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SMU seismology research shows North Texas earthquakes occurring on “dead” faults

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.

The full study, “Discriminating between natural vs induced seismicity from long-term deformation history of intraplate faults,” was published online Nov. 24, 2017 by the journal Science Advances.

“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

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Commerce Department selects scientific team to conduct independent abundance estimate of red snapper in Gulf of Mexico

The initiative addresses one of the most pressing issues currently facing U.S. Gulf of Mexico fisheries management, as the iconic red snapper supports one of the most economically valuable finfish fisheries in the Gulf.

An expert team of university and government scientists will determine the abundance of red snapper in the U.S. waters of the Gulf of Mexico, as availability of the fish is vital to the region’s economy.

“Red snapper have great economic value to all the gulf states,” said SMU statistician Lynne Stokes, a member of the team. “Maintaining the health of the species is vitally important, so it’s necessary to ensure species are fished at the right level.”

As an expert in surveys, polls and sampling, Stokes’ role in the project is to help design ways to sample the vast expanse of the gulf efficiently so that good estimates of abundance can be produced.

“The gulf is very diverse, and different sampling methods are needed for different habitats, which makes the sample design problem interesting,” said Stokes, a professor in the SMU Department of Statistical Science. “The cheapest way to collect data about the health of a marine fish species is by asking a sample of anglers about their catch. However, if fish are present in places where anglers are not, other methods are needed. There is some uncertainty about all the places red snapper exist in the gulf, so it is not known if catch-based methods provide accurate estimates of abundance.”

The project will obtain angler-independent data about red snapper abundance by sampling their potential habitat, Stokes said. The team will collect data on red snapper numbers by direct observation of a sample of transects on the sea bottom and structures on the sea floor, using remotely controlled video cameras. Stokes will help determine how extensive the observation must be.

The team of scientists was selected by an expert review panel convened by the Mississippi-Alabama Sea Grant Consortium to conduct the independent study.

“American communities across the Gulf of Mexico depend on their access to, as well as the long term sustainability of, red snapper,” said U.S. Secretary of Commerce Wilbur Ross. “I look forward to the insights this project will provide as we study and manage this valuable resource.”

Recreational anglers and commercial fishers will play a key role
The research team, made up of 21 scientists from 12 institutions of higher learning, a state agency and a federal agency, was awarded $9.5 million in federal funds for the project through a competitive research grant process. With matching funds from the universities, the project will total $12 million.

“We’ve assembled some of the best red snapper scientists around for this study,” said Greg Stunz, the project leader and a professor at the Harte Research Institute for Gulf of Mexico Studies at Texas A&M University – Corpus Christi. “The team members assembled through this process are ready to address this challenging research question. There are lots of constituents who want an independent abundance estimate that will be anxiously awaiting our findings.”

Recreational anglers and commercial fishers will be invited to play a key role in collecting data by tagging fish, reporting tags and working directly with scientists onboard their vessels.

“The local knowledge fishermen bring to this process is very valuable and meaningfully informs our study,” Stunz said.

Some stakeholder groups have expressed concerns that there are more red snapper in the Gulf than currently accounted for in the stock assessment. The team of scientists on this project will spend two years studying the issue.

In 2016, Congress directed the National Sea Grant College Program and NOAA Fisheries to fund independent red snapper data collections, surveys and assessments, including the use of tagging and advanced sampling technologies. Sea Grant and NOAA Fisheries worked collaboratively to transfer federal funds to Mississippi-Alabama Sea Grant to administer the competitive research grant process and manage this independent abundance estimate.

“Today’s announcement is welcome news for all red snapper anglers in the Gulf of Mexico,” said Sen. Richard Shelby of Alabama. “As Chairman of the U.S. Senate Appropriations Subcommittee on Commerce, Justice, Science and Related Agencies, I was proud to author and secure federal funding to address the need for better data, which is a fundamental issue plaguing the fishery. The management of red snapper must be grounded in sound science if we want to provide fair access and more days on the water for our anglers. It is my hope that these independent scientists will be able to accurately determine the abundance of red snapper in the Gulf of Mexico once and for all.”

Project team will determine abundance and distribution of red snapper
The research will be driven largely by university-based scientists with partners from state and federal agencies, Stunz said.

The funding will allow the scientists to carry out an abundance estimate using multiple sampling methods with a focus on advanced technologies and tagging for various habitat types, he said.

“I’m pleased to see that the independent estimate is moving forward and including the expertise of recreational fishermen,” said Rep. John Culberson of Texas. “I will continue to work with Texas fishermen and NOAA to address the inadequate access to red snapper.”

