Kansas began measuring seismic activity in 1977. From 1977 to 2012, there were just under 200 earthquakes recorded in Kansas. After a period of relative quiet, in 2013 there were 31 earthquakes recorded in the state. In 2014 that number jumped to 160. So far in 2015 nearly 600 earthquakes have been recorded.
Geologists in Kansas and Oklahoma say restrictions imposed on wastewater injection wells by oil and gas regulators are reducing in the number and severity of earthquakes rattling regions of both states.