More deep-sea vents discovered

Previously unknown deep-sea volcanic vents have been discovered in the Southern Ocean. -  NOC/SOES
Previously unknown deep-sea volcanic vents have been discovered in the Southern Ocean. – NOC/SOES

Scientists aboard the Royal Research Ship James Cook have discovered a new set of deep-sea volcanic vents in the chilly waters of the Southern Ocean. The discovery is the fourth made by the research team in three years, which suggests that deep-sea vents may be more common in our oceans than previously thought.

Using an underwater camera system, the researchers saw slender mineral spires three meters tall, with shimmering hot water gushing from their peaks, and gossamer-like white mats of bacteria coating their sides. The vents are at a depth of 520 metres in a newly-discovered seafloor crater close to the South Sandwich Islands, a remote group of islands around 500 kilometres south-east of South Georgia.

“When we caught the first glimpse of the vents, the excitement was almost overwhelming,” says Leigh Marsh, a University of Southampton PhD student who was on scientific watch at the time of the discovery.

Deep-sea vents are hot springs on the seafloor, where mineral-rich water nourishes lush colonies of microbes and deep-sea animals. In the three decades since scientists first encountered vents in the Pacific, around 250 have been discovered worldwide. Most have been found on a chain of undersea volcanoes called the mid-ocean ridge, however, and very few are known in the Antarctic.

“We’re finding deep-sea vents more rapidly than ever before,” says expedition leader Professor Paul Tyler of the University of Southampton’s School of Ocean and Earth Science, which is based at the National Oceanography Centre, Southampton. “And we’re finding some in places other than at mid-ocean ridges, where most have been seen before.”

By studying the new vents, the team hope to understand more about the distribution and evolution of life in the deep ocean, the role that deep-sea vents play in controlling the chemistry of the oceans, and the diversity of microbes that thrive in different conditions beneath the waves.

The researchers were exploring ‘Adventure Caldera’, a crater-like hole in the seafloor three kilometres across and 750 metres deep at its deepest point. Despite its size, Adventure Caldera was only discovered last year by geophysicists from the British Antarctic Survey.

The new vents are the fourth set to be discovered around Antarctica in three expeditions since 2009. Their discovery is part of a project funded by the UK Natural Environment Research Council (NERC), which involves researchers from the National Oceanography Centre in Southampton, the British Antarctic Survey in Cambridge, the Universities of Southampton, Newcastle, Oxford, Bristol and Leeds, and Woods Hole Oceanographic Institution in the US.

The current expedition is scheduled to end in Punta Arenas, Chile, on 22 February 22, and the team are posting regular updates and answering questions from school pupils via their expedition website at http://www.thesearethevoyages.net/

Researchers map out ice sheets shrinking during Ice Age

These maps show the rate at which the ice sheet over the British Isles during the last Ice Age melted. The ka on the images is short for thousand years and BP is 'before present.' So 27 Ka BP is the map of the ice sheet at 27,000 years ago. -  University of Sheffield
These maps show the rate at which the ice sheet over the British Isles during the last Ice Age melted. The ka on the images is short for thousand years and BP is ‘before present.’ So 27 Ka BP is the map of the ice sheet at 27,000 years ago. – University of Sheffield

A set of maps created by the University of Sheffield have illustrated, for the first time, how our last British ice sheet shrunk during the Ice Age.

Led by Professor Chris Clark from the University’s Department of Geography, a team of experts developed the maps to understand what effect the current shrinking of ice sheets in parts of the Antarctic and Greenland will have on the speed of sea level rise.

The unique maps record the pattern and speed of shrinkage of the large ice sheet that covered the British Isles during the last Ice Age, approximately 20,000 years ago. The sheet, which subsumed most of Britain, Ireland and the North Sea, had an ice volume sufficient to raise global sea level by around 2.5 metres when it melted.

Using the maps, researchers will be able to understand the mechanisms and rate of change of ice sheet retreat, allowing them to make predictions for our polar regions, whose ice sheets appear to be melting as a result of temperature increases in the air and oceans.

