“Faults are not like a light switch – you don’t turn off a well and automatically stop triggering earthquakes.” — Heather DeShon, SMU seismologist.
Science journalist Anna Kuchment covered the earthquake research of a team of SMU seismologists led by SMU Associate Professor Heather DeShon and SMU Post-doctoral Researcher Paul Ogwari, who developed a unique method of data analysis that yielded the study results.
The results of the analysis showed that efforts to stop human-caused earthquakes by shutting down wastewater injection wells that serve adjacent oil and gas fields may oversimplify the challenge. The seismologists analyzed a sequence of earthquakes at DFW Airport and found that even though wastewater injection was halted after a year, the earthquakes continued.
The sequence of quakes began in 2008, and wastewater injection was halted in 2009. But earthquakes continued for at least seven more years.
“This tells us that high-volume injection, even if it’s just for a short time, when it’s near a critically stressed fault, can induce long-lasting seismicity,” said Ogwari. The earthquakes may be continuing even now, he said.
By Anna Kuchment
The Dallas Morning News
Earthquakes beneath DFW International Airport continued for seven years after an oil and gas company shut a nearby wastewater injection well that had been linked to the quakes, according to a new study by scientists at Southern Methodist University.
A wastewater well that continues to operate at the northern end of the airport – and which some area residents have said should be closed — was probably not involved in the events and poses little earthquake hazard, the researchers concluded.
“Faults are not like a light switch – you don’t turn off a well and automatically stop triggering earthquakes,” said Heather DeShon, a seismologist at Southern Methodist University and co-author of the paper, in an email.
The earthquakes at DFW Airport started on Halloween 2008, seven weeks after Chesapeake Energy began injecting wastewater into a well at the southern end of the airport. Scientists at SMU and the University of Texas at Austin investigated the quakes at the time and concluded they were most likely associated with the well.
Though Chesapeake shut its well in August 2009, earthquakes continued through at least the end of 2015. The largest, a 3.4-magnitude event, struck three years after the well was closed.
“It’s very surprising that one year of injection could produce earthquakes running for more than seven years,” said Paul Ogwari, the study’s lead author and a post-doctoral researcher at SMU. The paper was published in the Journal of Geophysical Research.
While earthquake magnitudes did not decline, Ogwari said, earthquake rates did: More than 80 percent of quakes in the sequence occurred during the first seven months of seismicity.
The DFW quakes are significant, because they mark the start of an unprecedented surge of earthquakes in North Texas and across the middle of the country.
High rates of injection and large volumes can perturb critically stressed faults, triggering earthquakes years after wastewater wells are shut in.
Efforts to stop human-caused earthquakes by shutting down wastewater injection wells that serve adjacent oil and gas fields may oversimplify the challenge, according to a new study from seismologists at Southern Methodist University, Dallas.
The seismologists analyzed a sequence of earthquakes at DFW Airport and found that even though wastewater injection was halted after a year, the earthquakes continued.
The sequence of quakes began in 2008, and wastewater injection was halted in 2009. But earthquakes continued for at least seven more years.
“This tells us that high-volume injection, even if it’s just for a short time, when it’s near a critically stressed fault, can induce long-lasting seismicity,” said SMU seismologist Paul O. Ogwari, who developed a unique method of data analysis that yielded the study results.
The earthquakes may be continuing even now, said Ogwari, whose analysis extended through 2015.
The study’s findings indicate that shutting down injection wells in reaction to earthquakes, as some states such as Oklahoma and Arkansas are doing, may not have the desired effect of immediately stopping further earthquakes, said seismologist Heather DeShon, a co-author on the study and an associate professor in the SMU Earth Sciences Department.
“The DFW earthquake sequence began on Halloween in 2008 — before Oklahoma seismicity rates had notably increased,” said DeShon. “This study revisits what was technically the very first modern induced earthquake sequence in this region and shows that even though the wastewater injector in this case had been shut off very quickly, the injection activity still perturbed the fault, so that generated earthquakes even seven years later.”
That phenomenon is not unheard of. Seismologists saw that type of earthquake response from a rash of human-induced earthquakes in Colorado after wastewater injection during the 1960s at the Rocky Mountain Arsenal near Denver. Similarly in that case, injection was started and stopped, but earthquakes continued.
Such a possibility has not been well understood outside scientific circles, said DeShon. She is a member of the SMU seismology team that has studied and published extensively on their scientific findings related to the unusual spate of human-induced earthquakes in North Texas.
“The perception is that if the oil and gas wastewater injectors are leading to this, then you should just shut the injection wells down,” DeShon said. “But Paul’s study shows that there’s a lot to be learned about the physics of the process, and by monitoring continuously for years.”
Known DFW Airport quakes number more than 400
The DFW Airport’s unprecedented earthquake clusters were the first ever documented in the history of the North Texas region’s oil-rich geological system known as the Fort Worth Basin. The quakes are also the first of multiple sequences in the basin tied to large-scale subsurface disposal of waste fluids from oil and gas operations.
The DFW Airport earthquakes began in 2008, as did high-volume wastewater injection of brine. Most of the seismic activity occurred in the first two months after injection began, primarily within .62 miles, or 1 kilometer, from the well. Other clusters then migrated further to the northeast of the well over the next seven years. The quakes were triggered on a pre-existing regional fault that trends 3.7 miles, or 6 kilometers, northeast to southwest.
Ogwari, a post-doctoral researcher in the SMU Roy M. Huffington Earth Sciences Department in Dedman College, analyzed years of existing seismic data from the region to take a deeper look at the DFW Airport sequence, which totaled 412 earthquakes through 2015.
Looking at the data for those quakes, Ogwari discovered that they had continued for at least seven years into 2015 along 80% of the fault, even though injection was stopped after only 11 months in August of 2009.
Rate of quakes declined, but magnitude has never lessened
In another important finding from the study, Ogwari found that the magnitude of the DFW Airport earthquakes didn’t lessen over time, but instead held steady. Magnitude ranged from 0.5 to 3.4, with the largest one occurring three years after injection at the well was stopped.
“What we’ve seen here is that the magnitude is consistent over time within the fault,” Ogwari said. “We expect to see the bigger events during injection or immediately after injection, followed by abrupt decay. But instead we’re seeing the fault continue to produce earthquakes with similar magnitudes that we saw during injection.”
While the rate of earthquakes declined — there were 23 events a month from 2008 to 2009, but only 1 event a month after May 2010 — the magnitude stayed the same. That indicates the fault doesn’t heal completely.
“We don’t know why that is,” Ogwari said. “I think that’s a question that is out there and may need more research.”
More monitoring needed for human-induced quakes
Answering that question, and others, about the complex characteristics and behavior of faults and earthquakes, requires more extensive monitoring than is currently possible given the funding allotted to monitor quakes.
Monitoring the faults involves strategically placed stations that “listen” and record waves of intense energy echoing through the ground, DeShon said.
The Fort Worth Basin includes the Barnett shale, a major gas producing geological formation, atop the deep Ellenberger formation used for wastewater storage, which overlays a granite basement layer. The ancient Airport fault system extends through all units.
Friction prevented the fault from slipping for millions of years, but in 2008 high volumes of injected wastewater disturbed the Airport fault. That caused the fault to slip, releasing stored-up energy in waves. The most powerful waves were “felt” as the earth shaking.
“The detailed physical equations relating wastewater processes to fault processes is still a bit of a question,” DeShon said. “But generally the favored hypothesis is that the injected fluid changes the pressure enough to change the ratio of the downward stress to the horizontal stresses, which allows the fault to slip.”
Earthquakes in North Texas were unheard of until 2008, so when they began to be felt, seismologists scrambled to install monitors. When the quakes died down, the monitoring stations were removed.
“As it stands now, we miss the beginning of the quakes. The monitors are removed when the earthquakes stop being felt,” DeShon said. “But this study tells us that there’s more to it than the ‘felt’ earthquakes. We need to know how the sequences start, and also how they end. If we’re ever going to understand what’s happening, we need the beginning, the middle — and the end. Not just the middle, after they are felt.”
Innovative method tapped for studying earthquake activity
Monitors the SMU team installed at the DFW Airport were removed when seismic activity appeared to have died down in 2009.
Ogwari hypothesized he could look at historical data from distant monitoring stations still in place to extract information and document the history of the DFW Airport earthquakes.
The distant stations are a part of the U.S. permanent network monitored and maintained by the U.S. Geological Survey. The nearest one is 152 miles, 245 kilometers, away.
Earthquake waveforms, like human fingerprints, are unique. Ogwari used the local station monitoring data to train software to identify DFW earthquakes on the distant stations. Ogwari took each earthquake’s digital fingerprint and searched through years of data, cross-correlating waveforms from both the near and regional stations and identified the 412 DFW Airport events.
“The earthquakes are small, less than magnitude three,” DeShon said. “So on the really distant stations it’s like searching for a needle in a haystack, sifting them from all the other tiny earthquakes happening all across the United States.”
Each path is unique for every earthquake, and seismologists record each wave’s movement up and down, north to south, and east to west. From that Ogwari analyzed the evolution of seismicity on the DFW airport fault over space and time. He was able to look at data from the distant monitors and find seismic activity at the airport as recent as 2015.
“Earthquakes occurring close in space usually have a higher degree of similarity,” Ogwari said. “As the separation distance increases the similarity decreases.”
