Results for “Engineering Structures” — Page 40

USGS2008

Strong motion observations and recordings from the great Wenchuan Earthquake

The National Strong Motion Observation Network System (NSMONS) of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and a network management system. During the Wenchuan Earthquake, over 1,400 components of acceleration records were obtained from 460 permanent free-field stations and three arrays for topographical effect and structural response observation in the network system from the main shock, and over 20,000 components of acceleration records from strong aftershocks occurred before August 1, 2008 were also obtained by permanent free-field stations of the NSMONS and 59 mobile instruments quickly deployed after the main shock. The strong motion recordings from the main shock and strong aftershocks are summarized in this paper. In the ground motion recordings, there are over 560 components with peak ground acceleration (PGA) over 10 Gal, the largest being 957.7 Gal. The largest PGA recorded during the aftershock exceeds 300 Gal. ?? 2008 Institute of Engineering Mechanics, China Earthquake Administration and Springer-Verlag GmbH.

Earthquake Engineering and Engineering Vibration↗

USGS2013

Variability in wood-frame building damage using broad-band synthetic ground motions: a comparative numerical study with recorded motions

Earthquake damage to light-frame wood buildings is a major concern for North America because of the volume of this construction type. In order to estimate wood building damage using synthetic ground motions, we need to verify the ability of synthetically generated ground motions to simulate realistic damage for this structure type. Through a calibrated damage potential indicator, four different synthetic ground motion models are compared with the historically recorded ground motions at corresponding sites. We conclude that damage for sites farther from the fault (>20 km) is under-predicted on average and damage at closer sites is sometimes over-predicted.

Journal of Earthquake Engineering↗

USGS2024

Complex landslide patterns explained by local intra-unit variability of stratigraphy and structure: Case study in the Tyee Formation, Oregon, USA

Lithology and geologic structure are important controls on landslide susceptibility and are incorporated into many regional landslide hazard models. Typically, metrics for mapped geologic units are used as model input variables and a single set of values for material strength are assumed, regardless of spatial heterogeneities that may exist within a map unit. Here we describe how differences in bedding thickness, grain size, inferred uniaxial compressive strength, and bedding dip control the inherent susceptibility of slopes to deep-seated failure within a single mapped geologic unit - the Tyee Formation of Oregon, USA. The Tyee, which covers over 15,000 km2 and underlies much of the Oregon Coast Range, comprises gently folded alternating beds of sandstone and siltstone deposited as turbidites, forming a 2-km thick Eocene submarine fan which has been uplifted and exhumed through the Cenozoic. Deep-seated landslides are widespread in the Tyee, but form a complex spatial pattern such that landslide density ranges from 0 to 24% of the total landscape area. These slides are often extensive and sufficiently deep to reduce local hillslope gradients, resulting in a strong negative correlation between landslide density and mean local slope. Mean annual precipitation and predicted strong ground motions from Cascadia earthquake scenarios also fail to explain the spatial distribution of deep-seated landslides. Consequently, landslide stability models, which are strongly influenced by landscape slope, pore-water pressure, and seismic acceleration, yield landslide susceptibility maps which are broadly anti-correlated with mapped deep-seated landslide density. Through a multivariable linear regression model, we show that much of the variance in deep-seated landslide density can be explained by variability of intra-unit stratigraphic and structural characteristics, which we measure at 128 sites across two study areas totaling ∼3000 km2. Our results suggest bedding dip is only weakly correlated to landslide density, but strongly influences landslide failure style. Subtle increases in bedding dip, even in the gently folded Tyee Formation, result in a substantially higher likelihood of a landslide being cataclinal, or parallel to bedding. Overall, we find a slight majority of landslides fail within these cataclinal slopes, and that these landslides tend to be larger than non-cataclinal landslides. We also show that the lithological and structural properties that influence landslide susceptibility are distinct for these two populations of landslides. Our results demonstrate how localized, intra-unit, geologic variability can exert strong control on landslide susceptibility and failure style. This suggests that in some locations, landslide hazard models could be significantly improved by incorporating detailed, spatially variable, geologic properties rather than relying solely on generalized geologic map units.

Oregon↗

USGS1992

1993 Fiscal Year Water Resources Division Information Guide

This Guide briefly describes the Water Resources Division's mission, program, and organizational structure, and where and how to obtain specific types of hydrologic information. The Guide also contains a listing of addresses, telephone numbers, and office hours for Headquarters, Regional, District, and State offices. For some offices, two addresses are given: the mailing address of the office to which correspondence should be sent and the street address of the office. The map shows the location of the offices.

