Here’s how drilling and earthquakes have spread in the last four years.
The Prague 5.6 magnitude quake had one 4.8 magnitude foreshock and one 4.8 magnitude aftershock. Altogether there were 63 quakes of magnitude 3 or higher, concentrated mostly in the center of the state, where the 860 million barrels of waste pumping was centered.
Drilling activity increased in northern Oklahoma but the 34 earthquakes of magnitude 3 or greater remained concentrated in the center of the state. Waste pumping increased to more than 1.2 billion barrels, with a big increase in the north.
Earthquakes surged with 106 magnitude 3 or greater, including a string of quakes in the north of the state, where waste pumping also increased as the statewide volume rose to more than 1.5 billion barrels.
The rate of quakes multiplied with 567 jolts at least magnitude 3 with the heaviest concentration in the northern end of the state. Waste-pumping data for 2014 is not yet available.