Susan Garcia ( Phone: 650-346-0998 );
PASADENA, Calif. — In a new study involving researchers at the U.S. Geological Survey, scientists observed that a human-induced magnitude 5.0 earthquake near Prague, Oklahoma in November 2011 may have triggered the larger M5.7 earthquake less than a day later. This research suggests that the M5.7 quake was the largest human-caused earthquake associated with wastewater injection.
"The observation that a human-induced earthquake can trigger a cascade of earthquakes, including a larger one, has important implications for reducing the seismic risk from wastewater injection," said USGS seismologist and coauthor of the study Elizabeth Cochran.
Historically, earthquakes in the central United States have been uncommon. Yet in the year 2011 alone, numerous moderate-size earthquakes occurred in Colorado, Texas, Oklahoma, Ohio and Arkansas. Many of these earthquakes occurred near waste-water injection wells, and some have been shown to be caused by human activities.
The 2011 Oklahoma earthquake sequence included the November 6, 2011, M5.7 earthquake that ruptured a part of the Wilzetta fault system, a complex fault zone about 200 km (124 mi) in length near Prague, Oklahoma. Less than 24 hours prior to the M5.7 earthquake, a M5.0 foreshock occurred on November 5, 2011. That foreshock occurred near active waste-water disposal wells, and was linked in a previously published study to fluid injection in those wells. The earthquakes have not been directly linked to hydrofracturing.
The research published this week suggests that the foreshock, by increasing stresses where M5.7 mainshock ruptured, may have triggered the mainshock, which in turn, triggered thousands of aftershocks along the Wilzetta fault system, including a M5.0 aftershock on November 8, 2011. If this hypothesis is correct, the M5.7 earthquake would be the largest and most powerful earthquake ever associated with wastewater injection. All three earthquakes of magnitude 5.0 and greater along the Wilzetta fault exhibited strike-slip motion at three independent locations along the fault, suggesting that three separate portions of the Wilzetta fault system were activated.
The paper, "Observations of Static Coulomb Stress Triggering of the November 2011 M5.7 Oklahoma Earthquake Sequence," by D.F. Sumy, E.S. Cochran, K.M. Keranen, M. Wei, G.A. Abers, from the University of Southern California, USGS, University of Oklahoma, Brown University, and the Lamont Doherty Earth Observatory at Columbia University, was published in the "Journal of Geophysical Research" this week.
The first-ever, geologically-based global assessment of undiscovered copper resources estimates that 3.5 billion metric tons of copper may exist worldwide. The U.S. Geological Survey outlined 225 areas for undiscovered copper in 11 regions of the world. The amount of undiscovered global copper estimated by the USGS would be enough to satisfy current world demand for more than 150 years.
According to the assessment, South America is the dominant source for both identified and undiscovered copper resources. Particularly important, several regions of Asia including China have a large potential for undiscovered copper resources.
"This ground-breaking USGS assessment of future copper resources identifies a huge potential supply that is roughly six times greater than all the copper mined throughout human history," said Interior Assistant Secretary for Water and Science, Anne Castle. "If enough of this copper can be developed in an environmentally responsible and economical way, it will be a boon to new manufacturing and other initiatives that rely on the availability of copper such as the Administration's energy efficiency initiative."
Copper is one of the first metals ever extracted and its first use in coins dates back to about 8000 B.C. It continues to be the material of choice for a variety of industrial needs.
"Copper is one of the building blocks of civilization and is used in almost every aspect of modern life such as plumbing, electrical wiring, cars, cell phones, and energy systems such as wind turbines. In fact, copper has become so valuable that it is even being stolen from construction sites and out of backyards," said Larry Meinert, USGS Mineral Resources Program Coordinator.
U.S. consumption is 2 million metric tons of copper per year whereas world consumption is about 20 million metric tons per year.
The USGS Global Copper Assessment was completed in cooperation with numerous international collaborators from national geological surveys, industry, and academia. The USGS is the principal Federal provider of research and information on nonfuel mineral resources.
Supporting studies, including documentation of the assessment methodology, descriptions of individual tracts, and spatial data for use in geographic information systems (GIS) are available from the USGS Mineral Resources Program. Information on production and consumption of copper as well as general information about copper is available from the USGS.Global copper consumption. (High resolution image)
The President's fiscal year (FY) 2015 budget request for the U.S. Geological Survey is $1.1 billion, an increase of $41.3 million above the FY 2014 enacted level. The FY 2015 Budget reflects the President's ongoing commitment to scientific discovery and innovation to support decision making in addressing critical societal needs and to support a robust economy, while protecting the health and environment of the Nation.
The Budget includes increases totaling $76.4 million to advance key research and development priorities in the sustainable stewardship of natural resources, as identified in the USGS Science Strategy and Department of the Interior and Administration initiatives. This includes robust funding for science to support the sustainable development of energy and mineral resources, water resources management; ecosystem restoration and management; wildlife and environmental health; and climate resilience.
"The USGS has a strong 135-year legacy of providing reliable and relevant scientific information to decision-makers," said Suzette Kimball, Acting USGS Director. "The President's proposed budget recognizes the USGS is uniquely positioned to support our Nation's needs through multi-disciplinary earth science research. This is key for understanding our land, its resources, and our changing climate."
Key increases in the FY 2015 Budget are summarized below. For more detailed information on the President’s 2015 budget, visit the USGS Budget, Planning, and Integration website.
Science Research, Monitoring, and Tools to Support Climate Preparedness and Resilience
The FY 2015 Budget includes $67.6 million for Climate Change Science for a Changing world, a program increase of $18.2 million above the FY 2014 enacted level. The budget provides funding to the USGS National Climate Change and Wildlife Science Center/DOI Climate Science Centers Program, the Climate Research and Development Program, and the Biologic Carbon Sequestration Project for research and the development of information and tools to help communities, States, Tribes, and the Federal government understand, plan for, and respond to the impacts of global change. Resilience in the face of a changing climate requires that the Nation prepare for an increasingly wide range in temperature and precipitation patterns, which could impact all sectors of society, infrastructure, and natural systems. Natural resource managers and infrastructure planners face complex challenges under changing conditions such as drought, wildfire, flooding, and sea level rise. The USGS provides science necessary to inform planning and resource management strategies to help mitigate and adapt to changing conditions.