The maps are based on new information on glacial landforms, such as moraines and drumlins, which were discovered using new technology such as remote sensing data that is able to image the land surface and seafloor at unprecedented resolutions. Experts combined this new information with that from fieldwork, some of it dating back to the nineteenth century, to produce the final maps of retreat.

It is also possible to use the maps to reveal exactly when land became exposed from beneath the ice and was available for colonization and use by plants, animals and humans. This provides the opportunity for viewers to pinpoint when their town/region emerged.

Professor Chris Clark, from the University of Sheffield’s Department of Geography, said: “It took us over 10 years to gather all the information in order to produce these maps, and we are delighted with the results, It is great to be able to visualize the ice sheet and notice that retreat speeds up and slows down, and it is vital of course that we learn exactly why. With such understanding we will be able to better predict ice losses in Greenland and Antarctica.

“In our next phase of work we hope to really tighten up on the timing and rates of retreat in more detail, by dropping tethered corers from a ship to extract seafloor sediments that can be radiocarbon dated.”

Biogeochemistry at the core of global environmental solutions

In the pursuit of food and fuel, humans are disrupting Earth's biogeochemical cycles. -  www.avphotographics.com
In the pursuit of food and fuel, humans are disrupting Earth’s biogeochemical cycles. – www.avphotographics.com

If society wants to address big picture environmental problems, like global climate change, acid rain, and coastal dead zones, we need to pay closer attention to the Earth’s coupled biogeochemical cycles. So reports a special issue of Frontiers in Ecology and the Environment, published this month by the Ecological Society of America.

“There are nearly seven billion people on the planet. And our activities are throwing the Earth’s biogeochemical cycles out of sync, to the detriment of air and water resources, climate stability, and human health,” comments Dr. Jonathan J. Cole, a limnologist at the Cary Institute of Ecosystem Studies and co-editor of the special issue.

A biogeochemical cycle is a pathway by which a chemical element, such as carbon, moves through Earth’s biosphere, atmosphere, hydrosphere, and lithosphere. Some thirty cycles govern the composition of our environment, among them carbon, nitrogen, oxygen, and phosphorus.

Historically, biogeochemical cycles have been studied individually. But in the natural world, element cycles are intimately tied to one another, and seemingly small perturbations can have large impacts across cycles.

The Frontiers issue puts forth a new framework for understanding the biological, geological, and chemical processes that shape element cycles, and the ways in which they are coupled to one another.

It represents one of the first efforts to convene atmospheric scientists and ecologists on the topic. In addition to Cole, it was edited by Drs. Adrien C. Finzi of Boston University and Elisabeth A. Holland of the National Center for Atmospheric Research.

Dr. William H. Schlesinger, president of the Cary Institute and a contributor, notes, “The coupled biogeochemical cycle framework not only explains the causes of many of today’s leading environmental problems, it provides a road map for finding solutions at the global scale.”

Consider the connection between farms and fish. In the U.S., two-thirds of our estuaries are degraded by nitrogen and phosphorus pollution, which is often a by-product of agriculture. Livestock waste and crop fertilizer make their way into coastal waterways, where they stimulate algal blooms that strip oxygen from deep waters, degrade sensitive habitat, and ultimately kill fish.

A better understanding of how nitrogen, phosphorus, and oxygen cycles interact could help balance agricultural needs with the health and productivity of estuaries.

Coupled-cycles can also strengthen our ability to predict and manage climate change. Forests play a role in removing carbon dioxide from the atmosphere. A forest’s ability to sequester atmospheric carbon-an attribute that helps minimize climate change-is tied to nitrogen, phosphorus, and water availability. Yet current global climate models don’t incorporate these couplings in realistic ways.

An integrated view could provide a more accurate view of forest carbon sequestration limits, while helping to guide sustainable forestry practices.

Dr. Finzi concludes, “We are at a turning point. From satellite imagery to real-time environmental monitoring, we have the technology needed to reveal how coupled biogeochemical cycles shape the world and how our actions disrupt them. Now we need to focus on integrating data across observational and experimental networks and applying insights to management decisions.”

