I'm sure people remember those odd groaning/screeching/trumpet sounds that were seemingly coming from the Earth in various locations around the world a few years ago.
I'm yet to hear of an explanation for them. To me, they sound very mechanical, like heavy industrial machinery and I saw a comment somewhere referring to a video that made the link between tunnel boring machines and these sounds. Specifically when TBMs breakthrough the end of tunnel. I've watched a load of videos of these breakthroughs and they don't seem particularly loud, i.e. none of the work crews appear to be wearing any ear pro.
I was wondering if anyone recalls this video making the connection and if it sheds any light on this theory. Perhaps it depends on the rock composition etc. I don't know.
Example of the sounds in this video
I don't think you're gonna get an answer. Years have passed and nothing to show for it. Nobody finds this interesting enough, and probably because it isn't
You don't find a sound which no one can explain, that people have heard all around the world, interesting?
Considering the lack of real vetting on this (we have grainy videos, unsourced, which can easily be faked), no I don't. This seems like more of a distraction to keep people complacent. You're on a wild goose chase when the real issues are happening elsewhere.
Considering it got attention from the MSM, you may very well be right.