To understand the stress on the fault, the researchers also modeled the location and timing of the pressure in the pores of the rock as the injected water infiltrated.
For the various earthquake clusters, the researchers found that pore pressure increased along the fault at varying rates, depending on how far the clusters were from the injection well, the rate and timing of injection, and hydraulic permeability of the fault.
The analysis showed pore-pressure changes to the fault from the injection well where the earthquakes started in 2008; at the location of the May 2010 quakes along the fault; and at the northern edge of the seismicity.
Will the DFW Airport fault continue to slip and trigger earthquakes?
“We don’t know,” Ogwari said. “We can’t tell how long it will continue. SMU and TexNet, the Texas Seismic Network, continue to monitor both the DFW Airport faults and other faults in the Basin.” — Margaret Allen, SMU
For 300 million years faults showed no activity, and then wastewater injections from oil and gas wells came along. Study authors took a different approach in the new work — they hunted for deformed faults below Texas.
Science journalist Anna Kuchment covered the landmark earthquake research of a team of SMU geophysicists led by SMU Associate Professor Beatrice Magnani in the SMU Department of Earth Sciences. Kuchment wrote Drilling Reawakens Sleeping Faults in Texas, Leads to Earthquakes for Scientific American.
The SMU researchers tapped seismic data to analyze earthquakes in Texas over the past decade.
The results of the analysis showed that human activity is causing the earthquakes as a result of movement in faults that have been silent for at least 300 million years, until recent injection of oil and gas wastewater.
By Anna Kuchment
Scientific American
Since 2008, Texas, Oklahoma, Kansas and a handful of other states have experienced unprecedented surges of earthquakes. Oklahoma’s rate increased from one or two per year to more than 800. Texas has seen a sixfold spike. Most have been small, but Oklahoma has seen several damaging quakes stronger than magnitude 5. While most scientists agree that the surge has been triggered by the injection of wastewater from oil and gas production into deep wells, some have suggested these quakes are natural, arising from faults in the crust that move on their own every so often. Now researchers have traced 450 million years of fault history in the Dallas-Fort Worth area and learned these faults almost never move. “There hasn’t been activity along these faults for 300 million years,” says Beatrice Magnani, a seismologist at Southern Methodist University in Dallas and lead author of a paper describing the research, published today in Science Advances. “Geologically, we usually define these faults as dead.”
Magnani and her colleagues argue that these faults would not have produced the recent earthquakes if not for wastewater injection. Pressure from these injections propagates underground and can disturb weak faults. The work is another piece of evidence implicating drilling in the quakes, yet the Texas government has not officially accepted the link to one of its most lucrative industries.
Magnani and her colleagues studied the Texas faults using images of the subsurface similar to ultrasound scans. Known as seismic reflection data, the images are created by equipment that generates sound waves and records the speeds at which the waves bounce off faults and different rock layers deep within the ground. Faults that have produced earthquakes look like vertical cracks in a brick wall, where one side of the wall has sunk down a few inches so the rows of bricks no longer line up. Scientists know the age of each rock layer—each row of bricks–based on previous studies that have used a variety of dating techniques.
The study authors took a different approach in the new work — they hunted for deformed faults below Texas.
The Washington Post covered the landmark earthquake research of a team of SMU geophysicists led by SMU Associate Professor Beatrice Magnani in the SMU Department of Earth Sciences.
The researchers tapped seismic data to analyze earthquakes in Texas over the past decade.
The results of the analysis showed that human activity is causing the earthquakes as a result of movement in faults that have been silent for at least 300 million years, until recent injection of oil and gas wastewater.
By Ben Guarino
The Washington Post
An unnatural number of earthquakes hit Texas in the past decade, and the region’s seismic activity is increasing. In 2008, two earthquakes stronger than magnitude 3 struck the state. Eight years later, 12 did.
Natural forces trigger most earthquakes. But humans are causing earthquakes, too, with mining and dam construction the most frequent suspects. There has been a recent increase in natural gas extraction — including fracking, or hydraulic fracturing, but other techniques as well — which 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.
But for any given earthquake, it is virtually impossible to tell whether humans or nature triggered the quake. There are no known characteristics of a quake, not in magnitude nor in the shape of its seismic waves, that provide hints to its origins.
“It’s been a head-scratching period for scientists,” said Maria Beatrice Magnani, who studies earthquakes at Southern Methodist University in Dallas. Along with a team of researchers at the U.S. Geological Survey, Magnani, an author of a new report published Friday in the journal Science Advances, attempted to better identify what has been causing the rash of Texas quakes.
A cluster of earthquakes around a drilling project can, at best, suggest a relationship. “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.
Study by Beatrice Magnani, USGS and other SMU scientists shows recent seismicity in Fort Worth Basin occurred on faults not active for 300 million years
Recent earthquakes in the Fort Worth Basin — in the rural community of Venus and the Dallas suburb of Irving – occurred on faults that had not been active for at least 300 million years, according to research led by SMU seismologist Beatrice Magnani.
The research supports the assertion that recent North Texas earthquakes were induced, rather than natural – a conclusion entirely independent of previous analyses correlating seismicity to the timing of wastewater injection practices, but that corroborates those earlier findings.
“To our knowledge this is the first study to discriminate natural and induced seismicity using classical structural geology analysis techniques,” said Magnani, associate professor of geophysics in SMU’s Huffington Department of Earth Sciences. Co-authors for the study include Michael L. Blanpied, associate coordinator of the USGS Earthquake Hazard program, and SMU seismologists Heather DeShon and Matthew Hornbach.
The results were drawn from analyzing the history of fault slip (displacement) over the lifetime of the faults. The authors analyzed seismic reflection data, which allow “mapping” of the Earth’s subsurface from reflected, artificially generated seismic waves. Magnani’s team compared data from the North Texas area, where several swarms of felt earthquakes have been occurring since 2008, to data from the Midwestern U.S. region that experienced major earthquakes in 1811 and 1812 in the New Madrid seismic zone.
Frequent small earthquakes are still recorded in the New Madrid seismic zone, which is believed to hold the potential for larger earthquakes in the future.
“These North Texas faults are nothing like the ones in the New Madrid Zone – the faults in the Fort Worth Basin are dead,” Magnani said. “The most likely explanation for them to be active today is because they are being anthropogenically induced to move.”
In the New Madrid seismic zone, the team found that motion along the faults that are currently active has been occurring over many millions of years. This has resulted in fault displacements that grow with increasing age of sedimentary formations.
In the Fort Worth Basin, along faults that are currently seismically active, there is no evidence of prior motion over the past 300 million years.
“The study’s findings suggest that the recent Fort Worth Basin earthquakes, which involve swarms of activity on several faults in the region, have been induced by human activity,” said USGS scientist Blanpied.
The findings further suggest that these North Texas earthquakes are not simply happening somewhat sooner than they would have otherwise on faults continually active over long time periods. Instead, Blanpied said, the study indicates reactivation of long-dormant faults as a consequence of waste fluid injection.
Seismic reflection profiles in the Venus region used for this study were provided by the U.S. Geological Survey Earthquake Hazards Program.
Seismic reflection profiles for the Irving area are proprietary. Magnani and another team of scientists collected seismic reflection data used for this research during a 2008-2011 project in the northern Mississippi embayment, home to the New Madrid seismic zone. — Kim Cobb, SMU
Long-awaited study puts forth explanation for exponential increase in North Texas earthquakes, citing unprecedented wastewater injection into a geological formation above seismically active zones.
In an article contributed to The Dallas Morning News, science journalist Anna Kuchment covered the research of SMU seismologists on a possible explanation for the spate of earthquakes in North Texas in recent years.
Co-authors are SMU students and faculty Madeline Jones, Monique Scales, Heather DeShon, Beatrice Magnani, Brian Stump, Chris Hayward and Mary Layton, and University of Texas at Austin seismologist Cliff Frohlich.
By Anna Kuchment
Dallas Morning News
In a long-awaited study, researchers have offered a possible explanation for how oil and gas activity may have triggered earthquakes in Dallas and Irving last year.
The disposal of wastewater from oil and gas production and hydraulic fracturing “plausibly” set off the tremors, which shook Dallas, Irving, Highland Park and other cities from April 2014 through January 2016, said Matthew Hornbach, the study’s lead author and professor of geophysics at Southern Methodist University.
While the quakes were too small to cause much damage to buildings, they spread alarm through a metro area unaccustomed to feeling the ground shift.
The quakes contributed to a tenfold increase in North Texas’ earthquake hazard level, prompted the Federal Emergency Management Agency to warn of stronger quakes that could cause billions of dollars of damage, and moved local emergency managers to begin preparing for worst-case scenarios.
The study, posted online this week in the peer-reviewed journal Physics of the Earth and Planetary Interiors, is the first scientific work to offer an explanation for the Dallas and Irving quakes. It also provides new evidence that other recent quakes in North Texas’ were likely induced by humans.
Such findings in recent years have prompted pushback from oil and gas companies. This week, through a trade group, they again came out swinging. Steve Everley, a spokesman for an arm of the Independent Petroleum Association of America, questioned the scientists’ work. “Were they looking for media attention?” Everley said in an email. “The authors’ willingness to shift assumptions to fit a particular narrative is concerning, to say the least.”
The state agency that regulates oil and gas, the Railroad Commission, said in a statement that it was reviewing the report “to fully understand its methodology and conclusions.”
