This past week (7 days) has shown a buildup in seismic pressure coming from the West coast, translating out to multiple earthquakes at locations which normally do not show much movement.
Past 7 days (up to April 2 2015) of 4.0M+ events shows the Fracking operation in California had a 4.1M, dormant Pisgah Craters volcano had a 4.0M in Southern California, 2.7M strikes Dallas TX fracking operation, and a 4.0M strikes the New Madrid.
Information on this 4.0M in Missouri from the USGS: