Watching a ground motion in REV,
several types of ground motion wave can be seen.
I found a certain characteristic motion wave, a large wave like a very complex serration continuing rhythmically for a few hours.
It was recorded at eight stations of Michigan on May 27, 30, or June 4, 2014.
The wave was recorded at other stations, too, in Missouri on February 26, June 6 and 7, in South Carolina on February 13, and in Georgia on May 7 and 8.
And it was not identical to this, but the wave of the similar kind
was recorded at a station in Ontario, Canada, on May 31 and June 1.
This underground movement seems to be related to the recent progress of the bowing of the North American Plate.
And see also the map of big under ground alteration in North America.
I show a figure of record in every each station below.
1) 2014/05/27: TA.F45A; CMU Biological Station, Beaver Island, MI, USA; 45.68 N, 85.52 W
2) 2014/05/27: TA.G45A; Suttons Bay, MI, USA; 45.04 N, 85.66 W
3) 2014/05/27: TA.G46A; Petoskey, MI, USA; 45.32 N, 84.86 W
4) 2014/05/27, 06/04: TA.G47A; Hillman, MI, USA; 45.17 N, 83.86 W
5) 2014/05/27, 06/04: TA.I49A; Point Hope, MI, USA; 43.94 N, 82.82 W
6) 2014/05/27, 06/04: TA.J46A; Howard City, MI, USA; 43.35 N, 85.65 W
7) 2014/05/30: TA.H46A; Fife Lake, MI, USA; 44.54 N, 85.20 W
* Note: This station showed an interesting history of ground motion wave between 2014/05/26 and 2014/05/31. As shown in a figure below, there was a very big undulation at past 18:00 of May 27, and a type of a ground motion wave changed after that time. Then a large wave like a serration
appeared at past 12:00 of May 30, after that time the same type of ground motion wave as a type before May 27 appeared again.
8) 2014/05/30: N4.L46A; Eue Claire, MI, USA; 42.01 N, 86.30 W
9) 2014/02/13: TA.Y56A: Pelion, SC, USA; 33.79 N, 81.30 W
10) 2014/06/06, 07: N4.S39B; Bolivar, MO, USA; 37.69 N, 93.32 W
11) 2014/05/07, 08: N4.257A; Skidaway Island, Savannah, GA, USA; 31.97 N, 81.03 W
12) 2014/05/31, 06/01: CN.KAPO; KAPUSKASING, ON; 49.45 N, 82.51 W