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USGS2009

Web GIS in practice VII: stereoscopic 3-D solutions for online maps and virtual globes

Because our pupils are about 6.5 cm apart, each eye views a scene from a different angle and sends a unique image to the visual cortex, which then merges the images from both eyes into a single picture. The slight difference between the right and left images allows the brain to properly perceive the 'third dimension' or depth in a scene (stereopsis). However, when a person views a conventional 2-D (two-dimensional) image representation of a 3-D (three-dimensional) scene on a conventional computer screen, each eye receives essentially the same information. Depth in such cases can only be approximately inferred from visual clues in the image, such as perspective, as only one image is offered to both eyes. The goal of stereoscopic 3-D displays is to project a slightly different image into each eye to achieve a much truer and realistic perception of depth, of different scene planes, and of object relief. This paper presents a brief review of a number of stereoscopic 3-D hardware and software solutions for creating and displaying online maps and virtual globes (such as Google Earth) in "true 3D", with costs ranging from almost free to multi-thousand pounds sterling. A practical account is also given of the experience of the USGS BRD UMESC (United States Geological Survey's Biological Resources Division, Upper Midwest Environmental Sciences Center) in setting up a low-cost, full-colour stereoscopic 3-D system.

International Journal of Health Geographics↗

USGS2024

Atlas of microscopic images of biochar using reflected light microscopy in biochar characterization

Derived through the thermochemical conversion of biomass, biochar is a carbon-rich substance recognized for its significance in environmental applications and sustainable agriculture. As interest in its utilization continues to rise, it becomes crucial to comprehend how the source material and pyrolysis parameters influence the properties of biochar and, consequently, to research the suitability of various analytical methods for characterizing it. Despite the current utilization of numerous physical and chemical methods, the untapped potential of reflected light microscopy warrants further exploration. While a few recent studies suggest a correlation between certain microscopic characteristics and selected physical and chemical properties of biochar, the data are limited and difficult to compare. This is primarily due to variations in the types of original biomass used and lack of information about pyrolysis conditions. Moreover, because only a limited number of photographs taken under a reflected light microscope are publicly available to-date, it is difficult to evaluate morphological differences between various biochars and other organic materials such as inertinites from coal, charcoal, etc. To address limited availability of publicly available data, this “Atlas of Microscopic Images of Biochar” presents a collection of more than 300 images contributed by researchers from Poland, the United States, Canada, Australia, Brazil, and Denmark. These photomicrographs capture optical characteristics of a diverse array of biochar, demonstrating its unique morphological and structural features. This visual documentation can serve as a valuable resource for researchers, industry professionals, educators, and enthusiasts interested in investigating the complexities of biochar forms.

Indiana Journal of Earth Sciences↗

USGS2021

Crustal seismic attenuation of the central United States and Intermountain West

Seismic attenuation is generally greater in the western United States (WUS) than the central and eastern United States (CEUS), but the nature of this transition or location of this boundary is poorly constrained. We conduct crustal seismic (Lg) attenuation tomography across a region that stretches from the CEUS across the Rocky Mountains to the Basin and Range using a total of 115,870 amplitude measurements from 106 earthquakes recorded on 544 stations across five frequency bands spanning 0.5–16 Hz. Similar to previous studies, we find higher attenuation in the WUS ( Q 0 ∼ 190) than the nominally CEUS ( Q 0 ∼ 250) and comparatively high attenuation on the Gulf Coast ( Q 0 ∼ 175). Our models defy simple east versus west regionalization, however. Heterogeneity within the Rocky Mountain region—low attenuation in the Colorado Plateau interior and Wyoming Craton ( Q 0 ∼ 230) compared to high attenuation in the southern Rockies ( Q 0 ∼ 110)—exceeds the gross differences between the CEUS and western United States. These province-scale patterns are readily interpreted in terms of intrinsic attenuation. The boundary between the Colorado Plateau and Basin and Range hosts the highest attenuation imaged in the study area ( Q 0 ∼ 90), consistent with localized scattering across contrasting crustal structure. Focused high attenuation in the southern Rockies may represent the effects of represent in situ partial crustal melt. Within the CEUS, second-order bands of comparatively high attenuation align with the Proterozoic Yavapai-Mazatzal suture zone and Midcontinent Rift. This complex attenuation structure defies broad regionalization and suggests a need for path-specific models near these boundaries and for critical infrastructure.

