First evidence of under-ice volcanic eruption in Antarctica





BAS Twin Otter in flight during the aerial survey - Carl Robinson-British Antarctic Survey
BAS Twin Otter in flight during the aerial survey – Carl Robinson-British Antarctic Survey

The first evidence of a volcanic eruption from beneath Antarctica’s most rapidly changing ice sheet is reported this week in the journal Nature Geosciences. The volcano on the West Antarctic Ice Sheet erupted 2000 years ago (325BC) and remains active.



Using airborne ice-sounding radar, scientists from British Antarctic Survey (BAS) discovered a layer of ash produced by a ‘subglacial’ volcano. It extends across an area larger than Wales.



Lead author, Hugh Corr of the BAS says, “The discovery of a ‘subglacial’ volcanic eruption from beneath the Antarctic ice sheet is unique in itself. But our techniques also allow us to put a date on the eruption, determine how powerful it was and map out the area where ash fell. We believe this was the biggest eruption in Antarctica during the last 10,000 years. It blew a substantial hole in the ice sheet, and generated a plume of ash and gas that rose around 12 km into air.”



The discovery is another vital piece of evidence that will help determine the future of the West Antarctic Ice Sheet and refine predictions of future sea-level rise. Co-author Professor David Vaughan (BAS) says,



“This eruption occurred close to Pine Island Glacier on the West Antarctic Ice Sheet. The flow of this glacier towards the coast has speeded up in recent decades and it may be possible that heat from the volcano has caused some of that acceleration. However, it cannot explain the more widespread thinning of West Antarctic glaciers that together are contributing nearly 0.2mm per year to sea-level rise. This wider change most probably has its origin in warming ocean waters.”


The subglacial volcano has a ‘volcanic explosion index’ of around 3-4. Heat from the volcano creates melt-water that lubricates the base of the ice sheet and increases the flow towards the sea.



Pine Island Glacier on the West Antarctic Ice Sheet is showing rapid change and BAS scientists are part of an international research effort to understand this change.



Glaciers are like massive rivers of ice that flow towards the coast and discharge icebergs into the sea.



Since the 1970’s scientists have used radar, seismic and satellite technologies to discover a number of features – including lakes – hidden beneath the ice.



The volcano is located beneath the West Antarctic ice sheet in the Hudson Mountains at latitude 74.6°South, longitude 97°West.



Volcanoes are an important component of the Antarctic region. They formed in diverse tectonic settings, mainly as a result of mantle plumes acting on the stationary Antarctic plate. The region also includes amongst the world’s best examples of a long-lived continental margin arc (Antarctic Peninsula), a very young marginal basin (Bransfield Strait) and an oceanic island arc (South Sandwich Islands). Many extinct volcanoes are very well preserved and others are still active (e.g. Deception Island, Mount Erebus, and the South Sandwich Islands). Volcanic eruptions were common during the past 25 million years, and coincided with the great period of climatic deterioration that resulted in the formation of the Antarctic ice sheet. Many of the volcanoes show the effects of interaction with ice. BAS has played a major role in describing these effects and modelling their influences on the resulting volcanic sequences. It is important to describe and understand these interactions in geologically recent times in order to predict future configurations of the ice sheet and its role in the global system.

Newly Discovered Active Fault Building New Islands Off Croatian Coast





This old fortress in Dubrovnik sits on top of an ancient thrust fault, visible in the photo. The newly discovered active thrust fault lies not far offshore. (Richard A. Bennett)
This old fortress in Dubrovnik sits on top of an ancient thrust fault, visible in the photo. The newly discovered active thrust fault lies not far offshore. (Richard A. Bennett)

A newly identified fault that runs under the Adriatic Sea is actively building more of the famously beautiful Dalmatian Islands and Dinaride Mountains of Croatia, according to a University of Arizona researcher and colleagues.



Geologists had previously believed that the Dalmatian Islands and the Dinaride Mountains had stopped growing 20 to 30 million years ago.



From a region northwest of Dubrovnik, the new fault runs northwest at least 200 km (124 miles) under the sea floor.



The Croatian coast and the 1,185 Dalmatian Islands are an increasing popular tourist destination. Dubrovnik, known as “the Pearl of the Adriatic,” is a UNESCO-designated World Heritage site.



At the fault, the leading edge of the Eurasian plate is scraping and sliding its way over a former piece of the African plate called the South Adria microplate, said lead researcher Richard A. Bennett, an assistant professor of geosciences.



