Penny...I just came on to post on these. Note that about 2 or 3 days ago there was a M3 in Oklahoma at about the same longitude, but hundreds of km north...tricia for the day. It would be interesting to look at whether there is any oil or gas production going on. There is a big rush on natural gas when prices got high enough to produce it from tight sands and shale. They stimulate the rocks, and fracture the rocks. We know that messing with fluid pressures can trigger quakes. On the other hand, I have no clue whether there is any oil or gas work going on in this area.
Chris