Scientists and regulators agree that earthquakes like the 5.6-magnitude tremor that struck Oklahoma on Saturday, and thousands of smaller ones in recent years, have been spurred by the disposal of millions of tons of wastewater that is pumped to the surface, and then injected back into the ground, during oil and gas production. The shock last week tied a record set in 2011 in Prague, Okla., for the strongest such tremor in the state’s history.

State regulators have ordered well operators to stop wastewater injections in a 725-square-mile ellipse around the quake’s center. But they conceded that trying to prevent more quakes was an inexact science. And in Oklahoma, where oil and gas are dominant economic and political forces, any effort to regulate the industry produces an entirely different set of shocks.

Dr. Todd Halihan is a geologist and a specialist in hydraulic fracturing, known as fracking, at Oklahoma State University in Stillwater, about 30 minutes by car south of the center of Saturday’s quake. He answered some questions about the quake, and the risks the state still faces.

What happened?

We don’t know yet. There were several injection wells nearby, so it could be similar to the Prague event. The earthquake was about the same size as Prague. This time, there’s going to be a lot more seismological data available and a lot more understanding in terms of what’s going on in terms of injection well activity, so we hope we’ll be able to pinpoint what happened.