“It’s a collision zone,” Bennett said. “Two continents are colliding and building mountains.”



Bennett and his colleagues found that Italy’s boot heel is moving toward the Croatian coast at the rate of about 4 mm (0.16 inches) per year. By contrast, movement along parts of California’s San Andreas fault can be 10 times greater.



The region along the undersea fault has no evidence of large-magnitude earthquakes occurring in the last 2,000 years. However, if the fault is the type that could move abruptly and cause earthquakes, tsunami calculations for the region need to be redone, he said.



“It has implications for southern Italy, Croatia, Montenegro and Albania.”



At its southern end, the newly identified fault connects to a seismically active fault zone further south that caused a large-magnitude earthquake in Dubrovnik in 1667 and a magnitude 7.1 earthquake in Montenegro in 1979.



Bennett and his colleagues published their article, “Eocene to present subduction of southern Adria mantle lithosphere beneath the Dinarides,” in the January issue of the journal Geology. His co-authors are UA geoscientists Sigrún Hreinsdóttir and Goran Buble; Tomislav BaÅ¡ic’ of the University of Zagreb and the Croatian Geodetic Institute; Željko Bac(ic’ and Marijan Marjanovic’ of the Croatian State Geodetic Administration in Zagreb; and Gabe Casale, Andrew Gendaszek and Darrel Cowan of the University of Washington in Seattle.



The research was funded by the Croatian Geodetic Administration and the U.S. National Science Foundation.



Geologists have been trying to figure out how the collision between the African and Eurasian continents is being played out in the Mediterranean.



Bennett was studying the geology of Italy’s Alps and Apennine Mountains and realized he needed to know more about the mountains on the other side of the Adriatic.


The Croatian mountains and coasts are relatively understudied, in part because of years of political turmoil in the region, he said. So he teamed up with Croatian geologists.



Bennett is an expert in a technique called geodesy that works much like the Global Positioning System in a car.



“We put GPS units on rocks and watch them move around,” he said. “We leave an antennae fixed to a rock and record its movement all the time. We basically just watch it move.”



Just as the GPS in a rental car uses global positioning satellites to tell where the car is relative to a desired destination, the geodesy network can tell where one antenna and its rock are relative to another antenna.



Recent improvements in the technology make it possible to see very small movements of the Earth. “In Croatia we can resolve motions at the level of about one millimeter year,” he said.



The researchers found that the motion between Italy’s boot heel and Eurasia is absorbed at the Dinaride Mountains and Dalmatian Islands.



Combining geodetic data with other geological information revealed that the movement is accommodated by a previously unknown fault under the Adriatic.



Bennett likens movement of the Eurasian plate to a snowplow blade piling up snow in front of it. The snow represents the sea floor being pushed up to form the Dalmatian Islands and the Dinaride Mountains.



“You can see hints of new islands out there,” he said.



But those islands may not provide seaside vacations forever. Bennett said the Adriatic Sea is closing up at the rate of 4.5 km (2.8 miles) per million years. If things continue as they are now, he calculates the eastern and western shores of the Adriatic Sea will meet in about 50 to 70 million years.



“This new finding is an important piece in the puzzle to understanding Mediterranean tectonics,” he said.



He plans to set out additional antennas to learn more about current movement of the region and to figure out what the fault has been doing for the past 40 million years.



The additional information will also help gauge the region’s earthquake potential.



“We want to see if the fault is freely slipping or is accumulating strain and therefore may produce a large earthquake in the future,” Bennett said.

Seismic Images Show Dinosaur-killing Meteor Made Bigger Splash





A new study reveals that the asteroid that killed the dinosaurs landed in deeper water than once thought, perhaps explaining why its effects were so severe. Inset: 1996 (black) and 2005 (red) seismic surveys are shown over the Bouguer gravity anomaly map showing the buried Chicxulub impact crater. (Credit: Map from Nature Geoscience / Illustration courtesy of NASA)
A new study reveals that the asteroid that killed the dinosaurs landed in deeper water than once thought, perhaps explaining why its effects were so severe. Inset: 1996 (black) and 2005 (red) seismic surveys are shown over the Bouguer gravity anomaly map showing the buried Chicxulub impact crater. (Credit: Map from Nature Geoscience / Illustration courtesy of NASA)

The most detailed three-dimensional seismic images yet of the Chicxulub crater, a mostly submerged and buried impact crater on the Mexico coast, may modify a theory explaining the extinction of 70 percent of life on Earth 65 million years ago.



