Actually, Lowell and I were at Georgia tech for a while. There is a seismic zone in east Tennessee...right now June 2 is missing from the USGS page so I can't find the M3.9. Quakes in the SE can be easily triggered...there is a small reservoir in, I think, South Carolina where just a few meters of water level change would set off quakes. I think these are very shallow quakes...sound like explosions.....shallow rocks are often stressed to near failure in the east so anything that weakens the faults will set them off...
On the other hand, I don't know anything much about the east Tennesse seismic zone...your list is howing the bigger one as 13 km depth (may or may not be accurate)
Chris