Most of this seismicity is related to aftershocks of previous destructive earthquakes in the western margin of the Sichuan Basin. This event is southwest of a cluster of seismicity following an M6.6 earthquake on 20 April 2013 that resulted in 196 fatalities. A M7.9 earthquake on May 12, 2008, occurred near the September event and resulted in over 87,000 fatalities, making it one of the most destructive earthquakes in recent history.[1]