The Chicxulub crater was formed when an asteroid struck on the coast of the Yucatan Peninsula. Most scientists agree the impact played a major role in the “KT Extinction Event” that caused the extinction of most life on Earth, including the dinosaurs.



According to Sean Gulick, a research scientist at the Institute for Geophysics at The University of Texas at Austin’s Jackson School of Geosciences and principal investigator for the project, the new images reveal the asteroid landed in deeper water than previously assumed and therefore released about 6.5 times more water vapor into the atmosphere.



The impact site also contained sulfur-rich sediments called evaporites, which would have reacted with water vapor to produce sulfate aerosols. According to Gulick, an increase in the atmospheric concentration of the compounds could have made the impact deadlier in two ways: by altering climate (sulfate aerosols in the upper atmosphere can have a cooling effect) and by generating acid rain (water vapor can help to flush the lower atmosphere of sulfate aerosols, causing acid rain). Earlier studies had suggested both effects might result from the impact, but to a lesser degree.



“The greater amount of water vapor and consequent potential increase in sulfate aerosols needs to be taken into account for models of extinction mechanisms,” says Gulick.



An increase in acid rain might help explain why reef and surface dwelling ocean creatures were affected along with large vertebrates on land and in the sea. As it fell on the water, acid rain could have turned the oceans more acidic. There is some evidence that marine organisms more resistant to a range of pH survived while those more sensitive did not.



Gulick says the mass extinction event was probably not caused by just one mechanism, but rather a combination of environmental changes acting on different time scales, in different locations. For example, many large land animals might have been baked to death within hours or days of the impact as ejected material fell from the sky, heating the atmosphere and setting off firestorms. More gradual changes in climate and acidity might have had a larger impact in the oceans.





A new study reveals that the asteroid that killed the dinosaurs landed in deeper water than once thought, perhaps explaining why its effects were so severe. Inset: 1996 (black) and 2005 (red) seismic surveys are shown over the Bouguer gravity anomaly map showing the buried Chicxulub impact crater. (Credit: Map from Nature Geoscience / Illustration courtesy of NASA)
A new study reveals that the asteroid that killed the dinosaurs landed in deeper water than once thought, perhaps explaining why its effects were so severe. Inset: 1996 (black) and 2005 (red) seismic surveys are shown over the Bouguer gravity anomaly map showing the buried Chicxulub impact crater. (Credit: Map from Nature Geoscience / Illustration courtesy of NASA)

Gulick and collaborators originally set out to learn more about the trajectory of the asteroid. They had hoped the crater’s structure in the subsurface would hold a tell-tale signature. Instead, the structure seemed to be most strongly shaped by the pre-impact conditions of the target site.



“We discovered that the shallow structure of the crater was determined much more by what the impact site was like before impact than by the trajectory of the impactor,” says Gulick.



If scientists can determine the trajectory, it will tell them where to look for the biggest environmental consequences of impact, because most of the hazardous, shock-heated and fast-moving material would have been thrown out of the crater downrange from the impact.



Researchers at Imperial College in London are already using computer models to search for possible signatures in impact craters that could indicate trajectory regardless of the initial surface conditions at the impact site.



“As someone who simulates impact events using computers, this work provides valuable new constraints on both the pre-impact target structure and the final geometry of the cratered crust at Chicxulub,” says Gareth Collins, a research fellow at Imperial College.



The study “Importance of pre-impact crustal structure for the asymmetry of the Chicxulub impact crater” appears in the February 2008 print edition of the journal Nature Geoscience.



Collaborators on the project included Gail Christeson of the Institute for Geophysics, Penny Barton at the University of Cambridge, Joanna Morgan and Mike Warner at Imperial College, and several graduate students.

Hot springs microbes hold key to dating sedimentary rocks, researchers say





Mammoth Hotsprings in Yellowstone National Park
Mammoth Hotsprings in Yellowstone National Park

Scientists studying microbial communities and the growth of sedimentary rock at Mammoth Hot Springs in Yellowstone National Park have made a surprising discovery about the geological record of life and the environment.



Their discovery could affect how certain sequences of sedimentary rock are dated, and how scientists might search for evidence of life on other planets.