Restoring, Protecting, and Sustainably Managing Ecosystems
The FY 2015 Budget request includes a total of $52.9 million for Ecosystem Priorities, an increase of $12.4 million above the FY 2014 enacted level. Increases in FY 2015 provide support for research and development to advance ecosystem restoration in key landscapes, such as the California Bay-Delta and the Chesapeake Bay ($1.5 million each), the Puget Sound ($1.1 million), the Columbia River ($850,000) and the Upper Mississippi River ($200,000). These multi-disciplinary projects are designed to serve local ecosystem management needs and develop knowledge and approaches that are transferable to similar ecosystems across the nation.
Invasive plants and animals cause significant costs to society and impacts to the health of human and natural systems, including transmitting diseases, threatening fisheries, clogging waterways, increasing fire vulnerability, and adversely effecting ranchers and farmers. Increases of $4.5 million for invasive species research focus on brown tree snakes in Guam, invasive species in the Everglades, Asian carp in the Great Lakes and Upper Mississippi, and new and emerging invasive species of national concern.
The Budget provides a number of other increases to understand and manage ecological resources in priority areas, including $500,000 for managing and restoring landscapes after wildfires and $300,000 for research on pollinators critical to ecosystem health. The Budget provides $2.8 million for the development of critical ecosystem services tools to enable agencies to manage multiple sources of information into assessment products for land and resource management. Efforts to engage the next generation are illustrated with a requested increase of $2.7 million for the USGS’ Earth Scientists for Tomorrow initiative, which will be carried out in partnership with the Cooperative Research Units.
Sustainable Development of Energy Resources
The 2015 Budget provides $40.7 million for USGS research on conventional and renewable energy. The Budget supports the responsible development of renewable and conventional energy resources, with increases of $1.3 million for geothermal energy resource assessments on Federal lands, $8.3 million for studies on hydraulic fracturing, and $500,000 on research on energy development in the Outer Continental Shelf. The Budget supports the safe and responsible production of natural gas and cleaner energy from fossil fuels, including research and development to enable safe and responsible natural gas production. A total of $18.6 million is provided for the USGS as part of a $48 million interagency R&D initiative aimed at understanding and minimizing potential environmental, health, and safety impacts of unconventional gas resource development and production through hydraulic fracturing. This research is being coordinated between the USGS, the Department of Energy, and the Environmental Protection Agency and focuses on timely, policy-relevant science to enable prudent development while protecting human health and the environment. The development of unconventional oil and gas resources through hydraulic fracturing plays an important and rapidly growing role in the domestic energy portfolio of the Nation, and the USGS has unique capability to provide critically needed science to inform decisions.
The FY 2015 Budget provides $210.4 million for the USGS Water Mission Area, $3.1million above 2014 enacted. The request includes $14.5 million for the WaterSMART program, which is an increase of $6.4 million above the 2014 enacted level. As competition for water resources grows for activities like farming and energy production, so does the need for information and tools to aid water and natural resource managers. The 2015 Budget includes an increase of $2.4 million for the groundwater-monitoring network and $2.0 million for grants to State water resource agencies to improve the availability and quality of water-use data they collect and to integrate those data with the USGS Water Census. The Budget also proposes increases of $1.2 million to fund more than 50 streamgages in the National Streamflow Information Program, $1.0 million to expand work related to water availability issues on tribal lands, $750,000 for national hydrologic modeling for groundwater sustainability, and $700,000 to develop and improve the next generation of streamflow measurement techniques.
Earth Observations and Data to Support Global and Landscape Scale Understanding
The 2015 Budget invests in Earth observation systems, data, and tools to support understanding and management of lands and resources on a global and landscape scale. This includes continued funding for the operation of the Landsat satellite program, which is celebrating the anniversary of the successful launch of Landsat 8, continuing the program’s 41 year history of imaging the Earth’s surface. In 2015, the USGS will continue to work with NASA to analyze user requirements and implement a 20-year sustained land imaging program to provide for Landsat data continuity. Funding for the land imaging program is provided in the 2015 budget for NASA, which will be responsible for development of a sustained, space-based, global land imaging capability. Increases in FY 2015 for the USGS will support improving the accessibility and usability of Landsat data and products, particularly in resource decision making.
The Budget invests in numerous landscape scale earth observation and data efforts including the Federal Geospatial Platform, which provides the Nation with access to science, information, and geospatial frameworks for use in planning, natural resource management, and a myriad of other societal uses. Reflecting the multitude of societal benefits derived from Lidar elevation data, the Budget requests a $5.2 million increase for the 3D Elevation Program (3DEP) initiative as well as increased funding for collecting data and updating elevation maps in Alaska. A $2.0 million increase will support the Big Earth Data Initiative, which is working to make scientific data collected by the Federal government easier to find and use.
The 2015 budget request proposes funding for research on the impacts of human activities that introduce chemical and pathogenic contaminants into the environment and threaten human, animal, and ecological health. Increases proposed include $3.2 million to study the environmental impacts of uranium mining on public lands in the area of the Grand Canyon and $1.5 million to support a national assessment of 800 common and emerging contaminants in stream systems.
During this year, National Atlas of the United States and The National Map will transition into a combined single source for geospatial and cartographic information. This transformation is projected to streamline access to maps, data and information from the USGS National Geospatial Program (NGP). This action will prioritize our civilian mapping role and consolidate core investments while maintaining top-quality customer service.
The USGS will continue its long history of providing topographic maps, geospatial data and other geographic information by offering a range of scales and layers of geospatial information on The National Map Viewer and through US Topo maps. As a result of the conversion to an integrated single source for geospatial and cartographic information, nationalatlas.gov will be removed from service on September 30, 2014.
"We recognize how important it is for citizens to have access to the cartographic and geographic information of our nation. We are committed to providing that access through nationalmap.gov", said Mark DeMulder, NGP Director.
"We value the National Atlas customers and stakeholders and want to make this transition as easy as possible," explained Jay Donnelly, the National Atlas Program Manager. "We will post updates to The National Map and National Atlas Websites as this transition unfolds, including information on the future availability of the products and services currently delivered by nationalatlas.gov."
Further information is available at: http://nationalatlas.gov/transitionfaq.html
Yvette Gillies ( Phone: 907-786-7039 );
Sea otter in kelp. Photograph by Benjamin Weitzman, U.S. Geological Survey. (High resolution image)
ANCHORAGE Nearly 25 years after the Exxon Valdez oil spill injured wildlife off the coast of Alaska, a new report issued today by the U.S. Geological Survey indicates that sea otters have returned to pre-spill numbers within the most heavily oiled areas of Prince William Sound.