Independent experts contacted by The Dallas Morning News praised the study, while cautioning that more work remains before the cause of the Dallas and Irving earthquakes can be firmly established.
“It’s the single best explanation for the increase in earthquakes within the Dallas-Fort Worth basin,” said Rall Walsh, a Ph.D. candidate in geophysics at Stanford University who studies human-triggered earthquakes.
A new study Texas seismology researchers finds that humans have been causing earthquakes not just in North Texas but throughout the state for nearly 100 years.
Science journalist Anna Kuchment with The Dallas Morning News covered the research of SMU seismologists on the historical record of North Texas earthquakes and their causes.
The SMU seismology team on May 18 published online new evidence of human involvement in earthquakes since the 1920s in the journal Seismological Research Letters. The study found that human-caused earthquakes have been present since at least 1925, and widespread throughout the state. While they are tied to oil and gas operations, the specific production techniques behind these quakes have differed over the decades, according to Cliff Frohlich, Heather DeShon, Brian Stump, Chris Hayward, Mathew J. Hornbach and Jacob I. Walter.
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By Anna Kuchment
Dallas Morning News
Despite mounting evidence that oil and gas activity has triggered all of the recent earthquakes in Dallas and Fort Worth, Texas regulators have consistently questioned the link. Now a new study by University of Texas researchers argues that humans have been causing earthquakes not just in North Texas but throughout the state for nearly 100 years.
“The public thinks these started in 2008, but nothing could be further from the truth,” said Cliff Frohlich, a senior research scientist at UT-Austin and lead author of the new study.
The paper, to be published Wednesday in the journal Seismological Research Letters, concludes that activities associated with petroleum production “almost certainly” or “probably” set off 59 percent of earthquakes across the state between 1975 and 2015, including the recent earthquakes in Irving and Dallas. Another 28 percent were “possibly” triggered by oil and gas activities. Scientists deemed only 13 percent of the quakes to be natural.
A spokesperson for the Railroad Commission of Texas, which regulates the oil and gas industry, dismissed the study’s methods as “arbitrary,” but an expert at the U.S. Geological Survey said the study offers important new information that could affect the agency’s future threat assessments for Texas.
“The Commission will continue to use objective, credible scientific study as the basis for our regulatory and rulemaking functions,” Ramona Nye, a spokeswoman for the Railroad Commission, wrote in an email after she and her colleagues reviewed an embargoed copy of the paper. “However this new study acknowledges the basis for its conclusions are purely subjective in nature and in fact, admits its categorization of seismic events to be arbitrary.”
Frohlich and colleagues at UT and at Southern Methodist University argue in the paper that state regulators have been slow to acknowledge the link between industrial practices and ground shaking. Oklahoma, which experienced 890 earthquakes of magnitude 3 and above last year compared with Texas’ 21, has recognized the connection and ordered operators to slash the volume of wastewater from oil and gas production that they pump into wells. Studies by academic scientists and those at the USGS have shown that pressure from high-volume wastewater injections has disturbed faults in Oklahoma, Texas, Kansas, Arkansas and a handful of other states, creating earthquakes.
The Railroad Commission has taken some similar steps, Nye wrote. In November 2014 the commission tightened its rules for disposal wells. Since then, it has received 51 disposal well applications. Of these, 22 permits were issued with special conditions, such as requirements to reduce daily maximum injection volumes and pressure and to record volumes and pressures daily as opposed to monthly.
Following a 4-magnitude earthquake near Venus and Mansfield last year, the commission asked one operator to plug its well to a shallower depth, Nye added, presumably to lower the risk that it would disturb a deep fault. Texas’ man-made earthquakes date to the early days of the oil and gas industry, the new study reports.
The first man-made quake struck in 1925 in the Goose Creek oil field along the Gulf Coast east of Houston. Humble Oil, a precursor of Exxon, had extracted so much oil that the ground sank and caused houses to shake and dishes to crash to the floor.
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Since 2008 the rate of Texas earthquakes greater than magnitude 3 has increased from about two per year to 12 per year, say the authors.
Earthquakes triggered by human activity have been happening in Texas since at least 1925, and they have been widespread throughout the state ever since, according to a new historical review of the evidence publishing online May 18 in Seismological Research Letters.
The earthquakes are caused by oil and gas operations, but the specific production techniques behind these quakes have differed over the decades, according to Cliff Frohlich, the study’s lead author, and co-authors Heather DeShon, Brian Stump, Chris Hayward, Mathew J. Hornbach and Jacob I. Walter.
Frohlich is senior research scientist and associate director at the Institute for Geophysics at the University of Texas at Austin. DeShon, Stump, Hayward and Hornbach are seismologists in the Roy M. Huffington Department of Earth Sciences, Southern Methodist University, Dallas. Walter is at the University of Texas at Austin.
Frohlich said the evidence presented in the SRL paper should lay to rest the idea that there is no substantial proof for human-caused earthquakes in Texas, as some state officials have claimed as recently as 2015.
At the same time, he said, the study doesn’t single out any one or two industry practices that could be managed or avoided to stop these kinds of earthquakes from occurring. “I think we were all looking for what I call the silver bullet, supposing we can find out what kinds of practices were causing the induced earthquakes, to advise companies or regulators,” he notes. “But that silver bullet isn’t here.”
The researchers write in the article “A Historical Overview of Induced Earthquakes in Texas” that since 2008, the rate of Texas earthquakes greater than magnitude 3 has increased from about two per year to 12 per year. This change appears to stem from an increase in earthquakes occurring within 1-3 kilometers of petroleum production wastewater disposal wells where water is injected at a high monthly rate, they note.
Some of these more recent earthquakes include the Dallas-Fort Worth International Airport sequence between 2008 and 2013; the May 2012 Timpson earthquake; and the earthquake sequence near Azle that began in 2013.
The researchers suspected that induced seismicity might have a lengthy and geographically widespread history in Texas.
“For me, the surprise was that oil field practices have changed so much over the years, and that probably affects the kinds of earthquakes that were happening at each time,” Frohlich said.
In the 1920s and 1930s, for instance, “they’d find an oilfield, and hundreds of wells would be drilled, and they’d suck oil out of the ground as fast as they could, and there would be slumps” that shook the earth as the volume of oil underground was rapidly extracted, he said.
When those fields were mostly depleted, in the 1940s through the 1970s, petroleum operations “started being more aggressive about trying to drive oil by water flooding” and the huge amounts of water pumped into the ground contributed to seismic activity, said Frohlich.
In the past decade, enhanced oil and gas recovery methods have produced considerable amounts of wastewater that is disposed by injection back into the ground through special wells, triggering nearby earthquakes. Most earthquakes linked to this type of wastewater disposal in Texas are smaller (less than magnitude 3) than those in Oklahoma, the study concludes.
The difference may lie in the types of oil operations in each state, Frohlich said. The northeast Texas injection earthquakes occur near high-injection rate wells that dispose of water produced in hydrofracturing operations, while much of the Oklahoma wastewater is produced during conventional oil production and injected deep into the underlying sedimentary rock.
For the moment, there have been no magnitude 3 or larger Texas earthquakes that can be linked directly to the specific process of hydrofracturing or fracking itself, such as have been felt in Canada, the scientists concluded.
The researchers used a five-question test to identify induced earthquakes in the Texas historical records. The questions cover how close in time and space earthquakes and petroleum operations are, whether the earthquake center is at a relatively shallow depth (indicating a human rather than natural trigger); whether there are known or suspected faults nearby that might support an earthquake or ease the way for fluid movement, and whether published scientific reports support a human cause for the earthquake.
In 2015, the Texas legislature funded a program that would install 22 additional seismic monitoring stations to add to the state’s existing 17 permanent stations, with the hopes of building out a statewide monitoring network that could provide more consistent and objective data on induced earthquakes.
Seismological Research Letters is a publication of the Seismological Society of America. — Seismological Research Letters
Southern Methodist University preliminary earthquake catalog for the Irving-Dallas earthquake swarm. The SMU North Texas seismic network has recorded over 600 earthquakes ranging from magnitude 0.0-3.6 in the Dallas-Irving region. Earthquakes recorded prior to Jan. 17, 2015 have a higher location uncertainty than events recorded after the complete seismic network was installed. Current seismic sensors recording the sequence are shown as gray symbols; note that some sensors are outside of the map boundaries. US Geological Survey NetQuakes data (squares) can be viewed online. Earthquake symbol size is scaled by magnitude and color coded by date of occurrence. The map is provided as part of the ongoing collaboration between SMU, the USGS, Irving, Dallas, and neighboring cities. The SMU preliminary earthquake locations and magnitudes have not been published in the peer-reviewed scientific literature and are subject to change. Prepared March 22, 2016.
The United States Geological Survey (USGS) today released maps showing potential ground shaking from induced and natural earthquakes, including forecasts for the DFW metropolitan area. The North Texas Earthquake Study at Southern Methodist University provided data, and SMU scientists co-authored peer-reviewed publications cited in the report. The new earthquake ground shaking forecasts are a reminder to the cities and residents in the region that the occurrence of earthquakes increases the earthquake hazard in the area, regardless of cause. Residents should be prepared to experience ground shaking, just as we are prepared to experience tornadoes, hail storms and other events.
