In Possible Bubbles of Spacetime Curvature in the South Pacific, that R'lyeh might be exist within a bubble of spacetime. (It appears to be a joke paper since some of the references are fictional, but the math appears quite serious.)
If a Bubble like the one described in the paper existed somewhere on (or in/near) the Earth, could LIGO have detected?
The reason I think LIGO might be able to detect it is because it can detect gravitational waves, and a spacetime bubble would presumably cause some "noise" in the signal. That being said, spacetime bubbles don't really change quickly, whereas LIGO is designed to detect speedy gravitational waves.