Hydro-fracking: Fact vs. fiction

In communities across the U.S., people are hearing more and more about a controversial oil and gas extraction technique called hydraulic fracturing – aka, hydro-fracking. Controversies pivot on some basic questions: Can hydro-fracking contaminate domestic wells? Does it cause earthquakes? How can we know? What can be done about these things if they are true? A wide range of researchers will address these and related critical questions at the GSA Annual Meeting this week.

“When people talk about contamination from hydraulic fracturing, for instance, they can mean a lot of different things,” says hydrogeologist Harvey Cohen of S.S. Papadopulos & Associates in Bethesda, Maryland. “When it’s what’s happening near their homes, they can mean trucks, drilling machinery, noise.” These activities can potentially lead to surface water or groundwater contamination if there are, for example, accidental fuel spills. People also worry about fracking fluids leaking into the aquifers they tap for domestic or municipal water.

On the other hand, when petroleum companies talk about risks to groundwater from hydro-fracking, they are often specifically referring to the process of injecting fluids into geologic units deep underground and fracturing the rock to free the oil and gas it contains, says Cohen. This is a much smaller, much more isolated part of the whole hydraulic fracturing operation. It does not include the surface operations — or the re-injection of the fracking waste fluids at depth in other wells, which is itself another source of concern for many.

But all of these concerns can be addressed, says Cohen, who will be presenting his talk on groundwater contamination and fracking on the morning of Wednesday, 7 Nov. For instance, it has been proposed that drillers put non-toxic chemical tracers into their fracking fluids so that if a nearby domestic well is contaminated, that tracer will show up in the well water. That would sort out whether the well is contaminated from the hydro-fracking operations or perhaps from some other source, like a leaking underground storage tank or surface contaminants getting into the groundwater.

“That would be the 100 percent confident solution,” says Cohen of the tracers.

Another important strategy is for concerned citizens, cities, and even oil companies to gather baseline data on water quality from wells before hydro-fracking begins. Baseline data would have been very helpful, for example, in the case of the Pavillion gas field the Wind River Formation of Wyoming, according to Cohen, because there are multiple potential sources of contaminants that have been found in domestic wells there. The Pavillion field is just one of multiple sites now being studied by the U.S. Environmental Protection Agency (EPA) to learn about past and future effects of hydro-fracking on groundwater.

The same pre-fracking science approach is being taken in some areas to evaluate the seismic effects of disposing of fracking fluids by injecting them deep underground. In Ohio and Texas, this disposal method has been the prime suspect in the recent activation of old, dormant faults that have generated clusters of low intensity earthquakes. So in North Carolina, as well as other places where fracking has been proposed, some scientists are scrambling to gather as much pre-fracking seismic data as possible.

Potentially newsworthy hydro-fracking presentations and sessions will run throughout the meeting, include the following:

MONDAY

Paper No. 125-7

Local and Regional Water Supply Planning to Evaluate and Manage Hydrofracking

Presentation Time: 3:35-3:50 p.m., Monday, 5 Nov.

Charlotte Convention Center: Room 213BC

Abstract: https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_212125.htm

Session No. 125: Hydrogeology and Geochemistry of Shales

TUESDAY

Paper No. 135-1

Overview of the potential risks of shale gas development and hydrofracturing on water
resources in the United States

Presentation Time: 8:05-8:25 a.m., Tuesday, 6 Nov.

Charlotte Convention Center: Ballroom B

Abstract: https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_208960.htm

Session No 135: Shale Gas Development and Hydraulic Fracturing Impacts on Water Resources in the United States

Paper No. 142-2

Finding frack facts: The literature of hydraulic fracturing

Presentation Time: 8:30-8:45 a.m., Tuesday, 6 Nov.

Charlotte Convention Center: Room 201AB

Abstract: https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_208442.htm

Session No. 142: Geoscience Information: Investing in the Future

WEDNESDAY

Paper No. 219-8

Groundwater contamination from hydraulic fracturing – How will we know?

Presentation Time: 10:15-10:30 a.m., Wednesday, 7 Nov.

Charlotte Convention Center: Room 207BC

Abstract: https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_212844.htm

Session No. 219: Hydraulic Fracturing for Resource Development or Remediation: Methods, Results, and Industry-Regulatory Response to Environmental Impacts on Ground and Surface Waters

Paper No. 219-14

History and development of effective regulation of hydraulic fracturing: the genesis of Colorado rule 205A

Presentation Time: 11:45 a.m.-noon, Wednesday, 7 Nov.