Guam;Puerto Rico;Virgin Islands↗

USGS2006

The Hayward fault

This field guide consists of eleven stops at sites that illustrate the geological, geophysical, geographic, and engineering aspects of the Hayward fault in the East Bay. Section I (Stops 1–4) consists of stops that are part of the University of California at Berkeley (UC-Berkeley), including research facilities, retrofit of campus buildings, and geomorphic features along the fault. Section II (Stops 5 and 6) consists of stops along the Hayward fault north of the UC-Berkeley main campus, and Section III (stops 7–11) consists of stops related to the Hayward fault south of the UC-Berkeley main campus (Fig. 1 ). Stops are designed to illustrate geomorphic features of the fault, the effects of fault creep on structures sited on the fault, and retrofit design of structures to mitigate potential future deformation due to fault rupture.

California↗

USGS2009

Coastal change during Hurricane Ivan 2004

Category 3 Hurricane Ivan came ashore near Gulf Shores, Alabama, on September 16, 2004. The barrier islands of the northern Gulf of Mexico near the Florida/Alabama border were exposed to the strongest winds. The communities of Gulf Shores, Pine Island and Orange Beach, AL, are, in places, very low lying with their dunes rising up only several meters. These dunes were unable to contain the 3-4 meter storm surge. The U.S. Geological Survey (USGS), National Aeronautics and Space Administration (NASA), and U.S. Army Corps of Engineers (USACE) are cooperating in a research project investigating coastal change during Hurricane Ivan. On Friday September 17, 2004, the USGS acquired oblique aerial photography to help understand the impact of Ivan on the coastal environment. Two days later, airborne lidar was collected using NASA Experimental Advanced Airborne Research Lidar (EAARL). Gulf waters, driven by hurricane force winds spilled across the barrier islands creating currents strong enough to transport massive amounts of sand landward. These waters undermined buildings and roads and opened new island breaches. On top of the surge, breaking waves nearly as tall as the depth of the surge, eroded dunes and battered structures.

Alabama↗

USGS2015

Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin, USA

A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct population segment of conservation concern, we approached this problem by examining (1) landscape-scale habitat availability and distribution, (2) water body-scale habitat associations, and (3) resource management-identified threats to persistence. We found that areas with perennial aquatic habitat and suitable climate are extremely limited in the southern portion of the species’ range. Within these suitable areas, native and non-native predators (trout and American bullfrogs [Lithobates catesbeianus]) are widespread and may further limit habitat availability in upper- and lower-elevation areas, respectively. At the water body scale, spotted frog occupancy was associated with deeper sites containing abundant emergent vegetation and nontrout fish species. Streams with American beaver (Castor canadensis) frequently had these structural characteristics and were significantly more likely to be occupied than ponds, lakes, streams without beaver, or streams with inactive beaver ponds, highlighting the importance of active manipulation of stream environments by beaver. Native and non-native trout reduced the likelihood of spotted frog occupancy, especially where emergent vegetation cover was sparse. Intensive livestock grazing, low aquatic connectivity, and ephemeral hydroperiods were also negatively associated with spotted frog occupancy. We conclude that persistence of this species at the arid end of its range has been largely facilitated by habitat stability (i.e., permanent hydroperiod), connectivity, predator-free refugia, and a commensalistic interaction with an ecosystem engineer. Beaver-induced changes to habitat quality, stability, and connectivity may increase spotted frog population resistance and resilience to seasonal drought, grazing, non-native predators, and climate change, factors which threaten local or regional persistence.

California, Idaho, Oregon, Nevada, Utah↗

USGS2026

Coral reef protection may help avert risks to people, property, and economic activity caused by projected reef degradation