“We found microbes change the rate at which calcium carbonate precipitates, and that rate controls the chemistry and shape of calcium carbonate crystals,” said Bruce Fouke, a professor of geology and of molecular and cellular biology at the University of Illinois.



In fact, the precipitation rate can more than double when microbes are present, Fouke and his colleagues report in a paper accepted for publication in the Geological Society of America Bulletin.



The researchers’ findings imply changes in calcium carbonate mineralization rates in the rock record may have resulted from changes in local microbial biomass concentrations throughout geologic history.



A form of sedimentary rock, calcium carbonate is the most abundant mineral precipitated on the surface of Earth, and a great recorder of life.


“As calcium carbonate is deposited, it leaves a chemical fingerprint of the animals and environment, the plants and bacteria that were there,” said Fouke, who also is affiliated with the university’s Institute for Genomic Biology.



The extent to which microorganisms influence calcium carbonate precipitation has been one of the most controversial issues in the field of carbonate sedimentology and geochemistry. Separating biologically precipitated calcium carbonate from non-biologically precipitated calcium carbonate is difficult.



Fouke’s research team has spent 10 years quantifying the physical, chemical and biological aspects of the hot springs environment. The last step in deciphering the calcium carbonate record was performing an elaborate field experiment, which drew water from a hot springs vent and compared deposition rates with and without microbes being present.



“Angel Terrace at Mammoth Hot Springs in Yellowstone National Park is an ideal, natural laboratory because of the high precipitation rates and the abundance of microbes,” Fouke said. “Calcium carbonate grows so fast – millimeters per day – we can examine the interaction between microorganisms and the calcium-carbonate precipitation process.”



The researchers found that the rate of precipitation drops drastically – sometimes by more than half – when microbes are not present.



“So one of the fingerprints of calcium carbonate deposition that will tell us for sure if there were microbes present at the time it formed is the rate at which it formed,” Fouke said. “And, within the environmental and ecological context of the rock being studied, we can now use chemistry to fingerprint the precipitation rate.”



In a second paper, to appear in the Journal of Sedimentary Research, Fouke and colleagues show how the calcium carbonate record in a spring’s primary flow path can be used to reconstruct the pH, temperature and flux of ancient hot springs environments. The researchers also show how patterns in calcium carbonate crystallization can be used to differentiate signatures of life from those caused by environmental change.



“This means we can go into the rock record, on Earth or other planets, and determine if calcium carbonate deposits were associated with microbial life,” Fouke said.

New Antarctic Ice Core to Provide Clearest Climate Record Yet





Scientist Rebecca Anderson of the Desert Research Institute examines a section of the WAIS Divide ice core recovered from a depth of 500 meters. - Credit: Photo courtesy of Kendrick Taylor
Scientist Rebecca Anderson of the Desert Research Institute examines a section of the WAIS Divide ice core recovered from a depth of 500 meters. – Credit: Photo courtesy of Kendrick Taylor

After enduring months on the coldest, driest and windiest continent on Earth, researchers today closed out the inaugural season on an unprecedented, multi-year effort to retrieve the most detailed record of greenhouse gases in Earth’s atmosphere over the last 100,000 years.



Working as part of the National Science Foundation’s West Antarctic Ice Sheet Divide (WAIS Divide) Ice Core Project, a team of scientists, engineers, technicians and students from multiple U.S. institutions have recovered a 580-meter (1,900-foot) ice core–the first section of what is hoped to be a 3,465-meter (11,360-foot) column of ice detailing 100,000 years of Earth’s climate history, including a precise year-by-year record of the last 40,000 years.



The dust, chemicals and air trapped in the two-mile-long ice core will provide critical information for scientists working to predict the extent to which human activity will alter Earth’s climate, according to the chief scientist for the project, Kendrick Taylor of the Desert Research Institute of the Nevada System of Higher Education. DRI, along with the University of New Hampshire, operate the Science Coordination Office for the WAIS Divide Project.



WAIS Divide, named for the high-elevation region that is the boundary separating opposing flow directions on the ice sheet, is the best spot on the planet to recover ancient ice containing trapped air bubbles–samples of the Earth’s atmosphere from the present to as far back as 100,000 years ago.



While other ice cores have been used to develop longer records of Earth’s atmosphere, the record from WAIS Divide will allow a more detailed study of the interaction of previous increases in greenhouse gases and climate change. This information will improve computer models that are used to predict how the current, unprecedented high levels of greenhouse gases in the atmosphere caused by human activity will influence future climate.