Sea otters in the path of the oil incurred heavy mortality when 42 million liters of Prudhoe Bay crude oil were spilled in Prince William Sound in March 1989, with an estimated loss of several thousand otters. Through long-term data collection and analysis, scientists found that sea otters were slow to recover, likely because of chronic exposure to lingering oil. Other studies documented persistence of oil in the sea otters intertidal feeding habitats.
"Although recovery timelines varied widely among species, our work shows that recovery of species vulnerable to long-term effects of oil spills can take decades," said lead author of the study, Brenda Ballachey, research biologist with the U.S. Geological Survey. "For sea otters, we began to see signs of recovery in the years leading up to 2009, two decades after the spill, and the most recent results from 2011 to 2013 are consistent with recovery as defined by the Exxon Valdez Oil Spill Trustee Council."
Scientists assessed recovery by estimating the number of living sea otters based on aerial surveys and comparing that to pre-spill numbers. They also collected carcasses of otters that had died in the spill area. Carcasses were evaluated to determine how old sea otters were when they died. Historically, and prior to the spill, most dead otters were either very old or very young, but following the spill, more middle-aged otters were dying as well. The ages of dead animals has now returned to the pre-spill pattern.
Recovery also was assessed using studies to detect oil exposure using gene expression as a biochemical indicator. The most recent genetic evidence suggested a reduction in oil exposure since 2008.
Scientists concluded that the status of sea otters in western Prince William Sound is now consistent with the criteria established for population recovery set by the Exxon Valdez Oil Spill Trustee Council.
The sea otter was one of more than 20 nearshore species considered to have been injured by the spill.
The publication "2013 update on sea otter studies to assess chronic injury from the 1989 Exxon Valdez oil spill, Prince William Sound, Alaska" is available online.
EVERGLADES NATIONAL PARK, Fla. -- The estimated tens of thousands of Burmese pythons now populating the Everglades present a low risk to people in the park, according to a new assessment by U.S. Geological Survey and National Park Service scientists.
The human risk assessment looked at five incidents that involved humans and Burmese pythons over a 10-year period in Everglades National Park. All five incidents involved pythons striking at biologists who were conducting research in flooded wetlands.
"Visitor and staff safety is always our highest priority at Everglades National Park," said Superintendent Dan Kimball. "Everglades, as many other national parks, draws many thousands of visitors for the opportunity to view the wildlife that live here in a natural setting. Our guidance to visitors with respect to Burmese pythons is the same as for our native wildlife -- please maintain a safe distance and don't harass the wildlife. With respect to controlling Burmese pythons, we are working diligently with our state, federal, tribal, and local partners to manage this invasive species and educate the public on the importance of not letting invasive species loose in the wild."
Although there have been numerous bites to people provoking Burmese pythons by attempting to capture or kill the snakes, this study examined only unprovoked strikes directed at people.
"The strikes did not appear to be defensive, but were more likely were associated with aborted feeding behavior," said USGS wildlife biologist and herpetologist Bob Reed, the lead author of the study. "Pythons usually direct defensive strikes at the front of a person, not from the side or rear, as all of these strikes were. Additionally, Burmese pythons rely on being secretive and evading detection as their primary means of avoiding interactions with people, and typically don’t strike until provoked."
The biologists did not detect any of the snakes before the strikes occurred, making it even more likely that the attacks were related to feeding and not defense, Reed noted. Two of the attacks resulted in very minor injuries from the pythons’ teeth and none involved constriction.
Reed and his co-author, retired Everglades National Park scientist Skip Snow, consider the attacks as cases of mistaken identity. In four of five cases the python was small compared to the size of the person, which resulted in the snake likely aborting the attack upon realizing the large size of its prey. Aborting strikes before actual bites with the possible prey indicates that pythons may be able to assess the size of the prey mid-strike and adjust accordingly, the study said.
Although the pythons’ threat to people is low, previous studies have shown that this invasive snake species is having a negative effect on many of the native mammals in the South Florida Everglades. One study suggests the population of raccoons, opossums, and bobcats have declined significantly in the regions of Everglades National Park where pythons have been established the longest.
More than one million people visit Everglades National Park every year, often traveling along hiking and canoeing trails where Burmese pythons have been spotted or captured. Despite this close interaction, the study noted that none of the reported incidents involved a park visitor. All of the incidents were directed at biologists moving through remote and flooded areas of the park
"As people wade through shallow water, they produce ripples that move ahead of them, and these pressure waves may be detectable to a motionless snake in ambush posture," said Reed. "We speculate that detecting these changes in water pressure may alert a python that an animal is approaching, perhaps priming it to strike immediately when a potential prey item is detected."
Burmese pythons became established in Florida several decades ago as a result of the international pet trade. The largest snakes removed from the Everglades have exceeded 18 feet and 150 pounds. Snakes of this size are capable of ingesting large prey like deer and alligators.
This human risk assessment concluded that although the risk of an unprovoked attack by a Burmese python in Everglades National Park is low, it is not non-existent. Available evidence from captive snakes suggests that even those strikes that result from cases of mistaken identity or defensive behavior may still result in constriction, which can prove fatal to people when a large python or a small human is involved.
The study focused only on the risk associated with Burmese pythons, but did not address other invasive constrictor species, such as the Northern African python, which is also known as the African Rock python, which are also known to be established and breeding in South Florida outside of Everglades National Park. USGS scientists continue to work with partners to better understand the impacts on invasive reptiles in the Everglades, help reduce their spread into new areas and help prevent new species from becoming established.
"Assessing risks to humans from invasive Burmese pythons in Everglades National Park, Florida, USA" by Robert Reed and Skip Snow is published online in the Wildlife Society Bulletin.
LAFAYETTE, La. – Portions of the Mekong River Basin contain hotspots of persistent organic pollutants that pose a significant threat to the residents and wildlife of the Mekong Basin, according to a new U.S. Geological Survey study.
A research team comprised of members from the University Network for Wetland Research and Training in the Mekong Region, the International Crane Foundation and the USGS found that the total loading of persistent organic pollutants in wetland sediments of the Mekong Basin was generally low, but hotspot sites occurred where concentrations exceeded established ecological risk thresholds. Team members from the University Network are providing the results to officials within their own countries so they can determine how to address the issues.
