According to USGS, the 7.9 quake was followed by aftershocks of 6.2 and 6.4.
Update: Thursday, September 17th
Dozens of significant aftershocks have continued to shake Chile, and yesterday’s quake has been upgraded to an 8.3.
The following visual presentation helps put that magnitude in perspective:
The earthquake was felt throughout Chile, and across much of South America, including Peru, Argentina, and Ecuador. It is estimated that the earthquake has caused hundreds of millions of dollars in damages in Chile, which is no stranger to seismic activity.