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At least 541 records · Page 30Linked to original sources
USGS2022

System characterization report on the Satellogic NewSat multispectral sensor

Executive Summary This report addresses system characterization of Satellogic’s NewSat satellite (also known as ÑuSat) and is part of a series of system characterization reports produced and delivered by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence. These reports present and detail the methodology and procedures for characterization; present technical and operational information about the specific sensing system being evaluated; and provide a summary of test measurements, data retention practices, data analysis results, and conclusions. Since 2016, Satellogic has launched 17 NewSat satellites. All NewSat satellites have four-band imagers with a 1-meter (m) ground sample distance, and values in pixels are identical to values in meters. All NewSats have been launched into Sun-synchronous orbits of about 475 kilometers, with inclinations of about 97.5 degrees. The satellites have expected lifetimes of about 3 years. More information on the Satellogic satellites and sensors is available in the “2020 Joint Agency Commercial Imagery Evaluation—Remote Sensing Satellite Compendium” and from the manufacturer at https://satellogic.com/ . The Earth Resources Observation and Science Cal/Val Center of Excellence system characterization team completed data analyses to characterize the geometric (interior and exterior), radiometric, and spatial performances. Results of these analyses indicate that the NewSat satellites have an interior geometric performance in the range of −0.119 (−0.119 pixel) to 0.020 m (0.020 pixel) in easting and −0.148 (−0.148 pixel) to 0.014 m (0.014 pixel) in northing in band-to-band registration, an exterior geometric performance of −9.04 (−9.04 pixels) to −5.84 m (−5.84 pixels) in easting and 1.25 (1.25 pixels) to 3.11 m (3.11 pixels) in northing offset in comparison to Sentinel-2, an exterior geometric performance using ground control points of a 6.5-m circular error (95 percent), a radiometric performance in the range of 0.034 to 0.081 in offset and 0.652 to 0.808 in slope, and a spatial performance in the range of 1.61 to 1.76 pixels for full width at half maximum, with a modulation transfer function at a Nyquist frequency in the range of 0.081 to 0.138.

Open-File Report↗
USGS2023

System characterization report on the Pléiades Neo Imager

Executive Summary This report addresses system characterization of the Pléiades Neo satellite and is part of a series of system characterization reports produced and delivered by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence. These reports present and detail the methodology and procedures for characterization; present technical and operational information about the specific sensing system being evaluated; and provide a summary of test measurements, data retention practices, data analysis results, and conclusions. Pléiades Neo is a constellation of four identical very-high-resolution optical satellites operated by Airbus Defence and Space. The first two satellites, Pléiades Neo-3 and -4, were launched in April and August 2021, respectively. The next two satellites, launched in December 2022, did not reach orbit because of Vega-C launch vehicle failure. Pléiades Neo provides several technical improvements to previous Pléiades-HR satellites, including the addition of coastal aerosol (deep blue) and red edge spectral bands, with improved ground sample distance and swath. The Pléiades Neo satellites were designed and built by Airbus Defence and Space with the high-resolution, multispectral imager for Earth imaging and use the S950 optical satellite bus. The high-resolution sensor on Pléiades Neo collects Earth data in the visible and near-infrared region with six bands and a panchromatic band. The satellites can operate off nadir to achieve a revisit of less than 1 day. More information on Pléiades Neo satellites and sensors is available in the “Land Remote Sensing Satellites Online Compendium” ( https://calval.cr.usgs.gov/apps/compendium# ) and from the manufacturer ( https://www.intelligence-airbusds.com/imagery/constellation/pleiades-Neo/ ). The Earth Resources Observation and Science Cal/Val Center of Excellence system characterization team completed data analyses to characterize the geometric (interior and exterior), radiometric, and spatial performances. Results of these analyses indicate that Pléiades Neo has an interior geometric performance in the range of 0.01 meter (m; 0.008 pixel) to −0.017 m (−0.014 pixel) in band-to-band registration; an exterior geometric performance in the range of −7.015 m (−0.702 pixel) to 3.846 m (0.385 pixel) offset in comparison to Sentinel-2 using ground control points of 2.2 to 7.2 m (95-percent circular error); a radiometric performance in the range of −0.070 (minimum) to −0.053 (maximum) in offset and 1.107 (minimum) to 1.202 (maximum) in slope; and a spatial performance in the range of 1.002 to 1.226 pixels at full width at half maximum with a modulation transfer function at a Nyquist frequency in the range of 0.22 to 0.34 (bands 2–7).