"The overall results of this study provide crucial baseline data that will guide future development and conservation efforts in the Mekong Basin," said Scott Wilson of the USGS National Wetlands Research Center and co-author of the study. "Future work will focus on the classification and distribution of wetlands in the Mekong River Basin, an investigation into heavy metal contamination, and surface elevation monitoring in the coastal area of Southeast Asia."
Persistent organic pollutants are not readily biodegradable and are known to induce a variety of toxic effects in humans and other organisms. In humans, adverse health effects related to reproductive, developmental, behavioral, neurologic, endocrine, and immunologic processes have been linked to exposure. Since persistent organic pollutants do not degrade easily, they can persist in the environment for long periods of time. The pollutants come from agricultural pesticides, industrial pollutants, and other unintentional by-products. This study focused primarily on persistent organic pollutants used in agricultural practices.
The persistent organic pollutants accumulate in the fatty tissue of fish, amphibians, snakes and water birds that make up a large portion of the local population's diet. Animals tested in some hotspots, such as the Tonle Sap, are known to have high levels of bioaccumulation.
The international team looked at 531 samples from approximately 450 wetlands across five countries in Southeast Asia and analyzed them for 39 persistent organic pollutants -- in this case organochlorines and PCBs.
"Conducting quality science at this spatial scale requires intimate knowledge of local areas," said Wilson. "This effort could only be completed with the help of local universities, regional organizations like the International Crane Foundation, and the interdisciplinary science program of agencies like USGS."
Results showed that the use of DDT, a known persistent organic pollutant that has been banned in the study countries, has declined in the region, however, some wetland hotspots were found that contain levels of DDT above established risk thresholds and even suggest continued illegal use. The concentration and distribution of endosulfan, a chemical being phased out in the U.S. and other parts of the world, and its metabolites were also studied and represent a serious problem that requires further study and management action in the Mekong River Basin.
The USGS study, "Persistent Organic Pollutants in Wetlands of the Mekong Basin," was initiated by the U.S. Department of State and was prepared in cooperation with the University Network for Wetland Research and Training in the Mekong Region and the International Crane Foundation.
Scientists have successfully produced hybrid pups between a male western gray wolf and a female western coyote in captivity.
By artificially inseminating a female western coyote with western gray wolf sperm, U.S. Geological Survey scientists and partners from the St. Louis Zoo, University of California, Davis, and Wildlife Science Center recently demonstrated that coyotes are able to bear and nurture healthy hybrid offspring. The results contribute new information to an ongoing question about whether the eastern wolf of southeastern Canada (and formerly of the eastern U.S.) is a unique species that could be protected by the U. S. Endangered Species Act. The findings are published in the journal PLOS ONE.
"Our study adds one more piece to the ongoing controversy over whether the eastern wolf is a valid species," said David Mech, USGS scientist and the report's lead author.
During the 2012 and 2013 study, the scientists attempted to inseminate nine captive western coyotes with sperm from eight different gray wolves at the U.S. Department of Agriculture Wildlife Services National Wildlife Research Center Predator Research Facility in Logan, Utah. Three coyotes became pregnant, and one successfully birthed and nursed six live, healthy pups, currently housed at the Wildlife Science Center in Forest Lake, Minn., north of the Twin Cities.
Some geneticists have suggested recognizing the eastern wolf as a new species of wolf, and potentially adding it to the Endangered Species List. This proposal is based on mitochondrial DNA (mtDNA)—a type of DNA that can only be passed on to offspring by the mother—that has been found in wolves from Manitoba, Canada, through the Great Lakes into southeast Canada. Those wolves could have gotten their coyote-like mtDNA either from hybridization with coyotes or by hybridizing with the eastern wolf. The latter view is that of the geneticists who claim that the coyote-like mtDNA is from the eastern wolf, which is closely related to the coyote.
Scientists who propose that the coyote-like mtDNA came from female coyotes that bred with male, western wolves long ago believe that the eastern wolf is merely a smaller race of the wolf of the West.
The new USGS study shows that it is at least possible for western wolf sperm to fertilize western coyote eggs and that the mother coyote can bear and raise the hybrids.
"Our findings leave the eastern wolf debate open by adding further merit to the hybrid theory rather than disproving it," Mech said. "However, the findings are applicable to captive animals and are not necessarily true under natural conditions, so the counter-hybrid theory is not disproved either."
For more information on USGS wolf research, please visit the USGS Northern Prairie Wildlife Research Center website.
Nutrient enrichment of our nation's streams, lakes, and estuaries is widespread and can contribute to harmful algal blooms, increasing costs for drinking water and causing declines in ecosystem health.
Maps and tables describing the major sources and watershed inputs of nutrients to the Great Lakes and estuaries along the Atlantic coast, Gulf of Mexico, and the Pacific Northwest are now available online. These new maps and the data tables highlight the major sources of nutrients and the areas within a watershed that contribute the largest amounts of nutrients to 115 estuaries along the coastal areas and from 160 watersheds draining into the Great Lakes.
The data can serve further uses. For instance, water resource managers interested in a particular stream or estuary can use the online, interactive decision support tool to estimate how changes in nutrient inputs (source, type, and amount) affect nutrient loads at a downstream location.
A new reporting feature within the tool provides summary information on the amount and source of nutrients from upstream states or major hydrologic regions. For instance, output from the new tool shows the amount of nitrogen contributed from each of the 31 states that drain from the Mississippi River Basin into the Gulf of Mexico.
"This innovative combination of national maps and an online decision support tool provides unparalleled access to water-quality modeling information," said Jerad Bales, USGS acting associate director for Water. "It can be used to improve nutrient reduction strategies and inform nutrient policies across the nation."
These maps and data tables were produced using the USGS Spatially Referenced Regressions On Watershed attributes (SPARROW) nutrient models to explain spatial patterns in stream nutrient loads in relation to human nutrient inputs and natural processes and sources.
Successful management of our nation's waters requires an integrated approach that includes both monitoring and modeling to understand the affect, source type, input amounts, and performance of management activities on nutrients in local streams and ultimately in our Nation’s estuaries
Additional information on USGS nutrient monitoring and modeling activities by the National Water-Quality Assessment Program is available online.
FLAGSTAFF, Ariz. – An increase in the barred owl population is contributing to the decline of threatened Northern spotted owls, according to models developed by U.S. Geological Survey and U.S. Forest Service scientists.
The larger barred owl is considered to be a more aggressive competitor, with higher reproductive capacity as well as a more diverse diet and use of habitat. In the face of increasing barred owl populations and declining habitat, the medium size Northern spotted owl, which lives in old growth forests of northern California and the Pacific Northwest of the United States, is declining.
