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At least 847 records · Page 47Linked to original sources
USGS1971

Preliminary tectonic map of the Arabian Peninsula

In 1963, in response to a request from the Ministry of Petroleum and Mineral Resources, the Saudi Arabian Government and the U. S. Geological Survey, U. S. Department of the Interior, with the approval of the U. S. Department of State, undertook a joint and cooperative effort to map and evaluate the mineral potential of central and western Saudi Arabia. The results of this program are being released in USGS open files in the United States and are also available in the Library of the Ministry of Petroleum and Mineral Resources. Also on open file in that office is a large amount of material, in the form of unpublished manuscripts, maps, field notes, drill logs, annotated aerial photographs, etc., that has resulted from other previous geologic work by Saudi Arabian government agencies. The Government of Saudi Arabia makes this information available to interested persons, and has set up a liberal mining code which is included in "Mineral Resources of Saudi Arabia, a Guide for Investment and Development," published in 1965 as Bulletin 1 of the Ministry of Petroleum and Mineral Resources, Directorate General of Mineral Resources, Jiddah, Saudi Arabia.

Open-File Report↗
USGS1972

Report on field work in the Mahd adh Dhahab area, Saudi Arabia, February 29 to April 13, 1964

In 1963, in response to a request from the Ministry of Petroleum and Mineral Resources, the Saudi Arabian Government and the U. S. Geological Survey, U. S. Department of the Interior, with the approval of the U. S. Department of State, undertook a joint and cooperative effort to map and evaluate the mineral potential of central and western Saudi Arabia. The results of this program are being released in USGS open files in the United States and are also available in the Library of the Ministry of Petroleum and Mineral Resources. Also on open file in that office is a large amount of material, in the form. of unpublished manuscripts, maps, field notes, drill logs, annotated aerial photographs, etc:, that has resulted from-other previous geologic work by Saudi Arabian government agencies. The Government of Saudi Arabia makes this information available to interested persons, and has set up a liberal mining cods which is included in "Mineral Resources of Saudi Arabia, a Guide for Investment and Development," published in 1965 as Bulletin 1 of the Ministry of Petroleum and Mineral Resources,' Directorate General of Mineral Resources, Jiddah, Saudi Arabia.

Mahd adh Dhahab↗
USGS1972

Report of the field trip, February 24 to April 2, 1965 in part of the northeastern Hijaz quadrangle, Saudi Arabia

In 1963, in response to a request from the Ministry of Petroleum and Mineral Resources, the Saudi Arabian Government and the U. S. Geological Survey, U. S. Department of the Interior, with the approval of the U. S. Department of State undertook a joint and cooperative effort to map and evaluate the mineral potential of central and Saudi Arabia. The results of this program are being released in USGS open files in the United States and are also available in the Library of the Ministry of Petroleum and Mineral Resources. Also on open file in that office is a large amount of material, in the form of unpublished manuscripts, maps, field notes, drill logs, annotated aerial photographs, etc., that has resulted from other previous geologic work by Saudi Arabian government agencies. The Government of Saudi Arabia makes this information available to interested persons, and has set up a liberal mining coda which is included in "Mineral Resources of Saudi Arabia, a Guide for Investment and Development," published in 1965 as Bulletin 1 of the Ministry of Petroleum and Mineral Resources, Directorate General of Mineral Resources, Jiddah, Saudi Arabia.

