## 1 Introduction  
In recent years, a large number of hydropower projects have been under construction in southwest China. With economic and technical considerations taken into account, most of these hydropower projects have placed their hydraulic structures inside mountains, such as the Jinping-I [1], Houziyan [2], Shuangiangkou [3], and Baihetan [4] hydropower stations. Construction is more challenging in southwest China due to the uneven ground stress, complex rock mass structure, and development of weak structural planes. In addition, because the majority of ongoing hydropower projects are running behind schedule, it is essential to construct tunnels in a safe and efficient manner. To ensure the safety of project construction and operation, it is urgently necessary to find solutions to a number of problems related to the stability and control of the surrounding rock of deep tunnels.  
The initiation, growth, and propagation of micro-fractures in the rock mass can cause macroscopic deformation and failure of that rock mass, and MS events can fully describe how these micro-fractures develop in the rock mass. MS monitoring was firstly used to check on the safety of mines [5, 6, 7, 8]. Later, given its quick growth, widespread adoption, and extensive use, it was also widely used in the extraction of oil, natural gas, and geothermal energy [9, 10, 11]. In recent years, it has been applied in projects such as CO\({}_{2}\) storage [12, 13], deep-pit oil and gas reserves [14], and underground nuclear waste protection [15]. With the cascading development of hydropower stations in southwest China, MS monitoring has also been introduced into the safety monitoring of hydropower projects on a large scale.  
[PERSON] et al. [16; 17; 18] deployed an MS monitoring system in the deep underground powerhouse of several hydropower stations, analyzed the relationship between the b-value of MS events and macroscopic deformation of the surrounding rock and its change law over time, and identified the potential unstable zone of the underground cavern under the effect of excavation and unloading. The team, led by [PERSON] [19; 20; 21], successfully built an MS monitoring system in the Baihetan hydropower station and Jinping-II hydropower station, studied rock bursts in tunnels under high ground stress, and identified the evolution law and characteristics of MS events. [PERSON] et al. [22; 23; 24] introduced the MS monitoring system into several large hydropower stations, including the Jinping-I hydropower station, Baihetan hydropower station, Houziyan hydropower station, and Wudongde hydropower station, carried out research on engineering problems such as rock slope instability and surrounding rock failure in underground caverns, and achieved a wealth of engineering research results by combining numerical simulation means, conventional monitoring methods, source parameter analysis of MS events, and dynamic construction analysis.  
Based on engineering geological data and site surveys, MS monitoring was employed in this paper to monitor the surrounding rock deformation and failure in the spillway tunnel of the Jinchuan hydropower station online in real time, and source parameter analysis was used to analyze and study the stability of the surrounding rock.