Degradation of coral reefs over the past several decades has caused regional-scale erosion of the shallow seafloor that serves as a protective barrier against coastal hazards along southeast Florida, USA. How future change in coral reefs may affect coastal flooding, however, has been less attended than other factors contributing to increasing risks such as sea-level rise and more intense storms. Here, the increased flooding hazard faced by Florida's coastal communities from the projected future degradation of its adjacent coral reefs is evaluated through oceanographic, coastal engineering, habitat, geospatial, and socioeconomic modeling. Risk-based valuation approaches were followed to map flood zones at 10-m 2 resolution along 430 km of Florida's reef-lined coast for the current and projected future coral reef conditions. The projected degradation of Florida's coral reefs can increase annual flooding to more than 8.77 km 2 of land and 4,980 km of roads, affecting more than 7,315 people, $412.5 million in damages to 1,400 buildings, and economic disruption of $438.1 million annually (2024 US dollars). The degradation of Florida's coral reefs would increase the annual risk to people and structures by more than 42% and 47%, respectively, but is spatially variable due to the heterogeneous alongshore nature and distribution of the reefs and communities: the increased risk exceeds $1 million/km annually to more than 17% of the coastline but also disproportionately would affect vulnerable populations. These results help identify areas where coral reef protection could help reduce the projected increased storm flooding risk to Florida's coastal communities.

Florida↗

USGS2007

The microbial community structure in petroleum-contaminated sediments corresponds to geophysical signatures

The interdependence between geoelectrical signatures at underground petroleum plumes and the structures of subsurface microbial communities was investigated. For sediments contaminated with light non-aqueousphase liquids, anomalous high conductivity values have been observed. Vertical changes in the geoelectrical properties of the sediments were concomitant with significant changes in the microbial community structures as determined by the construction and evaluation of 16S rRNA gene libraries. DNA sequencing of clones from four 16S rRNA gene libraries from different depths of a contaminated field site and two libraries from an uncontaminated background site revealed spatial heterogeneity in the microbial community structures. Correspondence analysis showed that the presence of distinct microbial populations, including the various hydrocarbon-degrading, syntrophic, sulfate-reducing, and dissimilatory-iron-reducing populations, was a contributing factor to the elevated geoelectrical measurements. Thus, through their growth and metabolic activities, microbial populations that have adapted to the use of petroleum as a carbon source can strongly influence their geophysical surroundings. Since changes in the geophysical properties of contaminated sediments parallel changes in the microbial community compositions, it is suggested that geoelectrical measurements can be a cost-efficient tool to guide microbiological sampling for microbial ecology studies during the monitoring of natural or engineered bioremediation processes. Copyright ?? 2007, American Society for Microbiology. All Rights Reserved.

Applied and Environmental Microbiology↗

USGS2004

Earthquake scenario and probabilistic ground-shaking hazard maps for the Albuquerque-Belen-Santa Fe, New Mexico, corridor