The WAIS Divide core is also the Southern Hemisphere equivalent of a series of ice cores drilled in Greenland beginning in 1989, and will provide the best opportunity for scientists to determine if global-scale climate changes that occurred before human activity started to influence climate were initiated in the Arctic, the tropics or Antarctica.



The new core will also allow investigations of biological material in deep ice, which will yield information about biogeochemical processes that control and are controlled by climate, as well as lead to fundamental insights about life on Earth.



Says Taylor, “We are very excited to work with ancient ice that fell as snow as long as 100,000 years ago. We read the ice like other people might read a stack of old weather reports.”



The WAIS project took more than 15 years of planning and preparation, including extensive airborne reconnaissance and ground-based geophysical research, to pinpoint the one (less than a square mile) space on the 932,000-square-kilometer (360,000-square-mile) ice sheet that scientists believe will provide the clearest climate record for the last 100,000 years.



With only some 40 days a year when the weather is warm enough for drilling–yesterday’s temperature was a balmy -15 degrees Celsius (5 degrees Fahrenheit)–it is expected to take until January 2010 to complete the fieldwork.



For the project, Ice Coring and Drilling Services of the University of Wisconsin-Madison built and is operating a state-of-the-art, deep ice-coring drill, which is more like a piece of scientific equipment than a conventional rock drill used in petroleum exploration. The U.S. Geological Survey National Ice Core Laboratory in Denver designed the core handling system. Raytheon Polar Services Corporation provides the logistical support. The NSF Office of Polar Programs-U.S. Antarctic Program funds the project. The core will be archived at the National Ice Core Laboratory, which is run by the USGS with funding from NSF.

NSF Awards Carnegie Mellon’s Jacobo Bielak $1.6 Million for Earthquake Research


Carnegie Mellon University’s Jacobo Bielak was awarded $1.6 million over the next four years from the prestigious National Science Foundation (NSF) PetaApps program to develop earthquake computer simulations that play an important role in reducing seismic risk for large urban coastal cities.



Bielak leads a team of researchers from several campuses of the University of California along with David R. O’Hallaron, associate professor of computer science and electrical and computer engineering at Carnegie Mellon.



“These simulations will provide unprecedented detailed knowledge of how an urban system performs in a large earthquake and what is needed for improving disaster planning and preparation,” said Bielak, a professor of civil and environmental engineering at Carnegie Mellon.



“One of the keys to making such large-scale simulations possible is the ability to create extremely large models of earthquake prone areas like the Los Angeles basin. This new grant will give us the resources to create three-dimensional models that can simulate how earthquakes impact buildings, bridges and other critical urban infrastructures,” said Bielak, who was recently elected to the Mexican Academy of Engineering.


Over the past decade, Bielak, O’Hallaron and their students have successfully collaborated with researchers at the Southern California Earthquake Center (SCEC) on a series of increasingly ambitious and influential computer models of earthquake behavior, creating fully realistic three-dimensional representations of complex basin geology, earthquake sources and earthquake ground motion.



But Bielak reports that this new earthquake research is designed to push the capability of existing hardware and software programs. The new research will give Bielak and his team the opportunity to integrate the ground motion of large sedimentary basins like the Los Angeles area with a variety of large databases, such as entire building inventories, to study the impacts of large magnitude earthquakes on buildings, transportation systems and other important underground infrastructure.



James H. Garrett Jr., head of the Department of Civil and Environmental Engineering at Carnegie Mellon, said the NSF research award is another example of the university’s successful problem-solving environment. “The project draws upon our expertise in earthquake engineering, computer and computational science and seismology,” Garrett said.



Bielak and his team will also collaborate extensively with the Pittsburgh Supercomputing Center to test some of the special algorithms and simulation structures that will allow them to generate a more accurate picture of how to improve public safety during an earthquake.

2007 Was Earth’s Second Warmest Year in a Century





Temperature changes in 2007 from the previous year
Temperature changes in 2007 from the previous year

Climatologists at the NASA Goddard Institute for Space Studies (GISS) at Columbia University have found that 2007 tied with 1998 for Earth’s second warmest year in a century.



Goddard Institute researchers used temperature data from weather stations on land, satellite measurements of sea ice temperature since 1982 and data from ships for earlier years.



