Raw or undercooked Asian swamp eels could transmit a parasitic infection called gnathostomiasis to consumers.
U.S. Geological Survey scientists found parasitic worms known as gnathostomes in Asian swamp eels collected between 2010 and 2012 from ethnic food markets and in Florida waters where the eel species is invasive. If eaten raw or undercooked, these eels could transmit their parasites to people, causing mild to serious disease. Severe cases of the infection can lead to blindness, paralysis or death. The USGS study was published today in the journal Emerging Infectious Diseases.
"Because live Asian swamp eels are commonly imported to the U.S., a person's dietary history and not just travel history should be considered when diagnosing gnathostomiasis," said Rebecca Cole, USGS scientist and lead author of the study.
Swamp eels transported live from Southeast Asia are sold in many urban ethnic food markets in the United States, and have been released into waters in Florida, Georgia and New Jersey. During the USGS study, scientists found gnathostome worms in eels collected from markets in Manhattan, N.Y., Atlanta, Ga., and Orlando, Fla., and in wild eels caught in peninsular Florida. All of the infected eels obtained from markets were imported from Bangladesh.
"Consumers should be aware of the risk of contracting gnathostomiasis from Asian swamp eels if they are eating raw or undercooked eels," Cole said.
Co-author and USGS scientist Leo Nico said it is notable that North American species of gnathostome parasites have infected wild, invasive Asian swamp eels in Florida. Although the North American species found in the wild Florida eels has not been reported as infecting humans, some scientists suggest that all Gnathostoma species can most likely infect people. According to the authors, it is also concerning that this parasite could be transmitted into native fish and wildlife populations and domestic cats or dogs.
Swamp eels are native to Southeast Asia, and wild-caught and domestically-reared eels are widely consumed as food by humans. The eels are a common source of human gnathostomiasis in many parts of Asia. Wild populations of these invasive eels were first found in Florida in 1997, likely the result of the live food trade or aquarium releases. There are five established populations in the continental U.S. — three in Florida, and one each in Georgia and New Jersey. Introduced swamp eels have also been present in Hawaii for many decades.
The eels, which can reach lengths of about three feet, have the potential to become widespread in the U.S., impacting native aquatic and wetland species. The species has few known predators in the U.S., breathes air and can move across land, and can survive in both hot and cold climates.
Asian carp eggs, including late-stage embryos nearly ready to hatch from the egg, were recently identified in samples collected by U.S. Geological Survey scientists in 2013 from the Upper Mississippi River as far north as Lynxville, Wisc.
"This discovery means that Asian carp spawned much farther north in the Mississippi than previously recorded," said Leon Carl, USGS Midwest Regional Director. "The presence of eggs in the samples indicates that spawning occurred, but we do not know if eggs hatched and survived or whether future spawning events would result in live fish."
The Asian carp eggs and late-stage embryos were discovered two weeks ago while processing samples that were collected in mid-May and mid-June, 2013. The samples were taken as part of a larger research project designed to identify Asian carp spawning habitats. The eggs and late-stage embryos were 250 river miles upstream of previously known reproductive populations in the river. Spawning would have occurred upstream from this site.
Once the scientists visually identified the eggs, they examined other samples taken from the Mississippi River and found Asian carp eggs at seven locations between Pool 19 near Keokuk, Iowa, and Pool 9 of the main channel of the Upper Mississippi River near Lynxville. Iowa, Missouri, Illinois, Minnesota and Wisconsin border the navigation pools where these samples were collected.
The eggs and late-stage embryos were identified as bigheaded carps — either bighead carp or silver carp — through visual analyses of specific features of the eggs and embryos. It is also possible that some eggs could be from grass carp, although no eggs were visually identified as such. The USGS attempted genetic analyses to definitively determine which species of Asian carp the eggs belong to, but the results were inconclusive. Additional steps are being completed to attempt genetic confirmation, and those results are expected in one to two weeks.
The research project that collected these eggs is being coordinated by the USGS in collaboration with Western Illinois University. Scientists plan to collect additional samples from the Mississippi River in 2014 as part of their on-going research project.
"Invasive Asian carp could pose substantial environmental risks and economic impacts to the Upper Mississippi River if they become established," Carl said. "Further research will help us to better understand their habitat requirements and inform integrated control efforts."
For more information on Asian carp research, please visit the Asian Carp Regional Coordinating Committee (ACRCC) website. The ACRCC is a partnership of federal and state agencies, municipalities and other groups, led by the White House Council on Environmental Quality.
Leslie Gordon ( Phone: 650-329-4006 );
FLAGSTAFF, Ariz. — Researchers at the U.S. Geological Survey, the University of Michigan, the University of Arizona, and the University of Technology, Sydney (Australia) are collaborating with scientists in Brazil on a three-year research project that investigates a basic yet unanswered question in Earth-system and global carbon-cycle science: What controls the response of photosynthesis in Amazon tropical forests to seasonal variations in climate?
Results of the study will help improve the reliability of global climate forecasts by guiding improvements in the treatment of tropical forest photosynthesis and related water-cycle processes in Earth-system models.
This question of photosynthesis' response to climate variations, despite its seeming simplicity, is the subject of an ongoing scientific puzzle that has so far been remarkably difficult to answer with confidence. For example, seasonal patterns of photosynthesis simulated by several state-of-the-art, numerical models of the Earth system, and seasonal patterns of vegetation "greenness" as inferred from observations by Earth-observing satellites, disagree with patterns seen in measurements of ecosystem-atmosphere carbon dioxide exchange at monitoring sites in the central Amazon.