Charlotte Convention Center: 207BC

Abstract: https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_210026.htm

Session No. 219: Hydraulic Fracturing for Resource Development or Remediation: Methods, Results, and Industry-Regulatory Response to Environmental Impacts on Ground and Surface Waters

Paper No. 241-2 (Posters)

Pre-hydrofracking regional assessment of central Carolina seismicity

Presentation Time: 9 a.m.-6 p.m., Wednesday, 7 Nov. (authors will be present from 2 to 4 p.m. and 4:30 to 6 p.m.)

Charlotte Convention Center: Hall B, Booth #173

ABSTRACT: https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_209117.htm

Session No. 241: EarthScope and Geoprisms in Eastern North America: Ongoing Endeavors and a Look Ahead (Posters)

Paper No. 241-1 (Posters)

Insights on induced seismicity in Ohio from the Youngstown M4.0 earthquake

Presentation Time: 9 a.m.-6 p.m., Wednesday, 7 Nov. (authors will be present from 2 to 4 p.m. and 4:30 to 6 p.m.)

Charlotte Convention Center: Hall B, Booth #172

Abstract:https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_208780.htm

Session No. 241: EarthScope and Geoprisms in Eastern North America: Ongoing Endeavors and a Look Ahead (Posters)

Massive volcanic eruption puts past climate and people in perspective

This shows the bipolar matching of volcanic acidity spikes (sulphate) in Greenland and Antarctic ice cores at around the Toba eruption. -  Niels Bohr Institute
This shows the bipolar matching of volcanic acidity spikes (sulphate) in Greenland and Antarctic ice cores at around the Toba eruption. – Niels Bohr Institute

The largest volcanic eruption on Earth in the past millions of years took place in Indonesia 74,000 years ago and researchers from the Niels Bohr Institute can now link the colossal eruption with the global climate and the effects on early humans. The results are published in the scientific journal Climate of the Past.

The volcano Toba is located in Indonesia on the island Sumatra, which lies close to the equator. The colossal eruption, which occurred 74,000 years ago, left a crater that is about 50 km wide. Expelled with the eruption was 2,500 cubic kilometers of lava – equivalent to double the volume of Mount Everest. The eruption was 5,000 times larger than the Mount St. Helens eruption in 1980 in the United States. Toba is the largest volcanic eruption on Earth in the last 2 million years.

The volcanic eruption threw huge clouds of ash and sulphuric acid into the atmosphere and up into the stratosphere, from where it spread across the entire globe in both the northern and southern hemispheres and fell down as acid rain.

Traces of acid rain in the ice caps

“We have now traced this acid rain in the ice caps on Greenland and Antarctica. We have long had an idea of at what depth the Toba eruption could be found in the Greenland ice cap, but we found no ash, so we could not be sure. But now we have found the same series of acid layers from Toba in the Greenland ice sheet and in the ice cap in Antarctica. We have counted the annual layers between acid peaks in ice cores from the two ice caps and it fits together,” explains glaciologist Anders Svensson, Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.

“This means that we can compare the ice cores from Greenland and Antarctica with a annual accuracy and thus combine our knowledge of climate change in the northern and southern hemispheres,” emphasizes Anders Svensson.

There has been much speculation about how such a huge eruption affected the climate. The giant clouds of sulphur particles that are thrown up into the stratosphere form a blanket that shields from the sun’s radiation and this causes the Earth to cool. But how much and for how long? Modelling has shown that such an enormous eruption could cause a cooling of up to 10 degrees in the global temperature for decades

“In the temperature curves from the ice cores we can see that there is no general global cooling as a result of the eruption. There is certainly a cooling and large fluctuations in temperature in the northern hemisphere, but it becomes warmer in the southern hemisphere, so the global cooling has been short,” says Anders Svensson.

Consequences for man

But the eruption may still have had major consequences for nature, the environment and humans in large areas of Asia, where a clear layer of ash from the eruption has been found.

The eruption occurred at a fateful time in human history, around the time when there was a mass exodus of our ancestors, Homo sapiens, from Africa to Asia and researchers believe that early people living as far as 2000 km away in eastern India were affected by the eruption, which raged for weeks.

Archaeologist, however, strongly disagree about what the consequences of the Toba eruption were for people living in the areas of Asia that were affected by the eruption. Speculation ranges from almost no effect to total or partial extermination of the population in large areas. Material from this period is too old to be dated using the carbon-14 method and the Toba ash layer is therefore a very important reference horizon.

“The new precise location of the Toba eruption in the ice cores will place the archaeological finds in a climatic context, which will help to shed light on this critical period of human history,” says Anders Svensson.

