I live in this area and I came to notice the same thing a few months ago. I believe it is the trains. Theres are many around this area, and go all night.
Although I'm not a geologist (although I did take a couple of courses as an undergraduate), as I recall the escarpment formation extends out under Lake Huron and down the west side of Lake Michigan almost to Chicago and may well act as a seismic lens.
Usually twice daily.....the earth is gonna open up beneath our bedroomNope... That's a daily occurrence!
Yes they can be explained. They are caused by plate tectonics. Every once in a while a plate will spilt apart and form 2 new ones. It does this by the plate domeing upwards and having three large cracks form at a 120º spacing. Two of these cracks will open up into a rift valley and eventually separate the plate into 2 new ones. The third crack will become a failed rift. You can see these 120º angles all over the world, in the Great Rift Valley of Africa, where that rift intersects the Red Sea and all up the south Atlantic along the coast of Africa and Brazil. The Atlantic ocean did not open along a straight line but along a zig-zagged one with 120º angles at each zig and zag. This has defined the shape of the east coast of South America and West coast of Africa which fit together perfectly like a jig saw puzzle.
More likely part of the Wabash Valley Seismic Zone which is to the north of the NMSZ.
