I love this. We did indeed find this happening as soon as we got out first Auger going. On one occasion, I had a Screamer scream right at the top if my mine (by which I mean big hole in the ground) and she and everything she summoned fell in beside me. This included 2 other Screamers. I died. But since this mine was right beside our live-in base, we had to deal with it. Any time one of us walked anywhere near that mine all those Screamers down there went off (whatever happened to them needing line of sight to scream?????) and the surrounding area was soon full of 20+ zombies, including more Screamers and multiple Ferals and Rads. Massive surface battle ensued. This happened every time we went near the mine to try to clear it. In the end we had to stand on elevated blocks nearby and throw tons of grenades into the mine from afar to kill them off with setting them off.
I find this awesome. But then we also modded spawning.xml so we have tons of zombies in all biomes all the time, with very short respawn times. We like lots of zombies.
Basically if someone is mining with an Auger, you need to have a guard stand by on the surface to prevent this kind of thing. I look at this as the price of using the Auger. If you are playing solo, then basically the moment you hear a Screamer (you get lots of warning), then get OUT your mine immediately and deal with it.
We are running 6 Forges, 2 Chem Stations and 2 Cement Mixers more or less 24/7. We get lots of Screamers (I'd say 10+ per night on a 90 minute day cycle), but our live-in base kills them on its own with no action from us, so we ignore them. And for the record we live in a 10 x 10 x 5 Concrete box with solid walls (no windows or slits) and a nearby ramp to jump in the top. This is surrounded by 3 rows of Iron Spikes. Very very simple, but more than sufficient to kill anything wandering by, including Screamers, and they do not scream because they cannot see us. Our main horde-killer base is elsewhere.