Hijaz quadrangle↗
USGS2025

Comparison of methods for estimating wild turkey poult survival

Eastern wild turkey ( Meleagris gallopavo silvestris ) population growth is driven by variation in reproduction, and poult survival is a crucial vital rate. Traditional poult survival monitoring uses flush counts of radio-tagged females, but brood flocking (when broods and females merge into larger flocks) and mark retention are potential problems with this method and can produce biased estimates. Alternatively, radio-tagging poults to estimate survival offers a potentially less-biased method if tagging and tracking poults can be conducted without adverse effects on the poults. We compared poult survival estimates derived from flush counts and from radio-tagged poults over a 56-day monitoring period during 2018–2022 in south-central Tennessee, USA. We radio-tagged 183 poults and monitored 85 broods via 2-week flush counts and observed 572 individual poults during flush counts over the 56-day monitoring period. We used known-fate survival models for the telemetry data, Lukacs survival models for the flush count data, and a modified known-fate model to estimate whether radio-tagging poults affected their survival. Two-week survival estimates from the flush count of broods, and radio-tagged poults were similar (flush count: day 0–28: 0.25, 95% CI: 0.20–0.31, day 29–56: 0.56, 95% CI: 0.36–0.76; radio-tagged: day 0–28: 0.30, 95% CI: 0.23–0.37, day 29–56: 0.68, 95% CI: 0.49–0.87). Using known-fate survival models, radio-tagged poults had similar survival rates to non-tagged poults within the brood (day 0–28: Ŝ Radio-tagged = 0.15, 95% CI: 0.10–0.20 v. Ŝ Non-tagged = 0.20, 95% CI: 0.16–0.23), which suggests the radio-tags did not directly affect survival. However, survival of individuals that were trapped was lower than survival of broods that were not trapped during the first 14 days. Trapping methods may need to be adjusted to limit incidental capture effects when choosing to use radio-tagged poults. Conducting flush counts every 14 days until day 56 of the brood-rearing period likely is the most cost-effective method for estimating poult survival. However, monitoring individual radio-tagged poults may yield additional information, such as cause-specific mortality, that may better inform management.

Tennessee↗
USGS2015

Value of information and natural resources decision-making

Though the potential for information to measurably improve management has been highlighted for several decades, in recent years the “value of information” has surfaced with increasing frequency in natural resources. However, the use of this phrase belies the fact that many in natural resources have only a limited understanding about what it actually means, how to measure it, and what to do with it. We introduce and describe several forms of the value of information in a context of the management of renewable natural resources. The value of information is discussed in terms of a potential gain in value with the addition of new information, as well as a loss in value associated with the absence of information. Value metrics are developed for uncertainty about resource status as well as resource processes and responses to management. We provide a common notation for the metrics of value, and discuss linkages of the value of information to strategic approaches such as adaptive resources management and partially observable decision processes.

Wildlife Society Bulletin↗
USGS2026

Temporal and spatial changes in seismic attenuation associated with inferred fluid migration in the 2016 central Apennines earthquake sequence

Prior work suggests that high‐frequency seismic attenuation acts as a highly sensitive proxy for crustal permeability and fluid mobility in fractured media. We test the hypothesis that the fault system responsible for the 2016–2017 Amatrice–Visso–Norcia–Capitignano sequence acted as an impermeable seal, compartmentalizing pressurized fluids until dynamic rupture triggered widespread fluid diffusion. By tracking across the sequence the spatiotemporal evolution of the S ‐wave anelastic attenuation parameter, we identify large, positive low‐frequency attenuation anomalies emerging within the hanging wall following the Amatrice mainshock and strictly preceding subsequent large ruptures. Conversely, we observe weaker, negative anomalies in the footwall, anticorrelated in time with those of the hanging wall, revealing a massive asymmetry in fluid redistribution and permeability evolution across the fault system. Furthermore, aftershock migration rates reveal distinct linear alignments in a distance‐reduced time space, allowing us to explicitly track and quantify episodes of lateral and upward fluid migration. These physically consistent patterns suggest that stress‐driven fluid diffusion directly weakens adjacent fault patches, dictating the spatiotemporal migration of seismicity. We conclude that near‐real‐time monitoring of seismic attenuation may help detect fluid redistribution in active fault systems and may provide useful information for time‐dependent seismic hazard assessment.

central Apennines↗
USGS1939

Subsurface geology and oil and gas resources of Osage County, Oklahoma. Part 2, Townships 22 and 23 north, ranges 8 and 9 east

This report on the subsurface geology of Osage County, Okla., describes the structural features, the character of the oil- and gas-producing beds, and the localities where additional oil and gas may be found. It embodies a part of the results of a subsurface geologic investigation of the Osage Indian Reservation, which coincides in area with Osage County. The investigation was conducted by a field party of the Geological Survey of the United States Department of the Interior from 1934 to 1937 and involved the study of the records of about 17,000 wells that have been drilled in Osage County. Funds for the investigation were allotted to the Geological Survey by the Public Works Administration. The primary purpose of the examination was to obtain geologic data for use in the administration of the Indian lands. The results of the inquiry have shown that many localities in Osage County outside the present producing oil fields are worthy of prospecting for oil and gas and that additional oil and gas can be found also by exploring deeply buried beds in old producing fields. All townships in Osage County that contain many wells are described; the information furnished by such townships is ample for drawing detailed subsurface structure-contour maps. The descriptions of several contiguous townships are combined in separate reports, which are issued as parts of a single bulletin. No edition of the consolidated volume will be published, but the several parts can be bound together if desired.

