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At least 991 records · Page 55Linked to original sources

USGS1983

Maps for the nation: The current federal mapping establishment

The U.S. Government annually produces an estimated 53,000 new maps and charts and distributes about 160 million copies. A large number of these maps are produced under the national mapping program, a decentralized Federal/State cooperative approach to mapping the country at standard scales. Circular A-16, issued by the Office of Management and Budget in 1953 and revised in 1967, delegates the mapping responsibilities to various federal agencies. The U.S. Department of the Interior's Geological Survey is the principal federal agency responsible for implementing the national mapping program. Other major federal map producing agencies include the Departments of Agriculture, Commerce, Defense, Housing and Urban Development, and Transportation, and the Tennessee Valley Authority. To make maps and mapping information more readily available, the National Cartographic Information Center was established in 1974 and an expanded National Map Library Depository Program in 1981. The most recent of many technological advances made under the mapping program are in the areas of digital cartography and video disc and optical disc information storage systems. Future trends and changes in the federal mapping program will involve expanded information and customer service operations, further developments in the production and use of digital cartographic data, and consideration of a Federal Mapping Agency.

Government Publications Review↗

USGS1977

Long-term adequacy of metal resources

Although the earth's crust contains vast quantities of metals, extraction technologies and associated costs are inextricably bound to three fundamental geological factors — the amount of metal available in the earth's crust in each range of grades, the mineralogical form and chemical state of the metal, and the spatial distribution of the metal. The energy required to recover a given amount of metal increases substantially as grade declines. Most metal is produced from sulphide or oxide minerals, whereas most metal in the crust may be locked in the structures of the more refractory silicates. Recovery from silicate minerals could require orders of magnitude more energy than that used at present as also could exploitation of small, widely scattered or thin, deeply buried deposits. Although specific information on the fundamental factors is not available, each factor must in turn tend to further restrict exploitation. Independence of average grade and tonnage for many deposit types further reduces the availability of rock as a source of metal. In the long term, effects of these factors will be large increases in price for many metals.

Resources Policy↗

USGS1994

US North Slope gas and Asian LNG markets

Prospects for export of liquified natural gas (LNG) from Alaska's North Slope are assessed. Projected market conditions to 2010 show that new LNG capacity beyond announced expansions will be needed to meet regional demand and that supplies will probably come from outside the region. The estimated delivered costs of likely suppliers show that Alaska North Slope gas will not be competitive. The alternative North Slope gas development strategies of transport and sale to the lower 48 states and use on the North Slope for either enhanced oil recovery or conversion to liquids are examined. The alternative options require delaying development until US gas prices increase, exhaustion of certain North Slope oil fields, or advances occur in gas to liquid fuels conversion technology.

Resources Policy↗

USGS1992

Decomposition techniques

Sample decomposition is a fundamental and integral step in the procedure of geochemical analysis. It is often the limiting factor to sample throughput, especially with the recent application of the fast and modern multi-element measurement instrumentation. The complexity of geological materials makes it necessary to choose the sample decomposition technique that is compatible with the specific objective of the analysis. When selecting a decomposition technique, consideration should be given to the chemical and mineralogical characteristics of the sample, elements to be determined, precision and accuracy requirements, sample throughput, technical capability of personnel, and time constraints. This paper addresses these concerns and discusses the attributes and limitations of many techniques of sample decomposition along with examples of their application to geochemical analysis. The chemical properties of reagents as to their function as decomposition agents are also reviewed. The section on acid dissolution techniques addresses the various inorganic acids that are used individually or in combination in both open and closed systems. Fluxes used in sample fusion are discussed. The promising microwave-oven technology and the emerging field of automation are also examined. A section on applications highlights the use of decomposition techniques for the determination of Au, platinum group elements (PGEs), Hg, U, hydride-forming elements, rare earth elements (REEs), and multi-elements in geological materials. Partial dissolution techniques used for geochemical exploration which have been treated in detail elsewhere are not discussed here; nor are fire-assaying for noble metals and decomposition techniques for X-ray fluorescence or nuclear methods be discussed.