Lake-effect theory sinks, but quake timing questions go on

Ray Weldon, head of geological sciences at the University of Oregon, led a research team that has produced a 1,000-year chronology of earthquakes and lake conditions at the southern end of the San Andreas Fault. -  University of Oregon
Ray Weldon, head of geological sciences at the University of Oregon, led a research team that has produced a 1,000-year chronology of earthquakes and lake conditions at the southern end of the San Andreas Fault. – University of Oregon

A chronology of 1,000 years of earthquakes at the southern end of the San Andreas Fault nixes the idea that lake changes in the now-dry region caused past quakes. However, researchers say, the timeline pulled from sediment in three deep trenches confirms that this portion of the fault is long past the expected time for a major temblor that would strongly shake the Los Angeles Basin.

The new study, appearing in the February issue of the Bulletin of the Seismological Society of America, doesn’t change existing thinking about the threat of a major quake — potentially measuring 7.0 to 8.0 on the Richter scale — for southern California. It does, however, provide the first published documentation of much-discussed data that have emerged in the last three decades from an area that is now rapidly being built up and populated, just north of the Salton Sea.

Projections of such a quake in recent years led to the nation’s largest-ever drill, the Great Southern California ShakeOut, last year. The 2011 ShakeOut is set for Oct. 20. There’s even a video projection of the quake’s probable route created by the Southern California Earthquake Center. The last earthquake to originate from the area occurred in about 1690.

The new study, said co-author Ray Weldon, professor and head of the department of geological sciences at the University of Oregon, documents that the south end of the San Andreas fault has gone perhaps 140 years longer than the average 180 years between quakes.

“We have dated the last five to seven prehistoric earthquakes of the southernmost 100 kilometers (about 60 miles) of the San Andreas Fault, which is the only piece of the fault that hasn’t ruptured in historical times,” Weldon said. “If you were there in about 1690, when the last earthquake occurred, the odds of getting to 2010 without an earthquake would have been 20 percent or less.”

Weldon stopped short of concluding that a major earthquake is due or overdue, saying that data from this study and other recent work may just as well point to unknowns in current earthquake-modeling techniques.

The seven earthquake events, including the two possible temblors, were placed between 905-961 AD, 959-1015 (possible), 1090-1152, 1275-1347, 1320-1489 (possible), 1588-1662 and 1657-1713, based on analyses of seismic structures preserved in the sediment in the three trenches and 82 radiocarbon dates drawn from 61 samples of organic material.

Weldon and co-authors — former UO graduate student Belle Philibosian, now pursuing a doctorate at the California Institute of Technology (Cal Tech), and Thomas Fumal of the U.S. Geological Survey, who died in December — concluded there is a high probability of rupture in the fault because of a likely buildup of tectonic stress.

The study area is in the dry bed of prehistoric Lake Cahuilla at Coachella, Calif. The lake has been dry since about 1715, according to timelines found in early travelers’ descriptions of the area. Researchers found that the lakebed was full of water six times in the study period.

“We now have the best chronology of these lakes that has ever existed,” said Weldon, who knows the area well from previous work.

As a doctoral student, he was part of a Cal Tech team led by Kerry Sieh that studied a nearby site in the late 1970s and early 1980s. Seismologists have cited the team’s never-fully published findings often. Weldon’s return to the region began when researchers were granted access to three 26-foot-deep trenches dug to determine Alquist-Priolo earthquake fault zones as required under California law to assure that human dwellings are not built on fault lines. The trenches, two of which exposed the fault, provide direct access to layers of lake sediments and alluvial deposits.

The Lake Cahuilla Basin, 132 miles from downtown Los Angeles, is separated from the Gulf of California to the south by the expansive, ever-changing delta of the Colorado River. The current body of water in the lake’s southern basin, called the Salton Sea, was born in 1905, when heavy rain and snowmelt in the Colorado River drainage led to the collapse of an intake canal built for irrigation purposes just south of Yuma, Ariz. The river then poured into the sink.

The observation that the last lake and last quake were at about 1700 AD and that there have been seven earthquakes and seven lakes during the approximately past 1,000 years have led to the hypothesis that the filling or emptying of each lake triggered earthquake events by changing the pressure on the fault plane below. The new study, Weldon said, shoots down that idea.

