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At least 1,099 records · Page 61Linked to original sources
USGS2016

Archiving and access systems for remote sensing: Chapter 6

Focuses on major developments inaugurated by the Committee on Earth Observation Satellites, the Group on Earth Observations System of Systems, and the International Council for Science World Data System at the global level; initiatives at national levels to create data centers (e.g. the National Aeronautics and Space Administration (NASA) Distributed Active Archive Centers and other international space agency counterparts), and non-government systems (e.g. Center for International Earth Science Information Network). Other major elements focus on emerging tool sets, requirements for metadata, data storage and refresh methods, the rise of cloud computing, and questions about what and how much data should be saved. The sub-sections of the chapter address topics relevant to the science, engineering and standards used for state-of-the-art operational and experimental systems.

Book chapter↗
USGS2010

Paleoclimates: Understanding climate change past and present

The field of paleoclimatology relies on physical, chemical, and biological proxies of past climate changes that have been preserved in natural archives such as glacial ice, tree rings, sediments, corals, and speleothems. Paleoclimate archives obtained through field investigations, ocean sediment coring expeditions, ice sheet coring programs, and other projects allow scientists to reconstruct climate change over much of earth's history. When combined with computer model simulations, paleoclimatic reconstructions are used to test hypotheses about the causes of climatic change, such as greenhouse gases, solar variability, earth's orbital variations, and hydrological, oceanic, and tectonic processes. This book is a comprehensive, state-of-the art synthesis of paleoclimate research covering all geological timescales, emphasizing topics that shed light on modern trends in the earth's climate. Thomas M. Cronin discusses recent discoveries about past periods of global warmth, changes in atmospheric greenhouse gas concentrations, abrupt climate and sea-level change, natural temperature variability, and other topics directly relevant to controversies over the causes and impacts of climate change. This text is geared toward advanced undergraduate and graduate students and researchers in geology, geography, biology, glaciology, oceanography, atmospheric sciences, and climate modeling, fields that contribute to paleoclimatology. This volume can also serve as a reference for those requiring a general background on natural climate variability.

Book↗
USGS2009

Permafrost gas hydrates and climate change: Lake-based seep studies on the Alaskan north slope

The potential interactions between climate change and methane hydrate destabilization are among the most societally-relevant aspects of gas hydrates research. Massive dissociation of deep marine methane hydrates following rapid Earth warming is the most plausible explanation for carbon isotopic data that imply widespread release of microbial methane during the Late Paleocene Thermal Maximum (~55 million years ago), and massive methane hydrate degradation may have been associated with a major warming event in the Late Neoproterozoic as well. . On contemporary Earth, circumstantial evidence implies that permafrost-associated methane hydrate dissociation, possibly related to climate change, may be contributing to gas seeps in the MacKenzie Delta (Dallimore et al., 2008). Gas is also currently being released from shallow subseafloor hydrates in some areas, and transient bottom water temperature increases are sometimes known to be the destabilizing influence for these gas hydrates. Still, there is no direct evidence that gas hydrates are currently undergoing significant and systematic destabilization on contemporary Earth, that climate processes are responsible for driving any destabilization that may be occurring, or that methane released from dissociating hydrate is a substantial contributor to atmospheric methane concentrations.

Alaska↗
USGS2019

Landsat: The cornerstone of global land imaging

Since 1972, the joint NASA/ U.S. Geological Survey Landsat series of Earth Observation satellites have provided an uninterrupted space-based data record of the Earth’s land surface to help advance scientific research towards the understanding of our planet and the environmental impact of its inhabitants. Early Landsat satellites offered a wealth of new data that improved mapping of remote areas and geologic features along with digital analysis of vegetation. The utility of Landsat’s spatial and spectral resolution has advanced its use for applications that benefit society such as global crop forecasting, forest monitoring, water use, carbon assessments, and the base for Google Maps. Landsat’s long-term data record provides an unrivaled resource for observing land cover and land-use change over a timescale of decades. The free and open Landsat data policy in 2008 was a paradigm shift for the world. Today, due to improved analytical and computing capabilities, the Landsat archive is poised to shift into a more real-time monitoring and understanding of the Earth.