Climate modeler identifies trigger for Earth’s last big freeze

A new model of flood waters from melting of the Laurentide Ice Sheet and large glacial lakes along its edge that covered much of North America from the Arctic south to New
England over 13,000 years ago, shows the meltwater flowed northwest into the Arctic first. This weakened deep ocean circulation and led to Earth's last major cold period. A new model of flood waters from melting of the Laurentide Ice Sheet and large glacial lakes along its edge that covered much of North America from the Arctic south to New England over 13,000 years ago, shows the meltwater flowed northwest into the Arctic first. This weakened deep ocean circulation and led to Earth's last major cold period. -  Alan Condron, UMass Amherst
A new model of flood waters from melting of the Laurentide Ice Sheet and large glacial lakes along its edge that covered much of North America from the Arctic south to New
England over 13,000 years ago, shows the meltwater flowed northwest into the Arctic first. This weakened deep ocean circulation and led to Earth’s last major cold period. A new model of flood waters from melting of the Laurentide Ice Sheet and large glacial lakes along its edge that covered much of North America from the Arctic south to New England over 13,000 years ago, shows the meltwater flowed northwest into the Arctic first. This weakened deep ocean circulation and led to Earth’s last major cold period. – Alan Condron, UMass Amherst

For more than 30 years, climate scientists have debated whether flood waters from melting of the enormous Laurentide Ice Sheet, which ushered in the last major cold episode on Earth about 12,900 years ago, flowed northwest into the Arctic first, or east via the Gulf of St. Lawrence, to weaken ocean thermohaline circulation and have a frigid effect on global climate.

Now University of Massachusetts Amherst geoscientist Alan Condron, with Peter Winsor at the University of Alaska, using new, high-resolution global ocean circulation models, report the first conclusive evidence that this flood must have flowed north into the Arctic first down the Mackenzie River valley. They also show that if it had flowed east into the St. Lawrence River valley, Earth’s climate would have remained relatively unchanged.

“This episode was the last time the Earth underwent a major cooling, so understanding exactly what caused it is very important for understanding how our modern-day climate might change in the future,” says Condron of UMass Amherst’s Climate System Research Center. Findings appear in the current issue of Proceedings of the National Academy of Sciences.

Events leading up to the sharp climate-cooling period known as the Younger Dryas, or more familiarly as the “Big Freeze,” unfolded after glacial Lake Agassiz, at the southern edge of the Laurentide ice sheet covering Hudson Bay and much of the Canadian Arctic, catastrophically broke through an ice dam and rapidly dumped thousands of cubic kilometers of fresh water into the ocean.

This massive influx of frigid fresh water injected over the surface of the ocean is assumed to have halted the sinking of very dense, saltier, colder water in the North Atlantic that drives the large-scale ocean circulation, the thermohaline circulation, that transports heat to Europe and North America. The weakening of this circulation caused by the flood resulted in the dramatic cooling of North America and Europe.

Using their high resolution, global, ocean-ice circulation model that is 10 to 20 times more powerful than previously attainable, Condron and Winsor compared how meltwater from the two different drainage outlets was delivered to the sinking regions in the North Atlantic. They found the original hypothesis proposed in 1989 by Wally Broecker of Columbia University suggesting that Lake Aggasiz drained into the North Atlantic down the St. Lawrence River would have weakened the thermohaline circulation by less than 15 percent.

Condron and Winsor say this level of weakening is unlikely to have accounted for the 1,000-year cold climate event that followed the meltwater flood. Meltwater from the St. Lawrence River actually ends up almost 1,900 miles (3,000 km) south of the deep water formation regions, too far south to have any significant impact on the sinking of surface waters, which explains why the impact on the thermohaline circulation is so minor.

By contrast, Condron and Winsor’s model shows that when the meltwater first drains into the Arctic Ocean, narrow coastal boundary currents can efficiently deliver it to the deep water formation regions of the sub-polar north Atlantic, weakening the thermohaline circulation by more than 30 percent. They conclude that this scenario, showing meltwater discharged first into the Arctic rather than down the St. Lawrence valley, is “more likely to have triggered the Younger Dryas cooling.”

Condron and Windor’s model runs on one of the world’s top supercomputers at the National Energy Research Science Computing Center in Berkeley, Calif. The authors say, “With this higher resolution modeling, our ability to capture narrow ocean currents dramatically improves our understanding of where the fresh water may be going.”

Condron adds, “The results we obtain are only possible by using a much higher computational power available with faster computers. Older models weren’t powerful enough to model the different pathways because they contained too few data points to capture smaller-scale, faster-moving coastal currents.”

“Our results are particularly relevant for how we model the melting of the Greenland and Antarctic Ice sheets now and in the future. “It is apparent from our results that climate scientists are artificially introducing fresh water into their models over large parts of the ocean that freshwater would never have reached. In addition, our work points to the Arctic as a primary trigger for climate change. This is especially relevant considering the rapid changes that have been occurring in this region in the last 10 years.”

