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Published on December 15th, 2017 | by Cynthia Shahan

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Is The Oil & Gas Industry Causing Texas Earthquakes? A “Landmark” Study Suggests Yes

December 15th, 2017 by  


There is more than what hits the eye, or in some places, shakes the house. A new report, Discriminating between natural versus induced seismicity from long-term deformation history of intraplate faults (PDF), explains. While we all make assumptions on hunches, it takes a scientist assisted by a group of scientists and geologists to assess whether seismic activity is induced by human activity or is of natural origin.

I know that the residents of Texas value the scope and beauty of their chosen state. And they should — the state offers magnificent skyscapes similar to Florida on the Gulf Coast. Austin, the Texas capital, is a mecca for the independent Texan wanting diversity, Willie, Austin City Limits, and eclectic music. Texas terrain ranges from coastal swamps and piney wood to rolling plains and hills —  and desert and mountains. Let’s hope Texans care enough to consider what fracking might do to the state. Perhaps it’s time to revive the “Don’t mess with Texas” slogan created to cut down on littering.

The Washington Post reports on a strain from such practices in Texas. Ben Guarino’s article describes that an unnatural number of earthquakes hit Texas in the past decade. Continuing, he reports that the region’s seismic activity is increasing. “In 2008, two earthquakes stronger than magnitude 3 struck the state. Eight years later, 12 did.”

“Given the lack of faults in Texas’s most recent 300 million years of history, there is no known geologic process that could explain its sudden quake outbreak.” Maria Beatrice Magnani, who studies earthquakes at Southern Methodist University in Dallas, said that this has to be caused by humans. “There is no other explanation.” She was one of the researchers intent on getting to the bottom of the cause.

“Along with a team of researchers at the U.S. Geological Survey, Magnani, an author of a new report published in the journal Science Advances, attempted to better identify what has been causing the rash of Texas quakes.”

And what human activities popped up? Guarino points out the recent increase in natural gas extraction. The activity of fracking or hydraulic fracturing produces a lot of wastewater. “To get rid of it, the water is injected deep into the ground. When wastewater works its way into dormant faults, the thinking goes, the water’s pressure nudges the ancient cracks. Pent-up tectonic stress releases and the ground shakes.”

Magnani’s team of researchers attempted to make some sense of the rash of recent Texas quakes. “The main approach has been to correlate the location to where there has been human activity,” said Michael Blanpied, a USGS geophysicist and co-author of the new study.

The concerns about fracking have been forthcoming and the study is similar to what other earthquake experts had found — but with different analyses. From the abstract: “To our knowledge, this is the first study to discriminate natural and induced seismicity using classical structural geology analysis techniques.”

That sounds complicated, but the team notes that other researchers should see it as a solid approach. “We don’t expect a lot of pushback” from the scientific community, Blanpied said.

The Washington Post continues that the study authors’ unique approach sought out deformed faults below Texas. “This technique is called high-resolution seismic reflection imaging,” Magnani said. Using seismic reflection,  the same tool that allows extractors to find oil and gas deposits in underground structures, they collected seismic data in response to an artificially generated wave that reflects back to the surface. “The result is ‘a little bit like an ultrasound,’ Magnani said, revealing not baby toes but twisted rock.”

Back to the abstract and graphics from the abstract (if you want to get further into the nitty gritty): “We analyze fault displacements on high-resolution seismic reflection profiles for two regions in the central United States (CUS): the Fort Worth Basin (FWB) of Texas and the northern Mississippi embayment (NME).”

Fig. 1. Post-2008 seismicity rate change in the CUS. The post-2008 seismicity has occurred both in areas that were seismically active before 2008 (for example, the Mississippi embayment) and in regions with no pre-2008 historical or instrumental seismicity (for example, FWB). The two study areas are outlined and represented in Figs. 2 and 6. Modified with permissions from Rubinstein and Mahani (13)

Fig. 2. Earthquakes in the FWB, north Texas. The map shows the main tectonic features of the basin, instrumental seismicity (1.8 > Mw > 4.0), and the geographical extent of the Barnett Shale, the main oil and gas production unit. Produced brine and wastewater associated with stimulation of unconventional reservoirs are reinjected through deep wells (that is, saltwater disposal well; crosses in the figure) in the Ellenburger Group, below the Barnett Shale. NEFZ, Newark east fault zone; SWD, saltwater disposal. Llano uplift, stipple pattern–Precambrian metasedimentary rocks; light gray, Ordovician carbonates. Seismicity shows clusters around Azle (Parker County), Irving-Dallas (Dallas County), and Venus (Johnson County). Faults from Ewing et al. (36).