Oklahoma↗
USGS1999

Peak-flow frequency relations and evaluation of the peak-flow gaging network in Nebraska

Estimates of peak-flow magnitude and frequency are required for the efficient design of structures that convey flood flows or occupy floodways, such as bridges, culverts, and roads. The U.S. Geological Survey, in cooperation with the Nebraska Department of Roads, conducted a study to update peak-flow frequency analyses for selected streamflow-gaging stations, develop a new set of peak-flow frequency relations for ungaged streams, and evaluate the peak-flow gaging-station network for Nebraska. Data from stations located in or within about 50 miles of Nebraska were analyzed using guidelines of the Interagency Advisory Committee on Water Data in Bulletin 17B. New generalized skew relations were developed for use in frequency analyses of unregulated streams. Thirty-three drainage-basin characteristics related to morphology, soils, and precipitation were quantified using a geographic information system, related computer programs, and digital spatial data.For unregulated streams, eight sets of regional regression equations relating drainage-basin to peak-flow characteristics were developed for seven regions of the state using a generalized least squares procedure. Two sets of regional peak-flow frequency equations were developed for basins with average soil permeability greater than 4 inches per hour, and six sets of equations were developed for specific geographic areas, usually based on drainage-basin boundaries. Standard errors of estimate for the 100-year frequency equations (1percent probability) ranged from 12.1 to 63.8 percent. For regulated reaches of nine streams, graphs of peak flow for standard frequencies and distance upstream of the mouth were estimated.The regional networks of streamflow-gaging stations on unregulated streams were analyzed to evaluate how additional data might affect the average sampling errors of the newly developed peak-flow equations for the 100-year frequency occurrence. Results indicated that data from new stations, rather than more data from existing stations, probably would produce the greatest reduction in average sampling errors of the equations.

Nebraska↗
USGS2023

Development of a volcanic risk management system at Mount St. Helens—1980 to present

Here, we review volcanic risk management at Mount St. Helens from the perspective of the US Geological Survey’s (USGS) experience over the four decades since its 18 May 1980 climactic eruption. Prior to 1980, volcano monitoring, multidisciplinary eruption forecasting, and interagency coordination for eruption response were new to the Cascade Range. A Mount St. Helens volcano hazards assessment had recently been published and volcanic crisis response capabilities tested during 1975 thermal unrest at nearby Mount Baker. Volcanic unrest began in March 1980, accelerating the rate of advance of volcano monitoring, prompting coordinated eruption forecasting and hazards communication, and motivating emergency response planning. The destruction caused by the 18 May 1980 eruption led to an enormous emergency response effort and prompted extensive coordination and planning for continuing eruptive activity. Eruptions continued with pulsatory dome growth and explosive eruptions over the following 6 years and with transport of sediment downstream over many more. In response, USGS scientists and their partners expanded their staffing, deployed new instruments, developed new tools (including the first use of a volcanic event tree) for eruption forecasting, and created new pathways for agency internal and external communication. Involvement in the Mount St. Helens response motivated the establishment of response measures at other Cascade Range volcanoes. Since assembly during the early and mid-1990s, volcano hazard working groups continue to unite scientists, emergency and land managers, tribal nations, and community leaders in common cause for the promotion of risk reduction. By the onset of renewed volcanic activity in 2004, these new systems enabled a more efficient response that was greatly facilitated by the participation of organizations within volcano hazard working groups. Although the magnitude of the 2004 eruptive sequence was much smaller than that of 1980, a new challenge emerged focused on hazard communication demands. Since 2008, our understanding of Mount St. Helens volcanic system has improved, helping us refine hazard assessments and eruption forecasts. Some professions have worked independently to apply the Mount St. Helens story to their products and services. Planning meetings and working group activities fortify partnerships among information disseminators, policy and decision-makers, scientists, and communities. We call the sum of these pieces the Volcanic Risk Management System (VRMS). In its most robust form, the VRMS encompasses effective production and coordinated exchange of volcano hazards and risk information among all interested parties.

