Gracchus

I get none of the glory because blike posted first, but I do have the satisfaction of getting it right.

My guess is that it is part of an air bag covered with dust.

Aspirin can cause tinnitus. Any injury to the inner ear can cause it, or loud noises.

Focused sound of the right frequency might have that effect.

If the Earth were a bowling ball, it wouldn't even feel damp. So I don't think your experiment would engender any noticeable tectonic activity. Other effects, such as climatic catastrophies would, I think, depend upon the diameter of the shaft and other factors.

Anyone smarter than I is a genius. I just haven't met anyone that smart.