New Mexico's population is concentrated along the corridor that extends from Belen in the south to Española in the north and includes Albuquerque and Santa Fe. The Rio Grande rift, which encompasses the corridor, is a major tectonically, volcanically, and seismically active continental rift in the western U.S. Although only one large earthquake (moment magnitude (M) ≥ 6) has possibly occurred in the New Mexico portion of the rift since 1849, paleoseismic data indicate that prehistoric surface-faulting earthquakes of M 6.5 and greater have occurred on aver- age every 400 yrs on many faults throughout the Rio Grande rift. We have developed a series of nine scenario and probabilistic hazard maps that portray the ground shaking that could occur in the Albuquerque-Belen-Santa Fe corridor from future earthquakes in New Mexico. These maps, at a scale of 1:500,000, display color-contoured ground-motion values in terms of the parameters of peak horizontal acceleration and horizontal spectral accelerations at 0.2 and 1.0 second (sec) periods. The maps depict surficial ground shaking and incorporate the site-response effects at locations underlain by unconsolidated sediments. The scenario maps are for a M 7.0 earthquake rupturing the Sandia-Rincon faults, which are adjacent to and dip west beneath Albuquerque. The probabilistic maps are for the two annual exceedance probabilities of building code relevance, 10% and 2% exceedance probabilities in 50 yrs (corresponding to return periods of 500 and 2,500 yrs, respectively). We included 57 Quaternary faults, all located within the Rio Grande rift, in the probabilistic seismic hazard analysis. These faults were characterized in terms of their geometry, rupture behavior (including possible segmentation), maximum expected earthquake magnitude, recurrence model, probability of activity, and slip rate. Preferred maximum magnitude values for these faults ranged from M 6.1 to 7.4 and preferred slip rates from 0.01 to approximately 0.12 mm/yr. Regional source zones and Gaussian smoothing of the historical seismicity were also included in the probabilistic hazard analysis to account for the hazard from background earthquakes (M ≤ 6.5). A numerical ground-motion modeling approach and empirical attenuation relation- ships appropriate for extensional tectonic regimes were used to compute the scenario earthquake and probabilistic ground motions on rock. Amplification factors were then used to modify the rock motions and hence to incorporate site response into the hazard maps. These factors were based on three generalized geologic site-response categories (hard rock, soft rock, and firm/stiff soil) and were adopted from similar California-based categories because insufficient subsurface geologic and geotechnical data are available for the map area. The resulting hazard maps indicate that from both scenario and probabilistic perspectives, the ground-shaking hazard in the Albuquerque–Belen–Santa Fe corridor from future earthquakes could be severe, damaging, and potentially disastrous. In the event of a M 7.0 earthquake occurring on the Sandia–Rincon faults, ground shaking as characterized by peak ground acceleration could reach 0.7 g in much of the eastern half of the Albuquerque metropolitan area. (1 g = 980 cm/sec, the rate of gravitational acceleration.) These high ground motions will be attributable to the city’s location directly over the Sandia–Rincon faults and the amplifying effect of the unconsolidated sediments within the Albuquerque Basin. These levels of ground shaking will probably result in severe damage to traditional adobe construction and even to modern buildings. Long- period ground motions (> 1.0 sec), which are significant to long and tall structures (e.g., tall buildings, long bridges, and highway overpasses), will also be high (> 1.0 g). Injuries and loss of life will be likely. For the 500- and 2,500-yr return period maps, the highest peak accelerations are predicted to be at the damaging levels of 0.3 g and 0.6 g, respectively. All maps show dramatically the frequency-dependent amplification of unconsolidated sediments in the basins along the Rio Grande valley (e.g., Albuquerque Basin). The pattern of amplification and deamplification is clearly a function of the distribution of unconsolidated sediments. These maps are not intended to be a substitute for site-specific studies for engineering design nor to replace standard maps commonly referenced in building codes. Rather, we hope that these maps will be used as a guide by government agencies; the engineering, urban planning, emergency preparedness, and response communities; and the general public as part of an overall program to reduce earthquake risk and losses in New Mexico.

New Mexico↗

USGS2020

Evidence for large Holocene earthquakes along the Denali fault in southwest Yukon, Canada

The Yukon–Alaska Highway corridor in southern Yukon is subject to geohazards ranging from landslides to floods and earthquakes on faults in the St. Elias Mountains and Shakwak Valley. Here we discuss the late Holocene seismic history of the Denali fault, located at the eastern front of the St. Elias Mountains and one of only a few known seismically active terrestrial faults in Canada. Holocene faulting is indicated by scarps and mounds on late Pleistocene drift and by tectonically deformed Pleistocene and Holocene sediments. Previous work on trenches excavated against the fault scarp near the Duke River reveals paleoseismic sediment disturbance dated to ∼300–1,200, 1,200–1,900, and 3,000 years ago. Re-excavation of the trenches indicates a fourth event dated to 6,000 years ago. The trenches are interpreted to show a negative flower structure produced by extension of sediments by dextral strike-slip fault movement. Nearby Crescent Lake is ponded against the fault scarp. Sediment cores reveal four abrupt sediment and diatom changes reflecting seismic shaking at ∼1,200–1,900, 1,900–5,900, 5,900–6,200, and 6,500–6,800 years ago. At the Duke River, the fault offsets sediments, including two White River tephra layers (∼1,900 and 1,200 years old). Late Pleistocene outwash gravel and overlying Holocene aeolian sediments show in cross section a positive flower structure indicative of post-glacial contraction of the sediments by dextral strike-slip movement. Based on the number of events reflecting ∼M6, we estimate the average recurrence of large earthquakes on the Yukon part of the Denali fault to be about 1,300 years in the past 6,500–6,800 years.

