Another one to watch out for is mud diapirs. In coastal deltas where thousands of feet of infill has occurred over time the interaction between hydrocarbon formation and organic silts can create mud volcanoes.

https://www.researchgate.net/figure/Comparison-of-signatures...

These can be anywhere things that shoot liquid mud out of the ground to areas of very deep low seismic velocities where you could drive a pile thousands of feet to the bottom of hell and barely get any resistance.

Much the same, one should be careful when drilling into mud layers

https://en.wikipedia.org/wiki/Sidoarjo_mud_flow

Also don't accidentally let a lake--and the boats in it--start filling your tunnels through salt.

https://en.wikipedia.org/wiki/Lake_Peigneur

> Days after the disaster, once the water pressure equalized, nine of the eleven sunken barges popped out of the whirlpool and refloated on the lake's surface.

wow.

> there were no human deaths, three dogs were reported killed. All 55 employees in the mine at the time of the accident escaped

omF...g the mine was active!? and folks were just drilling on top of it!???

huh. good old 1980s.

Wow. I knew drilling could cause land to sink. I never imagined it could cause land to rise.

Fascinating, thanks!

This is fascinating, thankyou!