GIM International↗
USGS1974

The cartographic and scientific application of ERTS-1 imagery in polar regions

The first Earth Resources Technology Satellite (ERTS-1), launched by the National Aeronautics and Space Administration in. July 1972, is providing valuable data for investigations of the most inaccessible and hostile regions of the Earth the Arctic and Antarctic. ERTS images and map products derived from them offer a whole new dimension in source material for multidiscipline investigations in the earth sciences. For the first time scientists can view synoptic, repetitive scenes of the polar regions in four spectral bands. Ongoing experiments funded by NASA and conducted in the U.S. Geological Survey have demonstrated the feasibility of revising coastlines on maps of Antarctica, detected gross changes in the northern limits of the three largest ice shelves in the world, and led to the discovery of uncharted mountain ranges.

Journal of Research of the U.S. Geological Survey↗
USGS1974

Hydrogeologic aspects of structural deformation in the northern Gulf of Mexico Basin

The first Earth Resources Technology Satellite (ERTS-1), launched by the National Aeronautics and Space Administration in.July 1972, is providing valuable data for investigations of the most inaccessible and hostile regions of the Earth the Arctic and Antarctic. ERTS images and map products derived from them offer a whole new dimension in source material for multidiscipline investigations in the earth sciences. For the first time scientists can view synoptic, repetitive scenes of the polar regions in four spectral bands. Ongoing experiments funded by NASA and conducted in the U.S. Geological Survey have demonstrated the feasibility of revising coastlines on maps of Antarctica, detected gross changes in the northern limits of the three largest ice shelves in the world, and led to the discovery of uncharted mountain ranges.

Louisiana, Texas↗
USGS2010

Coordination of space data acquisition in support of geo forest carbon tracking

The Group on Earth Observation (GEO) required for their Forest Carbon Tracking (FCT) task the assistance of the Committee on Earth Observation Satellites (CEOS) space agencies to implement coordinated data acquisition strategies from Earth Observation (EO) over key areas of interest to demonstrate the value of linking coordinated acquisition of satellite data with standardised processing methods, forest inventory and ecosystem models. Both optical and radar of midresolution have been acquired within the coordinated acquisition campaigns developed in 2009 and 2010. Homogeneous and coherent EO databases have already started by means of full key areas coverage according with suitable sensor operating modes. CEOS effort seeks now continuing with an updated strategy over expanded area coverage.

Conference Paper↗
USGS2024

Geophysical characterization of mine influenced groundwater and surface water in the Mayflower section of the Animas River, Bonita Peak Mining District, Silverton Colorado

This report details findings from geophysical investigations to identify possible groundwater - surface water interactions near the Mayflower Section of the Animas River in Silverton, Colorado. The Mayflower Section is a mine influenced Superfund Site in Colorado. This investigation utilized electromagnetic induction (EM or EMI), magnetic, and fiber optic distributed temperature system (FODTS) geophysical methods to measure the bulk earth electrical conductivity, magnetic susceptibility, and temperature of specific surveyed volumes of the earth near the Mayflower Section of the Animas River. These physical parameters are used to understand the groundwater – surface water interactions, which can guide decision makers in their assessment of mine-impacted surface water. This report details the results from characterization and monitoring technologies to provide high data density and continuous monitoring of bulk earth electrical conductivity and temperature in the Mayflower section of the Animas River to identify zones of groundwater – surface water interactions and potential metal loading from mine influenced water. The investigation separated right and left bank characterization for each method and indicates more groundwater is entering from the right bank than the left bank and these predominantly right bank discharges potentially contain metal-rich water compared to the left bank. Results also indicate mineral veins facilitate preferential groundwater discharge to the river due to possible jointing, fractures, and permeability differences sometimes occurring along veins relative to host rock. For example, Boulder Gulch is likely groundwater dominated and may be receive water impacted by Mayflower Impoundments #1 and #2. Additionally, the beaver ponds near Blair Gulch may influence groundwater discharge and Mayflower Impoundment #4 is possibly impacting groundwater and surface water and may be connected to the wetlands to the west of the impoundment. These data could be further analyzed for smaller spatial scale analysis within areas of interest. The identification of these locations along sections of the river likely impacted by mine influenced groundwater potentially entering the Animas River and can be used by site investigators, decision makers, and stakeholders in mitigation decisions and strategies.