The data show that earthquakes occurred in all scenarios: when the lake was filling, while it was full, when it was draining and even when it had long been dried up. In fact, researchers found, the last quake in about 1690 occurred when the lake was full, just before it drained. Calculations of how long the lake would take to dry, if shut off from its Colorado River source coupled with travelers’ journals, cited in the study, actually provide witness to the lake’s disappearance. “If anything, the earthquake made the lake go away,” Weldon said.

“The most popular hypothesis has been that the filling of the lake causes an earthquake, or the draining of the lake causes a quake,” he said. “Neither can be true based on where we’ve found. There’s probably no relationship, but if you want to say there is a relationship, it could be that the quakes make or unmake the lakes.”

That scenario, he added, could mean that earthquakes have at times shifted the Colorado River’s pathway into or away from Lake Cahuilla’s bed, perhaps by shaken driven lateral spreading and collapse of its riverbanks

Seismic activity has been common in the Imperial Valley south of the Salton Sea, which is the continuation of the plate boundary to the south but not part of the actual fault, Weldon noted.

“At some point, this area will get kicked by shaking from one of the many quakes that happen south of the San Andreas Fault,” he said. “It will rupture northward along the fault. When it comes into the San Bernardino Valley, seismic energy will be directed by a series of basins, including the Los Angeles Basin, into the most highly populated part of Southern California”

Using mining by-products to reduce algal blooms

CSIRO research has shown that some mining by-products can be effective in preventing nutrients from entering river systems, thereby reducing the potential for algal blooms.
A joint project between CSIRO and the Western Australian Department of Water investigated a range of mining industry by-product materials, which are currently unused, to determine whether they could instead be used to filter nutrients from natural waters or to treat wastewater that would otherwise be discarded.

CSIRO project leader, Dr Grant Douglas, says the use of abundant, low-cost by-product materials generated from mineral processing offers a potentially cost-effective and environmentally-friendly strategy for the removal of nutrients.

“The largely unexploited by-product materials we generate in Western Australia could be developed as ‘designer’ contaminant adsorbents,” Dr Douglas said.

After assessing a range of potentially suitable by-products to determine their efficacy in removing nutrients or reducing acidity, a four-year field trial was conducted with a potentially suitable by-product.
The by-product was added to soil at a turf farm in the Swan Canning catchment, and was shown to remove 97 per cent of phosphorus and 82 per cent of nitrogen from the shallow groundwaters. Adding the by-product also reduced water use and improved turf health.

With around 400 hectares of turf farms currently under cultivation over the Swan Coastal Plain, use of this by-product as a soil amendment on turf farms would equate to the removal of around two tonnes of phosphorus and nitrogen from groundwater each year.

“This is good news for the health of Perth’s waterways, as it could lead to a substantial reduction in the key nutrients that eventually contribute to algal blooms,” Dr Douglas said.

“The productive use of the by-products also has the potential to reduce the environmental footprint of mining and mineral processing industries by lowering by-product stockpiles.”

The potential benefits of this project could be realised anywhere in the world where similar by-product materials are produced and similar water management issues exist.

The research is being delivered through CSIRO’s Water for a Healthy Country National Research Flagship for the Water Foundation of Western Australia, which promotes water-related research and development activities within Western Australia.

New discoveries improve climate models

New discoveries on how underwater ridges impact the ocean’s circulation system will help improve climate projections.

An underwater ridge can trap the flow of cold, dense water at the bottom of the ocean. Without the ridge, deepwater can flow freely and speed up the ocean circulation pattern, which generally increases the flow of warm surface water.

Warm water on the ocean’s surface makes the formation of sea ice difficult. With less ice present to reflect the sun, surface water will absorb more sunlight and continue to warm.

U.S. Geological Survey scientists looked back 3 million years, to the mid-Pliocene warm period, and studied the influence of the North Atlantic Ocean’s Greenland-Scotland Ridge on surface water temperature.