FAQs
1. How did SMU research contribute to the USGS report?
SMU and partners currently operate a 30-station seismic network across North Texas, and stations are denser around the ongoing earthquake sequences (Azle-Reno, Irving-Dallas, and Venus-Johnson County). We focus on cataloging the ongoing seismicity over a wider range of magnitudes than the national USGS catalog documents, conducting detailed source studies to understand the physics of faulting, and identifying and mapping faults currently or potentially generating seismicity. We also study cause with the aim of potentially mitigating the increased seismicity rates experienced in North Texas since 2008. Finally, in order to provide improved local estimates of both the size of the earthquakes as well as their source characteristics, we are analyzing the locally recorded waveforms to produce empirical estimates of how ground shaking decays with range for each of the instrumented source regions. These empirical decay rates may provide data for refining the ground shaking forecasts.
The SMU research in its entirety helps inform appropriate parameter ranges for earthquake hazard mapping, and we therefore collaborate and cooperate with the USGS, as was done in preparation for the 2016 report being released Monday, and with city, state and federal agencies.
Peer-reviewed publications by SMU scientists and collaborators were used to classify most North Texas earthquakes as induced. These publications include those on the 2008-2009 DFW sequence (Frohlich et al., 2011), the 2009 Cleburne earthquakes (Justinic et al., 2012), and the 2013-2014 Azle-Reno earthquakes (Hornbach et al., 2015). Dr. Cliff Frohlich (UT-Austin) has published on induced earthquakes in Johnson County near the eventual 2015 Venus earthquake (Frohlich, 2012). Peer-reviewed publications regarding cause for the Irving-Dallas sequence had not been accepted for publication and the earthquakes were left classified as “undetermined cause” in the 2016 Induced Earthquake Hazard Mapping Project and treated as natural earthquakes in the probabilistic calculations for ground motion.
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2. What can and should DFW Metroplex residents do with this information?
The new earthquake ground shaking forecasts are a reminder to the cities and residents in the region that the occurrence of earthquakes increases the earthquake hazard in the area, regardless of cause. Residents should be prepared to experience ground shaking, just as we are prepared to experience tornadoes, hail storms and other events. People should remember to Drop, Cover and Hold On during an earthquake and not to evacuate a building until after shaking has stopped. Brick façade damage is possible under low to mid-intensity shaking, and you are most likely to be injured by falling objects and broken windows than by building collapse at the levels of ground shaking outlined in the USGS report.
We encourage residents to explore online resources on preparedness, such as the resources made available through FEMA and the USGS. Following the seven steps to earthquake safety is always a good idea: http://earthquakecountry.org/sevensteps/.
3. Have you been recording earthquakes in the Dallas-Irving area or has that sequence stopped?
The Irving-Dallas earthquakes began in April 2014 with the largest events occurring in January 2015. Earthquake rates in the Dallas-Irving area have been highly variable. While the rate has decreased over the last few months, we have seen similar short-term decreases in the past, and therefore the rate change should not be over-interpreted.
4. What is the earthquake magnitude equivalent of the USGS ground shaking forecast?
Earthquake magnitude is not the same as ground shaking intensity. Hazard maps are used to forecast ground shaking intensities, regardless of the magnitude of the earthquake that creates the motion. Ground motion, and hence hazard, depends on the earthquake size, distance from the epicenter, local geology, etc. Online resources equating intensity to magnitude are “rule of thumb” and should not be interpreted as directly relating the ground shaking forecasts to earthquake magnitude in the DFW area. Risk calculations use the known properties of building and infrastructure to estimate the probability of damage based on the underlying hazard assessment from ground shaking intensities.
Magnitude tells you the overall size of the earthquake. A single earthquake has one magnitude.
Intensity tells you what the earthquake shaking was like at a particular location. A single earthquake produces a range of intensities that depend on the location. The USGS “Did you feel it?” for the 2015 Irving-Dallas M3.6 illustrates this point. The Modified Mercalli Scale is described further here: http://earthquake.usgs.gov/learn/topics/mercalli.php. — Kim Cobb
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
SMU scientists and their research have a global reach that is frequently noted, beyond peer publications and media mentions.
By Margaret Allen
SMU News & Communications
It was a good year for SMU faculty and student research efforts. Here is a small sampling of public and published acknowledgements during 2015:
Hot topic merits open access
Taylor & Francis, publisher of the online journal Environmental Education Research, lifted its subscription-only requirement to meet demand for an article on how climate change is taught to middle-schoolers in California.
Co-author of the research was Diego Román, assistant professor in the Department of Teaching and Learning, Annette Caldwell Simmons School of Education and Human Development.
Román’s research revealed that California textbooks are teaching sixth graders that climate change is a controversial debate stemming from differing opinions, rather than a scientific conclusion based on rigorous scientific evidence.
Research makes the cover of Biochemistry
Drugs important in the battle against cancer were tested in a virtual lab by SMU biology professors to see how they would behave in the human cell.
A computer-generated composite image of the simulation made the Dec. 15 cover of the journal Biochemistry.
Scientific articles about discoveries from the simulation were also published in the peer review journals Biochemistry and in Pharmacology Research & Perspectives.
The researchers tested the drugs by simulating their interaction in a computer-generated model of one of the cell’s key molecular pumps — the protein P-glycoprotein, or P-gp. Outcomes of interest were then tested in the Wise-Vogel wet lab.
The ongoing research is the work of biochemists John Wise, associate professor, and Pia Vogel, professor and director of the SMU Center for Drug Discovery, Design and Delivery in Dedman College. Assisting them were a team of SMU graduate and undergraduate students.
The researchers developed the model to overcome the problem of relying on traditional static images for the structure of P-gp. The simulation makes it possible for researchers to dock nearly any drug in the protein and see how it behaves, then test those of interest in an actual lab.
To date, the researchers have run millions of compounds through the pump and have discovered some that are promising for development into pharmaceutical drugs to battle cancer.
Strong interest in research on sexual victimization
Teen girls were less likely to report being sexually victimized after learning to assertively resist unwanted sexual overtures and after practicing resistance in a realistic virtual environment, according to three professors from the SMU Department of Psychology.
The finding was reported in Behavior Therapy. The article was one of the psychology journal’s most heavily shared and mentioned articles across social media, blogs and news outlets during 2015, the publisher announced.
The study was the work of Dedman College faculty Lorelei Simpson Rowe, associate professor and Psychology Department graduate program co-director; Ernest Jouriles, professor; and Renee McDonald, SMU associate dean for research and academic affairs.
Consumers assume bigger price equals better quality
Even when competing firms can credibly disclose the positive attributes of their products to buyers, they may not do so.
Instead, they find it more lucrative to “signal” quality through the prices they charge, typically working on the assumption that shoppers think a high price indicates high quality. The resulting high prices hurt buyers, and may create a case for mandatory disclosure of quality through public policy.
That was a finding of the research of Dedman College’s Santanu Roy, professor, Department of Economics. Roy’s article about the research was published in February in one of the blue-ribbon journals, and the oldest, in the field, The Economic Journal.
Published by the U.K.’s Royal Economic Society, The Economic Journal is one of the founding journals of modern economics. The journal issued a media briefing about the paper, “Competition, Disclosure and Signaling,” typically reserved for academic papers of broad public interest.
Chemistry research group edits special issue
Chemistry professors Dieter Cremer and Elfi Kraka, who lead SMU’s Computational and Theoretical Chemistry Group, were guest editors of a special issue of the prestigious Journal of Physical Chemistry. The issue published in March.
The Computational and Theoretical research group, called CATCO for short, is a union of computational and theoretical chemistry scientists at SMU. Their focus is research in computational chemistry, educating and training graduate and undergraduate students, disseminating and explaining results of their research to the broader public, and programming computers for the calculation of molecules and molecular aggregates.
The special issue of Physical Chemistry included 40 contributions from participants of a four-day conference in Dallas in March 2014 that was hosted by CATCO. The 25th Austin Symposium drew 108 participants from 22 different countries who, combined, presented eight plenary talks, 60 lectures and about 40 posters.
CATCO presented its research with contributions from Cremer and Kraka, as well as Marek Freindorf, research assistant professor; Wenli Zou, visiting professor; Robert Kalescky, post-doctoral fellow; and graduate students Alan Humason, Thomas Sexton, Dani Setlawan and Vytor Oliveira.
There have been more than 75 graduate students and research associates working in the CATCO group, which originally was formed at the University of Cologne, Germany, before moving to SMU in 2009.
Vertebrate paleontology recognized with proclamation
Dallas Mayor Mike Rawlings proclaimed Oct. 11-17, 2015 Vertebrate Paleontology week in Dallas on behalf of the Dallas City Council.
The proclamation honored the 75th Annual Meeting of the Society of Vertebrate Paleontology, which was jointly hosted by SMU’s Roy M. Huffington Department of Earth Sciences in Dedman College and the Perot Museum of Science and Nature. The conference drew to Dallas some 1,200 scientists from around the world.
Making research presentations or presenting research posters were: faculty members Bonnie Jacobs, Louis Jacobs, Michael Polcyn, Neil Tabor and Dale Winkler; adjunct research assistant professor Alisa Winkler; research staff member Kurt Ferguson; post-doctoral researchers T. Scott Myers and Lauren Michael; and graduate students Matthew Clemens, John Graf, Gary Johnson and Kate Andrzejewski.