Open-File Report↗
USGS2024

System characterization report on Vision-1

Executive Summary This report addresses system characterization of the Airbus Vision-1 satellite and is part of a series of system characterization reports produced and delivered by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence. These reports present and detail the methodology and procedures for characterization; present technical and operational information about the specific sensing system being evaluated; and provide a summary of test measurements, data retention practices, data analysis results, and conclusions. Vision-1 is a high-resolution Earth observation satellite launched in September 2018 as a collaborative effort between Airbus and Surrey Satellite Technology Ltd. It features a Newtonian telescope with a refractive relay, capturing images in panchromatic and multispectral bands. Operating in a Sun-synchronous orbit at an altitude of 583 kilometers, Vision-1 ensures consistent illumination conditions during image acquisition. It has a revisit time of 1 to 8 days depending on latitude and viewing angle, and it features an off-pointing agility of plus or minus 45 degrees, allowing for multiple target captures in a single pass using spot, strip, and mosaic imaging modes. The panchromatic band offers a resolution of 0.87 meter (m), whereas the multispectral bands (blue, green, red, and near infrared) provide a resolution of 3.48 m. These capabilities support a variety of applications including urban planning, agricultural monitoring, land classification, natural resource management, and disaster response. More information on the Vision-1 satellite and sensors is available in the “2022 Joint Agency Commercial Imagery Evaluation—Remote Sensing Satellite Compendium.” The Earth Resources Observation and Science Cal/Val Center of Excellence system characterization team completed data analyses to characterize the geometric (interior and exterior), radiometric, and spatial performances. Results of these analyses indicate that the Vision-1 satellite has an interior geometric performance in the range of 0 to 0.02 m in easting and −0.01 to 0.03 m in northing in band-to-band registration, an exterior geometric performance of 1.7 to 2.2 m in easting and −1.1 to −0.7 m in northing offset with a 90-percent circular error of 3.4 to 3.7 m, a radiometric performance in the range of −0.029 to 0.017 in offset and 0.884 to 0.984 in slope, and a spatial performance in the range of 0.992 to 1.092 pixels for multispectral full width at half maximum and 1.895 pixels for the panchromatic band full width at half maximum, with a modulation transfer function at a Nyquist frequency in the range of 0.29 to 0.36 for the multispectral bands and 0.05 for the panchromatic band.

Open-File Report↗
USGS2022

Underwater videographic observations of domesticated Delta smelt in field enclosures

The delta smelt ( Hypomesus transpacificus ) is a small, euryhaline fish species endemic to the Sacramento–San Joaquin Delta; it is protected under the U.S. and California Endangered Species Acts, and because of declines in population abundance, the delta smelt may be vulnerable to extinction. The California Department of Water Resources (DWR) is conducting studies to test the viability of using domesticated fish to supplement the wild population of delta smelt. These studies have focused on examining the health and survival of domesticated delta smelt placed inside enclosures (circular cages that are approximately 1.5 meters tall by 1 meter in diameter) into the wild. We completed two parts within this study using underwater cameras inside the enclosures to observe fish behavior and their responses to certain stimuli. In both parts of the study, delta smelt behaviors were broadly categorized into two basic categories: (1) normal and (2) alarm. Normal behavior was characterized as calm, non-polarized, and docile swimming behavior. Alarm behavior was characterized by sudden and rapid darting, polarized frantic swimming activity, and tighter schooling polarization of individuals. The first part of the study took place in a semi-controlled agricultural pond on the campus of the University of California, Davis. At this agricultural pond, we developed methods of observation and documented how fish behaved in response to enclosure disturbances associated with routine cleaning and service that is required during extended field deployments of the enclosures. We observed that delta smelt behavior changed from normal to alarm at the onset of an enclosure service and from alarm to normal within about 2 minutes after the service ended. The second part of the study was completed in cooperation with the DWR. In October 2019, DWR deployed three enclosures in the Sacramento River near Rio Vista, California. To monitor survival rate of delta smelt, DWR permitted us to deploy cameras in one enclosure to document the frequency and duration of alarm behaviors exhibited by delta smelt and the frequency, duration, and intensity of three types of disturbances: (1) noise generated from passing boats, (2) noise generated from the enclosure moving in response to wave energy, and (3) vertical movements of the enclosure generated from wave energy. Alarm behaviors averaged about 2 minutes in duration and occurred most frequently during the evening compared to midday or morning. Each disturbance variable exhibited substantial variability in duration and intensity and occurred least frequently during the morning and evening compared to midday. Alarm behaviors appeared to be most associated with high intensity enclosure noises and vertical movements; however, limited replicate samples prohibited developing a statistical relation. Alarm behaviors did not directly contribute to injury or mortality of individual delta smelt; however, indirect or sublethal effects of alarm behaviors were not examined.