The greatest warming in 2007 occurred in the Arctic and neighboring high-latitude regions. Global warming has a larger effect in polar areas, as the loss of snow and ice leads to more open water, which absorbs more sunlight and warmth. Snow and ice reflect sunlight; when they disappear, so too does their ability to deflect warming rays. The large Arctic warming anomaly of 2007 is consistent with observations of record-low levels of Arctic sea ice in September 2007.



“As we predicted last year, 2007 was warmer than 2006, continuing the strong warming trend of the past 30 years that has been confidently attributed to the effect of increasing human-made greenhouse gases,” said James Hansen, director of NASA GISS.


“It is unlikely that 2008 will be a year with truly exceptional global mean temperature,” said Hansen. “Barring a large volcanic eruption, a record global temperature clearly exceeding that of 2005 can be expected within the next few years, at the time of the next El Nino, because of the background warming trend attributable to continuing increases of greenhouse gases.”



The eight warmest years in the GISS record have all occurred since 1998, and the 14 warmest years in the record have all occurred since 1990.



A minor data processing error found in the GISS temperature analysis in early 2007 does not affect the present analysis. The data processing flaw was the result of a failure to apply NOAA adjustments to U. S. Historical Climatology Network stations in 2000-2006, as the records for those years were taken from a different database (Global Historical Climatology Network). This flaw affected only 1.6% of the Earth’s surface (the contiguous 48 states) and only the last several years in the 21st century. The data processing flaw did not alter the ordering of the warmest years on record and the global ranks were unaffected. In the contiguous 48 states, the statistical tie among 1934, 1998 and 2005 as the warmest year(s) was unchanged. In the current analysis, in the flawed analysis, and in the published GISS analysis, 1934 is the warmest year in the contiguous states (but not globally) by an amount (magnitude on the order of 0.01°C) that is an order of magnitude smaller than the certainty.



The NASA Goddard Institute for Space Studies, at Columbia University in New York City, is a laboratory of the Earth Sciences Division of NASA’s Goddard Space Flight Center and a unit of the Columbia University Earth Institute.

Unconventional natural gas reservoir poised to dramatically increase U.S. production





PSU geoscientist Terry Engelder shows natural fractures in a piece of shale. - Photo By: Greg Grieco, Penn State Public Information
PSU geoscientist Terry Engelder shows natural fractures in a piece of shale. – Photo By: Greg Grieco, Penn State Public Information

Natural gas distributed throughout the Marcellus black shale in northern Appalachia could conservatively boost proven U.S. reserves by trillions of cubic feet if gas production companies employ horizontal drilling techniques, according to a Penn State and State University of New York, Fredonia, team.



“The value of this science could increment the net worth of U.S. energy resources by a trillion dollars, plus or minus billions,” says Terry Engelder, professor of geosciences, at Penn State.



The Marcellus shale runs from the southern tier of New York, through the western portion of Pennsylvania into the eastern half of Ohio and through West Virginia. In Pennsylvania, the formation extends from the Appalachian plateau into the western valley and ridge. This area has produced natural gas for years, but the Marcellus shale, a deep layer of rock, is officially identified as holding a relatively small amount of proven or potential reserves. However, many gas production companies are now interested in the Marcellus.



Engelder, working with Gary Lash, professor of geoscience, SUNY Fredonia, has conservatively estimated that the Marcellus shale contains 168 trillion cubic feet of natural gas in place and optimistically suggests that the amounts could be as high as 516 trillion cubic feet.



“Conservatively, we generally only consider 10 percent of gas in place as a potential resource,” says Engelder. “The key, of course, is that the Marcellus is more easily produced by horizontal drilling across fractures, and until recently, gas production companies seemed unaware of the presence of the natural fractures necessary for magnifying the success of horizontal drilling in the Marcellus.”



The U.S. currently produces roughly 30 trillion cubic feet of gas a year, and these numbers are dropping. According to Engelder, the technology exists to recover 50 trillion cubic feet of gas from the Marcellus, thus keeping the U.S. production up. If this recovery is realized, the Marcellus reservoir would be considered a Super Giant gas field.



Engelder, who has studied this area of the U.S. for most of his career and began looking into fractures under a National Science Foundation grant 25 years ago, has identified and mapped natural fractures in the Marcellus shale. He and Lash will present some of their recent work at the 2008 American Association of Petroleum Geologists Annual Convention and Exhibition this spring.



The researchers look at the patterns of fractures in the shale and determine which are important for gas production. Fractures that correlate with the folding of the ridge and valley system are less common in black shale. However, because of their orientation, the fractures that formed prior to the folding will release gas if the wells cross the fracture zones.