The project team will determine abundance and distribution of red snapper on artificial, natural and unknown bottom habitat across the northern Gulf of Mexico.

As a statistician chosen for the team, SMU’s Stokes is also an expert in non-sampling survey errors, such as errors by interviewers and respondents. She recently conducted research on evaluating the accuracy of contest judges and on improving estimates of marine fishery yields by the National Oceanic and Atmospheric Administration.

Stokes also contributes to the National Assessment of Educational Progress, or “Nation’s Report Card,” examining the way schools and students are selected for the large study.

Besides SMU, others on the team include Texas A&M University, University of Florida, University of South Alabama, Louisiana State University, Florida International University, NOAA Fisheries, Auburn University, Mississippi State University, Louisiana Department of Wildlife and Fisheries, College of William and Mary, University of Southern Mississippi, and the University of South Florida. — Mississippi-Alabama Sea Grant and Southern Methodist University

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Prehistoric puzzle settled: carbon dioxide link to global warming 22 million years ago

The modern link between high carbon dioxide levels and climate change didn’t appear to hold true for a time interval about 22 million years ago; but now a new study has found the link does indeed exist.

Fossil leaves from Africa have resolved a prehistoric climate puzzle — and also confirm the link between carbon dioxide in the atmosphere and global warming.

Research until now has produced a variety of results and conflicting data that have cast doubt on the link between high carbon dioxide levels and climate change for a time interval about 22 million years ago.

But a new study has found the link does indeed exist for that prehistoric time period, say researchers at Southern Methodist University, Dallas.

The finding will help scientists understand how recent and future increases in the concentration of atmospheric carbon dioxide may impact the future of our planet, say the SMU researchers.

The discovery comes from new biochemical analyses of fossil leaves from plants that grew on Earth 27 million years ago and 22 million years ago, said geologist Tekie Tesfamichael, lead scientist on the research.

The new analyses confirm research about modern climate — that global temperatures rise and fall with increases and decreases in carbon dioxide in our atmosphere — but in this case even in prehistoric times, according to the SMU-led international research team.

Carbon dioxide is a gas that is normally present in the Earth’s atmosphere, even millions of years ago. It’s dubbed a greenhouse gas because greater concentrations cause the overall temperature of Earth’s atmosphere to rise, as happens in a greenhouse with lots of sunlight.

Recently greenhouse gas increases have caused global warming, which is melting glaciers, sparking extreme weather variability and causing sea levels to rise.

The new SMU discovery that carbon dioxide behaved in the same manner millions of years ago that it does today has significant implications for the future. The finding suggests the pairing of carbon dioxide and global warming that is seen today also holds true for the future if carbon dioxide levels continue to rise as they have been, said Tesfamichael.

“The more we understand about the relationship between atmospheric carbon dioxide concentrations and global temperature in the past, the more we can plan for changes ahead,” said Tesfamichael, an SMU postdoctoral fellow in Earth Sciences.

“Previous work reported a variety of results and conflicting data about carbon dioxide concentrations at the two intervals of time that we studied,” he said. “But tighter control on the age of our fossils helped us to address whether or not atmospheric carbon dioxide concentration corresponded to warming — which itself is independently well-documented in geochemical studies of marine fossils in ocean sediments.”

The researchers reported their findings in Geology, the scientific journal of the Geological Society of America. The article is “Settling the issue of ‘decoupling’ between atmospheric carbon dioxide and global temperature: [CO2]atm reconstructions across the warming Paleogene-Neogene divide.”

Co-authors from the Roy M. Huffington Department of Earth Sciences in Dedman College are professors Bonnie Jacobs, an expert in paleobotany and paleoclimate, and Neil J. Tabor, an expert in sedimentology and sedimentary geochemistry.

Other co-authors are Lauren Michel, Tennessee Technological University; Ellen Currano, University of Wyoming; Mulugeta Feseha, Addis Ababa University; Richard Barclay, Smithsonian Institution; John Kappelman, University of Texas; and Mark Schmitz, Boise State University.

Discovery of rare, well-preserved fossil leaves enables finding
The findings were possible thanks to the rare discovery of two sites with extraordinarily well-preserved fossil leaves of flowering plants from the Ethiopian Highlands of eastern Africa.

Such well-preserved fossil leaves are a rarity, Tesfamichael said.

“Finding two sites with great preservation in the same geographic region from two important time intervals was very fortunate, as this enabled us to address the question we had about the relationship between atmospheric carbon dioxide concentration and global temperatures,” he said.

Scientists know that variations in the concentration of atmospheric carbon dioxide affect carbon fixation in leaves during photosynthesis. This causes leaves to develop anatomical and physiological changes such as the frequency and size of stomata — the pores on the surface of a leaf through which carbon passes.