Journal of Geochemical Exploration↗

USGS1995

Graphical and PC-software analysis of volcano eruption precursors according to the Materials Failure Forecast Method (FFM)

The Materials Failure Forecasting Method for volcanic eruptions (FFM) analyses the rate of precursory phenomena. Time of eruption onset is derived from the time of “failure” implied by accelerating rate of deformation. The approach attempts to fit data, Ω, to the differential relationship Ω Ω ¨ = A Ω ˙ "> ¨ = AΩ˙ , where the dot superscript represents the time derivative, and the data Ω may be any of several parameters describing the accelerating deformation or energy release of the volcanic system. Rate coefficients, A and α, may be derived from appropriate data sets to provide an estimate of time to “failure”. As the method is still an experimental technique, it should be used with appropriate judgment during times of volcanic crisis. Limitations of the approach are identified and discussed. Several kinds of eruption precursory phenomena, all simulating accelerating creep during the mechanical deformation of the system, can be used with FFM. Among these are tilt data, slope-distance measurements, crater fault movements and seismicity. The use of seismic coda, seismic amplitude-derived energy release and time-integrated amplitudes or coda lengths are examined. Usage of cumulative coda length directly has some practical advantages to more rigorously derived parameters, and RSAM and SSAM technologies appear to be well suited to real-time applications. One graphical and four numerical techniques of applying FFM are discussed. The graphical technique is based on an inverse representation of rate versus time. For α = 2, the inverse rate plot is linear; it is concave upward for α < 2 and concave downward for α > 2. The eruption time is found by simple extrapolation of the data set toward the time axis. Three numerical techniques are based on linear least-squares fits to linearized data sets. The “linearized least-squares technique” is most robust and is expected to be the most practical numerical technique. This technique is based on an iterative linearization of the given rate-time series. The hindsight technique is disadvantaged by a bias favouring a too early eruption time in foresight applications. The “log rate versus log acceleration technique”, utilizing a logarithmic representation of the fundamental differential equation, is disadvantaged by large data scatter after interpolation of accelerations. One further numerical technique, a nonlinear least-squares fit to rate data, requires special and more complex software. PC-oriented computer codes were developed for data manipulation, application of the three linearizing numerical methods, and curve fitting. Separate software is required for graphing purposes. All three linearizing techniques facilitate an eruption window based on a data envelope according to the linear least-squares fit, at a specific level of confidence, and an estimated rate at time of failure.

Journal of Volcanology and Geothermal Research↗

USGS1987

Inter-laboratory comparison of X-ray fluorescence analyses of eruptive products of El Chichón Volcano, Chiapas, Mexico

An inter-laboratory comparison has been made of X-ray fluorescence analyses of 10 samples of lava and pumices from El Chichón Volcano, Chiapas, Mexico. Some determinations of major-element constituents agree within analytical uncertainty, whereas others exchibit significant bias. Analyses carried out at the Michigan Technological University (MTU) laboratory are systematically lower in MgO (26–48%), Fe total (5–18%), CaO (4–15%) and higher in K 2 O (0–15%) than analyses made at the U.S. Geological Survey (USGS) Denver laboratory. These differences are ascribed in part to a complex combination of calibration assumptionsand mineralogical and particle-size effects inherent in the use of pressed rock-powder pellets in the analytical procedure of the MTU laboratory. Other, but as yet unknown, differences in sample preparation and/or analytical technique may also be important; effects related to natural sample inhomogeneityare believed to be insignificant. The inter-laboratory differences in the analytical data complicated accurate assessment of whether El Chichón magmas have changed composition during the past 300 000 a. Knowledge of such change is needed for understanding petrogenetic history and for such related studies as evaluation of volcanic hazards.

Applied Geochemistry↗

USGS2014

Deep-ocean ferromanganese crusts and nodules

Ferromanganese crusts and nodules may provide a future resource for a large variety of metals, including many that are essential for emerging high- and green-technology applications. A brief review of nodules and crusts provides a setting for a discussion on the latest (past 10 years) research related to the geochemistry of sequestration of metals from seawater. Special attention is given to cobalt, nickel, titanium, rare earth elements and yttrium, bismuth, platinum, tungsten, tantalum, hafnium, tellurium, molybdenum, niobium, zirconium, and lithium. Sequestration from seawater by sorption, surface oxidation, substitution, and precipitation of discrete phases is discussed. Mechanisms of metal enrichment reflect modes of formation of the crusts and nodules, such as hydrogenetic (from seawater), diagenetic (from porewaters), and mixed diagenetic–hydrogenetic processes.