These fractures, referred to as J1 fractures by Engelder and Lash, run as slices from the northeast to the southwest in the Marcellus shale and are fairly close together. While a vertical well may cross one of these fractures and other less productive fractures, a horizontally drilled well aimed to the north northwest will cross a series of very productive J1 fractures.



“It takes $800,000 to drill a vertical well in the Marcellus, but it takes $3 million to drill a horizontal well,” says Engelder.



Companies that drill gas wells need to be certain that horizontal drilling will produce the gas they expect and the work by Engelder and Lash suggests that it will.



“We know that the Marcellus shale appears as an outcrop near Batavia, N.Y., east of Buffalo,” says Engelder. “And we can see the fractures in the Marcellus in the exposed sections of the ridge and valley areas to the southeast. Because we see them going through the folded areas, we know they were there before the folding. If it happened earlier, then we know they have to be in the intervening basin as well.”



The natural fractures in the Marcellus shale are the key to recovering large amounts of gas. As heavily organic sediments were laid down 365 million years ago, the black shale of the Marcellus formed. As the organic material decayed and degraded, methane and other components of natural gas formed and dispersed through the pores in the rock. About 300 million years ago, the pressure of the gas caused fractures to form in the shale. It was not until 280 million years ago that the eastern portion of Pennsylvania was pushed into the folding of the ridge and valley province that makes up that area. Gas that occurs in pockets underground is considered a conventional reservoir; gas that is distributed throughout the rock, like the Marcellus, is called an unconventional reservoir.



The Penn State-Fredonia approach is not restricted to production of the Marcellus shale, but can be applied to any gas-bearing shale with this type of fracture. Because the approach begins with a vertical well and then drills horizontally in the direction that will crosscut the productive fractures, old vertical wells can be reused.



“We can go back to wells that are already drilled and played out, and then drill horizontal from there,” says Engelder. “Reusing old wells has both economic and environmental value.”



Engelder and Lash are principals in Appalachian Fracture Systems Inc., a consulting firm.

Alaska Glacier Speed-up Tied To Internal Plumbing Issues, Says Study





Alaska's Kennicott Glacier recently has been observed by scientists to be lurching, a result of meltwater and floodwater overwhelming its interior plumbing. (Credit: Robert. S. Anderson/University of Colorado at Boulder)
Alaska’s Kennicott Glacier recently has been observed by scientists to be lurching, a result of meltwater and floodwater overwhelming its interior plumbing. (Credit: Robert. S. Anderson/University of Colorado at Boulder)

A University of Colorado at Boulder study indicates meltwater periodically overwhelms the interior drainpipes of Alaska’s Kennicott Glacier and causes it to lurch forward, similar to processes that may help explain the acceleration of glaciers observed recently on the Greenland ice sheet that are contributing to global sea rise.



According to CU-Boulder Professor Robert Anderson of the Institute of Arctic and Alpine Research, the amount of water passing through conduits inside and underneath the Kennicott Glacier increases during seasonal melting and also following annual flooding from a nearby lake. The addition of excess water from melting and flooding causes water to back up into a honeycomb of passages inside the glacier, he said, suggesting the resulting increase in water pressure causes the glacier to slide more rapidly down its bedrock valley.



“The phenomenon is similar to the plumbing system of a house that is incapable of handling excess water or waste, causing it to back up,” said Anderson. “This is a feedback we are still trying to understand and one that has big implications for understanding the dynamics of glaciers and ice sheets, including the behavior of outlet glaciers on the Greenland ice sheet.”



A paper on the subject appears in the January edition of the new monthly scientific journal, Nature Geoscience. The study was authored by former CU-Boulder graduate student Timothy Bartholomaus, Robert Anderson, and INSTAAR’s Suzanne Anderson. Robert Anderson is a faculty member in the CU-Boulder geological sciences department and Suzanne Anderson is a faculty member the geography department.



The sliding eventually halts when the moving glacier opens up spaces in its bed that can accommodate some of the excess water, helping to relieve the water pressure, the authors said. In addition, high rates of water flow eventually enlarge the conduits and ducts permeating the glacier, “melting them back and allowing more water to bleed from the system, further decreasing the pressure,” said Robert Anderson.