Washington↗
USGS2000

Paleoearthquake recurrence on the East Paradise fault zone, metropolitan Albuquerque, New Mexico

A fortuitous exposure of the East Paradise fault zone near Arroyo de las Calabacillas has helped us determine a post-middle Pleistocene history for a long-forgotten Quaternary fault in the City of Albuquerque, New Mexico. Mapping of two exposures of the fault zone allowed us to measure a total vertical offset of 2.75 m across middle Pleistocene fluvial and eolian deposits and to estimate individual surface-faulting events of about 1, 0.5, and 1.25 m. These measurements and several thermoluminescence ages allow us to calculate a long-term average slip rate of 0.01 ± 0.001 mm/yr and date two surface-faulting events to 208 ± 25 ka and 75 ± 7 ka. The youngest event probably occurred in the late Pleistocene, sometime after 75 ± 7 ka. These data yield a single recurrence interval of 133 ± 26 ka and an average recurrence interval of 90 ± 10 ka. However, recurrence intervals are highly variable because the two youngest events occurred in less than 75 ka. Offsets of 0.5-1.25 m and a fault length of 13-20 km indicate that surface-rupturing paleoearthquakes on the East Paradise fault zone had probable M s or M w magnitudes of 6.8-7.0. Although recurrence intervals are long on the East Paradise fault zone, these data are significant because they represent some of the first published slip rate, paleoearthquake magnitude, and recurrence information for any of the numerous Quaternary faults in the rapidly growing Albuquerque-Rio Rancho metropolitan area.

Bulletin of the Seismological Society of America↗
USGS2023

Evidence of Seattle Fault earthquakes from patterns of deep-seated landslides

Earthquake‐induced landslides can record information about the seismic shaking that generated them. In this study, we present new mapping, Light Detection and Ranging‐derived roughness dating, and analysis of over 1000 deep‐seated landslides from the Puget Lowlands of Washington, U.S.A., to probe the landscape for past Seattle fault earthquake information. With this new landslide inventory, we observe spatial and temporal evidence of landsliding related to the last major earthquake on the Seattle fault ∼1100 yr before present. We find spatial clusters of landslides that correlate with ground motions from recent 3D kinematic models of Seattle fault earthquakes. We also find temporal patterns in the landslide inventory that suggest earthquake‐driven increases in landsliding. We compare the spatial and temporal landslide data with scenario‐based ground motion models and find stronger evidence of the last major Seattle fault earthquake from this combined analysis than from spatial or temporal patterns alone. We also compare the landslide inventory with ground motions from different Seattle fault earthquake scenarios to determine the ground motion distributions that are most consistent with the landslide record. We find that earthquake scenarios that best match the clustering of ∼1100‐year‐old landslides produce the strongest shaking within a band that stretches from west to east across central Seattle as well as along the bluffs bordering the broader Puget Sound. Finally, we identify other landslide clusters (at 4.6–4.2 ka, 4.0–3.8 ka, 2.8–2.6 ka, and 2.2–2.0 ka) in the inventory which let us infer potential ground motions that may correspond to older Seattle fault earthquakes. Our method, which combines hindcasting of the surface response to the last major Seattle fault earthquake, using a roughness‐aged landslide inventory with forecasts of modeled ground shaking from 3D seismic scenarios, showcases a powerful new approach to gleaning paleoseismic information from landscapes.

Bulletin of the Seismological Society of America↗
USGS1988

Birds and environmental contaminants in San Francisco and Chesapeake Bays

The direct and indirect effects of human activities, including environmental contamination, upon bird populations in San Francisco Bay and Chesapeake Bay are imperfectly understood, and few data are available. that allow a comparison of the contamination levels in birds from these two areas. Certain trace elements and organochlorine compounds have been found at sufficiently high concentrations in bird tissues or their foods to expect adverse effects in these birds, based upon results of field and laboratory studies conducted with other avian species. The decline and recovery of populations of many avian species have been recorded, including some associated with organochlorine contamination. The present paper summarizes available information on the occurrence and potential effects of contaminants upon birds in these two regions.

