Oklahoma has been ailed this decade by an “induced-earthquake” problem, the consequences of which have wrecked walls, windows, and property values around the state. In a normal year—that is, in almost any before 2009—the state only saw one or two quakes. It now experiences one to two quakes per day. In 2015, it endured 857 earthquakes with a magnitude of 3.0 or higher, more than struck the rest of the lower 48 states combined.

These tremors are not naturally occurring. They are caused by wastewater injection, a process in which million of gallons of salty water are pumped deep underground. This water is often a by-product of fracking, the natural-gas mining process that has spread across the country and revolutionized the U.S. energy industry.

During Pruitt’s time as attorney general, Oklahoma developed the worst human-made-earthquake problem in the country. The state as a whole was slow to deal with the problem, and, for many years, it did not admit the quakes had a human origin. After that, it neglected to rapidly slow the rate of wastewater injection. This has allowed medium-scale earthquakes to continue: In November, a 5.0-magnitude quake damaged the structures of downtown Cushing, Oklahoma.

Johnson Bridgwater, the director of the Sierra Club’s Oklahoma chapter, says that the failure to address the quakes lies with every state official, Pruitt included.

“There are various places where the attorney general’s office could have stepped in to fix this overall problem,” he told me. “Its job is to protect citizens. Other states were proactive and took these issues on.” He criticized Pruitt for staying “completely silent” in the face of a major environmental problem for the state’s taxpayers.

Bridgwater’s concerns have been echoed by the national Sierra Club. “When a 2015 report from the Oklahoma Geological Survey found a direct link between oil and gas mining and increased destruction and property damage from earthquakes, Pruitt did nothing, even though as attorney general he is responsible for protecting Oklahomans,” said a statement from the organization last month.

This allegation is true, as it goes. There was a human-made earthquake epidemic in Pruitt’s home state, and the best thing you can say about his response is that it didn’t exist. But how much responsibility did Pruitt plausibly bear for the slow-moving disaster? And what could he have done about it?

Oklahoma is not the only state to have seen a surge in earthquakes this decade. Nearly every state in its region—Texas, Kansas, Arkansas, and Colorado—watched the number of earthquakes rise in the years after 2008. So did other states that embraced hydraulic fracturing, like Ohio, Pennsylvania, and New York.