Journal of Geophysical Research: Solid Earth↗

USGS1985

Digital to Analog Conversion and Visual Evaluation of Thematic Mapper Data

As a part of the National Aeronautics and Space Administration Landsat D Image Data Quality Analysis Program, the Earth Resources Observation Systems Data Center (EDC) developed procedures to optimize the visual information content of Thematic Mapper data and evaluate the resulting photographic products by visual interpretation. A digital-to-analog transfer function was developed which would properly place the digital values on the most useable portion of a film response curve. Individual black-and-white transparencies generated using the resulting look-up tables were utilized in the production of color-composite images with varying band combinations. Four experienced photointerpreters ranked 2-cm-diameter (0. 75 inch) chips of selected image features of each band combination for ease of interpretability. A nonparametric rank-order test determined the significance of interpreter preference for the band combinations.

Journal of Imaging Technology↗

USGS1985

Digital to analog conversion and visual evaluation of Thematic Mapper data

Journal of Imaging Technology↗

USGS2022

Constructing a large-scale landslide database across heterogeneous environments using task-specific model updates

Preparation and mitigation efforts for widespread landslide hazards can be aided by a large-scale, well-labeled landslide inventory with high location accuracy. Recent smallscale studies for pixel-wise labeling of potential landslide areas in remotely-sensed images using deep learning (DL) showed potential but were based on data from very small, homogeneous regions with unproven model transferability. In this paper we consider a more realistic and practical setting for large-scale heterogeneous landslide data collection and DL-based labeling. In this setting, remotely sensed images are collected sequentially in temporal batches, where each batch focuses on images from a particular ecoregion, but different batches can focus on different ecoregions with distinct landscape characteristics. For such a scenario, we study the following questions: (1) How well do DL models trained in homogeneous regions perform when they are transferred to different ecoregions, (2) Does increasing the spatial coverage in the data improve model performance in a given ecoregion (even when the extra data do not come from the ecoregion), and (3) Can a landslide pixel labeling model be incrementally updated with new data, but without access to the old data and without losing performance on the old data (so that researchers can share models obtained from proprietary datasets)' We address these questions by extending the Learning without Forgetting framework, which is used for incremental training of image classification models, to the setting of incremental training of semantic segmentation models (e.g., identifying all landslide pixels in an image). We call the resulting extension Task-Specific Model Updates (TSMU). TSMU semantic segmentation framework consists of an encoder shared by all ecoregions to capture the similarities between them, and ecoregion-specific decoders to capture the nuances of each ecoregion. This framework is continually updated using a threestage training procedure for each new addition of an ecoregion without having to revisit data from old ecoregions and without losing performance on them.

IEEE Journal of Selected Topics in Applied Earth O↗

USGS2004

Landsat yesterday and today: An American vision and an old challenge

Since the late 1960s, the United States government has invested more than $1 billion in designing, launching, and operating the Landsat (land satellite) series of Earth-observing satellites. Global change researchers, geologists, and environmental scientists have used images gathered by the satellites for purposes ranging from human health research, energy exploration, and pollution detection to agricultural assessments, urban growth monitoring, and earthquake lineament studies. The earliest data were captured on a digital medium called wide-band video tape (WBVT). However, two decades of unsound media storage conditions and a poorly maintained processing system have left the physically deteriorating WBVTs with no mechanism for interpretation. A national treasure was in jeopardy. With seed money from the National Aeronautics and Space Administration (NASA), the U.S. Geological Survey (USGS) began a project to rescue the data. More than 21,000 tapes from the 1970s have been transcribed to stable, archival media, preserving the data for future studies in Earth System Science.

Journal of Map & Geography Libraries↗

USGS2026

Constraining the permeability and outer-rise hydration at the Central America margin

