West Texas earthquake highlights new seismicity rules ` Texas

Texans from San Antonio to Dallas felt the effects of an earthquake that began in far west Texas on Wednesday. The 5.4-magnitude tremor was the third-strongest tremor recorded in Texas by the US Geological Survey.

The earthquake occurred in an area closely monitored by the Railroad Commission of Texas. Because there, a lot of wastewater from fracking is pressed into the ground – a process that can trigger earthquakes.

Hugh Daigle, associate professor in the Department of Petroleum and Geosystems Engineering at the University of Texas at Austin, spoke to the Texas Standard about efforts to reduce seismic activity in the region. Listen to the story above or read the transcript below.

This transcript has been edited slightly for clarity:

Texas Standard: After this quake, you sent out a series of tweets about how the quake’s epicenter fell into what is called a seismic response zone. What is that?

Hugh Daigle: Yes, that’s a good question. So the Railroad Commission has developed a number of these seismic response areas in west Texas, and this particular one is the Northern Culberson-Reeves earthquake area, which is native to the counties where it’s located. And that’s an area that has had a lot of earthquakes that they believe are related to the disposal of water that comes from oil and gas operations in the region. And this is one area where they are looking very carefully at allowing water disposal wells to fully reduce any magnitude 3.5 or greater earthquakes within 18 months of implementation, which took place in March of this year.

Just to avoid confusion, the Railroad Commission is the agency that regulates the oil and gas industry in Texas. So, if I understand you correctly, this region was specifically set up to reduce the number of earthquakes caused by fracking, right?

That is exactly right. So between January 1, 2017 and October 20, 2021, they recorded 42 of these events with a magnitude greater than 3.5. And based on the locations of those events, they drew a contour map around the east and pinpointed that area. And they said, “Okay, this is a problematic area and we have to deal with the seismicity that’s going on here.”

I have it. Just to be clear, we’re not talking about fracking itself. We’re talking about what the companies are doing with the wastewater. Just to be clear, what, if anything, is actually triggered by this earthquake occurring in this seismic reaction area?

Over the years, my Bureau of Economic Geology colleagues here at the University of Texas have mapped a number of actually a large number of faults that are not currently active. And what happens when you inject water, you increase the pressure in the rocks. And if you change that pressure, you can actually re-enable some of those bugs. And that causes an earthquake.

Ultimately, what impact could this have on the local oil and gas industry? I mean, are we looking at the likelihood, possibility of new regulations for fracking activities or what?

Well, that’s an interesting question. So, under the terms of this seismic response program, there really isn’t any specific action that anyone needs to take as a result of this earthquake, because there aren’t any of these deep injection wells that are close enough to the epicenter of the earthquake. So it will be interesting to see if we may need to have any other regulations coming out of this. But interestingly at the moment it doesn’t look like there will need to be a change in behavior according to the regulations we have in place.

Do I understand when you say that the fracked water, the sewage, does not appear to have caused or be directly related to this earthquake?

Well, you know, it’s really difficult to establish causality in a situation like this. And I am sure that in the months and years to come we will see some detailed studies to find out what really happened. The depth of the earthquake is certainly consistent with being triggered by some of these deep injection wells. The closest is about 9 to 10 miles from the epicenter, and it’s not inconceivable that the pressure could have spread that far. But again, like I said, it’s really difficult to pinpoint a specific event in this type of activity.

So what does the future hold for seismic activity in this part of West Texas?

Well, we know that in the 1930’s there was a major earthquake, the Valentine earthquake, that was considerably further south of where we are. In 2020 there was a magnitude 5 in that area. And I think it’s reasonable to assume that the high volumes of water that are being injected — I mean, we’re talking about hundreds of thousands of barrels a day, so millions of gallons a day these Drilling wells in that particular area – it’s reasonable to assume that this will have an impact on what’s going on underground. And I think it’s really important to realize that some of this is very poorly understood at this point.

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