Fig. 3. Generalized subsurface stratigraphic section of the central and eastern FWB. Most of the saltwater disposal in the FWB takes place in the Early Ordovician Ellenburger Group, close to the Precambrian basement where the majority of seismicity occurs. Few wells penetrate below the Ellenburger, and details of the Cambrian stratigraphy are from the Llano uplift, central Texas. The schematic stratigraphic column to the right shows the main horizons identified in the seismic reflection profiles shown in Figs. 4 and 5. Modified with permissions from Pollastro et al. (24) and Ewing (97)

Fig. 4 Seismic reflection data in the Venus, Texas, study area. (A) Location map of seismic reflection profiles near Venus, Texas, Johnson County (for location, see Fig. 2), showing interpreted faults at the top of the crystalline basement, the 2008–2016 relocated seismicity (colored circles) (32), the ANSS moment tensor location of the 2015 Mw 4.0 event (location uncertainty ± 4.5 km). SHmax orientation from Lund Snee and Zoback (42). Squares are saltwater disposal wells with production well numbers [American Petroleum Institute (API)]. (B) Unmarked time-migrated, depth-converted seismic reflection profiles. (C) Interpreted seismic reflection profiles. Red rectangles on wells show saltwater disposal injection depth intervals. Hypocentral locations (green circles) were projected only along line A. See Fig. 3 for corresponding stratigraphy in the FWB.

Fig. 5. Seismic reflection data in the Dallas-Irving, Texas, study area. (A) SMU earthquake catalog hypocentral locations projected onto the trace of the seismic profile near Irving, Texas (see map in Fig. 2). Depths of geological unit tops are based on nearby well logs. (B) Unmarked and interpreted time-migrated seismic reflection profile near Irving, Texas. Tops of stratigraphic units are constrained by the well ~500 m NE of the profile [star in (C)]. Black arrows show the two-way travel time (TWTT) of the horizontal time slice shown in (C). (C) Horizontal time slice at 2.076 s (TWTT) (normal polarity amplitude map at the top of crystalline basement) shows structures (marked by blue arrows) striking ~N40°E parallel to the general trend of the hypocenters in the basement (shown by circles, color-coded by depth) and to the average focal mechanism of the Dallas-Irving seismic sequence (N39°E). NW-SE black line shows the location of the seismic profile in (B). The yellow star is the location of production well pad.

Magnani and the group acknowledged what we’ve come to learn more and more regarding fracking ramifications: “On the basis of these observations, we must reject the hypothesis that these earthquake swarms are being triggered by tectonic forces. Rather, the data indicate that the FWB faults have experienced a remarkable lack of deformation in the past ~300 My, until the recent 2008 surge in seismicity, and independently confirm the interpretation by other authors of the recent seismic sequences in the FWB as induced rather than natural.”

The Washington Post points to supportive experts outside the study. “’This is a landmark contribution in the question of whether the Fort Worth basin earthquakes are man-made,’ said Cliff Frohlich, a geophysicist at the University of Texas at Austin who was not involved with the study. Frohlich said this research eliminates the possibility, sometimes raised by the oil and gas industry, that the Texas quakes are part of a natural cycle of faults that awaken every few thousand or million years.

“The seismic reflection data provide a powerful argument ‘that these earthquakes are something new and different,’ he said — activity stemming from the injection of wastewater deep into basement rock. (‘Most of the time it’s the large volume injection,’ he said, ‘not the little frack jobs.'”

Our sister site Planetsave reported a while back on the largest earthquake in Kansas — caused by fracking. What was the cause? Perhaps the video deserves another look.

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It Makes No Sense To Say Fracking Can Be Safe, No Matter What Guidelines Are In Place

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About the Author

Cynthia Shahan started writing by doing research as a social cultural and sometimes medical anthropology thinker. She studied and practiced both Waldorf education, and Montessori education. Eventually becoming an organic farmer, licensed AP, and mother of four unconditionally loving spirits, teachers, and environmentally conscious beings born with spiritual insights and ethics beyond this world. (She was able to advance more in this way led by her children.)



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