Subduction zones are important drivers of Earth's geochemical evolution; the presence of water within the subduction system has substantial implications for geohazards, including the style of seismicity and the volume of magma generated at arc volcanoes. We utilize estimates of pore fluid distributions in the outer-rise region of the Central American margin imaged using controlled-source electro-magnetic surveys and novel two-dimensional forward models simulating poro-elastic deformation of slab bending to constrain the background permeability structure of the Cocos Plate and within outer-rise fault damage zones. The model results suggest that a relatively low background permeability structure is required to match the observed porosity at depths greater than 3 km (less than ~10 −21 m 2 . Similarly, increasing the permeability within the damage zones of outer-rise faults by more than a factor of 10 also over-predicts observed porosity distributions at depths greater than 3 km. However, the simulations consistently underpredict pore fluid distributions between depths of 1–3 km, which may reflect nonlinear elastic or anelastic deformation processes not included in the simulations or inherent uncertainty in the conversion of resistivity measurements to porosity distributions. The best-fitting depth-permeability relationship is relatively low, which has important implications for the timing of pore fluid release down-dip of the trench, as it restricts shallow fluid release, likely leading to higher pore fluid pressures, more widespread hydraulic fracturing, and deeper release of pore fluid along the plate interface.

Journal of Geophysical Research, Solid Earth↗

USGS2012

Surface seismic and electrical methods to detect fluids related to faulting

In the absence of drilling, surface-based geophysical methods are necessary to observe fault zones and fault zone physical properties at seismogenic depths. These in situ physical properties can then be used to infer the presence and distribution of fluids along faults, although such observations are by nature indirect and become less exact with greater depth. Multiple observations of a range of such geophysical properties as compressional and shear seismic velocity ( V p and V s ), V p /V5 ratio (related to Poisson's ratio), resistivity and attenuation in and adjacent to fault zones offer the greatest hope of making inferences of the fault zone geometry, fluids in the fault zone, and fluid reservoirs in the surrounding crust. For simple geometries, fault zone guided waves can provide information on fault zone width and velocities for faults of the order of 200 m wide. To address the question of whether a narrow fault zone can be imaged well enough at depths of seismic rupture to infer the presence of anomalously high fluid/rock ratios, we present synthetic seismic tomography and magnetotelluric examples for an ideal case of a narrow fault zone with a simple geometry, large changes in material properties, and numerous earthquakes within the fault zone. A synthetic 0.5-km wide fault zone with 20% velocity reduction is well imaged using local earthquake tomography. When sequential velocity inversions are done, the true fault width is found, even to 9 km depth, although the calculated amplitude of the velocity reduction is lower than the actual amplitude. V p / V s is as well determined as V p . Magnetotelluric imaging of a synthetic fault zone shows that a conductive fault zone can be well imaged within the upper 10 km. Further, a narrow (1 km) very low resistivity (3 ohm m) fault core can be imaged within a broad (5 km) low resistivity (10 ohm m) fault zone, illustrating that regions of a fault containing large quantities of interconnected fluids within a broader, conductive fault zone should be detectable. Thus variations in fluid content and fluid pressure can be inferred from electrical and seismic methods but there will always be uncertainty in these inferences due to the trade-off with other factors, such as intrinsic variations in porosity, mineralogy, and pore geometry. The best approach is combined modeling of varied seismic and electrical data.

Journal of Geophysical Research Solid Earth↗

USGS2012

Application of wave field continuation to the inversion of refraction data

Three examples of the inversion of refraction data by downward continuation illustrate the applicability of the method to field data. The first example is a refraction profile from the Mojave Desert, California. These data are spatially aliased and contain clear evidence of lateral inhomogeneity. The inversion in this case produces a broken image in the slowness‐depth domain due to the lateral inhomogeneity, but a useful average velocity model is still obtained. The second example is a shallow marine reflection profile. Here, the truncation effects due to the finite horizontal aperture of the recording cable produce artifacts in the slowness‐depth domain. The velocity model is, however, distinct from these artifacts, and the presence of strong precritical reflections aids in the inversion. The third example is another shallow marine reflection profile. The inversion of these data illustrate the utilization of constraints provided by multiples as well as primary arrivals.

Journal of Geophysical Research B: Solid Earth↗

USGS2021

Airborne geophysical imaging of weak zones on Iliamna Volcano, Alaska: Implications for slope stability