Scientists can measure those attributes, among others, in fossil leaves, so that leaf fossils can be used as proxies for Earth’s atmospheric carbon dioxide history.

The sites producing the leaves for the SMU study were discovered separately in years past, but major fossil collections were produced through field work coordinated by the SMU research team and their co-authors, who have been collaborating on this project for several years.

The work has had funding from the National Science Foundation, The National Geographic Committee for Research and Exploration, the SMU Ford Fellowship Program, SMU Research Council, the Institute for the Study of Earth and Man, and the Dallas Paleontological Society Frank Crane Scholarship.

The fossils are housed permanently in the collections at the National Museum of Ethiopia in Addis Ababa. Institutional and governmental support came from the National Museum of Ethiopia, the Authority for Research and Conservation of Cultural Heritage, and Addis Ababa University.

Previous studies firmly established a temperature difference
One of the sites dates to the late Oligocene Epoch, and the other to the early Miocene.

Previous studies that measured ocean temperatures from around the world for the two intervals have firmly established a temperature difference on Earth between the two times, with one much warmer than the other. So the SMU study sought to measure the levels of carbon dioxide for the two time periods.

For the SMU analyses, fossil leaves of a single species were collected from the 27 million-year-old late Oligocene site. The leaves had been deposited during prehistoric times in the area of Chilga in northwest Ethiopia most likely at a river bank. The Earth’s climate during the late Oligocene may have been somewhat warmer than today, although glaciers were forming on Antarctica. The SMU study found carbon dioxide levels, on average, around 390 parts per million, about what it is on Earth today.

Fossil leaves of the 22 million-year-old species from the early Miocene were collected from ancient lake deposits, now a rock called shale, from the modern-day Mush Valley in central Ethiopia. The early Miocene climate at that time was warmer than the late Oligocene and likewise the SMU study found higher carbon dioxide levels. Atmospheric carbon dioxide was about 870 parts per million, double what it is on Earth today.

The SMU study confirmed a relationship between carbon dioxide and temperature during the late Oligocene and early Miocene.

Paleoclimate data can help predict our planet’s future climate
While carbon dioxide isn’t the only factor affecting Earth’s climate or global mean temperature, it is widely considered by scientists among the most significant. Much is known about climate change and global warming, but questions still remain.

“One of those is ‘What’s the sensitivity of the Earth’s temperature to carbon dioxide concentration? Is it very sensitive? Is it not so sensitive?’ Estimating temperature and carbon dioxide concentrations for times in the past can help find the answer to that question,” Jacobs said. “There’s a lot of work on paleoclimate in general, but not as much on the relationship between carbon dioxide and temperature.”

The finding is an important one.

“The amount of temperature change during this interval is approximately within the range of the temperature change that is estimated from climate models for our next century given a doubling of carbon dioxide concentration since the industrial revolution,” Jacobs said.

With the new model reaffirming the prehistoric relationship, scientists can look now at related questions, said climate change scientist Lauren Michel, who worked on the study as a post-doctoral researcher at SMU.

“Answering questions about the rate of change and which factors changed first, for example, will ultimately give a clearer picture of the Earth’s climate change patterns,” Michel said. “I think it is valuable to understand the relationship of greenhouse gases and climate factors represented in the rock record so we can have a better idea of what we can expect in the future and how we can prepare for that.”

SMU study confirms relationship that previous methods overlooked
Previous studies found little to no correlation between temperature and carbon dioxide for the late Oligocene and early Miocene. That has puzzled paleoclimate researchers for at least a decade.

“We have a good test-case scenario with these well-preserved plants from both time slices, where we know one time slice, with higher levels of carbon dioxide, was a warmer climate globally than the other,” Tesfamichael said.

“It’s been a puzzle as to why the previous methods found no relationship, or an inverse correlation,” he said. “We think it’s for lack of the well-dated proxy — such as our fossil leaves from two precise times in the same region — which deliver a reliable answer. Or, perhaps the models themselves needed improvement.”

Previous studies used methodologies that differed from the SMU study, although all methods (proxies) incorporate some aspects of what is known about living organisms and how they interact with atmospheric carbon dioxide.

Some studies rely on biochemical modeling of the relationship between single-celled marine fossils and atmospheric carbon dioxide, and others rely on the relationship between stomata and atmospheric carbon dioxide concentration observed in the living relatives of particular fossil plant species.

“Each method has its assumptions,” said Tesfamichael. “We will see if our results hold up with further studies of this time interval using the same methodology we used.” — Margaret Allen, SMU

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Mission Foods Texas-Mexico Center awards first research grants to shape economic, migration policies

Research findings will be presented at the second annual Mission Foods Texas-Mexico Center Symposium to be held in Mexico City April 6, 2018.