Yukon↗

USGS2021

Improved fire severity mapping in the North American boreal forest using a hybrid composite method

Fire severity is a key driver shaping the ecological structure and function of North American boreal ecosystems, a biome dominated by large, high-intensity wildfires. Satellite-derived burn severity maps have been an important tool in these remote landscapes for both fire and resource management. The conventional methodology to produce satellite-inferred fire severity maps generally involves comparing imagery from 1 year before and 1 year after a fire, yet environmental conditions unique to the boreal have limited the accuracy of resulting products. We introduce an alternative method – the ‘hybrid composite’ – based on deriving mean severity over time on a per-pixel basis within the cloud-computing environment of Google Earth Engine. It constructs the post-fire image from satellite data composited from all valid images (i.e., clear-sky and snow-free) acquired in the time period immediately after fire through the early growing season of the following year. We compare this approach to paired-scene and composite approaches where the post-fire time period is from the growing season 1 year after fire. Validation statistics based on field-derived data for 52 fires across Alaska and Canada indicate that the hybrid composite method outperforms the other approaches. This approach presents an efficient and cost-effective means to monitor and explore trends and patterns across broad spatial domains, and could be applied to fires in other regions, especially those with frequent cloud cover or rapid vegetation recovery.

Alaska↗

USGS2017

Fishing activities

Unlike the major anthropogenic changes that terrestrial and coastal habitats underwent during the last centuries such as deforestation, river engineering, agricultural practices or urbanism, those occurring underwater are veiled from our eyes and have continued nearly unnoticed. Only recent advances in remote sensing and deep marine sampling technologies have revealed the extent and magnitude of the anthropogenic impacts to the seafloor. In particular, bottom trawling, a fishing technique consisting of dragging a net and fishing gear over the seafloor to capture bottom-dwelling living resources has gained attention among the scientific community, policy makers and the general public due to its destructive effects on the seabed. Trawling gear produces acute impacts on biota and the physical substratum of the seafloor by disrupting the sediment column structure, overturning boulders, resuspending sediments and imprinting deep scars on muddy bottoms. Also, the repetitive passage of trawling gear over the same areas creates long-lasting, cumulative impacts that modify the cohesiveness and texture of sediments. It can be asserted nowadays that due to its recurrence, mobility and wide geographical extent, industrial trawling has become a major force driving seafloor change and affecting not only its physical integrity on short spatial scales but also imprinting measurable modifications to the geomorphology of entire continental margins.

Book chapter↗

USGS2001

The National Map - Washington-Idaho Pilot Project

Governments depend on a common set of geographic base information as a tool for economic and community development, land and natural resource management, and health and safety services. Emergency management and defense operations rely on this information. Private industry, nongovernmental organizations, and individual citizens use the same geographic data. Geographic information underpins an increasingly large part of the Nation's economy. Available geographic data often have the following problems: * They do not align with each other because layers are frequently created or revised separately, * They do not match across administrative boundaries because each producing organization uses different methods and standards, and * They are not up to date because of the complexity and cost of revision. The U.S. Geological Survey (USGS) is developing The National Map to be a seamless, continuously maintained, and nationally consistent set of online, public domain, geographic base information to address these issues. The National Map will serve as a foundation for integrating, sharing, and using other data easily and consistently. In collaboration with other government agencies, the private sector, academia, and volunteer groups, the USGS will coordinate, integrate, and, where needed, produce and maintain base geographic data. The National Map will include digital orthorectified imagery; elevation data; vector data for hydrography, transportation, boundary, and structure features; geographic names; and land cover information. The data will be the source of revised paper topographic maps. Many technical and institutional issues must be resolved as The National Map is implemented. To begin the refinement of this new paradigm, pilot projects are being designed to identify and investigate these issues. The pilots are the foundation upon which future partnerships for data sharing and maintenance will be built.

Fact Sheet↗

USGS2001

The National Map - Missouri Pilot Project

Governments depend on a common set of geographic base information as a tool for economic and community development, land and natural resource management, and health and safety services. Emergency management and defense operations rely on this information. Private industry, nongovernmental organizations, and individual citizens use the same geographic data. Geographic information underpins an increasingly large part of the Nation's economy. Available geographic data often have the following problems: * They do not align with each other because layers are frequently created or revised separately, * They do not match across administrative boundaries because each producing organization uses different methods and standards, and * They are not up to date because of the complexity and cost of revision. The U.S. Geological Survey (USGS) is developing The National Map to be a seamless, continuously maintained, and nationally consistent set of online, public domain, geographic base information to address these issues. The National Map will serve as a foundation for integrating, sharing, and using other data easily and consistently. In collaboration with other government agencies, the private sector, academia, and volunteer groups, the USGS will coordinate, integrate, and, where needed, produce and maintain base geographic data. The National Map will include digital orthorectified imagery; elevation data; vector data for hydrography, transportation, boundary, and structure features; geographic names; and land cover information. The data will be the source of revised paper topographic maps. Many technical and institutional issues must be resolved as The National Map is implemented. To begin the refinement of this new paradigm, pilot projects are being designed to identify and investigate these issues. The pilots are the foundation upon which future partnerships for data sharing and maintenance will be built.