Using 22 years of detection data from a 1000 square kilometer site in Oregon, researchers found that both species are more likely to abandon an area when the other species is present.
"While both species feel the effects of competition, spotted owls are far more sensitive," said Charles Yackulic, a USGS research statistician and lead author of the study. "As a result, spotted owls at this site, and in many other areas, are declining while barred owl numbers steadily increase."
The authors simulated future population dynamics and found that barred owls are likely to drive down spotted owls to low numbers over the next few decades.
"Scientists in other parts of the Pacific northwest have suggested that differences in the habitat preferences of the barred owl and spotted owl might allow them to coexist. While the two species showed different habitat preferences in this study site, there is still substantial overlap in habitat use," said Yackulic. "As a result, in recent years, barred owls have frequently excluded spotted owls from habitat that they would otherwise prefer."
Some of the spotted owls forced to leave a territory in response to barred owl invasions may establish territories in another area. However, the areas that are available for colonization often contain less suitable habitat and this may lead to a lowered probability of successfully producing young, further contributing to population decline. While habitat differences in this site are unlikely to allow for coexistence, it is unknown whether habitat preferences of barred and spotted owls at sites elsewhere in the spotted owl range are sufficiently different for barred owls and spotted owls to coexist.
"The results of the model show that should the barred owl population be reduced to about a quarter of its current size through management actions, it would minimize the costs associated with managing barred owl populations indefinitely, while also providing substantial benefits to the spotted owl population," said Yackulic.
Janice Reid, U.S. Forest Service wildlife biologist and study coauthor, commented on the importance of long term management. "It is important that long term management plans include protection of currently occupied and reproductively successful spotted owl territories from habitat degradation if we are to have any hope of slowing the spotted owl population decline in the face of the increasing barred owl population."
"The roles of competition and habit in the dynamics of populations and species distributions" by C.B. Yackulic, J. Reid, J.D. Nichols, J.E. Hines, R. Davis and E. Forsman in the journal Ecology, is available online.
Concentrations of polycyclic aromatic hydrocarbons (PAHs) in runoff from pavement with coal-tar-based sealcoat remain elevated for months following sealcoat application, according to a new study by the U.S. Geological Survey.
PAHs are an environmental health concern because they are toxic to fish and other aquatic life. A 2012 human health-risk analysis found that people living near pavement sealed with coal-tar-based products have an elevated risk of cancer.
USGS scientists evaluated concentrations of PAHs and azaarenes (chemicals similar in structure to PAHs but containing a nitrogen atom in the place of a carbon atom) in runoff from test plots sealed with either coal-tar-based or asphalt-based sealcoat starting five hours after sealcoat application and continuing for as long as three months after application. The full report, published in the journal Environmental Pollution, is available online.
Concentrations of PAHs and azaarenes in runoff from the coal-tar-sealcoated pavement were about 20 times higher than in runoff from the asphalt-sealcoated pavement, and about 40 times higher than in runoff from unsealed asphalt. Concentrations and assemblages of PAHs indicated that the asphalt-based sealcoat might have contained a small amount (5-10%) of coal-tar-based sealcoat.
Although the total concentration of PAHs varied relatively little over the three months following application, the concentration of high molecular weight (large) PAHs increased and the concentration of low molecular weight (small) PAHs decreased. The low molecular weight PAHs are acutely toxic to aquatic life, but the high molecular weight PAHs are more likely to cause mutations, birth defects, and cancer. The high molecular weight PAHs in the runoff were mostly in the form of particles.
This study is the first to investigate concentrations of azaarenes associated with sealcoat runoff. Sources of azaarenes include coal-tar and oil-shale processing, wood preserving, and chemical manufacturing. In samples of runoff collected just hours after sealcoat application, concentrations of the azaarene carbazole exceeded those of any other PAH or azaarene measured. Azaarenes have a large range of ecotoxicological effects, including acute toxicity, but have been less well studied than PAHs.
Sealcoat products are widely used in the United States, both commercially and by homeowners. The products are commonly applied to commercial parking lots (including strip malls, schools, churches and shopping centers), residential driveways, apartment complexes and playgrounds.
@USGSLive (Twitter account) will be live-tweeting this event
It's 1964 in Alaska. Imagine 4.5 minutes of powerful ground shaking underneath you from a magnitude 9.2 earthquake. You and your loved ones are then faced with resulting landslides and a devastating tsunami. You just experienced the largest earthquake ever recorded in North America. In that moment, scientists did not know how or why it occurred.
That event marked a turning point for earthquake science. Come learn about the great leaps in research over the last 50 years, and the research still underway to understand the remaining mysteries of earthquake hazards.
It is essential to start with science, because we can't plan if we don’t know what we are planning for.
The USGS and the Hazards Caucus Alliance invite you to a congressional briefing on exploring earthquakes, focusing on analysis of the past and essential science still needed to protect lives and property.
Friday, February 28, 2014
Rayburn House Office Building
David Applegate, U.S. Geological Survey
Peter Haeussler, U.S. Geological Survey
Tom Jordan, Seismological Society of America
John Schelling, Washington State Military Department's Emergency Management Division
American Geosciences Institute
American Geophysical Union
Geological Society of America
Seismological Society of America
Please send your RSVP to Jessica Robertson at firstname.lastname@example.org if you plan to attend.
Refreshments will be provided courtesy of the Seismological Society of America.
Clearer views of waters along the U.S. and Canadian border are now possible with new seamless digital maps. These maps make it easier to solve complex water issues that require a thorough understanding of drainage systems on both sides of the International Boundary.
"In the past, cross-border maps were not always accurate, but now these new digital maps are fully linked across the entire U.S. and Canadian border," said Peter Steeves, physical scientist with the USGS. "This cooperative project allows scientists on either side to look at the water just as nature does, irrespective of the artificial line separating the two nations."
Developed cooperatively by both countries, the digital maps make tackling difficult issues more effective. For example, levels of phosphorous flowing from Lake Champlain in Vermont into Quebec can now be better understood; flooding in the Red River Valley (which flows north from Minnesota and the Dakotas into Manitoba) can be traced; salmon fisheries in the Columbia River Basin in the Pacific Northwest can be efficiently restored; and understanding localized water use and water availability all along the border is now improved.
