According to the US Geological Survey, early on September 23, 2017, a magnitude 6.1 earthquake struck 12 miles southeast of Matías Romero. The epicenter was approximately between the centers of the two more violent earthquakes seen earlier in the month. On September 8, an 8.1 magnitude quake had struck off of the southern Pacific coast, near Chiapas state. Mexico City, on September 19, then endured a 7.1 magnitude quake, which also marked the 32nd anniversary of the devastating 1985 earthquake, in which more than 10,000 people had been killed.