The M4.7 earthquake that occurred at the end of 2012 confirmed the danger of triggered earthquakes in the Song Tranh 2 hydropower region, where earthquakes have not ever been recorded before the impoundment in 2010. The task of assessing the triggered earthquake hazard and forecasting its impact on the hydroelectric dam is extremely urgent. To improve the accuracy of this impact assessment, it is necessary to access the active faults for triggered earthquakes to be more effective in earthquake seismic hazard assessment. In this paper, the authors presented a combination of analytical methods combining geological - geophysical data in identifying active sources of triggered earthquakes that stimulate Song Tranh 2 hydropower reservoir with a 3-step analysis process. Research results have identified 5 sources of earthquakes related to 4 active faults connected with the Song Tranh 2 hydropower reservoir.