"The USA/Canada coordinated mapping efforts along the International Border have opened doors to joint scientific analysis that rely on hydrography integration", said David Harvey, National Manager with the Environment Service of Canada. "Water quality and quantity modelling are already being developed on top of this enriched database."
The advent of Geographic Information Systems (GIS) over the past 20 years has allowed for advancements in the analysis potential of digitally mapped water features to a degree hardly imagined when the USGS started mapping in the 19th century. As technology improves in the years to come, even more progress will be made, such as in the use of lasers to map the earth, new techniques to analyze information, and faster computers to process the data.
For more than 125 years, the USGS has provided accurate maps of the nation's surface waters. During the last two decades this mapping has become digital, using computers and new technologies to provide unprecedented knowledge of water resources. This data is stored in the National Hydrography Dataset (NHD) and Watershed Boundary Dataset (WBD).
The principle agencies involved in this effort are the USGS and Natural Resources Canada (NRCan), with oversight by the International Joint Commission (IJC). The U.S. Environmental Protection Agency, Agricultural Foods Canada, Environment Canada along with many provincial and in-state partners participated throughout the process.
Additional information on the NHD and WBD can be found at http://nhd.usgs.gov/.Digital Surface Watersheds along the U.S. and Candian International Boundary. (Larger image) U.S. and Canadian harmonized international sub-basins displaying Canadian 5-digit and U.S. 8-digit hydrologic unit codes; now available within the Watershed Boundary Dataset. (Larger image, 6.7 MB)
FLAGSTAFF, Ariz. – More than 400 years after its discovery by Galileo, the largest moon in the Solar System – Ganymede – has finally claimed a spot on the map.
A group of scientists led by Dr. Geoffrey Collins of Wheaton College (Norton, MA) has produced the first global geologic map of Ganymede, Jupiter’s seventh moon. The map, which was published by the U. S. Geological Survey, technically illustrates the varied geologic character of Ganymede’s surface, and is the first complete global geologic map of an icy, outer-planet moon. The geologic map of Ganymede is available for download online.
"After Mars, the interiors of icy satellites of Jupiter are considered the best candidates for habitable environments for life in our Solar System," said USGS Astrogeology Science Center director Laszlo Kestay. "This geologic map will be the basis for many decisions by NASA and partners regarding future U.S. missions under consideration to explore these worlds."
Since its discovery in January 1610, Ganymede has been the focus of repeated observation, first by Earth-based telescopes, and later by fly-by missions and spacecraft orbiting Jupiter. These studies depict a complex icy world whose surface is characterized by the striking contrast between its two major terrain types; the dark, very old, highly cratered regions, and the lighter, somewhat younger (but still ancient) regions marked with an extensive array of grooves and ridges.
"Three major geologic periods have been identified for Ganymede that involve the dominance of impact cratering, then tectonic upheaval, followed by a decline in geologic activity," said USGS research geologist Dr. Ken Tanaka.
The Ganymede geologic map is unique from other planetary geologic maps because it represents, for the first time, named geologic time periods for an object in the outer solar system.
Surface features, such as furrows, grooves, and impact craters, were characterized using a global image mosaic produced by the USGS. This image mosaic combines the best images from NASA’s Voyager 1 and 2 missions (acquired in 1979) as well as the Galileo orbiter (1995-2003).
"The highly detailed, colorful map confirmed a number of outstanding scientific hypotheses regarding Ganymede’s geologic history, and also disproved others," said USGS scientist Baerbel Lucchitta, who has been involved with geologic mapping of Ganymede since 1980. "For example, the more detailed Galileo images showed that cryovolcanism, or the creation of volcanoes that erupt water and ice, is very rare on Ganymede."
The Ganymede global geologic map will enable researchers to compare the geologic characters of other icy satellite moons, because almost any type of feature that is found on other icy satellites has a similar feature somewhere on Ganymede.
"The surface of Ganymede is over half as large as all the land area on Earth, so there is a wide diversity of locations to choose from," said map lead and Wheaton geology professor Geoff Collins. "Ganymede also shows features that are ancient alongside much more recently formed features, adding historical diversity in addition to geographic diversity."
The new geologic map of Ganymede is just one of many cartographic products that help drive scientific thought. The production of these products has been a focal point of research at the USGS Astrogeology Science Center since its inception in the early 1960s. USGS began producing planetary maps in support of the Apollo moon landings, and continues to help establish a framework for integrating and comparing past and future studies of extraterrestrial surfaces. In many cases, these planetary geologic maps show that, despite the many differences between bodies in our Solar System, there are many notable similarities that link the evolution and fate of our planetary system together.
Amateur astronomers can observe Ganymede (with binoculars) in the evening sky this month, as Jupiter is in opposition and easily visible.
An online video, Rotating Globe of Ganymede Geology, is available for viewing.
The project was funded by NASA through its Outer Planets Research and Planetary Geology and Geophysics Programs.
The mission of the USGS Astrogeology Science Center is to serve the Nation, the international planetary science community, and the general public’s pursuit of new knowledge of our Solar System. The Team's vision is to be a national resource for the integration of planetary geosciences, cartography, and remote sensing. As explorers and surveyors, with a unique heritage of proven expertise and international leadership, USGS astrogeologists enable the ongoing successful investigation of the Solar System for humankind.To present the best information in a single view of Jupiter's moon Ganymede, a global image mosaic was assembled, incorporating the best available imagery from Voyagers 1 and 2 and Galileo spacecraft. This image shows Ganymede centered at 200 West Longitude. This mosaic (right) served as the base map for the geologic map of Ganymede (left). (High resolution image)
BLACKSBURG, VA. – Recording bats' echolocation "calls" is the most efficient and least intrusive way of identifying different species of bats in a given area, providing insight into some populations that have been decimated by white-nose syndrome.This new research by scientists from Virginia Tech, the U.S. Geological Survey and the U.S. Army is published in the Journal of Ecology and the Natural Environment.
White-nose syndrome, an unprecedented disease of cave hibernating bats caused by a cold-loving fungus, has caused the deaths of more than six million bats. It has spread from central New York to at least 22 states and five Canadian provinces since 2006. In addition to the endangered Indiana bat, populations of the formerly abundant little brown bat and northern long-eared bat have experienced severe disease-related declines, particularly in the Northeast and central Appalachians.
