The cover photo illustrates the source area and maximum value of triggered earthquake for Hoa Binh hydro-electric reservoir through the study into "The characteristics of seismic activity in the ladder zone of Da river hydro-electric plants".
The largest observed triggered earthquake at the Hoa Binh reservoir was of a magnitude of M=4.9. This maximum value is also predicted for triggered earthquakes. This means that earthquake activity in the Hoa Binh reservoir reached the maximum value. No likelihood of triggered earthquake occurrence at the Hoa Binh hydro-electric plant is predicted since no earthquake has been observed at the Hoa Binh reservoir since 1996.
To get more understanding about the topic, please see the full article "The characteristics of seismic activity in the ladder zone of Da river hydro-electric plants" in pages 82-91 of this issue.