Colorado↗
USGS1979

Minerals, lands, and geology for the common defence and general welfare, Volume 1, Before 1879 : A history of public lands, federal science and mapping policy, and development of mineral resources in the United States

This volume, the first of a four-volume study, is concerned with events in the United States before the establishment of the U.S. Geological Survey, during the years in which geology evolved as a science and began to influence economic development and national policy. Subsequent volumes continue the story but focus on the Survey and its role in the events and developments of later years. The method of analysis demonstrates that knowledge of the Earth and its history, processes, and resources has provided a basis for intelligent economic development; also that geologists very soon realized that uncontrolled development of the land and other natural resources could not continue, that some limitations must be made on man's use of the Earth. The Geological Survey was established when public awareness of the need for balance between development and conservation of our resources was becoming evident. That balance is even more necessary now and in the future for the "general welfare" and "common defence" of the Nation. We can be grateful for the wisdom of our Founding Fathers in providing for publicly supported studies in earth science and engineering by well-trained and motivated scientists and engineers. Such studies, undertaken objectively in the search for facts, can continue to be of great value in the formulation and execution of wise policies to protect our environment and to maintain that balance between development and conservation of the natural resources.

Book↗
USGS2014

Slip rates and spatially variable creep on faults of the northern San Andreas system inferred through Bayesian inversion of Global Positioning System data

Fault creep, depending on its rate and spatial extent, is thought to reduce earthquake hazard by releasing tectonic strain aseismically. We use Bayesian inversion and a newly expanded GPS data set to infer the deep slip rates below assigned locking depths on the San Andreas, Maacama, and Bartlett Springs Faults of Northern California and, for the latter two, the spatially variable interseismic creep rate above the locking depth. We estimate deep slip rates of 21.5 ± 0.5, 13.1 ± 0.8, and 7.5 ± 0.7 mm/yr below 16 km, 9 km, and 13 km on the San Andreas, Maacama, and Bartlett Springs Faults, respectively. We infer that on average the Bartlett Springs fault creeps from the Earth's surface to 13 km depth, and below 5 km the creep rate approaches the deep slip rate. This implies that microseismicity may extend below the locking depth; however, we cannot rule out the presence of locked patches in the seismogenic zone that could generate moderate earthquakes. Our estimated Maacama creep rate, while comparable to the inferred deep slip rate at the Earth's surface, decreases with depth, implying a slip deficit exists. The Maacama deep slip rate estimate, 13.1 mm/yr, exceeds long-term geologic slip rate estimates, perhaps due to distributed off-fault strain or the presence of multiple active fault strands. While our creep rate estimates are relatively insensitive to choice of model locking depth, insufficient independent information regarding locking depths is a source of epistemic uncertainty that impacts deep slip rate estimates.

California↗
USGS2017

Links between atmosphere, ocean, and cryosphere from two decades of microseism observations on the Antarctic Peninsula

The lack of landmasses, climatological low pressure, and strong circumpolar westerly winds between the latitudes of 50°S to 65°S produce exceptional storm‐driven wave conditions in the Southern Ocean. This combination makes the Antarctic Peninsula one of Earth's most notable regions of high‐amplitude wave activity and thus, ocean‐swell‐driven microseism noise in both the primary (direct wave‐coastal region interactions) and secondary (direct ocean floor forcing due to interacting wave trains) period bands. Microseism observations are examined across 23 years (1993–2015) from Palmer Station (PMSA), on the west coast of the Antarctic Peninsula, and from East Falkland Island (EFI). These records provide a spatially integrative measure of both Southern Ocean wave amplitudes and the interactions between ocean waves and the solid Earth in the presence of sea ice, which can reduce wave coupling with the continental shelf. We utilize a spatiotemporal correlation‐based approach to illuminate how the distribution of sea ice influences seasonal microseism power. We characterize primary and secondary microseism power due to variations in sea ice and find that primary microseism energy is both more sensitive to sea ice and more capable of propagating across ocean basins than secondary microseism energy. During positive phases of the Southern Annular Mode, sea ice is reduced in the Bellingshausen Sea and overall storm activity in the Drake Passage increases, thus strongly increasing microseism power levels.

