions  
1. An MS monitoring system was built during the excavation of the underground powerhouse at the Shuangjiangkou hydropower station. The temporal distribution pattern of the MS events was obtained during the excavation of benches I and II of the underground powerhouse from 19 July 2018 to 31 October 2020. The study reveals that MS events occurred frequently during the excavation of bench I, with an average of more than nine events in a single day. Moreover, the MS events still appeared during the support period when the blasting was stopped, indicating that the surrounding rock experienced a long stress adjustment under high geostress. However, the MS events occurred less frequently overall during the excavation of bench II due to the stress release and minor disturbance from the blasting, with an average of less than five events in a single day. The spatial distribution pattern of the MS events indicates that the high ground stress environment usually had a large number of MS events. There were three concentration zones of MS events with large energy and high moment magnitude, which are closely related to the construction dynamics and planes of geological structures.
2. The intensive blasting and construction periods from 19 July 2018 to 3 December 2018 were selected to examine the dynamic relationship between the evolution of the MS events, the site construction conditions, and the geological structures. In summary, site blasting construction was the main factor inducing MS events in and around underground caverns under high geostress. The distribution of the MS events were strongly correlated with the location of the site blasting. Moreover, the frequency of the MS events was positively correlated with that of the blasting. The number of MS events was increased by the structural plane. The possibility of the surrounding rock becoming unstable was raised by the structural plane.
3. The simulated maximum cross-sectional displacement of each turbine generally appeared near the spandrel during the excavation of the underground powerhouse for bench I. The maximum displacement occurred in the vicinity of the lamprophyre dyke near the upstream spandrel. The numerical modeling results closely matched the MS monitoring data and the site failure status of the rock mass. The failure and deformation of the rock mass were greatly impacted by the geological structure of the underground powerhouse under high geostress.  
Figure 13: Displacement at the exposure of the lamprophyre dyke.  
**Author Contributions:** [PERSON] conducted the literature review and wrote the first draft of the manuscript. [PERSON] developed the overarching research goals and analyzed the microseismic data. [PERSON] edited the draft of the manuscript. [PERSON] carried out the numerical simulation. [PERSON] processed the microseismic monitoring data. All authors have read and agreed to the published version of the manuscript.  
**Funding:** The research is supported by the National Natural Science Foundation of China (No. 42177143, 42277461), the Science Foundation for Distinguished Young Scholars of Sichuan Province (Grant No. 2020 JDJQ0011).  
**Institutional Review Board Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** Thanks are given to colleagues at the hydropower station for their valuable contributions to the project. Additionally, the authors would like to thank the editors and reviewers for their valuable comments and constructive suggestions.  
**Conflicts of Interest:** The authors declare no conflict of interest.