California↗
USGS2024

U.S. Geological Survey Karst Interest Group proceedings, Nashville, Tennessee, October 22-24, 2024

Karst hydrogeologic systems represent challenging and unique conditions to scientists studying groundwater flow and contaminant transport. Karst terrains are characterized by distinct and beautiful landscapes, caverns, and springs, and many of the exceptional karst areas are designated as national or state parks. The range and complexity of landforms and groundwater flow systems associated with karst terrains are enormous, perhaps more than any other aquifer type. The U.S. Geological Survey (USGS) Karst Interest Group (KIG), formed in 2000, is a loosely knit, grassroots organization of USGS and non-USGS scientists and researchers devoted to fostering better communication among scientists working on, or interested in, karst aquifers. The primary mission of the KIG is to encourage and support interdisciplinary collaboration and technology transfer among scientists working in karst areas. To accomplish its mission, the KIG has organized a series of workshops. To date (2024), nine KIG workshops, including the workshop documented in this report, have been held. The abstracts and extended abstracts provide a snapshot in time of past and current karst related studies. The USGS Water Availability and Use Science Program funded the workshop and proceedings. The planning committee for the ninth workshop includes Thomas D. Byl (USGS and Tennessee State University), Allan K. Clark (USGS), Laura M. DeMott (USGS), Eve L. Kuniansky (USGS, Emeritus), Benjamin V. Miller (USGS), and Lawrence E. Spangler (USGS, Emeritus). The workshop proceedings are edited by Eve L. Kuniansky and Lawrence E. Spangler. The field trip guide was produced by Benjamin V. Miller and Brian Ham (Tennessee Department of Environment and Conservation) and included in the proceedings from the KIG’s 2021 virtual workshop to be used on the optional field trip held on Thursday, October 24, 2024.

Open-File Report↗
USGS1954

Determination of readily soluble copper, zinc, and lead in soils and rocks; nitric acid extraction

Procedures for the determination of copper, lead and zinc are described by Almond and Morris (1951); Lakin, Stevens and Almond (1949); and Lovering, Herf and Almond (1950). They are also summarized in U.S. Geological Survey Circular 161. In the procedure given below, a simple attack or the sample with 1+3 nitric acid serves to effect adequate solution of the heavy metals for purposes of geochemical prospecting. Copper, lead, and zinc may be determined on a single sample solution prepared in this way. About 30 samples can be analyzed daily for the constituents.

Open-File Report↗
USGS1953

Stratigraphic sections of the Phosphoria formation measured and sampled in 1952

A series of reports presenting detailed stratigraphic sections and analyses of samples of the Phosphoria formation in the western phosphate field is being prepared for publication as U. S. Geological Survey Circulars. To speed the availability of these data to industry and others having immediate need for such basic information, many of the tables already typed and photographed were reproduced without text and placed on open file in advance of publication. This includes six reports of data gathered during the 1947 and 1948 field seasons.

Open-File Report↗
USGS1954

Fusion of arkosic sand by intrusive andesite

An andesite dike in the Valles Mountains of northern New Mexico has intruded and partly fused arkosic sediments for a distance of 50 feet from its contacts. The dike is semi-circular in form, has a maximum width of about 100 feet, and is about 500 feet long. Small associated arcuate dikes are arranged in spiral fashion around the main dike, suggesting that they were intruded along shear fractures similar to those described by Burbank (1941). The fused rocks surrounding the andesite dike are of three general types: 1) partly fused arkosic sand, 2) fused clay, and 3) hybrid rocks. The fused arkosic sand consists of relict detrital grains of quartz, orthoclose, and plagioclase, imbedded in colorless glass containing microlites of tridymite, cordierite, and magnetite. The relict quartz grains are corroded and embayed by glass; the orthoclase is sanidinized and partly fused; and the plagioclase is inverted to the high temperature form and is partly fused. The fused clay, which was originally a mixture of montmorillonite and hydromica, consists primarily of cordierite but also contains needle-like crystals of sillimanite (?) or mullite (?). The hybrid rocks originated in part by intermixing of fused arkosic sediments and andesitic liquid and in part by diffusion of mafic constituents through the fused sediments. They are rich in cordierite and magnetite and also contain hypersthene, augite, and plagioclase. The composition of pigeonite in the andesite indicates that the temperature of the andesite at the time of intrusion probably did not exceed 1200?C. Samples of arkosic sand were fused in the presence of water in a Morey bomb at 1050?C. Stability relations of certain minerals in the fused sand suggest that fusion may have taken place at a lower temperature, however, and the fluxing action of volatiles from the andesite are thought to have made this possible.

