AUDIE CORNISH, HOST:
With the way things have been going in Oklahoma, this didn't come as a surprise. The state opened 2016 with a 4.2-magnitude earthquake this morning. There have been at least a dozen earthquakes in the state just since Tuesday. Now, for all of 2015, Oklahoma saw more than 800 earthquakes at magnitude 3.0 or greater. This is not the way it used to be. Regulators and researchers say the rise in quakes is due to oil and gas production that involves re-injecting vast amounts of salty water into the earth. To talk more, we turn to Todd Halihan. He's a professor in the School of Geology at Oklahoma State. Welcome to the program, Todd.
TODD HALIHAN: Thanks.
CORNISH: So what can you tell us about today's quake? I understand it happened about 15 miles outside of Oklahoma City.
HALIHAN: Right, so we've had a lot of seismicity that's happened out in rural areas, and the folks in the rural areas don't appreciate it very much. But we've had a couple recently right underneath Edmond, which is one of our very populated areas with a lot of people sitting on top of it. So it's made a lot of press lately.
CORNISH: We mentioned earlier about the quakes being connected to oil and gas production. Obviously, people have heard about fracking. Can you help us understand how this works? What's causing the quakes?
HALIHAN: So when you're producing oil and gas, you're actually pumping a water well, and you happen to get some oil and gas out of it. And so in some formations, you get mostly oil, which is a great thing to do. In ours, you're getting about 10 gallons of water per gallon of oil. And then you have this leftover salty water that you can't do much with. It's much saltier than ocean water, and so the only choice that they found was we could put it down to depth and dispose of it. That process, for a very long time, has worked very, very effectively. But in the modern day with higher volumes and higher rates, it's caused seismicity. For us, that's not been something we've had to deal with previously until a few years ago.
CORNISH: So what steps has the state taken to try and counter this pattern? What are they asking the companies to do differently?
HALIHAN: So when they design an injection well, it's designed to protect the fresh water up above and keep it from coming into the surface or coming into groundwater where people are drinking. When you design for seismicity, you want to design to protect the well from the water going down below where you're injecting. And so they've done a lot of changes to the wells to try to prevent water from getting down into the - what we call the granitic basement and finding faults down there that it can lubricate and move. And so that change from protecting the upper part of the well to changing the lower part of the well - they put out some mandates saying, we'd like you to modify your wells in these ways if you're in the seismically active areas.
CORNISH: Are there any seismologists or researchers out there who still say that the link isn't strong enough - who are denying a connection?
HALIHAN: There are still some people that the pattern for this type of activity is not a really clean one. It's not, hey, there's an injection well, and you made an earthquake right next to it. It's that there's an injection well, and miles away, there's an earthquake. And so the pattern isn't really simple. And in Okla., if you're miles away from an injection well, you're close to another injection well. And so figuring out what caused it and where - that pattern isn't simple. It's really difficult to say, yes, we're really, really certain about this and that. But what you can check is when the rates have been lowered or wells have been shut in, seismicity has dropped, so that's a pretty good indicator that there's that nice connection where you see that those changes and injection have resulted in less seismicity in some areas.
CORNISH: What does this mean for states who are watching Okla. and try to figure out how to regulate this kind of activity in their communities?
HALIHAN: Well, one of the tricks is - is that you need to get the technical components out in the front. And that's been done in the airline industry. And I talk about if you have a plane crash, they don't want that to happen, but there's a neutral technical group that can look at that and make a call on it. It's difficult in the oil industry because there's not that neutral ref to say, what's the next step? And so I think what we're going to be looking at is, how do we properly address these problems so the public is comfortable, but the energy industry can operate with some certainty? And that balance is something that's difficult in the energy industry because there's no referee.
CORNISH: Todd Halihan is a professor in the School of Geology at Oklahoma State. Thank you so much for speaking with us.
HALIHAN: Thanks for having me. Transcript provided by NPR, Copyright NPR.