Identification of triggered seismic sources in Song Tranh 2 reservoir based on the geological - geophysical data

Abstract

Two M4.6 and M4.7 earthquakes that occurred consecutively at the end of 2012 have added confirmation to be danger of triggered earthquakes in the Song Tranh 2 hydropower area and surroundings, where earthquakes have not ever been recorded before the impoundment in 2010. The task of assessing the earthquake hazard, and forecasting the impact of the triggered earthquake on the hydroelectric dam is extremely urgent. To improve the accuracy of this impact assessment, the faults in the areas are not only generally taken as the earthquake source, but it is necessary to access the active faults for triggered earthquakes to be more effective in earthquake seismic hazard assessment. In this paper, 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 is presented. Research results have identified 5 sources of earthquakes related to 4 active faults connected with the Song Tranh 2 hydropower reservoir.