The host committee co-chairs were Anthony Fiorillo, adjunct research professor; and Louis Jacobs, professor. Committee members included Polcyn; Christopher Strganac, graduate student; Diana Vineyard, research associate; and research professor Dale Winkler.
KERA radio reporter Kat Chow filed a report from the conference, explaining to listeners the science of vertebrate paleontology, which exposes the past, present and future of life on earth by studying fossils of animals that had backbones.
SMU earthquake scientists rock scientific journal
Modelled pressure changes caused by injection and production. (Nature Communications/SMU)
Findings by the SMU earthquake team reverberated across the nation with publication of their scientific article in the prestigious British interdisciplinary journal Nature, ranked as one of the world’s most cited scientific journals.
The article reported that the SMU-led seismology team found that high volumes of wastewater injection combined with saltwater extraction from natural gas wells is the most likely cause of unusually frequent earthquakes occurring in the Dallas-Fort Worth area near the small community of Azle.
The research was the work of Dedman College faculty Matthew Hornbach, associate professor of geophysics; Heather DeShon, associate professor of geophysics; Brian Stump, SMU Albritton Chair in Earth Sciences; Chris Hayward, research staff and director geophysics research program; and Beatrice Magnani, associate professor of geophysics.
The article, “Causal factors for seismicity near Azle, Texas,” published online in late April. Already the article has been downloaded nearly 6,000 times, and heavily shared on both social and conventional media. The article has achieved a ranking of 270, which puts it in the 99th percentile of 144,972 tracked articles of a similar age in all journals, and 98th percentile of 626 tracked articles of a similar age in Nature.
“It has a very high impact factor for an article of its age,” said Robert Gregory, professor and chair, SMU Earth Sciences Department.
The scientific article also was entered into the record for public hearings both at the Texas Railroad Commission and the Texas House Subcommittee on Seismic Activity.
Researchers settle long-debated heritage question of “The Ancient One”
The skull of Kennewick Man and a sculpted bust by StudioEIS based on forensic facial reconstruction by sculptor Amanda Danning. (Credit: Brittany Tatchell)
The research of Dedman College anthropologist and Henderson-Morrison Professor of Prehistory David Meltzer played a role in settling the long-debated and highly controversial heritage of “Kennewick Man.”
Also known as “The Ancient One,” the 8,400-year-old male skeleton discovered in Washington state has been the subject of debate for nearly two decades. Argument over his ancestry has gained him notoriety in high-profile newspaper and magazine articles, as well as making him the subject of intense scholarly study.
Officially the jurisdiction of the U.S. Army Corps of Engineers, Kennewick Man was discovered in 1996 and radiocarbon dated to 8500 years ago.
Because of his cranial shape and size he was declared not Native American but instead ‘Caucasoid,’ implying a very different population had once been in the Americas, one that was unrelated to contemporary Native Americans.
But Native Americans long have claimed Kennewick Man as theirs and had asked for repatriation of his remains for burial according to their customs.
Meltzer, collaborating with his geneticist colleague Eske Willerslev and his team at the Centre for GeoGenetics at the University of Copenhagen, in June reported the results of their analysis of the DNA of Kennewick in the prestigious British journal Nature in the scientific paper “The ancestry and affiliations of Kennewick Man.”
The results were announced at a news conference, settling the question based on first-ever DNA evidence: Kennewick Man is Native American.
The announcement garnered national and international media attention, and propelled a new push to return the skeleton to a coalition of Columbia Basin tribes. Sen. Patty Murray (D-WA) introduced the Bring the Ancient One Home Act of 2015 and Washington Gov. Jay Inslee has offered state assistance for returning the remains to Native Tribes.
Science named the Kennewick work one of its nine runners-up in the highly esteemed magazine’s annual “Breakthrough of the Year” competition.
The research article has been viewed more than 60,000 times. It has achieved a ranking of 665, which puts it in the 99th percentile of 169,466 tracked articles of a similar age in all journals, and in the 94th percentile of 958 tracked articles of a similar age in Nature.
In “Kennewick Man: coming to closure,” an article in the December issue of Antiquity, a journal of Cambridge University Press, Meltzer noted that the DNA merely confirmed what the tribes had known all along: “We are him, he is us,” said one tribal spokesman. Meltzer concludes: “We presented the DNA evidence. The tribal members gave it meaning.”
Prehistoric vacuum cleaner captures singular award
Paleontologists Louis L. Jacobs, SMU, and Anthony Fiorillo, Perot Museum, have identified a new species of marine mammal from bones recovered from Unalaska, an Aleutian island in the North Pacific. (Hillsman Jackson, SMU)
Science writer Laura Geggel with Live Science named a new species of extinct marine mammal identified by two SMU paleontologists among “The 10 Strangest Animal Discoveries of 2015.”
The new species, dubbed a prehistoric hoover by London’s Daily Mail online news site, was identified by SMU paleontologist Louis L. Jacobs, a professor in the Roy M. Huffington Department of Earth Sciences, Dedman College of Humanities and Sciences, and paleontologist and SMU adjunct research professor Anthony Fiorillo, vice president of research and collections and chief curator at the Perot Museum of Nature and Science.
Jacobs and Fiorillo co-authored a study about the identification of new fossils from the oddball creature Desmostylia, discovered in the same waters where the popular “Deadliest Catch” TV show is filmed. The hippo-like creature ate like a vacuum cleaner and is a new genus and species of the only order of marine mammals ever to go extinct — surviving a mere 23 million years.
Desmostylians, every single species combined, lived in an interval between 33 million and 10 million years ago. Their strange columnar teeth and odd style of eating don’t occur in any other animal, Jacobs said.
As noted by the CERN Courier — the news magazine of the CERN Laboratory in Geneva, which hosts the Large Hadron Collider, the world’s largest science experiment — more than 250 scientists from 30 countries presented more than 200 talks on a multitude of subjects relevant to experimental and theoretical research. SMU physicists presented at the conference.
The SMU organizing committee was led by Fred Olness, professor and chair of the SMU Department of Physics in Dedman College, who also gave opening and closing remarks at the conference. The committee consisted of other SMU faculty, including Jodi Cooley, associate professor; Simon Dalley, senior lecturer; Robert Kehoe, professor; Pavel Nadolsky, associate professor, who also presented progress on experiments at CERN’s Large Hadron Collider; Randy Scalise, senior lecturer; and Stephen Sekula, associate professor.
Sekula also organized a series of short talks for the public about physics and the big questions that face us as we try to understand our universe.
Evidence that human activity is behind the Dallas quakes includes a new analysis showing that the faults beneath Dallas and Fort Worth had been dormant for hundreds of millions of years until 2008.
SMU seismologists presented new earthquake findings at the American Geophysical Union annual meeting. (Credit: DMN)
Science journalist Anna Kuchment with The Dallas Morning News covered the comments of SMU seismologists Heather DeShon and Beatrice Magnani speaking during the annual American Geophysical Union meeting in San Francisco, Calif. DeShon and Magnani presented their latest research on North Texas ground shaking.
The SMU seismology team, which includes DeShon and Magnani, published new evidence of human involvement in earthquakes in Nature Communications in April 2015. Their data showed that large volumes of wastewater injection combined with saltwater (brine) extraction from natural gas wells is the most likely cause of earthquakes near Azle, Texas, from late 2013 through spring 2014.
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By Anna Kuchment
The Dallas Morning News
Scientists presented new evidence this week suggesting that all five North Texas earthquake sequences, including those in Dallas, have been triggered by humans.
Until now, researchers have not commented on the cause of the Dallas-Irving quakes or the 4-magnitude quake that struck Venus, 30 miles south of Dallas, in May.
While scientists believe that high-volume injection wells may have triggered the quakes in Venus, they have not yet worked out a specific mechanism behind the Dallas and Irving quakes.
“We don’t think they’re natural,” SMU seismologist Heather DeShon told The Dallas Morning News. “But we don’t understand the subsurface physics surrounding the Irving earthquake sequence, so we’re still considering all causes.”
DeShon’s comments came during the annual American Geophysical Union meeting in San Francisco, where she and her colleagues presented their latest research on North Texas ground shaking. The research has not yet been independently vetted and published.
“Any discussion of causation for the Dallas-area quakes is premature, and more speculative than scientific,” said Steve Everley, a senior advisor for Energy In Depth, a program of the Independent Petroleum Association of America. “But the SMU team has helped advance our understanding of the conditions that can ultimately lead to induced seismicity, so we’re eager to see what they will publish about the seismic events near Dallas.”
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
Scientists had been observing smaller quakes in area; SMU seismology team has developed expertise to deploy instruments, analyze and sharedata
SMU’s seismology team was not surprised by the magnitude 4.0 earthquake that occurred near Venus, Texas, Thursday evening, having been aware of multiple smaller earthquakes identified by the United States Geological Survey (USGS) in the area in recent months. They are recommending a regional monitoring network.
“We emphasized to the House Committee on Energy Resources the need for a permanent regional network, supplemented by portable instruments, that we can deploy in a time-sensitive manner when earthquakes occur,” said Matthew Hornbach, SMU associate professor of geophysics.
“The seismology team at SMU has developed the expertise to deploy these instruments, analyze and share that data,” said Brian Stump, SMU Albritton Chair of Geological Sciences. “We are committed to cooperate, as resources allow, with both state and federal agencies in addressing these issues,” Stump said.
