Starting in 2009 the state of Oklahoma has seen a dramatic increase in seismic activity, according to Wikipedia, it has gone from an average of less than two 3.0+ Mw earthquakes per year to hundreds in 2014 and 2015. This has been caused by increased drilling for oil and the subsequent pumping of waste water into disposal wells deep underground. Read more here. As a result of the increased seismic activity, the U.S. Geological Survey (USGS) has released a new ‘damage map’ showing the risk of damage due to earthquakes significantly increased for the region. Read more about it here and find the map here.
Google Earth has a built in ‘Earthquakes’ layer found in the ‘Gallery’ layer. It only shows earthquakes over 3.0 Mw and as you zoom out it filters out the smaller ones. The result is that when looking at the whole of the continental U.S., Oklahoma doesn’t stand out as being particularly unusual.
However, the ‘Earthquakes’ layer is provided by the USGS and it is possible to obtain more detailed layers directly from them. Go here for automatic live feeds that show recent earthquakes, or here for more advanced queries.