Water‐saturated, hydrothermally altered rocks reduce the strength of volcanic edifices and increase the potential for sector collapses and far‐traveled mass flows of unconsolidated debris. Iliamna Volcano is an andesitic stratovolcano located on the western side of the Cook Inlet, ∼225 km southwest of Anchorage and is a source of repeated avalanches. The widespread snow and ice cover on Iliamna Volcano make surface alteration difficult to identify. However, intense hydrothermal alteration significantly reduces both the electrical resistivity and magnetization of volcanic rock and can therefore be identified with airborne geophysical measurements. We use airborne electromagnetic and magnetic data to map snow and ice thickness and identify underlying alteration zones at Iliamna Volcano, Alaska. Resistivities were calculated to an average depth of >300 m, and a 3‐D susceptibility model extends from the surface to the base of the volcano, about 3,000 m below the summit. Geophysical models image low resistivity (<30 ohm‐m) and low susceptibilities near the summit of Iliamna and below its older vent complex, with the low susceptibilities indicating alteration up to ∼800 m in thickness. Thin conductors (∼50–100 m thick) on the edifice slopes coincide with recorded locations of repeated debris avalanches over the past ∼60 years and are attributed to saturated zones at high elevation. Three‐dimensional slope stability models based upon the geophysically constrained alteration distribution suggest the edifice of Iliamna is unstable and could lead to collapse scars ∼400 m deep near the current and former vent complexes.

Alaska↗

USGS2009

Experimental study of near-field air entrainment by subsonic volcanic jets

The flow structure in the developing region of a turbulent jet has been examined using particle image velocimetry methods, considering the flow at steady state conditions. The velocity fields were integrated to determine the ratio of the entrained air speed to the jet speed, which was approximately 0.03 for a range of Mach numbers up to 0.89 and Reynolds numbers up to 217,000. This range of experimental Mach and Reynolds numbers is higher than previously considered for high-accuracy entrainment measures, particularly in the near-vent region. The entrainment values are below those commonly used for geophysical analyses of volcanic plumes, suggesting that existing 1-D models are likely to understate the tendency for column collapse.

Journal of Geophysical Research B: Solid Earth↗

USGS1985

Total chemical management in photographic processing

The mission of the U. S. Geological Survey's Earth Resources Observation Systems (EROS) Data Center is to produce high-quality photographs of the earth taken from aircraft and Landsat satellite. In order to meet the criteria of producing research-quality photographs, while at the same time meeting strict environmental restrictions, a total photographic chemical management system was installed. This involved a three-part operation consisting of the design of a modern chemical analysis laboratory, the implementation of a chemical regeneration system, and the installation of a waste treatment system, including in-plant pretreatment and outside secondary waste treatment. Over the last ten years the result of this program has yielded high-quality photographs while saving approximately 30,000 per year and meeting all Environmental Protection Agency (EPA) restrictions.

Journal of Imaging Technology↗

USGS1977

Urban and regional land use change detected by using Landsat data

The Atlanta Regional Commission and the Earth Resources Observation Systems Data Center participated in a demonstration of the use of Landsat digital data to detect land use change in the Atlanta, Ga., area. Temporal overlays combining Landsat band-5 data from October 1972 and 1974 were made by using the General Electric Image 100 system. The 1972 data were divided by the 1974 data, and low ratios indicate areas where land use and land cover had changed. These low ratios were classified into a land-use-change theme. A classification based on the use of the four bands of the multispectral scanner data, taken in 1974, yielded six land use categories: (1) Commercial-industrial-multifamily, (2) single-family residential, (3) cleared land, (4) open space, (5) forested land, and (6) water. These six 1974 categories and the change theme were combined to determine changes between 1972 and 1974.

Georgia↗

USGS2012

Photogrammetric portrayal of Mars topography

Special photogrammetric techniques have been developed to portray Mars topography, using Mariner and Viking imaging and nonimaging topographic information and earth-based radar data. Topography is represented by the compilation of maps at three scales: global, intermediate, and very large scale. The global map is a synthesis of topographic information obtained from Mariner 9 and earth-based radar, compiled at a scale of 1:25,000,000 with a contour interval of 1 km; it gives a broad quantitative view of the planet. At intermediate scales, Viking Orbiter photographs of various resolutions are used to compile detailed contour maps of a broad spectrum of prominent geologic features; a contour interval as small as 20 m has been obtained from very high resolution orbital photography. Imagery from the Viking lander facsimile cameras permits construction of detailed, very large scale (1:10) topographic maps of the terrain surrounding the two landers; these maps have a contour interval of 1 cm. This paper presents several new detailed topographic maps of Mars.