Book chapter↗

USGS2021

Ocean floor manganese deposits

Much of the dissolved Mn delivered to the oceans is slowly oxidized and precipitated alongside varying amounts of Fe into Mn and ferromanganese (FeMn) mineral deposits that occur extensively in the deep ocean wherever sediment accumulation is low and substrate is available. FeMn crusts grow as pavements on rock outcrops throughout the global ocean whereas nodules form as individual FeMn-encrusted particles on the sediment-covered abyssal plains. Both crusts and nodules are composed predominantly of Fe and Mn oxide minerals that precipitate from seawater and for some nodules also from porewaters of deep-sea sediment. In contrast, hydrothermal oxide deposits consist predominantly of Mn or Fe oxide. FeMn crusts and nodules exhibit very high specific surface areas that allow them to scavenge abundant metals and other elements, recording the history of the source waters. Crusts especially serve as an important record of paleoceanographic conditions over the past 70 + million years. Critical metals essential to many computer, military, and green technologies are enriched in crust and nodule deposits to concentrations high enough to compare with, or exceed, typical terrestrial deposits, and they can be considered as potential resources for mining in the near future. Twenty-three contracts pertaining to exploration for nodules and crusts have been signed with the International Seabed Authority, and resource/reserve, baseline, and environmental impact assessments are underway. Many challenges remain to be addressed before full-scale mining of marine FeMn deposits will occur. However, their unique genesis and the growing worldwide need for rare and critical metals keep these deep-ocean deposits relevant to industry, scientists, and governments.

Book chapter↗

USGS2015

Volcano warning systems: Chapter 67

Messages conveying volcano alert level such as Watches and Warnings are designed to provide people with risk information before, during, and after eruptions. Information is communicated to people from volcano observatories and emergency management agencies and from informal sources and social and environmental cues. Any individual or agency can be both a message sender and a recipient and multiple messages received from multiple sources is the norm in a volcanic crisis. Significant challenges to developing effective warning systems for volcanic hazards stem from the great diversity in unrest, eruption, and post-eruption processes and the rapidly advancing digital technologies that people use to seek real-time risk information. Challenges also involve the need to invest resources before unrest to help people develop shared mental models of important risk factors. Two populations of people are the target of volcano notifications–ground- and aviation-based populations, and volcano warning systems must address both distinctly different populations.

Book chapter↗

USGS2019

Monitoring volcanic deformation

Whereas research in volcano geodesy seeks to push the boundaries of our knowledge of the physics of volcanoes, monitoring looks at changes in volcano behavior to predict when a volcanic crisis might develop. To be effective, geodetic monitoring must be done before, during, and after eruptions and must be integrated with other monitoring techniques . It requires the type of long-term commitment of time and resources that academic and industry scientists generally cannot make. A few, well-placed geodetic monitoring stations can make a huge difference to a country's ability to alert its people to an imminent volcanic eruption . Monitoring strategies vary greatly depending on several factors such as the activity of the individual volcano, access, and available personnel and funding. Rapid advances in technology allow for more precise geodetic monitoring today than was imaginable when many of the existing volcano observatories were established. Today, deformation measurements at active volcanoes are usually made with continuous Global Positioning System (CGPS) stations, supplemented by Interferometric Synthetic Aperture Radar (InSAR) images. Neither method requires a continuous presence of personnel in the field, except for the installation and maintenance of the GPS stations; however subsequent data analysis can be highly complex.

Book chapter↗

USGS2019

Reproduction and reproductive strategies relevant to management of Whooping Cranes ex situ

Due to the small population size (∼400 birds) and continuing threats to wild Whooping Cranes ( Grus americana ), an ex situ (captive) population is maintained to contribute to the recovery of the species. The goals of the captive breeding program are to provide opportunity for research and birds for reintroduction. However, reproduction among captive birds is far from optimal. Specifically, whooping cranes maintained ex situ experience delayed onset of reproduction as well as low rates of egg production and egg fertility when compared to wild populations. To improve the contribution of the captive population to Whooping Crane recovery, there is a need to (1) advance the understanding about the mechanisms regulating ovarian function and egg production, especially the influence of males (their presence and behavior) on endocrine and reproductive behavior in females, as well as (2) identify the underlying cause(s) of poor reproduction in Whooping Cranes housed ex situ. In this chapter, we summarize current knowledge of Whooping Crane reproduction with a focus on egg production and fertility. We also discuss management strategies, such as environmental management, and reproductive technologies, including artificial insemination and sperm cryopreservation that may benefit captive reproduction, and finish with a discussion of future research priorities.