Antarctic Penninsula↗
USGS2018

Temporal stress changes caused by earthquakes: A review

Earthquakes can change the stress field in the Earth’s lithosphere as they relieve and redistribute stress. Earthquake-induced stress changes have been observed as temporal rotations of the principal stress axes following major earthquakes in a variety of tectonic settings. The stress changes due to the 2011 Mw9.0 Tohoku-Oki, Japan, earthquake were particularly well documented. Earthquake stress rotations can inform our understanding of earthquake physics, most notably addressing the long-standing problem of whether the Earth’s crust at plate boundaries is “strong” or “weak.” Many of the observed stress rotations, including that due to the Tohoku-Oki earthquake, indicate near-complete stress drop in the mainshock. This implies low background differential stress, on the order of earthquake stress drop, supporting the weak crust model. Earthquake stress rotations can also be used to address other important geophysical questions, such as the level of crustal stress heterogeneity and the mechanisms of postseismic stress reloading. The quantitative interpretation of stress rotations is evolving from those based on simple analytical methods to those based on more sophisticated numerical modeling that can capture the spatial-temporal complexity of the earthquake stress changes.

Journal of Geophysical Research B: Solid Earth↗
USGS1979

Trace element and strontium isotope characteristics of volcanic rocks from Isla Tortuga: A young seamount in the Gulf of California

Isla Tortuga is a small isolated central volcano which is located near an actively spreading trough in the Gulf of California. The basalt lavas from Tortuga which have the highest Mg/Fe and Ni contents have trace element abundances and ratios and 87 Sr/ 86 Sr which are similar to those of mid-ocean ridge tholeiite. The major element, rare earth element and Sr abundances of fractionated tholeiite (low Mg/Fe) and tholeiitic andesite of Tortuga are consistent with an origin by closed-system fractional crystallization. This hypothesis is not supported by K, Na, Rb and Ba abundances in the lavas nor by their variable 87 Sr/ 86 Sr (0.7024–0.7035). It is proposed that the apparent decoupling of light rare earth elements, other incompatible trace elements and 87 Sr/ 86 Sr is due to contamination of some Tortuga magmas while they are fractionated in a high-level crustal magma chamber. The mantle source of least-contaminated, high Mg/Fe basalt lavas of Tortuga is similar, although not identical to the source of normal mid-ocean ridge tholeiite; significant differences exist. The reasons for these differences are not yet known.

Earth and Planetary Science Letters↗
USGS1989

Contribution of metapelitic sediments to the composition, heat production, and seismic velocity of the lower crust of southern New Mexico, U.S.A.

Granulite xenoliths erupted at Kilbourne Hole maar were recently extracted from the lower crust of southern New Mexico. Garnet- and sillimanite-bearing quartzofeldspathic xenoliths had pelitic protoliths and were probably emplaced in the lower crust by tectonic underplating at a lower Proterozoic subduction zone. Thus the Kilbourne Hole metapelitic xenoliths illustrate the potential role of tectonosedimentary processes at convergent margins in determining the ultimate composition of the crust. Average P-wave velocities for metapelitic xenoliths from Kilbourne Hole are ∼ 7 km/s at 6 kbar, like those of mafic metagabbros and anorthosites. However, in contrast to mafic lithologies, the major element composition of the representative pelitic paragneiss (RPP) described in this paper is relatively siliceous and like that of average upper crust. Except for depletions of U and Cs, the trace element characteristics of the RPP are like those of pelitic sediments and are 3–10 times higher than those typically estimated for the lower crust. The heat production of the RPP is high (1.0 μW/m 3 ) as are those of many granulite- and amphibolite-grade metapelites. In general, portions of the lower crust in which sediments are present may be high in light ion lithophile and rare earth element abundances, heat production, δ 18 O , and 87 Sr/ 86 Sr. Moreover, the high Pb contents and unradiogenic Pb isotope signatures of metapelites provide an important reservoir for unradiogenic Pb in the earth as a whole.