Currently SMU has 26 seismic instruments deployed in North Texas, split between an area near Azle, Texas, SMU, earthquakes, seismology that experienced a series of earthquakes from late 2013 through spring 2014, and along a fault straddling the Irving-Dallas, Texas, earthquakes, SMU, seismology line where earthquakes have been occurring near the site of the old Texas Stadium.
“We are in the process of determining what resources might be available so that we can respond to the largest earthquake now felt in North Texas,” said Heather DeShon, SMU associate professor of geophysics. Previous SMU deployments have relied heavily on loaned monitoring equipment from the USGS and the academic consortium known as IRIS – Incorporated Research Institutions for Seismology. “We are still in the process of determining how many instruments might be available for this purpose in light of ongoing earthquake activity around the world, such as the recent earthquake in Nepal,” DeShon said.
The magnitude 4.0 earthquake (M4) recorded by the USGS in Venus at 5:58 p.m. Thursday is part of a series of smaller earthquakes the SMU team has been following in the Midlothian area. The National Earthquake Information Center (NEIC) has reported seven earthquakes within 10 kilometers of the USGS location for the May 7 Venus earthquake, with three of them (including the most recent) occurring at or above magnitude 3. There have been 23 earthquakes recorded within 20 kilometers of the Venus location, since 2009, with five of them registering higher than an M3.
SMU first started studying earthquakes in Johnson County for a series of earthquakes occurring in Cleburne in 2009, culminating in the peer reviewed “Analysis of the Cleburne, Texas, Earthquake Sequence from June 2009 to June 2010 (doi: 10.1785/0120120336 Bulletin of the Seismological Society of America October 2013). The SMU team also is watching with interest an additional area of seismicity (based on USGS locations) near Mineral Wells.
“I don’t think any of us was surprised by Thursday’s event,” DeShon said. “There have been a series of magnitude 3 and greater earthquakes in the Johnson County area. If you have movement on a fault and change the stresses, you increase the likelihood of additional earthquakes. In other words, one earthquake frequently leads to another.”
The SMU team noted that the USGS web site for the event contains an analysis of the data that estimates fault motion striking from the northeast to the southwest – consistent with other earthquake sequences SMU has studied in North Texas.
“This illustrates that we all need to think about the possibility of larger earthquakes in the region where we live,” Stump said. — Kimberly Cobb
Injecting fluids into the ground or extracting them has long been known to cause quakes, but rarely — if ever — have the two been caught acting in concert.
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WFAA 8 ABC news reporter Byron Harris reported on the SMU-led team of seismologists whose recent study found that large volumes of wastewater injection combined with saltwater (brine) extraction from natural gas wells is the most likely cause of earthquakes near Azle, Texas, from late 2013 through spring 2014.
By Byron Harris
WFAA 8 ABC
The seismology team led by SMU that has been researching local earthquakes believes it’s found a cause for the ones that hit Azle a couple of years ago.
“Causal Factors for Seismicity near Azle, Texas” was published in Nature Communications. A press release about the findings of the study was released on Tuesday.
It states that the team at SMU found “high volumes of wastewater injection combined with saltwater (brine) extraction from natural gas wells is the most likely cause of earthquakes.”
Oil and gas drilling takes water out of the ground as a product of energy production. And that water is pumped back into the ground in wastewater injection wells. SMU geologists measured those activities, centered around the Newark East Gas Field north and east of Azle.
They found 70 energy-producing wells in the field, and two adjacent wastewater injection wells. Increased levels of water injection and withdrawal corresponded with the earthquakes, the report says.
The quakes hit Azle between late 2013 and spring of 2014. The town saw seven quakes of magnitude 3.0 or higher in that period. A 3D model was developed to investigate two intersecting faults and estimate stress changes.
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
Injecting fluids into the ground or extracting them has long been known to cause quakes, but rarely — if ever — have the two been caught acting in concert.
A sign marks the entrance to an EnerVest wellsite in Parker County. SMU researchers detemined that an EnerVest wastewater well was one of two such sites exerting the greatest pressure on the fault where earthquakes occurred starting in November 2013. Workers buried about 120 million gallons of fluid at the site between October 2010 and September 2013. (DMN)
Science journalist Anna Kuchment with The Dallas Morning News covered the research of an SMU-led team of seismologists whose recent study found that large volumes of wastewater injection combined with saltwater (brine) extraction from natural gas wells is the most likely cause of earthquakes near Azle, Texas, from late 2013 through spring 2014.
The study published in Nature Communications.
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Book a live or taped interview with an SMU seismologist in the SMU Broadcast Studio. Call 214-768-7650 or email SMU News at news@smu.edu.
By Anna Kuchment
The Dallas Morning News
Oil and gas operations are the most likely cause of dozens of earthquakes that began rattling the North Texas towns of Azle and Reno in November 2013, a group of scientists has concluded.
The study, led by researchers at SMU and published Tuesday in the journal Nature Communications, presents some of the most conclusive evidence yet that humans are shifting faults below Dallas-Fort Worth that have not budged in hundreds of millions of years.
While experts have not yet determined what’s causing the shaking in Dallas and Irving, the new paper previews aspects of that study and includes suggestions that will help speed research.
“It’s certainly one of the best cases in the literature,” said Art McGarr of the U.S. Geological Survey’s Earthquake Hazards Program in Menlo Park, Calif.
The new findings contradict statements by the Railroad Commission of Texas that there are no definitive links between oil and gas activity and earthquakes in the state.
Shown an embargoed version of the paper, the commission’s staff seismologist Craig Pearson wrote in a statement that “the study raises many questions with regard to its methodology, the information used and conclusions it reaches.” But he declined to answer specific questions before meeting with the paper’s authors. The Railroad Commission regulates the oil and gas industry.
The Azle study is the result of a yearlong collaboration involving 11 researchers at SMU, the University of Texas at Austin, and the U.S. Geological Survey and was reviewed by independent experts before publication.
The scientists zeroed in on an unusual mechanism behind the quakes: workers pushing liquid into the ground on one side of a fault and sucking gas and groundwater from the other side of the fault.
“The combination of these activities seems to have triggered the earthquakes, and that was a real surprise to us,” said Matthew Hornbach, a geophysicist at SMU and a lead author of the paper.
Injecting fluids into the ground or extracting them has long been known to cause quakes, but rarely — if ever — have the two been caught acting in concert.
The geology of each region is unique, however, so these mechanisms may not be at work elsewhere.
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
SMU-led seismology team reveals Azle findings for an area where the seismology team identified two intersecting faults
Natural and man-made stress changes that may trigger earthquakes in the Azle area. (SMU)
An SMU-led seismology team finds that high volumes of wastewater injection combined with saltwater (brine) extraction from natural gas wells is the most likely cause of earthquakes occurring near Azle, Texas, from late 2013 through spring 2014.
In an area where the seismology team identified two intersecting faults, they developed a sophisticated 3D model to assess the changing fluid pressure within the rock formation. They used the model to estimate stress changes induced in the area by two wastewater injection wells and the more than 70 production wells that remove both natural gas and significant volumes of salty water known as brine.
Conclusions from the modeling study integrate a broad-range of estimates for uncertain subsurface conditions. Ultimately, better information on fluid volumes, flow parameters, and subsurface pressures in the region will provide more accurate estimates of the fluid pressure along this fault.
“The model shows that a pressure differential develops along one of the faults as a combined result of high fluid injection rates to the west and high water removal rates to the east,” said Matthew Hornbach, SMU associate professor of geophysics. “When we ran the model over a 10-year period through a wide range of parameters, it predicted pressure changes significant enough to trigger earthquakes on faults that are already stressed.”
Modelled pressure changes in the Ellenburger caused by injection and production. The images show the system prior to injection (a) through the onset of seismicity (e). Note that the most significant amount of brine removal occurs along the fault trend.
Model-predicted stress changes on the fault were typically tens to thousands of times larger than stress changes associated with water level fluctuations caused by the recent Texas drought.
“What we refer to as induced seismicity – earthquakes caused by something other than strictly natural forces – is often associated with subsurface pressure changes,” said Heather DeShon, SMU associate professor of geophysics. “We can rule out stress changes induced by local water table changes. While some uncertainties remain, it is unlikely that natural increases to tectonic stresses led to these events.”
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Surprisingly small changes in stress can reactivate certain faults
DeShon explained that some ancient faults in the region are more susceptible to movement – “near critically stressed” – due to their orientation and direction. “In other words, surprisingly small changes in stress can reactivate certain faults in the region and cause earthquakes,” DeShon said.
The study, “Causal Factors for Seismicity near Azle, Texas,” has been published in the journal Nature Communications. The study was produced by a team of scientists from SMU’s Roy M. Huffington Department of Earth Sciences in Dedman College of Humanities and Sciences, the U.S. Geological Survey, the University of Texas Institute for Geophysics and the University of Texas Department of Petroleum and Geosystems Engineering. SMU scientists Hornbach and DeShon are the lead authors.
Fluid pressure modeling of industry activity and water table fluctuations is first of its kind
SMU seismologists have been studying earthquakes in North Texas since 2008, when the first series of felt tremors hit near DFW International Airport between Oct. 30, 2008, and May 16, 2009. Next came a series of quakes in Cleburne between June 2009 and June 2010, and this third series in the Azle-Reno area northwest of Fort Worth occurred between Nov. 2013 and Jan. 2014. The SMU team also is studying an ongoing series of earthquakes in the Irving-Dallas area that began in April 2014.