Journal of Geophysical Research Solid Earth↗

USGS2014

The 2010 slow slip event and secular motion at Kilauea, Hawai`i inferred from TerraSAR-X InSAR data

We present here an Small BAseline Subset (SBAS) algorithm to extract both transient and secular ground deformations on the order of millimeters in the presence of tropospheric noise on the order of centimeters, when the transient is of short duration and known time, and the background deformation is smooth in time. We applied this algorithm to study the 2010 slow slip event as well as the secular motion of Kīlauea's south flank using 49 TerraSAR-X images. We also estimate the tropospheric delay variation relative to a given reference pixel using an InSAR SBAS approach. We compare the InSAR SBAS solution for both ground deformation and tropospheric delays with existing GPS measurements and confirm that the ground deformation signal andtropospheric noise in InSAR data are successfully separated. We observe that the coastal region on the south side of the Hilina Pali moves at a higher background rate than the region north side of the Pali. We also conclude that the 2010 SSE displacement is mainly horizontal and the maximum magnitude of the 2010 SSE vertical component is less than 5 mm.

Hawaii↗

USGS2012

Reflected and mode-converted seismic waves within the shallow Aleutian subduction zone, southern Kenai Peninsula, Alaska

Pronounced secondary phases observed in local recordings of quarry shots and earthquakes on the southern Kenai Peninsula, Alaska, are identified as reflected P and S and converted S-to-P phases originating within four depth ranges: in the upper few kilometers of the Cook Inlet Tertiary basin, at midcrustal depths within the overthrust North American plate, at about 35 km depth near the top of the Wadati-Benioff seismic zone in proximity to the inferred interplate megathrust, and at about 5–10 km below the megathrust in the subducted Pacific plate. Beneath the landward margin of the accreted Chugach terrane, the mid-upper plate (MUP) discontinuity dips as steeply as 20°–30° to the west-northwest over the depth range 12–18 km. At shallower depths it flattens and possibly arches with the crest at about 10 km depth. Similar midcrustal reflectors have been imaged about 125 km to the southwest and about 350 km to the northeast along the structural trend of the Chugach terrane. The extensive reflectors may have a common origin, possible caused by the presence of underplated rocks. Relative amplitudes and polarities of the secondary phases originating at MUP depths provide few constraints on the nature of the discontinuity. It appears that the MUP discontinuity is seismically inactive and does not represent a brittle-ductile transition zone within the upper plate. The two converted S -to- P phases generated near the top of the subducted plate could indicate a low-velocity zone associated with subducted oceanic crust.

Journal of Geophysical Research Solid Earth↗

USGS1999

Analysis of stress-induced oval fractures in a borehole at Deep Sea Drilling Project Site 504, eastern equatorial Pacific

Deep Sea Drilling Project (DSDP) Hole 504B is located in the eastern equatorial Pacific Ocean and extends to a total depth of 2111 m beneath the seafloor (mbsf). Several acoustic televiewer logs have been obtained in this well during successive stages of drilling, and the resulting digital images have revealed numerous oval-shaped fractures seemingly etched into the borehole wall. A theoretical examination of these stress-induced features identifies a unique and ephemeral set of stress distributions and magnitudes that are necessary for their production. Consequently, the ovals provide a basis for quantifying the magnitudes and orientations of the maximum and minimum horizontal principal stresses, S H and S h at this site. Vertical, truncated breakouts and horizontal tensile fractures define the spatial boundaries of the ovals. Explicit criteria for their occurrence are combined with estimates for various physical properties of the rock to yield a range of possible values for the horizontal principal stresses. The conspicuous oval geometry is completed by a curved fracture that joins the vertical and horizontal components. Its degree of curvature is delineated by the modified Griffith failure criterion and is directly related to the principal stress difference ( S H − S h ). Matching a series of type curves corresponding to specific values for ( S H − S h ) with the actual undistorted well bore images allows the magnitude of the stress difference to be further constrained. With a value for ( S H − S h ) of 45 ± 5 MPa the individual magnitudes of S H and S h are determined more precisely. Final estimates for the horizontal principal stresses in DSDP Hole 504B at a depth of 1200 mbsf are 141 MPa ≤ S H ≤ 149 MPa and 91 MPa ≤ S h ≤ 109 MPa. Stress magnitudes derived from this approach rely heavily upon the values of a variety of physical properties, and complementary laboratory measurements performed on relevant rock samples provide critical information. Uncertainties in estimating these properties translate into less precise predictions of principal stresses.

Journal of Geophysical Research B: Solid Earth↗