“Sea-surface temperatures in the North Atlantic and Arctic Oceans were much warmer during the mid-Pliocene warm period than they are today, but climate models so far have been unable to fully understand and account for the cause of this large scale of warming,” said USGS scientist Marci Robinson. “Our research suggests that a lower height of the Greenland-Scotland Ridge during this geologic age was a contributor to the increase of poleward heat transport.”

“This is the first time the impact of a North Atlantic underwater ridge on the ocean circulation system was tested in a mid-Pliocene experiment,” said Robinson. “Understanding this process allows for more accurate predictions of factors such as ocean temperature and ice volume changes.

Research was conducted on the mid-Pliocene because it is the most recent interval in the earth’s history in which global temperatures reached and remained at levels similar to those projected for the 21st century by the Intergovernmental Panel on Climate Change. Therefore, it may be one of the closest analogs in helping to understand the earth’s current and future conditions.

2 severe Amazon droughts in 5 years alarms scientists

New research shows that the 2010 Amazon drought may have been even more devastating to the region’s rainforests than the unusual 2005 drought, which was previously billed as a one-in-100 year event.

Analyses of rainfall across 5.3 million square kilometres of Amazonia during the 2010 dry season, published tomorrow in Science, shows that the drought was more widespread and severe than in 2005. The UK-Brazilian team also calculate that the carbon impact of the 2010 drought may eventually exceed the 5 billion tonnes of CO2 released following the 2005 event, as severe droughts kill rainforest trees. For context, the United States emitted 5.4 billion tonnes of CO2 from fossil fuel use in 2009.

The authors suggest that if extreme droughts like these become more frequent, the days of the Amazon rainforest acting as a natural buffer to man-made carbon emissions may be numbered.

Lead author Dr Simon Lewis, from the University of Leeds, said: “Having two events of this magnitude in such close succession is extremely unusual, but is unfortunately consistent with those climate models that project a grim future for Amazonia.”

The Amazon rainforest covers an area approximately 25 times the size of the UK. University of Leeds scientists have previously shown that in a normal year intact forests absorb approximately 1.5 billion tonnes of CO2 (1). This counter-balances the emissions from deforestation, logging and fire across the Amazon and has helped slow down climate change in recent decades.

In 2005, the region was struck by a rare drought which killed trees within the rainforest. On the ground monitoring showed that these forests stopped absorbing CO2 from the atmosphere, and as the dead trees rotted they released CO2 to the atmosphere.

The unusual drought, affecting south-western Amazonia, was described by scientists at the time as a ‘one-in-100-year event’ (2), but just five years later the region was struck by a similar extreme drought that caused the Rio Negro tributary of the Amazon river to fall to its lowest level on record.

The new research, co-led by Dr Lewis and Brazilian scientist Dr Paulo Brando, used the known relationship between drought intensity in 2005 and tree deaths to estimate the impact of the 2010 drought.

They predict that Amazon forests will not absorb their usual 1.5 billion tonnes of CO2 from the atmosphere in both 2010 and 2011, and that a further 5 billion tonnes of CO2 will be released to the atmosphere over the coming years once the trees that are killed by the new drought rot.

Dr Brando, from Brazil’s Amazon Environmental Research Institute (IPAM), said “We will not know exactly how many trees were killed until we can complete forest measurements on the ground.

“It could be that many of the drought susceptible trees were killed off in 2005, which would reduce the number killed last year. On the other hand, the first drought may have weakened a large number of trees so increasing the number dying in the 2010 dry season.

“Our results should be seen as an initial estimate. The emissions estimates do not include those from forest fires, which spread over extensive areas of the Amazon during hot and dry years. These fires release large amounts of carbon to the atmosphere.”

Some global climate models suggest that Amazon droughts like these will become more frequent in future as a result of greenhouse gas emissions.

Dr Lewis added: “Two unusual and extreme droughts occurring within a decade may largely offset the carbon absorbed by intact Amazon forests during that time. If events like this happen more often, the Amazon rainforest would reach a point where it shifts from being a valuable carbon sink slowing climate change, to a major source of greenhouse gasses that could speed it up.