Book chapter↗

USGS2018

The San Andreas Fault System--Complexities along a major transform fault system and relation to earthquake hazards

The San Andreas Fault System is a 1300-km-long transform boundary that accommodates motion between the North American and Pacific Plates. New technologies and data reveal rich details about the present configuration of faults, distribution of strain and associated seismic hazard on this complex network of faults. This contribution provides a brief summary of the geologic history of the San Andreas Fault System, followed by an introduction to recent research that has changed understanding of the hazards along the main faults. Organized by region, we highlight a selection of recent research using new geodetic techniques, improved topographic data, advanced geochronologic methods, and high-resolution geophysics. The contribution ends with a review of the historic earthquakes on the San Andreas and San Jacinto Faults, comparing these to past ruptures interpreted from paleoseismic studies.

California↗

USGS2022

Greenhouse gas balances in coastal ecosystems: Current challenges in “blue carbon” estimation and significance to national greenhouse gas inventories

Coastal wetlands are defined herein as inundated, vegetated ecosystems with hydrology, and biogeochemistry influenced by sea levels, at timescales of tides to millennia. Coastal wetlands are necessary components of global greenhouse gas estimation and scenario modeling, both for continental and oceanic mass balances. The carbon pools and fluxes on coastal lands, especially those influenced by tidal drivers and sea level rise, are distinct in their magnitude, rates, and uncertainties. We describe herein the pathways taken for a US scale estimation of blue carbon based on annual timesteps and bottom-up modeling, as appropriate for the first effort to include coastal wetlands in the Intergovernmental Panel on Climate Change (IPCC) guidelines for a National Greenhouse Gas Inventory (NGGI). As such, we summarize multiple efforts to reconcile mapping, modeling, and measurement issues and we report the assumptions we made based on data availability. Provided as requested feedback to the IPCC. Subsidiary Body for Scientific and Technological Advice (SBSTA) evaluation of guidance criteria, these analyses synergistically point scientists, practitioners, and policy makers toward the greatest uncertainties to address in future assessments: coastal wetland methane emissions and carbon dioxide emissions associated with the fate of eroded soil. This is a story of what was learned in the 2014–2018 NASA Carbon Monitoring System project (https://carbon.nasa.gov/cgi-bin/cms_projects.pl), how it informs “good practice” (IPCC 2006) in reporting coastal wetland emissions and removals, and where it points scientifically toward data needs at different temporal and spatial scales.

Book chapter↗

USGS2019

Evidence for widespread microbivory of endophytic bacteria in roots of vascularplants through oxidative degradation in root cell periplasmic spaces

In this chapter we present a hypothesis, and data supporting it, that vascular plants in diverse families possess symbiotic/endophytic bacteria that frequently vector on or within their seeds; seedlings degrade symbiotic bacteria within roots. Evidence of widespread microbivory was found in a survey for intracellular bacteria that we conducted including seedlings in 36 species of vascular plants distributed in 20 plant families. Experiments indicate that when seeds germinate, bacteria colonize seedlings and internalize into root cells where they are oxidatively-degraded in the periplasmic spaces of cells. The process of degradation of microbes in roots has been termed “rhizophagy”, and “rhizophagy cycle” or “rhizophagy symbiosis” in the case of symbiotic bacteria that alternate between a free-living soil phase and intracellular/endophytic phase. We hypothesize that microbivory could account for a significant portion of nutrients acquired by plants from soils—with one estimate suggesting that as much as 30% of the nutrients acquired by seedlings may stem from rhizophagy symbiosis. Developing a better understanding of rhizophagy symbiosis could lead to new ways to cultivate crops without reliance on excessive agrochemical applications. Learning how to manipulate rhizophagy symbiosis could result in new technologies for reducing growth of weedy or invasive plant species by inhibiting rhizophagy symbiosis.

Book chapter↗

USGS2021

Volcano geodesy: A critical tool for assessing the state of volcanoes and their potential for hazardous eruptive activity

Since the beginning of the 20th century, volcano geodesy has evolved from time- and personnel-intensive methods for collecting discrete measurements to automated and/or remote tools that provide data with exceptional spatiotemporal resolution. By acknowledging and overcoming limitations related to data collection and interpretation, geodesy becomes a powerful tool for forecasting the onset and tracking the evolution of volcanic eruptions. In addition, geodetic data can be used for novel applications, such as mapping surface and topographic change due to the emplacement of volcanic deposits, detecting volcanic plumes, and constraining the properties of magmatic systems. These collective capabilities provide critical support for understanding magmatic processes at erupting volcanoes, while also offering important baseline data in advance of potential volcanic unrest. Future developments in volcano geodesy will involve not just new technology, but also advanced modeling and automated analysis methods that will provide a new understanding of the volcanic activity.