Tabletop fault model reveals why some quakes result in faster shaking

Gregory McLaskey (L) and Steven Glaser examine a tabletop model of a fault at UC Berkeley. -  Preston Davis photo
Gregory McLaskey (L) and Steven Glaser examine a tabletop model of a fault at UC Berkeley. – Preston Davis photo

The more time it takes for an earthquake fault to heal, the faster the shake it will produce when it finally ruptures, according to a new study by engineers at the University of California, Berkeley, who conducted their work using a tabletop model of a quake fault.

“The high frequency waves of an earthquake – the kind that produces the rapid jolts – are not well understood because they are more difficult to measure and more difficult to model,” said study lead author Gregory McLaskey, a former UC Berkeley Ph.D. student in civil and environmental engineering. “But those high frequency waves are what matter most when it comes to bringing down buildings, roads and bridges, so it’s important for us to understand them.”

While the study, to be published in the Nov. 1 issue of the journal Nature and funded by the National Science Foundation, does nothing to bring scientists closer to predicting when the next big one will hit, the findings could help engineers better assess the vulnerabilities of buildings, bridges and other structures when a fault does rupture.

“The experiment in our lab allows us to consider how long a fault has healed and more accurately predict the type of shaking that would occur when it ruptures,” said Steven Glaser, UC Berkeley professor of civil and environmental engineering and principal investigator of the study. “That’s important in improving building designs and developing plans to mitigate for possible damage.”

To create a fault model, the researchers placed a Plexiglas slider block against a larger base plate and equipped the system with sensors. The design allowed the researchers to isolate the physical and mechanical factors, such as friction, that influence how the ground will shake when a fault ruptures.

It would be impossible to do such a detailed study on faults that lie several miles below the surface of the ground, the authors said. And current instruments are generally unable to accurately measure waves at frequencies higher than approximately 100 Hertz because they get absorbed by the earth.

“There are many people studying the properties of friction in the lab, and there are many others studying the ground motion of earthquakes in the field by measuring the waves generated when a fault ruptures,” said McLaskey. “What this study does for the first time is link those two phenomena. It’s the first clear comparison between real earthquakes and lab quakes.”

Noting that fault surfaces are not smooth, the researchers roughened the surface of the Plexiglas used in the lab’s model.

“It’s like putting two mountain ranges together, and only the tallest peaks are touching,” said McLaskey, who is now a postdoctoral researcher with the U.S. Geological Survey in Menlo Park.

As the sides “heal” and press together, the researchers found that individual contact points slip and transfer the resulting energy to other contact points.

“As the pressing continues and more contacts slip, the stress is transferred to other contact points in a chain reaction until even the strongest contacts fail, releasing the stored energy as an earthquake,” said Glaser. “The longer the fault healed before rupture, the more rapidly the surface vibrated.”

“It is elegant work,” said seismologist John Vidale, a professor at the University of Washington who was not associated with the study. “The point that more healed faults can be more destructive is dismaying. It may not be enough to locate faults to assess danger, but rather knowing their history, which is often unknowable, that is key to fully assessing their threat.”

Glaser and McLaskey teamed up with Amanda Thomas, a UC Berkeley graduate student in earth and planetary sciences, and Robert Nadeau, a research scientist at the Berkeley Seismological Laboratory, to confirm that their lab scenarios played out in the field. The researchers used records of repeating earthquakes along the San Andreas fault that Nadeau developed and maintained. The data were from Parkfield, Calif., an area which has experienced a series of magnitude 6.0 earthquakes two to three decades apart over the past 150 years.

Thomas and McLaskey explored the records of very small, otherwise identically repeating earthquakes at Parkfield to show that the quakes produced shaking patterns that changed depending on the time span since the last event, just as predicted by the lab experiments.

In the years after a magnitude 6.0 earthquake hit Parkfield in 2004, the small repeating earthquakes recurred more frequently on the same fault patches.

“Immediately after the 2004 Parkfield earthquake, many nearby earthquakes that normally recurred months or years apart instead repeated once every few days before decaying back to their normal rates,” said Thomas. “Measurements of the ground motion generated from each of the small earthquakes confirmed that the shaking is faster when the time from the last rupture increases. This provided an excellent opportunity to verify that ground motions observed on natural faults are similar to those observed in the laboratory, suggesting that a common underlying mechanism – fault healing – may be responsible for both.”

Understanding how forcefully the ground will move when an earthquake hits has been one of the biggest challenges in earthquake science.

“What makes this study special is the combination of lab work and observations in the field,” added Roland Burgmann, a UC Berkeley professor of earth and planetary sciences who reviewed the study but did not participate in the research. “This study tells us something fundamental about how earthquake faults evolve. And the study suggests that, in fact, the lab setting is able to capture some of those processes correctly.”

Glaser said the next steps in his lab involve measuring the seismic energy that comes from the movement of the individual contact points in the model fault to more precisely map the distribution of stress and how it changes in the run-up to a laboratory earthquake event.