Open-File Report↗
USGS1955

Fossils from bore holes on the Eastern Shore Peninsula, Virginia

This report lists Foraminifera, Mollusca, and Ostracoda in five bore holes that penetrated a maximum of 445 feet of section in sediments of Pleistocene and Miocene age, and discusses the paleoecologic and stratigraphic significance of the fossils. It includes the contents of references 6, 16, and 18 of Virginia Division of Geology Mineral Resources Circular No. 2, dealing with the geology and groundwater resources of the Eastern Shore peninsula.

Virginia↗
USGS1961

Dacitic ash-flow sheet near Superior and Globe, Arizona

Remnants of a dacitic ash-flow sheet near Globe, Miama, and Superia, Arizona cover about 100 square miles; before erosion the area covered by the sheet was at least 400 square miles and perhaps as much as 1,500 square miles. Its maximum thickness is about 2,000 feet, its average thickness is about 500 feet, and its original volume was at least 40 cubic miles. It was erupted on an eroded surface with considerable relief. The main part of the deposit was thought by early workers to be a lava flow. Even after the distinctive character of welded tuffs and related rocks was discovered, the nature and origin of this deposit remained dubious because textures did not correspond to those in other welded tuff bodies. Yet a lava flow as silicic as this dacite would be viscous instead of spreading out as an extensive sheet. The purpose of this investigation has been to study the deposit, resolve the inconsistencies, and deduce its origin and history. Five stratigraphic zones are distinguished according to differences in the groundmass. From bottom to top the zones are basal tuff, vitrophyre, brown zone, gray zone, and white zone. The three upper zones are distinguished by colors on fresh surfaces, for each weathers to a similar shade of light reddish brown. Nonwelded basal tuff grades upward into the vitrophyre, which is a highly welded tuff. The brown and gray zones consist of highly welded tuff with a lithoidal groundmass. Degree of welding decreases progressively upward through the gray and the white zones, and the upper white zone is nonwelded. Textures are clearly outlined in the lower part of the brown zone, but upward they become more diffuse because of increasing devitrification. In the white zone, original textures are essentially obliterated, and the groundmass consists of spherulites and microcrystalline intergrowths. The chief groundmass minerals are cristobalite and sanidine, with lesser quartz and plagioclase. Phenocrysts comprise about 40 percent of the rock, and their relative proportions are fairly uniform. Almost three-fourths of the phenocrysts are plagioclase, one-tenth quartz, one-tenth biotite, and the remainder sanidine, magnetite, and hornblende, with accessory sphene, zircon, and appetite. Pumice fragments are nearly equidimensional near the top of the sheet, and downward they become progressively more flattened until they finally disappear. The zones and the pumice fragment flattening ration (ratio of length to height) provide means for recognizing several faults within the sheet. Twelve new chemical analyses are nearly uniform in composition. If named according to chemical composition, the rock would be a quartz latite, but when named according to phenocrysts, it is a dacite. From the field occurrence and the interpretation of relict textures, it is concluded that the deposit is an ash-flow sheet containing large amounts of welded tuff, and that it was emplaced by a type of nuee ardente instead of a lava flow or air-fall shower. The nature of zoning and trend of flattening ratios indicate a series of eruptions in rapid enough succession for the sheet to form a single cooling unit. Except in the lower part of the sheet, original textures were obscured by devitrification and crystallization during cooling. Nearly uniform mineralogy and chemistry suggest a single magnetic source. A nearly circular area, about 3? miles in diameter, of altered dacite and earlier volcanic rocks, bounded by intricately faulted and brecciated older rocks, may be the site of a caldera that represents the source of the eruptions.

