I made this video to show how an elevator affects the magnetometer trace. This is something, for those using a magnetometer to detect earthquake precurors, to be aware of. Notice the characteristic of the trace. Not to be mistaken as an earthquake precursor.
(Editor’s note: Simon is using the magnetometer described in this post. He lives on the 7th floor and sees very little traffic noise on his daily recordings, but at certain times of day he had been plagued by some very regular signals, always about the same size. In this video he shows how he finally tracked down where they’re coming from.)