“Considerable uncertainty remains surrounding the impacts of climate change on the Amazon. This new research adds to a body of evidence suggesting that severe droughts will become more frequent leading to important consequences for Amazonian forests. If greenhouse gas emissions contribute to Amazon droughts that in turn cause forests to release carbon, this feedback loop would be extremely concerning. Put more starkly, current emissions pathways risk playing Russian roulette with the world’s largest rainforest.”

The research was a collaboration between the Universities of Leeds, Sheffield and the Instituto de Pesquisa Ambiental da Amazonia (IPAM) in Brazil. The work was funded by the Royal Society, Gordon and Betty Moore Foundation and the US National Science Foundation.

New model for how Nevada gold deposits formed may help in gold exploration

Barrick Gold Corporation's large open pit at its Goldstrike Mine on the Carlin Trend. The mine has Carlin-type gold deposits, the formation of which has been newly modeled by University of Nevada researchers. -  Photo by John Mundean, University of Nevada, Reno and it's public service department, the Nevada Bureau of Mines and Geology.
Barrick Gold Corporation’s large open pit at its Goldstrike Mine on the Carlin Trend. The mine has Carlin-type gold deposits, the formation of which has been newly modeled by University of Nevada researchers. – Photo by John Mundean, University of Nevada, Reno and it’s public service department, the Nevada Bureau of Mines and Geology.

A team of University of Nevada, Reno and University of Nevada, Las Vegas researchers have devised a new model for how Nevada’s gold deposits formed, which may help in exploration efforts for new gold deposits.

The deposits, known as Carlin-type gold deposits, are characterized by extremely fine-grained nanometer-sized particles of gold adhered to pyrite over large areas that can extend to great depths. More gold has been mined from Carlin-type deposits in Nevada in the last 50 years – more than $200 billion worth at today’s gold prices – than was ever mined from during the California gold rush of the 1800s.

This current Nevada gold boom started in 1961 with the discovery of the Carlin gold mine, near the town of Carlin, at a spot where the early westward-moving prospectors missed the gold because it was too fine-grained to be readily seen. Since the 1960s, geologists have found clusters of these “Carlin-type” deposits throughout northern Nevada. They constitute, after South Africa, the second largest concentration of gold on Earth. Despite their importance, geologists have argued for decades about how they formed.

“Carlin-type deposits are unique to Nevada in that they represent a perfect storm of Nevada’s ideal geology – a tectonic trigger and magmatic processes, resulting in extremely efficient transport and deposition of gold,” said John Muntean, a research economic geologist with the Nevada Bureau of Mines and Geology at the University of Nevada, Reno and previously an industry geologist who explored for gold in Nevada for many years.

“Understanding how these deposits formed is important because most of the deposits that cropped out at the surface have likely been found. Exploration is increasingly targeting deeper deposits. Such risky deep exploration requires expensive drilling.

“Our model for the formation of Carlin-type deposits may not directly result in new discoveries, but models for gold deposit formation play an important role in how companies explore by mitigating risk. Knowing how certain types of gold deposits form allows one to be more predictive by evaluating whether ore-forming processes operated in the right geologic settings. This could lead to identification of potential new areas of discovery.”

Muntean collaborated with researchers from the University of Nevada, Las Vegas: Jean Cline, a facultyprofessor of geology at UNLV and a leading authority on Carlin-type gold deposits; Adam Simon, an assistant professor of geoscience who provided new experimental data and his expertise on the interplay between magmas and ore deposits; and Tony Longo, a post-doctoral fellow who carried out detailed microanalyses of the ore minerals.

The team combined decades of previous studies by research and industry geologists with new data of their own to reach their conclusions, which were written about in the Jan. 23 early online issue of Nature Geoscience magazine and will appear in the February printed edition. The team relates formation of the gold deposits to a change in plate tectonics and a major magma event about 40 million years ago. It is the most complete explanation for Carlin-type gold deposits to date.

“Our model won’t be the final word on Carlin-type deposits,” Muntean said. “We hope it spurs new research in Nevada, especially by people who may not necessarily be ore deposit geologists.”

