[machogirl]

What I’ve noticed is that unlike the usual smoothness of the lines, the needle has been non-stop amplitude while it’s moving horizontally. Like a constant background noise, interrupted by a quake every now and then. I’ve only noticed this seismo sensitive like this, a few times only. Mostly it’s smooth horizontally.

[Errant]

That's usually the sign of something on the move, be it magma or other liquid or maybe in this case, plate tectonics. I have to go find my link... :)

Is it harmonics?