The Mission Foods Texas-Mexico Center at SMU has awarded grants to four scholars from both sides of the border who aim to support the Center’s goal of providing policy-relevant, action-oriented research on the dynamic relationship between Texas and Mexico.

Findings from each of the four projects, selected by the Texas-Mexico Center’s Faculty Advisory Board, will be shared this spring, says Luisa del Rosal, executive director of the Center.

“This is a tremendous benefit to Dedman College, where so many faculty members research and teach about Texas and Mexico,” says SMU Dedman College of Humanities and Sciences Dean Thomas DiPiero. “This will help strengthen the social, economic and cultural ties between the two regions.”

The four projects are:

  • “Migration, Inequality & Public Policies in Mexico and the United States”
    Lead researcher: Colegio de Mexico President Silvia Giorguli, Mexico City
  • “Are Mexican and U.S. Workers Complements or Substitutes?”
    Lead researcher: Raymond Robertson, Helen and Roy Ryu Chair in Economics
    & Government, Texas A&M Bush School of Government & Public Service, College Station
  • “Institutions, Trade and Economic Prosperity: An Examination of the U.S. and Mexican States”
    Lead researcher: Dean Stansel, associate professor, O’Neil Center for Global Markets and Freedom, SMU Cox School of Business
  • “Slowdown in Mexico-U.S. Migration: Why is Texas Different?”
    Lead researcher: Colegio Tlaxcala President Alfredo Cuecuecha, Tlaxcala, Mexico

Grant recipient Stansel said his team will focus on the potential economic damage from a possible new regime of trade restrictions in the U.S.

“By examining the interconnected relationships between trade policy, trade volume and economic prosperity in the U.S. and Mexico,” he said, “we hope to provide insights into the importance of maintaining a system of relatively free trade.”

Research findings will be presented at the second annual Mission Foods Texas-Mexico Center Symposium to be held in Mexico City April 6, 2018.

Three dozen applicants applied for the grants, which was “more than we expected for the first year,” says Javier Velez, vice-chair of the Texas-Mexico Center Executive Advisory Board and CEO of Mission Foods’ U.S. headquarters in Dallas.

“It was pleasing for us how much interest there is in effectively promoting and facilitating a better understanding of the relation between Texas and Mexico,” Velez said.

The Mission Foods Texas-Mexico Center at SMU is dedicated to improving relations between Texas and Mexico through dialogue and research. It works to encourage greater cross-border integration and cross-sector collaboration in academia, government, non-governmental organizations and business. The Center strives to enhance a political dialogue to reshape the policies that govern the relationship between Texas and Mexico, focusing on five areas: trade and investment, energy, human capital and education, border issues and migration. — Denise Gee, SMU

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The CW33: Dark Matter Day rocks SMU’s campus

The CW33 TV visited SMU on Halloween to get a glimpse of International Dark Matter Day in action on the SMU campus.

The CW33 TV stopped at the SMU campus during the early morning hours of Halloween to interview SMU physics professor Jodi Cooley about the capers afoot in celebration of International Dark Matter Day.

The SMU Department of Physics in Dedman College of Humanities and Sciences hosted the Oct. 31, 2017 Dark Matter Day celebration for students, faculty, staff and Dallas-area residents.

As part of the festivities, there were speaking events by scientists in the field of dark matter, including dark matter expert Cooley, to explain the elusive particles that scientists refer to as dark matter.

Then throughout Halloween day, the public was invited to test their skills at finding dark matter — in this case, a series of 26 rocks bearing educational messages related to dark matter, which the Society of Physics Students had painted and hidden around the campus. Lucky finders traded them for prizes from the Physics Department.

“In the spirit of science being a pursuit open to all, we are excited to welcome all members of the SMU family to become dark matter hunters for a day,” said Cooley, whose research is focused on the scientific challenge of detecting dark matter. “Explore your campus in the search for dark matter rocks, just as physicists are exploring the cosmos in the hunt for the nature of dark matter itself.”

Watch the full news segment.

EXCERPT:

By Shardae Neal
The CW33

On Halloween (excuse us) “International Dark Matter Day,” SMU students hosted a public witch hunt to search for the unknown: dark matter.

“What we’re doing is hiding 26 rocks that we have with the help of our society of physic students,” explained SMU Physicist Jodi Cooley.

What exactly is dark matter?

“Think about all the stuff there is in the universe,” Cooley added. “What we can account for makes up only four to five percent of the universe. The rest of it is unknown. Turns out 26% of that unknown stuff is dark matter.”

Watch the full news segment.