Baker Institute conference to examine safety, effectiveness of US offshore drilling industry

The explosion on the Deepwater Horizon rig in the Gulf of Mexico last April led to the largest oil spill in U.S. history and threatened Gulf ecosystems, the local Gulf Coast economy and the future of U.S. offshore drilling. A Feb. 11 conference at Rice University’s Baker Institute for Public Policy will examine the policy implications of the disaster in light of new scientific and technical information. The conference will feature academic scholars from Rice University, as well as other southwest universities, including the University of Texas at Austin, Texas A&M, Tulane University and Louisiana State University.

“U.S. Offshore Oil Exploration: Managing Risks to Move Forward” will begin at 9 a.m. in Baker Hall’s DorĂ© Commons on the Rice University campus, 6100 Main St. For directions, go to www.rice.edu/maps/maps.html.

The conference will bring together students, scientists and industry leaders, as well as national and Gulf Coast policymakers and political leaders, to discuss the path forward toward ensuring a safe and effective U.S. offshore drilling industry.

J. Robinson West, founder and CEO of PFC Energy, will deliver the opening keynote address, “U.S. Offshore Drilling: What is at Stake?” The morning panels will discuss the ecological impact of offshore drilling and ways policy decisions can make offshore drilling safer.

Michael R. Bromwich, director of the Bureau of Ocean Energy Management, Regulation and Enforcement, will give the luncheon keynote. Afternoon panels will consider engineering challenges facing deepwater drilling and how to foster an improved “safety culture” in the offshore drilling industry.

Amy Myers Jaffe, the Wallace S. Wilson Fellow in Energy Studies at the Baker Institute, will offer closing remarks titled “Offshore Drilling and U.S. Energy Security.”

Researcher says the next large central US earthquake may not be in New Madrid

This December marks the bicentennial of the New Madrid earthquakes of 1811-12, which are the biggest earthquakes known to have occurred in the central U.S.

Now, based on the earthquake record in China, a University of Missouri researcher says that mid-continent earthquakes tend to move among fault systems, so the next big earthquake in the central U.S. may actually occur someplace else other than along the New Madrid faults.

Mian Liu, professor of geological sciences in the College of Arts and Science at MU, examined records from China, where earthquakes have been recorded and described for the past 2,000 years. Surprisingly, he found that during this time period big earthquakes have never occurred twice in the same place.

“In North China, where large earthquakes occur relatively frequently, not a single one repeated on the same fault segment in the past two thousand years,” Liu said. “So we need to look at the ‘big picture’ of interacting faults, rather than focusing only on the faults where large earthquakes occurred in the recent past.”

Mid-continent earthquakes, such as the ones that occurred along the New Madrid faults, occur on a complicated system of interacting faults spread throughout a large region. A large earthquake on one fault can increase the stress on other faults, making some of them more likely to have a major earthquake. The major faults may stay dormant for thousands of years and then wake up to have a short period of activity.

Along with co-authors Seth Stein, a professor of earth and planetary sciences at Northwestern University, and Hui Wang, a Chinese Earthquake Administration researcher, Liu believes this discovery will provide valuable information about the patterns of earthquakes in the central and eastern United States, northwestern Europe, and Australia. The results have been published in the journal Lithosphere.

“The New Madrid faults in the central U.S., for example, had three to four large events during 1811-12, and perhaps a few more in the past thousand years. This led scientists to believe that more were on the way,” Stein said. “However, high-precision Global Positioning System (GPS) measurements in the past two decades have found no significant strain in the New Madrid area. The China results imply that the major earthquakes at New Madrid may be ending, as the pressure will eventually shift to another fault.”

While this study shows that mid-continent earthquakes seem to be more random than previously thought, the researchers believe it actually helps them better understand these seismic events.

“The rates of earthquake energy released on the major fault zones in North China are complementary,” Wang said. “Increasing seismic energy release on one fault zone was accompanied by decreasing energy on the others. This means that the fault zones are coupled mechanically.”

Studying fault coupling with GPS measurements, earthquake history, and computer simulation will allow the scientists to better understand the mysterious mid-continent earthquakes.

“What we’ve discovered about mid-continent earthquakes won’t make forecasting them any easier, but it should help,” Liu said.