"Improving our understanding of how a changing climate affects the fundamental processes that control absorption of atmospheric carbon dioxide by tropical forests, can help us improve Earth system models, and help improve the reliability of global climate forecasts," said USGS geographer and project leader, Dennis Dye.
The project is designed to resolve disagreements between the computer models, and actual forest measurements by developing new knowledge and deeper understanding of seasonal climate, photosynthesis, and water relationships in Amazon tropical forests, through the use of advanced remote-sensing techniques and field observations. The project focuses on existing tropical forest study sites near Manaus and Santarem, Brazil. Scientists will measure physiological properties of leaves and trees, and water flow, and use innovative remote-sensing instruments to monitor the light-reflecting properties of the forest and the effects of clouds and smoke on solar radiation. Scientists will also model the three-dimensional variation in photosynthesis in various forest structures and light levels.
"The ability to monitor the ecohydrologic function of the rainforest at a range of scales – from leaf, to tree, to stand levels – will offer an unprecedented observational support for testing hypotheses and developing new types of forest representation in land-surface models," said University of Michigan Hydrologist Valeriy Ivanov.
The project is supported in part by the U.S. Department of Energy, Office of Biological and Environmental Research, Climate and Environmental Sciences Division, GOAmazon campaign.
ANCHORAGE, Alaska —A recent U.S. Geological Survey-led study of the bar-tailed godwit, a shorebird known famously as the ultimate marathon champion of bird flight, suggests that these birds can sense broad weather patterns and optimally time their long, nonstop, transoceanic migrations to destinations thousands of miles away.
Like airplane pilots examining weather charts for the course ahead, godwits awaiting to take flight ultimately selected dates of departure that corresponded to the best atmospheric wind conditions possible within a two-week window. Remarkably, not only were the conditions optimal for take-off, but they almost always provided the best possible conditions for the birds' entire transoceanic flights.
"We think that these behaviors represent a previously unknown cognitive ability that allows bar-tailed godwits to assess changes in weather conditions across widely separated atmospheric regions in different parts of the Pacific Ocean and to time their migration patterns accordingly," said Robert Gill, Jr., an Emeritus Scientist with the USGS and lead author of the study.
These findings are part of a new scientific publication by collaborators from the USGS, the National Oceanic and Atmospheric Administration, and the University of Groningen and the NIOZ Royal Netherlands Institute for Sea Research. The researchers used detailed information on individuals tracked by satellite transmitters, along with data on wind conditions across the Pacific Ocean, to investigate migration patterns along the 18,000 mile annual route of the bar-tailed godwit. Their study determined that bar-tailed godwits are able to make efficient decisions about when and where to fly during nonstop flights of up to 10 days long between wintering areas in New Zealand and breeding areas in Alaska.
"There are a number of broad-scale prevailing wind patterns through the Pacific Ocean, and the godwits take advantage of these winds to facilitate successful migration between their wintering and breeding areas. These wind patterns appear to be teleconnected, or linked, across broad expanses of the Pacific Ocean," said Gill. "Just like airline pilots, birds occasionally have to abort flights or change course drastically when they encounter severe, unexpected weather," noted David Douglas, Research Wildlife Biologist, who like Gill, works out of the USGS Alaska Science Center and is co-author of the study.
The researchers observed two birds that made abrupt course changes when they encountered rapidly developing cyclones along their flight paths. In one case, the prolonged flight change resulted in the bird not breeding that season, likely due to energy spent fighting the headwinds of the storm.
The report on this study, entitled "Hemispheric-scale wind selection facilitates bar-tailed godwit circum-migration of the Pacific," was recently published in the journal Animal Behaviour.
Photos of bar-tailed godwits, their migration and habitats, are available from the USGS online.
A coalition of scientists from the United States and Afghanistan today released 60 high-tech maps that will help Afghanistan chart a course for future economic development. These maps represent a milestone as Afghanistan is the first country to be almost completely mapped using hyperspectral imaging data.
The coalition of the U.S. Geological Survey, the Afghanistan Ministry of Mines and Petroleum, and the Task Force for Business and Stability Operations (TFBSO), was created by the U.S. Department of Defense, to share American international science and technology as a strategic tool for promoting economic development.
"Hyperspectral data from this research provides a fingerprint that identifies Afghanistan’s natural resources," said Dr. Suzette Kimball, acting USGS director. "This detailed data serves as the backbone of crucial scientific information needed for economic development of natural resources as well as the potential to identify water, biological and natural hazard information."
Hyperspectral imaging is an advanced imaging technique that measures visible and near-infrared light reflecting off the Earth's surface. Researchers use hyperspectral imaging spectrometer data to identify and characterize mineral deposits, vegetation, and other land surface features.
Data were collected in 28 flights that commenced from Kandahar Air Field in 2007. Because of great advances in technology, this information was gathered in just two months where in the past, it would have likely taken up to 25 years to acquire.
The project utilized NASA's WB-57 high altitude research jet outfitted with an imaging spectrometer. Flying at an altitude of 50,000 feet, the spectrometer captured hyperspectral images over 400,000 square kilometers. Scientists using data from the flights have mapped an area that covers more than 70 percent of Afghanistan.
The maps are the newest and most detailed addition to a series of hyperspectral data from the USGS and the TFBSO. In July 2012, the hyperspectral data team released two surface materials maps of Afghanistan produced in partnership with the Afghan Geological Survey and TFBSO.
Learn more about USGS projects in Afghanistan.
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, Cornell University, 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 $51.1 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.
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.
@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 email@example.com 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, firstname.lastname@example.org
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
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.
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)