In both the DFW sequence and the Cleburne sequence, the operation of injection wells used in the disposal of natural gas production fluids was listed as a possible cause of the seismicity. The introduction of fluid pressure modeling of both industry activity and water table fluctuations in the Azle study represents the first of its kind, and has allowed the SMU team to move beyond assessment of possible causes to the most likely cause identified in this report.
Prior to the DFW Airport earthquakes in 2008, an earthquake large enough to be felt had not been reported in the Fort Worth Basin since 1950. The North Texas earthquakes of the last seven years have all occurred in areas developed for natural gas extraction from a geologic formation known as the Barnett Shale. The Texas Railroad Commission reports that production in the Barnett Shale grew exponentially from 216 million cubic feet a day in 2000, to 4.4 billion cubic feet a day in 2008, to a peak of 5.74 billion cubic feet of gas a day in 2012.
While the SMU Azle study adds to the growing body of evidence connecting some injection wells and, to a lesser extent, some oil and gas production to induced earthquakes, SMU’s team notes that there are many thousands of injection and/or production wells that are not associated with earthquakes.
The area of study addressed in the report is in the Newark East Gas Field (NEGF), north and east of Azle. In this field, hydraulic fracturing is applied to loosen and extract gas trapped in the Barnett Shale, a sedimentary rock formation formed approximately 350 million years ago. The report explains that along with natural gas, production wells in the Azle area of the NEGF can also bring to the surface significant volumes of water from the highly permeable Ellenburger Formation – both naturally occurring brine as well as fluids that were introduced during the fracking process.
Subsurface fluid pressures are known to play a key role in causing seismicity. A primer produced by the U.S. Department of Energy explains the interplay of fluids and faults:
The fluid pressure in the pores and fractures of the rocks is called the ‘pore pressure.’ The pore pressure acts against the weight of the rock and the forces holding the rock together (stresses due to tectonic forces). If the pore pressures are low (especially compared to the forces holding the rock together), then only the imbalance of natural in situ earth stresses will cause an occasional earthquake. If, however, pore pressures increase, then it would take less of an imbalance of in situ stresses to cause an earthquake, thus accelerating earthquake activity. This type of failure…is called shear failure.
Injecting fluids into the subsurface is one way of increasing the pore pressure and causing faults and fractures to “fail” more easily, thus inducing an earthquake, he said. Thus, induced seismicity can be caused by injecting fluid into the subsurface or by extracting fluids at a rate that causes subsidence and/or slippage along planes of weakness in the earth.
All seismic waveform data used in the compilation of the report are publically available at the IRIS Data Management Center. Wastewater injection, brine production and surface injection pressure data are publicly available at the Texas Railroad Commission (TRC). Craig Pearson at the TRC, Bob Patterson from the Upper Trinity Groundwater Conservation District; scientists at XTO Energy, ExxonMobil, MorningStar Partners and EnerVest provided valuable discussions and, in some instances, data used in the completion of the report.
“This report points to the need for even more study in connection with earthquakes in North Texas,” said Brian Stump, SMU’s Albritton Chair in Earth Sciences. “Industry is an important source for key data, and the scope of the research needed to understand these earthquakes requires government support at multiple levels.” — Kimberly Cobb
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
It is significant that underground conditions have changed to trigger slips on a fault line that hasn’t moved in human memory.
Journalist Dylan Baddour covered the recent interim report about the research findings of Southern Methodist University’s seismology team surrounding a recent series of earthquakes in the Irving, Texas area.
His Houston Chronicle report, “New data shows North Texas fault line,” covered the preliminary findings and the progress on the team’s earthquake research.
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Book a live or taped interview with Brian Stump in the SMU Broadcast Studio. Call 214-768-7650; email news@smu.edu.
Book a live interview
Book a live or taped interview with Heather DeShon in the SMU Broadcast Studio. Call 214-768-7650; email news@smu.edu.
Initial results reveal that the earthquakes that occurred near the site of the old Texas Stadium were relatively shallow and concentrated along a narrow two mile line that indicates a fault extending from Irving into West Dallas.
SMU and the United States Geological Survey shared the report with the mayors of Dallas and Irving spelling out preliminary information gleaned after SMU’s installation in January of more than 20 portable earthquake monitors around the earthquake sites. SMU seismologists Heather DeShon and Brian Stump, in the Roy M. Huffington Department of Earth Sciences, answered questions during the briefing with reporters.
By Dylan Baddour
Houston Chronicle
North Texas earthquake swarms still baffle geologists, who never expected to study seismic tremors in the Lone Star State. But last month scientists installed equipment to record quakes near Irving, Texas, and last week the first numbers came in.
We still don’t know much about why the region shakes, but here’s what we just learned: the quakes have all been relatively shallow, and have centered along a newly-identified fault line near Irving. The data is thanks 20 seismic monitoring machines, supplied by the U.S. Geological Survey and deployed by scientists from Texas’ Southern Methodist University last month.
“This is a first step, but an important one, in investigating the cause of the earthquakes,” said SMU seismologist Brian Stump. “Now that we know the fault’s location and depth, we can begin studying how this fault moves – both the amount and direction of motion.”
Irving, just north of Dallas, shook first in April 2014, but the area’s strongest quakes struck last month. The so-called “earthquake swarm” follows others since 2008 that have hit North Texas—a region with no history of seismic action. This year, the USGS announced plans to raise the region’s official earthquake risk level. Still, no one knows why the region has started to tremble.
“The two views about them. One: in 150 years there haven’t been natural earthquakes in the Dallas-Fort Worth area, so if these earthquakes were natural, that’s very interesting,” said Cliff Frolich, a geologist at the University of Texas at Austin and a veteran researcher of the North Texas quakes. “On the other hand the earthquakes that occurred in 2008 and subsequently appear to be close to injection wells. The fact that these earthquakes are occurring only a few years later, some people would probably conclude they are related to oil and gas activities.”
Injection wells are where oil and gas drillers dispose of tens of millions of gallons of toxic wastewater left over from hydraulic fracturing, or “fracking,” an extraction technique that’s proliferated in Texas and across the country since 2008. Some scientists have suggested that pressure put on fault lines by high-powered injection into bedrock could trigger the quakes, but nothing is conclusive.
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
Now that SMU’s seismology team has located the fissure, they can begin to study how and why it’s moving.
Science journalist Anna Kuchment covered a recent interim report on the research findings of Southern Methodist University’s seismology team surrounding a recent series of earthquakes in the Irving, Texas area.
Initial results reveal that the earthquakes that occurred near the site of the old Texas Stadium were relatively shallow and concentrated along a narrow two mile line that indicates a fault extending from Irving into West Dallas.
SMU and the United States Geological Survey shared the report with the mayors of Dallas and Irving spelling out preliminary information gleaned after SMU’s installation in January of more than 20 portable earthquake monitors around the earthquake sites. SMU seismologists Heather DeShon and Brian Stump, in the Roy M. Huffington Department of Earth Sciences, answered questions during the briefing with reporters.
By Anna Kuchment and Avi Selk
Dallas Morning News
Scientists finally have a rough picture of the ancient fault that’s been rattling the Dallas area, and the fissure isn’t where the public thought it was.
Armed with more equipment and better data, SMU scientists have relocated dozens of quakes on the federal government’s imprecise maps. The team released a new map on Friday that shifts the epicenters of nearly all of last month’s temblors, arranging them in a neat line that shadows a fissure miles beneath the earth.
And while the team has just begun to study that fault, they already have some early hints about its nature.
It’s not beneath the old Texas Stadium site, as federal maps suggested.
It’s small (for a fault) and appears to be quieting down after tossing off about four dozen quakes in a year. But it could still produce a tremor much more powerful than any Dallas has yet seen.
And while scientists are skeptical that gas drilling woke it up, they now know the fault runs much closer than previously thought to the only two fracking wells in the area.
If you’ve felt any of the earthquakes to hit the Dallas area since last fall, you may have looked up a map of their epicenters. The rough bull’s eye of quakes around the old Texas Stadium site has sparked wild theories about the stadium’s demolition and jokes about the “Jerry Jones Fault.”
That map is wrong, and scientists have always known it.
The federal government estimated the North Texas epicenters using a small handful of quake detectors, some of which sat miles away and produced inaccurate readings.
The U.S. Geological Survey’s blob of approximate quake locations was of little use to scientists trying to map the underground crack producing them. So in early January, the SMU team began to install nearly two dozen detectors in the Irving area to collect more accurate data.
The earth obliged with more than two dozen quakes since then, including the most powerful yet in Dallas County.
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
Shallow depths explain why so many felt relatively small quakes; not unusual for earthquakes to occur at different fault levels.
Locations of seismic instruments as of Jan. 30, 2015, with revised earthquake locations in dark red. (USGS)
Initial results from the seismology team at Southern Methodist University reveal that a recent series of North Texas earthquakes occurring near the site of the old Texas Stadium in the Dallas-Fort Worth area were relatively shallow and concentrated along a narrow two mile line that indicates a fault extending from Irving into West Dallas.
SMU and the United States Geological Survey on Friday, Feb. 6, 2015 shared an interim report with the mayors of Dallas and Irving spelling out preliminary information gleaned after SMU’s installation in January of more than 20 portable earthquake monitors around the earthquake sites.