Marine Pollution Bulletin↗
USGS1993

Quaternary tectonics of Utah with emphasis on earthquake-hazard characterization

This report consolidates and synthesizes information on Quaternary faulting, folding, and volcanism in Utah and characterizes recent tectonic activity throughout the state. The primary purpose is to provide a comprehensive reference on faultspecific seismic sources and surface rupture to facilitate the evaluation of earthquake hazards in Utah. Two 1:500,000-scale maps show Quaternary tectonic features categorized according to probable ages of most recent surface deformation (plate 1) and ages of volcanic rocks (plate 2). Two appendix tables summarize significant data on the activity of mapped features, including ages of surface displacements and volcanism, slip rates, recurrence intervals, displacement amounts, and lengths of surface ruptures. Good age control and quantitative activity data are available for relatively few tectonic features in Utah and detailed work is needed in many areas of the state. Existing information is adequate to demonstrate that Quaternary crustal deformation, principally normal faulting, is concentrated within a broad, north-trending zone coincident with the Intermountain seismic belt and the transitional tectonic boundary between the Basin and Range and Middle Rocky MountainsColorado Plateau physiographic provinces. Large, regionally significant structures with evidence of relatively high lateQuaternary slip rates include the Wasatch fault zone in the northern half of the state and, to the south, the Hurricane and Sevier faults. Tectonic activity during the Holocene has been concentrated on the Wasatch fault zone and, to a lesser extent, on other faults and folds in the broader Wasatch Front region and in west-central Utah. The average regional recurrence interval for large-magnitude earthquakes in the Wasatch Front region during the Holocene appears to be 125 to 300 years or less, although events have been non-uniformly distributed in time. Most notably, the composite recurrence interval for the particularly active, segmented Wasatch fault zone is roughly 400 years for the middle to late Holocene, but only 220 years for the past 1,500 years. Other patterns of spatially and temporally clustered tectonic activity in northern and west-central Utah appear to be related to persistent structural controls or to tectonic perturbations, such as crustal loading from deep-lake cycles. Most normal faults with evidence of geologically young surface displacements (or faults which may be expressed at the surface as large-scale folds) are inferred to be moderate- to high-angle structures extending down to mid-crustal levels and capable of producing large (magnitude -6.5 to 7 .5) earthquakes. However, the seismogenic potential of faults associated with shallow, low-angle geometries (identified mainly in west -central Utah, the High Plateaus, and the Middle Rocky Mountains) is poorly understood. Some faults and folds in the state may be associated with relatively aseismic processes, such as magmatism, salt diapirism, or shallow, secondary deformation arising from activity on major structures. It is hoped that the broad scope of compiled information and text discussion will yield new insights and help direct future research into Quaternary tectonics and earthquake hazards in Utah.

Utah↗
USGS2014

Methods for estimating the magnitude and frequency of floods for urban and small, rural streams in Georgia, South Carolina, and North Carolina, 2011

Reliable estimates of the magnitude and frequency of floods are essential for the design of transportation and water-conveyance structures, flood-insurance studies, and flood-plain management. Such estimates are particularly important in densely populated urban areas. In order to increase the number of streamflow-gaging stations (streamgages) available for analysis, expand the geographical coverage that would allow for application of regional regression equations across State boundaries, and build on a previous flood-frequency investigation of rural U.S Geological Survey streamgages in the Southeast United States, a multistate approach was used to update methods for determining the magnitude and frequency of floods in urban and small, rural streams that are not substantially affected by regulation or tidal fluctuations in Georgia, South Carolina, and North Carolina. The at-site flood-frequency analysis of annual peak-flow data for urban and small, rural streams (through September 30, 2011) included 116 urban streamgages and 32 small, rural streamgages, defined in this report as basins draining less than 1 square mile. The regional regression analysis included annual peak-flow data from an additional 338 rural streamgages previously included in U.S. Geological Survey flood-frequency reports and 2 additional rural streamgages in North Carolina that were not included in the previous Southeast rural flood-frequency investigation for a total of 488 streamgages included in the urban and small, rural regression analysis. The at-site flood-frequency analyses for the urban and small, rural streamgages included the expected moments algorithm, which is a modification of the Bulletin 17B log-Pearson type III method for fitting the statistical distribution to the logarithms of the annual peak flows. Where applicable, the flood-frequency analysis also included low-outlier and historic information. Additionally, the application of a generalized Grubbs-Becks test allowed for the detection of multiple potentially influential low outliers. Streamgage basin characteristics were determined using geographical information system techniques. Initial ordinary least squares regression simulations reduced the number of basin characteristics on the basis of such factors as statistical significance, coefficient of determination, Mallow’s Cp statistic, and ease of measurement of the explanatory variable. Application of generalized least squares regression techniques produced final predictive (regression) equations for estimating the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probability flows for urban and small, rural ungaged basins for three hydrologic regions (HR1, Piedmont–Ridge and Valley; HR3, Sand Hills; and HR4, Coastal Plain), which previously had been defined from exploratory regression analysis in the Southeast rural flood-frequency investigation. Because of the limited availability of urban streamgages in the Coastal Plain of Georgia, South Carolina, and North Carolina, additional urban streamgages in Florida and New Jersey were used in the regression analysis for this region. Including the urban streamgages in New Jersey allowed for the expansion of the applicability of the predictive equations in the Coastal Plain from 3.5 to 53.5 square miles. Average standard error of prediction for the predictive equations, which is a measure of the average accuracy of the regression equations when predicting flood estimates for ungaged sites, range from 25.0 percent for the 10-percent annual exceedance probability regression equation for the Piedmont–Ridge and Valley region to 73.3 percent for the 0.2-percent annual exceedance probability regression equation for the Sand Hills region.