"Acoustic sampling is a noninvasive sampling technique for bats, and its use often allows for the detection of a greater number of bat species in less time than traditional sampling methods such as netting," said study co-author W. Mark Ford, a USGS scientist at the Virginia Cooperative Fish and Wildlife Research Unit at Virginia Tech. "Low population numbers make netting both time and cost prohibitive. Netting also has low capture rates for WNS affected species. Moreover, acoustic sampling minimizes the handling of bats, which lessens the chance of unintended cross-contamination and exposure to the white-nose fungus from one bat to another or from equipment and personnel to uninfected bats."
Using acoustic bat detectors, researchers were able to assess the presence of bats by identifying their calls. Field work was conducted at Fort Drum in New York, which, with it's mix of wetlands, mature forests, newly regenerating sites and a large river corridor, provides optimal habitat for both little brown bats and Indiana bats. Before white-nose syndrome affected the bats locally in 2008, these bat species were abundant, Ford noted.
"These species have not been eliminated, but because of white-nose syndrome they occur in low numbers," said Ford. "Acoustic sampling allows us to sample for affected bat species and determine where on the landscape they are and what habitats they continue to use. At Fort Drum, these data are critical for the Army's land managers and the U.S. Fish and Wildlife Service's regulators in working together to conserve endangered and declining bat species while providing range conditions necessary for the military mission."
Managers are seeking the most effective and least intrusive monitoring and survey techniques available for these populations to fulfill stewardship and regulatory requirements, and study authors explored the use of acoustic sampling as an alternative method to determine the presence of bats.
"The studies of bat ecology and management at Fort Drum have been a collaborative effort between USGS, the Department of Defense, U.S. Forest Service, Virginia Tech and West Virginia University since 2003," said Ford. "This long term data collection effort made the study particularly useful for managers, including the U.S. Fish and Wildlife Service, which, because of white-nose syndromes devastating effects, announced a proposed rule to list the northern long-eared bat as an endangered species in 2013."
"Effect of passive acoustic sampling methodology on detecting bats after declines from white- nose syndrome" by L.S. Coleman, W.M. Ford, C.A. Dobony and E.R. Britzke, is published in the current issue of the Journal of Ecology and the Natural Environment.
Additional Contact: Larry Moore, 303-202-4019, email@example.com
Newly released US Topo maps for Washington now feature segments of the Pacific Crest and Pacific Northwest National Scenic Trails. Several of the 1,446 new US Topo quadrangles for the state now display parts of the Trails along with other improved layers.
These trails are two of 11 National Scenic Trails in the U.S.
"Recreationists love maps and the Washington State US Topo maps will provide great planning and navigation tools for hikers and equestrians using the PCT," said Beth Boyst, U.S. Forest Service Pacific Crest Trail Program Manager. "'Plan ahead and prepare' for the trip is the corner stone of 'Leave No Trace' principles of backcountry travel."
The Pacific Crest National Scenic Trail is a treasured pathway through some of the most scenic terrain in the nation. Beginning in southern California at the Mexican border, the PCT travels a total distance of 2,650 miles through California, Oregon, and Washington until reaching the Canadian border. The PCT is one of the original National Scenic Trails established by Congress in the 1968 National Trails System Act and fifty-four percent of the trail lies within designated wilderness.
"The Pacific Northwest Trail travels through rugged, remote wilderness areas and downtown Main Streets in gateway communities," says Matt McGrath, the Pacific Northwest Trail Program Manager for the U.S. Forest Service. "These new maps will improve recreational experiences by better connecting visitors to the varied opportunities available along the PNT."
The Pacific Northwest Trail begins near the Continental Divide in Glacier National Park and travels more than 1,200 miles through Montana, Idaho, and Washington before reaching its western terminus at the Pacific Ocean near Cape Alava. The Trail was designated by Congress as a NST in the Omnibus Public Lands Management Act of 2009.
The USGS partnered with the National Forest Service to incorporate the two trails onto the Washington US Topo maps. These two NST's join the Ice Age National Scenic Trail in Wisconsin as being featured on the new Topo maps. The USGS hopes to eventually include all National Scenic Trails in The National Map products.
As with all US Topo map updates, the replaced maps will be added to the USGS Historical Topographic Map Collection and are also available for download.
To download US Topo maps: http://nationalmap.gov/ustopo/
The National Trails System was established by Act of Congress in 1968. The Act grants the Secretary of Interior and the Secretary of Agriculture authority over the National Trails System. The Act defines four types of trails. Two of these types, the National Historic Trails and National Scenic Trails, can only be designated by Act of Congress. National scenic trails are extended trails located as to provide for maximum outdoor recreation potential and for the conservation and enjoyment of nationally significant scenic, historic, natural, and cultural qualities of the area through which such trails may pass.
There are 11 National Scenic Trails:
- Appalachian National Scenic Trail
- Pacific Crest National Scenic Trail
- Continental Divide National Scenic Trail
- North Country National Scenic Trail
- Ice Age National Scenic Trail
- Potomac Heritage National Scenic Trail
- Natchez Trace National Scenic Trail
- Florida National Scenic Trail
- Arizona National Scenic Trail
- New England National Scenic Trail
- Pacific Northwest National Scenic Trail
The USGS and the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) have teamed up to teach six online workshops open to public discussing Laser Specs for Field Hydrology and Biogeochemistry: Lessons Learned and Future Prospects.
The goal of this video workshop series is two-fold:
- To exchange technical information on application of laser spectrometry, both in field deployment and for analyzing field samples in the lab, and to compare performance with isotope-ratio mass spectrometry, the laboratory standard.
- To highlight research that makes use of this relatively recent and novel technology, both for understanding basic hydrologic processes, and as part of multi-tracer projects that allow new insights into hydrologic and geochemical systems.
Laser spectrometry enables new insights in environmental sciences for many problem-solving applications in hydrology, the science behind our understanding of water resources. Laser spectrometry enables measurements of the relative ratios of the stable isotopes of hydrogen and oxygen, found in all water, by determining absorption of water vapor of selected wavelengths of light reflected ten thousand times between mirrors in the spectrometer laser.
“With a commitment to both the advancement of water-quality science and education, this partnership with CUAHSI to promote these new breakthroughs in Laser Spectrometry is very exciting,” said Donna Myers, Chief of the USGS Office of Water Quality.
Participants are able to view the workshops live and participate by asking questions and posting comments on the discussion boards. By being a virtual workshop held online, national and international experts are able to provide their insights to participants on this new technology and its applications without traveling to a meeting. Each session of the series will be recorded and posted online after the event for those who cannot attend live or would like to watch them again.
