I have had spikes similar to @scaron on my RS4D in the early morning as well. I’ll see if I can find it. I’ve also had larger spikes but they have another signature and were a complete other issue.
Edit: Was not able to find my spike/blip.
Edit 2: Something I’ve also noticed is that some spikes just dip down, and others dip both up and down.
Another thing I noticed is that on my accelerometer channel (ENZ) I noticed I have this “Permanent Dip” not sure if it’s related at all though as the other spikes have been on the Geophone (ENZ) channel. See the picture below for the “Perma-dip”.