New Mexico↗
USGS1990

What do we mean by accuracy in geomagnetic measurements?

High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

Physics of the Earth and Planetary Interiors↗
USGS1990

Determination of the accuracy and operating constants in a digitally biased ring core magnetometer

By using a very stable voltage reference and a high precision digital-to-analog converter to set bias in digital increments, the inherently high stability and accuracy of a ring core magnetometer can be significantly enhanced. In this case it becomes possible to measure not only variations about the bias level, but to measure the entire value of the field along each magnetometer sensing axis in a nearly absolute sense. To accomplish this, one must accurately determine the value of the digital bias increment for each axis, the zero field offset value for each axis, the scale values, and the transfer coefficients (or nonorthogonality angles) for pairs of axes. This determination can be carried out very simply, using only the Earth's field, a proton magnetometer, and a tripod-mounted fixture which is capable of rotations about two axes that are mutually perpendicular to the Earth's magnetic field vector. ?? 1990.

Physics of the Earth and Planetary Interiors↗
USGS2017

Expanding the role of reactive transport models in critical zone processes

Models test our understanding of processes and can reach beyond the spatial and temporal scales of measurements. Multi-component Reactive Transport Models (RTMs), initially developed more than three decades ago, have been used extensively to explore the interactions of geothermal, hydrologic, geochemical, and geobiological processes in subsurface systems. Driven by extensive data sets now available from intensive measurement efforts, there is a pressing need to couple RTMs with other community models to explore non-linear interactions among the atmosphere, hydrosphere, biosphere, and geosphere. Here we briefly review the history of RTM development, summarize the current state of RTM approaches, and identify new research directions, opportunities, and infrastructure needs to broaden the use of RTMs. In particular, we envision the expanded use of RTMs in advancing process understanding in the Critical Zone, the veneer of the Earth that extends from the top of vegetation to the bottom of groundwater. We argue that, although parsimonious models are essential at larger scales, process-based models offer tools to explore the highly nonlinear coupling that characterizes natural systems. We present seven testable hypotheses that emphasize the unique capabilities of process-based RTMs for (1) elucidating chemical weathering and its physical and biogeochemical drivers; (2) understanding the interactions among roots, micro-organisms, carbon, water, and minerals in the rhizosphere; (3) assessing the effects of heterogeneity across spatial and temporal scales; and (4) integrating the vast quantity of novel data, including “omics” data (genomics, transcriptomics, proteomics, metabolomics), elemental concentration and speciation data, and isotope data into our understanding of complex earth surface systems. With strong support from data-driven sciences, we are now in an exciting era where integration of RTM framework into other community models will facilitate process understanding across disciplines and across scales.

Earth-Science Reviews↗
USGS2005

An astrobiological perspective on Meridiani Planum

Sedimentary rocks exposed in the Meridiani Planum region of Mars record aqueous and eolian deposition in ancient dune and interdune playa-like environments that were arid, acidic, and oxidizing. On Earth, microbial populations have repeatedly adapted to low pH and both episodic and chronic water limitation, suggesting that, to a first approximation, the Meridiani plain may have been habitable during at least part of the interval when deposition and early diagenesis took place. On the other hand, the environmental conditions inferred for Meridiani deposition would have posed a challenge for prebiotic chemical reactions thought to have played a role in the origin of life on Earth. Orbital observations suggest that the combination of sulfate minerals and hematite found in Meridiani rocks may be unusual on the martian surface; however, there is reason to believe that acidity, aridity, and oxidizing conditions were broadly distributed on ancient Mars. When these conditions were established and how much environmental heterogeneity existed on early Mars remain to be determined. Because sulfates and iron oxides can preserve detailed geochemical records of environmental history as well as chemical, textural and microfossil signatures of biological activity, Meridiani Planum is an attractive candidate for Mars sample return. ?? 2005 Elsevier B.V. All rights reserved.

Earth and Planetary Science Letters↗