Open-File Report↗
USGS1969

Geochemical maps of an area northwest of the Chulitna River, central Alaska Range

An area northwest of the Chulitna River in west-central Alaska Range locally shows local anomalous concentrations of gold, silver, arsenic, copper, zinc, and lead in stream-sediment samples. Most stream sediments showing anomalous concentrations of metals can be correlated with either known or newly discovered deposits or occurrences described in Circular 617.

Alaska↗
USGS1970

Qualitative analysis of airborne magnetometer data: The Arabian Shield, Kingdom of Saudi Arabia

A qualitative analysis and interpretation of magnetic data obtained from airborne magnetometer and scintillometer surveys of the Precambrian Arabian Shield, Kingdom of Saudi Arabia, show that some rock units and geologic features exhibit characteristic magnetic expressions and anomalies. Circular to elliptical anomalies are attributed to younger intrusive or less commonly older masses, stocks, and plugs of granitic rocks. The linear anomalies may be expressions of faults, lineation trends, or dike swarms. Reconnaissance exploration for evidence of mineralization are recommended in the vicinity of some of these anomalies.

Open-File Report↗
USGS1970

Estimates of the mechanical properties of lunar surface using tracks and secondary impact craters produced by blocks and boulders

Estimates of bearing capacities of lunar surfaces using tracks and secondary impact craters produced by blocks and boulders shown in photographs taken by Lunar Orbiters II and III are the same order of magnitude as those reported by the Surveyor project, but they are generally less. Static analyses of 48 lunar blocks and boulders and their tracks yield friction angles between 10° and 30° and averaging about 17°. These values were computed using: (1) Terzaghi's bearing capacity equations for circular footings, (2) Meyerhof's dimensionless numbers for general shear on level surfaces, (3) a cohesion of 10 3 dynes per cm 2 , (4) a density of 1.35 gm per cm 3 for the near surface materials, (5) a density of 2.7 gm per cm 3 for the block or boulder, (6) spheroidal (triaxial) boulders unless definite shapes can be established, (7) footing radii equal to the half-width of the block or boulder, the half-width of the track, and(or) the half-width of the shadow near the base of the block or boulder. For 115 secondary impact craters and their corresponding blocks, dynamic strengths are estimated using: (1) the product of one-half the mass per unit area of the block and the normal component of velocity squared divided by the crater depth, and (2) the ratio of the kinetic energy of the block and the volume of the secondary crater. Velocities of the blocks are calculated using a ballistics equation and assuming an ejection angle of 45°. Block densities are taken as 2.7 gm per cm 3 . Dynamic strengths of the near surface materials using the first procedure average 25.2 x 10 5 dynes per cm 2 (37 psi); and, for the second procedure, they average 19.2 x 10 5 dynes per cm 2 (28 psi). Comparison between dynamic strengths and expected static strengths, computed for each block using the assumptions above, show that most of the dynamic strengths correspond to the static strengths when the friction angle is 30° and larger. Data on experimental low velocity impacts with natural targets are compared with the lunar data on secondary impacts. Nara's modified Poncelet equation for sand yields an average angle of internal friction near 34° using the appropriate block and soil constants mentioned above. Comparison of coefficients computed using the equations for sand of Clark and McCarty, Mortensen, and Moore for the lunar data with the corresponding constants for terrestrial data indicate the lunar coefficients are generally low. These low values can be brought into better agreement with terrestrial data on sand by increasing the assumed ejection angles to 60° or 70° and considering the effect of the low acceleration of gravity at the lunar surface.

Open-File Report↗
USGS1972

Geological and geophysical investigations of an Apollo 9 photo anomaly near Point of Pines, Arizona

