Note that both quakes in the Baltimore area occurred in uninhabited areas (a cemetary and a park.
The Macon, Ga. quake 2 days ago was similar- centered in parkland in the middle of a dense urban area.
This selectivity can be seen all over, especially with larger 5.0 and higher quakes occurring mostly offshore or in remote mountainous areas.
This phenomenon lends credence to the theory we are witnessing man made, surgical strikes on underground transportation infrastructure, while minimizing damage and terror to surface populations.