Book chapter↗

USGS2005

Development of a solenoid pumped in situ zinc analyzer for environmental monitoring

A battery powered submersible chemical analyzer, the Zn-DigiScan (Zn Digital Submersible Chemical Analyzer), has been developed for near real-time, in situ monitoring of zinc in aquatic systems. Microprocessor controlled solenoid pumps propel sample and carrier through an anion exchange column to separate zinc from interferences, add colorimetric reagents, and propel the reaction complex through a simple photometric detector. The Zn-DigiScan is capable of self-calibration with periodic injections of standards and blanks. The detection limit with this approach was 30 μg L −1 . Precision was 5–10% relative standard deviation (R.S.D.) below 100 μg L −1 , improving to 1% R.S.D. at 1000 μg L −1 . The linear range extended from 30 to 3000 μg L −1 . In situ field results were in agreement with samples analyzed by inductively coupled plasma mass spectrometry (ICPMS). This pump technology is quite versatile and colorimetric methods with complex online manipulations such as column reduction, preconcentration, and dilution can be performed with the DigiScan. However, long-term field deployments in shallow high altitude streams were hampered by air bubble formation in the photometric detector.

Analytica Chimica Acta↗

USGS2005

Supporting users through integrated retrieval, processing, and distribution systems at the Land Processes Distributed Active Archive Center

The US Geological Survey's EROS Data Center (EDC) hosts the Land Processes Distributed Active Archive Center (LP DAAC). The LP DAAC supports NASA's Earth Observing System (EOS), which is a series of polar-orbiting and low inclination satellites for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans. The EOS Data and Information Systems (EOSDIS) was designed to acquire, archive, manage and distribute Earth observation data to the broadest possible user community. The LP DAAC is one of four DAACs that utilize the EOSDIS Core System (ECS) to manage and archive their data. Since the ECS was originally designed, significant changes have taken place in technology, user expectations, and user requirements. Therefore the LP DAAC has implemented additional systems to meet the evolving needs of scientific users, tailored to an integrated working environment. These systems provide a wide variety of services to improve data access and to enhance data usability through subsampling, reformatting, and reprojection. These systems also support the wide breadth of products that are handled by the LP DAAC. The LP DAAC is the primary archive for the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data; it is the only facility in the United States that archives, processes, and distributes data from the Advanced Spaceborne Thermal Emission/Reflection Radiometer (ASTER) on NASA's Terra spacecraft; and it is responsible for the archive and distribution of “land products” generated from data acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra and Aqua satellites.

Acta Astronautica↗

USGS2013

The role of photogeologic mapping in traverse planning: Lessons from DRATS 2010 activities

We produced a 1:24,000 scale photogeologic map of the Desert Research and Technology Studies (DRATS) 2010 simulated lunar mission traverse area and surrounding environments located within the northeastern part of the San Francisco Volcanic Field (SFVF), north-central Arizona. To mimic an exploratory mission, we approached the region “blindly” by rejecting prior knowledge or preconceived notions of the regional geologic setting and focused instead only on image and topographic base maps that were intended to be equivalent to pre-cursor mission “orbital returns”. We used photogeologic mapping techniques equivalent to those employed during the construction of modern planetary geologic maps. Based on image and topographic base maps, we identified 4 surficial units (talus, channel, dissected, and plains units), 5 volcanic units (older cone, younger cone, older flow, younger flow, and block field units), and 5 basement units (grey-toned mottled, red-toned platy, red-toned layered, light-toned slabby, and light-toned layered units). Comparison of our remote-based map units with published field-based map units indicates that the two techniques yield pervasively similar results of contrasting detail, with higher accuracies linked to remote-based units that have high topographic relief and tonal contrast relative to adjacent units. We list key scientific questions that remained after photogeologic mapping and prior to DRATS activities and identify 13 specific observations that the crew and science team would need to make in order to address those questions and refine the interpreted geologic context. We translated potential observations into 62 recommended sites for visitation and observation during the mission traverse. The production and use of a mission-specific photogeologic map for DRATS 2010 activities resulted in strategic and tactical recommendations regarding observational context and hypothesis tracking over the course of an exploratory mission.

Acta Astronautica↗