An infrared photograph of southeastern Arizona, taken during the Apollo 9 multispectral terrain photography experiment in 1969, reveals a ringlike feature, some 3-4 miles (5-6 kin) in diameter, on the Natanes Plateau, 35 miles (56 kin) north of the town of Safford. Because the feature occurs in an area of nearly flat lying Tertiary volcanic rocks, the possibilities of its being a small collapse caldera or an exposed circular intrusive body were considered. Geological and geophysical studies of the area were made to test these hypotheses. The local stratigraphic section consists of approximately 1,500 feet (457 m) of Oligocene and perhaps older volcanic rocks, resting on a moderately irregular basement surface carved from nearly flat lying trending Basin-and-Range faults define a broad horst within which two arcuate cross faults, with 300-600 feet (91-183 m) of displacement, bound a downdropped area. Deep erosion along these faults has created a polygonal network of canyons which constitutes the 'ring' seen on the photograph. A mild arching of the volcanic rocks within the ring is suggested by structure contours on the base of the youngest flows. A sharp 350-gamma positive aeromagnetic anomaly is centered within the ring. In its southwest quadrant the anomaly has an elongate extension that trends northwest along an adjoining Basin-and-Range fault. Associated with both is a subtle gravity low. The geophysical data thus suggest the presence of a small blind silicic pluton, possibly of middle Tertiary or younger age. Although it can be argued that the arcuate faults and mild arching of the volcanic pile are related to this postulated pluton, no evidence of hydrothermal alteration or thermal metamorphism of the country rocks was seen. Thus if a pluton is present and of postvolcanic age, it must have been emplaced as a relatively cool dry body; or alternatively, it is older than the surface volcanic rocks. In either instance, its magnetic expression contrasts with that of the known mineralized Laramide porphyry intrusive bodies of the region.

Arizona↗
USGS1974

Geological Survey published reports on Alaska, 1940-1959, indexed by quadrangle

Geological Survey reports published as Professional Papers, Bulletins, Water Supply Papers, and Circulars are listed by the quadrangles (scale 1:250,000) into which Alaska has been divided for topographic mapping (p. 2). This index does not include reports that deal only with administrative matters or that were placed in open files but not formally published. Reports that deal with Alaska as a whole, with areas that cannot be identified with any specific quadrangle, or with offshore areas that are not within quadrangle boundaries, or that consist mainly of statistical data on the quality or quantity of water are listed under ALASKA - GENERAL, as are bibliographies, indexes, and similar publications. The ALASKA - GENERAL list appears before the alphabetically arranged quadrangle listings.

Alaska↗
USGS1974

Geological Survey published reports on Alaska, 1915-1939, indexed by quadrangle

Geological Survey reports published as Professional Papers, Bulletins, Water Supply Papers, and Circulars are listed by the quadrangles (scale 1:250,000) into which Alaska has been divided for topographic mapping (p. 3). This index does not include reports that deal only with administrative matters or that were placed in open files but not formally published. Reports that deal with Alaska as a whole, with areas that can not be identified with any specific quadrangle, or with offshore areas that are not within quadrangle boundaries, or that consist mainly of statistical data on the quality or quantity of water are listed under ALASKAGENERAL, as are bibliographies, indexes, and similar publications. The ALASKA - GENERAL list appears before the alphabetically arranged quadrangle listings.

Alaska↗
USGS1975

Aluminum resources of Brazil

Large deposits of bauxite, the principal ore of aluminum, occur at several places in Brazil. The largest deposits now undergoing extensive exploration and development are in the eastern Amazon Basin. Most of these deposits are in the State of Para, but some are in Amazonas and Maranhao. Discovery of large-scale resources of bauxite in the Amazon Region is so recent that mining has not begun, but government geologists estimate the total resources in aluminum deposits in the lower Amazon to be in the multibillion ton range. The annual production rate of bauxite ore in Brazil, much of it from Pops de Caldas in Minas Gerais, is about 760,000 metric tons of ore from which about 100,000 tons of aluminum metal is produced, most of which is consumed by Brazilian industry. The Amazon bauxite deposits are on terraces formed on sedimentary rocks of Tertiary age; in Minas Gerais the deposits are formed on Precambrian metasedimentary rock, and at Poos de Caldas on a circular alkalic pluton of Cretaceous age.

Open-File Report↗
USGS1975

Physical factors determining the fraction of stored energy recoverable from hydrothermal convection systems and conduction-dominated areas

This report contains background analyses for the estimates of Nathenson and Muffler (1975) of geothermal resources in hydrothermal convection systems and conduction-dominated areas. The first section discusses heat and fluid recharge potential of geothermal reservoirs. The second section analyzes the physical factors that determine the fraction of stored energy obtainable at the surface from a geothermal reservoir. Conversion of heat to electricity and the use of geothermal energy for direct-heating applications are discussed in the last two sections. Nathenson, Manuel, and Muffler, L.J.P., 1975, Geothermal resources in hydrothermal convection systems and conduction dominated areas, in White, D.E., and Williams, D.L., eds., Assessment of the Geothermal Resources of the United States--1975: U.S. Geological Survey Circular 726, p. 104-121, available at http://pubs.er.usgs.gov/usgspubs/cir/cir726

Open-File Report↗