"These visual workshops provide a no-cost, informative, and exciting opportunity for anyone interested to learn about hydrological science and technology from anywhere at their convenience," said Dr. Richard P. Hooper, Executive Director & President of CUAHSI, and former National Coordinator of the National Stream Quality Accounting Network (NASQAN) in the USGS Office of Water Quality from 1998-2003.
Education technology, specifically within higher education, is moving in the direction of Massive Open Online Courses (MOOCs), which is the newest innovation in distance learning, allowing students from all over the world to enroll in the courses.
This is the third such workshop jointly organized by USGS and CUAHSI, and the first to be held on-line. Past workshops have similarly focused on bringing new technologies to the forefront of water monitoring and research. CUAHSI is supported by a grant from the National Science Foundation.
St. Petersburg, Fla. – A newly developed computer model holds the promise of helping scientists track and predict where oil will go after a spill, sometimes years later. U.S. Geological Survey scientists developed the model as a way of tracking the movement of sand and oil found along the Gulf of Mexico since the Deepwater Horizon oil spill. The new tool can help guide clean-up efforts, and be used to aid the response to future oil spills.
Following the Deepwater Horizon spill, denser-than-water conglomerates of sand and oil have been found in the surf zone, ranging in size from less than a millimeter to mats up to a few meters in size. The surf zone is where waves break as they approach the shore. The USGS study looked at conglomerates several centimeters thick – known as "surface residual balls," or "SRBs", which continue to emerge in some beach locations more than three years after the first oil reached the shoreline.
Applying the model to movement of SRBs along the coast of Alabama and western Florida showed that normal wave conditions, less than 1.5 to 2 meters, will not move centimeter-sized SRBs alongshore. However, tropical storms, or winter storms can mobilize and redistribute these SRBs alongshore.
The numerical model indicated that inlets trap SRBs, where they could accumulate over time. The model also suggests that when larger SRBs are found they are more likely to have been formed locally when the oil came ashore, rather than being transported from a different location along the coast.
Published this week in Marine Pollution Bulletin, the report also shows that SRBs are likely to be covered and uncovered by sand that is relatively easily moved by waves and currents in the surf zone.
"SRBs are dense enough to rest on the seafloor, rather than floating. Because sand grains are smaller and more mobile than the larger SRBs, under non-storm conditions when the SRBs themselves are not moving, they can be buried and exhumed by mobilized sand," said P. Soupy Dalyander, a research oceanographer and lead author of the study.
In addition to providing guidance for the Deepwater Horizon clean-up effort, the USGS methodology has broader potential application.
"The techniques developed here can be applied to evaluate the potential alongshore movement of SRBs in other locations or from any future spill where large quantities of oil and sand mix in the surf zone", said Dalyander.
Donita Turk ( Phone: 785-832-3570 );
Evaluations of water nutrient ratios suggest that concentrations of a class of cyanobacteria toxins (cyanotoxins), called microcystins, tended to decrease as the total nitrogen to total phosphorus (TN:TP) ratio increased.
Nitrogen addition and phosphorus removal treatments were used to control nutrient ratios in confined experimental chambers in Willow Creek Reservoir, Ore., over two consecutive summers.
Two scientific articles on this research, recently published in the scholarly journal Lake and Reservoir Management, were completed as a joint partnership between the University of Idaho and the U.S. Geological Survey. The study supports previous work done on nutrient ratios and microcystins. The articles, entitled "Experimental manipulation of TN:TP ratios suppress cyanobacterial biovolume and microcystin concentration in large-scale in situ mesocosms," and "Experimental additions of aluminum sulfate and ammonium nitrate to in situ mesocosms to reduce cyanobacterial biovolume and microcystin concentration," are available online.
"This does not necessarily mean that increasing nitrogen in a lake will decrease cyanotoxins," said USGS scientist Ted Harris. "This was a study done in one location, and warrants further research."
This case study suggested that a TN:TP ratio of 75:1 or larger resulted in the growth of green algae instead of toxic cyanobacteria. Toxic cyanobacteria can produce toxins such as microcystins which can be harmful to aquatic life, terrestrial animals, and humans. Cyanotoxin exposure has led to illness in wildlife, livestock, and humans and can result in death in severe exposure cases.
Results from this research could help manage cyanobacteria toxin production; however these approaches need to be studied more extensively in whole-lake settings to fully understand the implications of using these approaches to control cyanobacteria toxin production balanced against other potential environmental harm and socio-economic conditions.
For more information:
- USGS Kansas Algal Toxin Research Website
- USGS Nutrients National Synthesis Project
- USGS Toxic Substances Hydrology Program
PASADENA, Calif. — Earthquake activity in the New Madrid Seismic Zone in the central United States does not seem to be slowing down. In a new study published in the journal "Science," seismologists Morgan Page and Susan Hough of the U.S. Geological Survey investigate whether current quakes in the region could be aftershocks of large earthquakes that occurred 200 years earlier.
Using extensive computer modeling of aftershock behavior, they show that the dearth of moderate (Magnitude 6) earthquakes following the series of large earthquakes in 1811-1812, combined with the high rates of small earthquakes today, is not consistent with the long-lived aftershock hypothesis.
A debate has swirled in recent years, fueled in part by past studies suggesting that continuing New Madrid seismic activity could be the tail end of a long-lived aftershock sequence following the 1811-1812 earthquakes. If modern activity is an aftershock sequence, the argument goes, then there is no evidence that stress is currently building in the zone. Instead, Page and Hough conclude that the current level of activity must be the signature of active, ongoing processes that continue to generate stress in the region –stress that we expect will eventually be released in future large earthquakes. In other words, the New Madrid Seismic Zone is not dead.
The New Madrid Seismic Zone in the central United States produced 4 large earthquakes with magnitudes upwards of 7 over the winter of 1811-1812. Over the last two centuries, small quakes have continued to occur in the zone at a higher rate than elsewhere in the central United States. Geologic evidence also shows that large earthquake sequences occurred there in about 1450 A.D. and 900 A.D.Recent earthquakes in the New Madrid Seismic Zone (CEUS-SSC catalog, 1990-2008). (Larger image) A timeline of earthquakes in the New Madrid Seismic Zone (top) differs significantly from a typical aftershock sequence (bottom). A new study shows that earthquakes occurring today in the region are not aftershocks of the 1811-1812 earthquakes. Rather, they are evidence that stress is continuing to accumulate. Data source: CEUS-SSC catalog. (Larger image)