The Kennicott Glacier roughly doubled its normal 1-to-2 feet of movement per day during the 2006 sliding episodes tied to water pressure, said Anderson. When the glacier responded to a 2006 “outburst” flood — when water from Hidden Creek Lake adjacent to the glacier rushed into the sub-glacial tunnel system and released an estimated 10 billion gallons of water under the glacier — the pace ramped up to nearly 9 feet a day for the duration of the two-day period.



The team used GPS receivers positioned on the glacier as well as pressure gauges, temperature sensors, sonic distance measuring sensors and electrical conductivity probes. The conductivity levels in the water draining out of the glacier rose after backpressure in the glacier dissipated and expelled water high in chloride ions abundant in the salty bedrock beneath the ice, said co-author Suzanne Anderson.



“Nature essentially provided us with an extra probe to determine these sub-glacial processes, and ultimately provided an additional avenue of support for our model of how this system works,” said Robert Anderson. The National Science Foundation funded the research.



An awareness of such glacial dynamics is important information for glaciologists studying the Greenland ice sheet, which is undergoing record surface melt and the subsequent drainage of large volumes of water through the ice sheet and associated outlet glaciers, the researchers said. Some of Greenland’s outlet glaciers have sped up from 50 percent to 100 percent during the annual melt season and discharged substantially more ice into the seas, according to recent research led by CU-Boulder glaciologist Konrad Steffen.



“There are a number of catastrophic draining events of slush ponds on the Greenland ice sheet that may well promote increased sliding of the ice sheet as this water is jammed into a sub-glacial pipe system that is ill-prepared for such inputs,” Robert Anderson said. “This phenomenon is also relevant to small glaciers around the world, because it may help to explain their nonsteady rates of sliding.



“People are becoming increasingly aware that sea-level rise is a very real problem,” he said. “As scientists, we need to acknowledge the role of all of the world’s ice masses and to understand the physical mechanisms by which they deliver water to the sea.”

Geoscientists use radar to locate lost graves





Acquiring GPR data at Wyatt Chapel Cemetery
Acquiring GPR data at Wyatt Chapel Cemetery

Participants in a summer course for educators used ground-penetrating radar (GPR) to locate a pair of lost graves at an abandoned cemetery outside Houston. The site might become a historical monument.



Nineteen in-service K-12 teachers from urban Houston school districts where the majority of students are members of historically underrepresented minority groups enrolled in the class — ESCI 515: Geophysical Field Work for Educators.



Alison Henning, lecturer in the Department of Earth Science, taught the course. Dale Sawyer, professor of Earth science, and graduate student Priyank Jaiswal also took part in the endeavor.



Henning said some faculty members at Prairie View A&M University (PVAMU), aware of a previous Rice project in the summer of 2006 that investigated the Evergreen Negro Cemetery in Houston, suggested they focus attention on a site near the campus about 50 miles northwest of Houston. The PVAMU faculty members are hoping to turn the site, which is believed to have originated as a slave burial ground in the 1850s, into a historical monument to the early settlers of Prairie View.


Joined by PVAMU students and faculty, Henning and her crew began their work last July. Over two weeks, the group acquired and interpreted 59 GPR profiles in Wyatt Chapel Cemetery and surrounding areas to determine the local stratigraphy and try to locate unmarked graves.



“The soil at Prairie View is ideally suited for GPR investigations, and we obtained some spectacular results,” Henning said. The stratigraphy in the area consists of three to six feet of reddish-brown, medium-grained sand overlying a light gray, highly compacted clay, she explained. The sand-clay boundary appears as a strong reflector on the GPR profiles.



“The class identified numerous subsurface anomalies that might have indicated unmarked burials,” Henning said. Archeologists from Texas A&M later joined the project in the field and excavated two of the anomalies. The first consisted of a pair of bright hyperbolae on the GPR, suggesting two edges of a metal object. This excavation resulted in the discovery of a metal plank thought to be a burial cover. The second anomaly consisted of a break in the horizon representing the top of the clay layer, and subsequent excavation revealed a grave shaft.



ESCI 515 is aimed at educators who are currently teaching science without a science degree. Participants in the Wyatt Chapel Cemetery project included elementary, middle and high school teachers. This summer experience is followed by a content-intensive academic year course in physical geology.



“GPR is an excellent tool for archeological and cultural investigations,” Henning said, “because it is nondestructive (no digging or trenching required). It also provides the opportunity for service learning. As a geoscientist, I find it very gratifying to use geophysics for community service.”