Fact Sheet↗

USGS2001

The National Map - Delaware Pilot Project

Governments depend on a common set of geographic base information as a tool for economic and community development, land and natural resource management, and health and safety services. Emergency management and defense operations rely on this information. Private industry, nongovernmental organizations, and individual citizens use the same geographic data. Geographic information underpins an increasingly large part of the Nation's economy. Available geographic data often have the following problems: * They do not align with each other because layers are frequently created or revised separately, * They do not match across administrative boundaries because each producing organization uses different methods and standards, and * They are not up to date because of the complexity and cost of revision. The U.S. Geological Survey (USGS) is developing The National Map to be a seamless, continuously maintained, and nationally consistent set of online, public domain, geographic base information to address these issues. The National Map will serve as a foundation for integrating, sharing, and using other data easily and consistently. In collaboration with other government agencies, the private sector, academia, and volunteer groups, the USGS will coordinate, integrate, and, where needed, produce and maintain base geographic data. The National Map will include digital orthorectified imagery; elevation data; vector data for hydrography, transportation, boundary, and structure features; geographic names; and land cover information. The data will be the source of revised paper topographic maps. Many technical and institutional issues must be resolved as The National Map is implemented. To begin the refinement of this new paradigm, pilot projects are being designed to identify and investigate these issues. The pilots are the foundation upon which future partnerships for data sharing and maintenance will be built.

Fact Sheet↗

USGS2001

The National Map - Utah Transportation Pilot Project

Governments depend on a common set of geographic base information as a tool for economic and community development, land and natural resource management, and health and safety services. Emergency management and defense operations rely on this information. Private industry, nongovernmental organizations, and individual citizens use the same geographic data. Geographic information underpins an increasingly large part of the Nation's economy. Available geographic data often have the following problems: * They do not align with each other because layers are frequently created or revised separately, * They do not match across administrative boundaries because each producing organization uses different methods and standards, and * They are not up to date because of the complexity and cost of revision. The U.S. Geological Survey (USGS) is developing The National Map to be a seamless, continuously maintained, and nationally consistent set of online, public domain, geographic base information to address these issues. The National Map will serve as a foundation for integrating, sharing, and using other data easily and consistently. In collaboration with other government agencies, the private sector, academia, and volunteer groups, the USGS will coordinate, integrate, and, where needed, produce and maintain base geographic data. The National Map will include digital orthorectified imagery; elevation data; vector data for hydrography, transportation, boundary, and structure features; geographic names; and land cover information. The data will be the source of revised paper topographic maps. Many technical and institutional issues must be resolved as The National Map is implemented. To begin the refinement of this new paradigm, pilot projects are being designed to identify and investigate these issues. The pilots are the foundation upon which future partnerships for data sharing and maintenance will be built.

Fact Sheet↗

USGS2001

The National Map - Florida Pilot Project

Governments depend on a common set of geographic base information as a tool for economic and community development, land and natural resource management, and health and safety services. Emergency management and defense operations rely on this information. Private industry, nongovernmental organizations, and individual citizens use the same geographic data. Geographic information underpins an increasingly large part of the Nation's economy. Available geographic data often have the following problems: * They do not align with each other because layers are frequently created or revised separately, * They do not match across administrative boundaries because each producing organization uses different methods and standards, and * They are not up to date because of the complexity and cost of revision. The U.S. Geological Survey (USGS) is developing The National Map to be a seamless, continuously maintained, and nationally consistent set of online, public domain, geographic base information to address these issues. The National Map will serve as a foundation for integrating, sharing, and using other data easily and consistently. In collaboration with other government agencies, the private sector, academia, and volunteer groups, the USGS will coordinate, integrate, and, where needed, produce and maintain base geographic data. The National Map will include digital orthorectified imagery; elevation data; vector data for hydrography, transportation, boundary, and structure features; geographic names; and land cover information. The data will be the source of revised paper topographic maps. Many technical and institutional issues must be resolved as The National Map is implemented. To begin the refinement of this new paradigm, pilot projects are being designed to identify and investigate these issues. The pilots are the foundation upon which future partnerships for data sharing and maintenance will be built.

Fact Sheet↗