Book a live interview
Book a live or taped interview with Brian Stump in the SMU Broadcast Studio. Call 214-768-7650; email news@smu.edu.
Book a live interview
Book a live or taped interview with Heather DeShon in the SMU Broadcast Studio. Call 214-768-7650; email news@smu.edu.
“This is a first step, but an important one, in investigating the cause of the earthquakes,” said SMU seismologist Brian Stump. “Now that we know the fault’s location and depth, we can begin studying how this fault moves — both the amount and direction of motion.”
“Then we can move on to what might have triggered it – examining factors both natural and manmade,” said SMU seismologist Heather DeShon. “Sometimes what triggers an earthquake can be very small, so all of these factors have to be considered when looking for that trigger.”
The earthquakes have occurred in the granite “basement,” below the layers of sedimentary rock that make up the large geological formation known as the Fort Worth Basin, at depths between 4.5 and 7 kilometers, according to the report. It is not unusual for earthquakes to occur at different levels on a fault. Those depths are considered relatively close to the surface in earthquake terms, however, which helps explain why people as far away as the northern suburb of Plano feel even smaller magnitude 2 earthquakes in the area.
January 2015 earthquakes actually have occurred along a line from Irving to West Dallas
The USGS initially mapped the earthquake locations as being spread out in a roughly circular area centered on the old Texas Stadium site, developing those locations from data collected by distant seismic monitors ranging from the closest at about 40 miles away to as far as 900 miles away. But once SMU installed more than 20 monitors in the immediate area – supplied by the USGS and the academic consortium IRIS – the enhanced data they were able to retrieve shows the January 2015 earthquakes actually have occurred along a line from Irving to West Dallas, running north-by-northeast from TX Highway 114 to Walnut Hill Road along the Trinity River.
That line indicates the approximate location of a subsurface fault.
This initial mapping of the fault provides important information for municipal hazard assessment in Irving and Dallas, Stump said, allowing city officials to know which parts of their cities might experience the worst shaking if the fault remains active. As has been the case with other earthquake sequences in North Texas since 2008, this latest bout of seismic activity appears to be diminishing over time. But SMU scientists stress that there is no way to predict when the series will end, or what the largest magnitude will be.
The earthquakes in the Irving area began in April 2014. SMU scientists had just installed the first of its local monitors in the city of Irving on Jan. 5, 2015 when the area recorded its two largest earthquakes – 3.5 and 3.6 magnitude events – on Jan. 6.
SMU seismology team installed more than 20 seismographs in the affected area
During January, members of the SMU seismology team installed more than 20 seismographs in the affected area, including 12 short-term units that had to be removed from the field to collect their data. There will be 11 temporary seismographs running as part of the Irving network moving forward.
The report notes the presence of two wells drilled for shale gas (only one was put into production, last producing in 2012) near the earthquake epicenters and the location of a wastewater injection well approximately eight miles to the northwest. Production and disposal activities in this region are generally confined to the sedimentary layers above the “basement” layers where regional earthquakes have occurred.
“Scientific questions about the nature of events in North Texas have heightened local and national concerns about the impact of activities related to shale gas production on geological infrastructure and subsurface infrastructure,” the report reads. “SMU scientists continue to explore all possible natural and anthropogenic (due to human activity) causes for the Irving earthquakes and do not have a conclusion at this time.”
The next steps of the Irving study already are underway.
Signing the report were Heather DeShon, SMU associate professor of geophysics; Brian Stump, SMU Albritton Chair of Geological Sciences; Chris Hayward, senior scientist and director of SMU’s Geophysics Research Program; Beatrice Magnani, SMU associate professor of geophysics; Matthew Hornbach, SMU associate professor of geophysics; and Robert Williams and Michael Blanpied of the USGS Earthquake Hazards Program. — Kimberly Cobb
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
NBC News has covered the research of SMU marine geologist Matthew Hornbach, who led the study that has uncovered a powerful new way to use data from the geological record to discover non-anthropogenic climate changes underway.
The study suggests warmer temperatures are destabilizing up to 2.5 gigatonnes of methane hydrate along the continental slope of the eastern United States.
Co-author on the study is SMU geophysics doctoral student Benjamin Phrampus.
The researchers say it isn’t clear if the methane will release, but the gas would have the potential to rise up through the ocean and into the atmosphere, where it would add to the greenhouse gases warming Earth.
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From the study, the authors write:
“Here, using seismic data combined with thermal models, we show that recent changes in intermediate-depth ocean temperature associated with the Gulf Stream are rapidly destabilizing methane hydrate along a broad swathe of the North American margin. The area of active hydrate destabilization covers at least 10,000 square kilometres of the United States eastern margin, and occurs in a region prone to kilometre-scale slope failures. Previous hypothetical studies, postulated that an increase of five degrees Celsius in intermediate-depth ocean temperatures could release enough methane to explain extreme global warming events like the Palaeocene–Eocene thermal maximum (PETM) and trigger widespread ocean acidification. Our analysis suggests that changes in Gulf Stream flow or temperature within the past 5,000 years or so are warming the western North Atlantic margin by up to eight degrees Celsius and are now triggering the destabilization of 2.5 gigatonnes of methane hydrate (about 0.2 per cent of that required to cause the PETM).”
By Miguel Llanos
NBC News
A changing Gulf Stream off the East Coast has destabilized frozen methane deposits trapped under nearly 4,000 square miles of seafloor, scientists reported Wednesday. And since methane is even more potent than carbon dioxide as a global warming gas, the researchers said, any large-scale release could have significant climate impacts.
Temperature changes in the Gulf Stream are “rapidly destabilizing methane hydrate along a broad swathe of the North American margin,” the experts said in a study published Wednesday in the peer-reviewed journal Nature.
Using seismic records and ocean models, the team estimated that 2.5 gigatonnes of frozen methane hydrate are being destabilized and could separate into methane gas and water.
It is not clear if that is happening yet, but that methane gas would have the potential to rise up through the ocean and into the atmosphere, where it would add to the greenhouse gases warming Earth.
The 2.5 gigatonnes isn’t enough to trigger a sudden climate shift, but the team worries that other areas around the globe might be seeing a similar destabilization.
“It is unlikely that the western North Atlantic margin is the only area experiencing changing ocean currents,” they noted. “Our estimate … may therefore represent only a fraction of the methane hydrate currently destabilizing globally.”
The wider destabilization evidence, co-author Ben Phrampus told NBC News, includes data from the Arctic and Alaska’s northern slope in the Beaufort Sea.
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information, www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
A changing Gulf Stream is warming deep waters along the eastern United States and destabilizing greenhouse gases trapped in sediments.
Sand is not the only thing on the move in the waters off the eastern United States — a shift in the Gulf Stream is melting methane hydrate in sediments that could release methane gas. (Image: D. Harvey/Natl. Geographic/Getty Images)
Nature magazine covered the research of SMU marine geologist Matthew Hornbach, who led the study that has uncovered a powerful new way to use data from the geological record to discover non-anthropogenic climate changes underway.
The study suggests warmer temperatures are destabilizing up to 2.5 gigatonnes of methane hydrate along the continental slope of the eastern United States.
From the study, the authors write:
“Here, using seismic data combined with thermal models, we show that recent changes in intermediate-depth ocean temperature associated with the Gulf Stream are rapidly destabilizing methane hydrate along a broad swathe of the North American margin. The area of active hydrate destabilization covers at least 10,000 square kilometres of the United States eastern margin, and occurs in a region prone to kilometre-scale slope failures. Previous hypothetical studies, postulated that an increase of five degrees Celsius in intermediate-depth ocean temperatures could release enough methane to explain extreme global warming events like the Palaeocene–Eocene thermal maximum (PETM) and trigger widespread ocean acidification. Our analysis suggests that changes in Gulf Stream flow or temperature within the past 5,000 years or so are warming the western North Atlantic margin by up to eight degrees Celsius and are now triggering the destabilization of 2.5 gigatonnes of methane hydrate (about 0.2 per cent of that required to cause the PETM).”
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To book a live or taped interview with Matt Hornbach in the SMU News Broadcast Studio call 214-768-7650 or email news@smu.edu.
By Virginia Gewin
Nature
Somewhere off the eastern coast of North Carolina, a frozen mixture of water and methane gas tucked in seabed sediments is starting to break down. Researchers blame a shifting Gulf Stream — the swift Atlantic Ocean current that flows north from the Gulf of Mexico — which is now delivering warmer waters to areas that had previously only experienced colder temperatures.
“We know methane hydrates exist here and, if warming continues, it can potentially lead to less stable sediments in this region,” says Matthew Hornbach, a marine geologist at the Southern Methodist University in Dallas, Texas, who led the study that is published online today in Nature1. The results suggest that the warmer temperatures are destabilizing up to 2.5 gigatonnes of methane hydrate along the continental slope of the eastern United States. This region is prone to underwater landslides, which could release the methane, a powerful greenhouse gas.
Whether that methane would make it to the atmosphere and worsen global warming is unclear, but scientists think that it is unlikely. “We don’t need to worry about any huge blow of methane into the atmosphere,” says Carolyn Ruppel, a geophysicist at the US Geological Survey in Woods Hole, Massachusetts. Rather, she says, Hornbach and his co-author Benjamin Phrampus, also of the Southern Methodist University, have uncovered a powerful new way to use data from the geological record to catch non-anthropogenic climate changes that are already happening.
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information, www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
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