Don’t know of anything.
Earthquake in SE Melbourne outer suburb of Pakenham ‘sounded’ suspicious.
Recent aborted underground railway tunnelling due to contaminated soil also seemed a bit off.
There are tunnels in the area I live in which is an inner south eastern suburb but I have never been in them but I know people first hand who did when we were kids.
I also know a Telecom worker who used to travel the tunnels in the city. Said they were expansive.
Nothing sinister to report but I’m sure it’s going on.