Georgia, North Carolina, South Carolina↗
USGS2012

Population size of island loggerhead shrikes on Santa Rosa and Santa Cruz Islands

Island loggerhead shrikes ( Lanius ludovicianus anthonyi ) are an endemic, genetically distinct subspecies of loggerhead shrike on California's Santa Rosa, Santa Cruz, and Santa Catalina Islands (USA). This subspecies is listed as a Species of Special Concern by the California Department of Fish and Game and has been petitioned for federal listing under the Endangered Species Act. The combination of suspected low numbers and the possibility of federal listing, prompted us to undertake a study to rigorously estimate the number of remaining individuals on Santa Rosa and Santa Cruz Islands. During the 2009 and 2010 breeding seasons, we surveyed sample units on Santa Rosa and Santa Cruz Islands using a double‐observer method with independent observers to estimate joint detection probabilities ( p ), where we selected units under a stratified random sampling design. We estimated shrike abundance to be 169 in 2009 ( p = 0.476) and 240 in 2010 ( p = 0.825) for Santa Rosa Island, and 35 in 2009 ( p = 0.816) and 42 in 2010 ( p = 0.710) for Santa Cruz Island. These numbers, especially for Santa Rosa Island, are higher than previously reported but nevertheless are still low. Rapid vegetation change on both islands due to recent removal of nonnative herbivores may threaten the habitat and status of this subspecies and, therefore, we suggest that intensive demographic and habitat use research be initiated immediately to obtain additional information vital for the management of this subspecies.

California↗
USGS2018

Mapping elemental contamination on Palmyra Atoll National Wildlife Refuge

Palmyra Atoll, once a WWII U.S. Navy air station, is now a U.S. National Wildlife Refuge with nearly 50 km 2 of coral reef and 275 ha of emergent lands with forests of Pisonia grandis trees and colonies of several bird species. Due to the known elemental and organic contamination from chemicals associated with aviation, power generation and transmission, waste management, and other air station activities, a screening survey to map elemental concentrations was conducted. A map of 1944 Navy facilities was georeferenced and identifiable features were digitized. These data informed a targeted survey of 25 elements in soils and sediment at locations known or suspected to be contaminated, using a hand-held X-ray fluorescence spectrometer. At dozens of locations, concentrations of elements exceeded established soil and marine sediment thresholds for adverse ecological effects. Results were compiled into a publicly available geospatial dataset to inform potential remediation and habitat restoration activities.

Marine Pollution Bulletin↗
USGS2001

Geographic deaggregation of seismic hazard in the United States

The seismic hazard calculations for the 1996 national seismic hazard maps have been geographically deaggregated to assist in the understanding of the relative contributions of sources. These deaggregations are exhibited as maps with vertical bars whose heights are proportional to the contribution that each geographical cell makes to the ground-motion exceedance hazard. Bar colors correspond to average source magnitudes. We also extend the deaggregation analysis reported in Harmsen et al. (1999) to the western conterminous United States. In contrast to the central and eastern United States (CEUS); the influence of specific faults or characteristic events can be clearly identified. Geographic deaggregation for 0.2-sec and 1.0-sec pseudo spectral acceleration (SA) is performed for 10% probability of exceedance (PE) in 50 yr (475-yr mean return period) and 2% PE in 50 yr (2475-yr mean return period) for four western U.S. cities, Los Angeles, Salt Lake City, San Francisco, and Seattle, and for three central and eastern U.S. cities, Atlanta, Boston, and Saint Louis. In general, as the PE is lowered, the sources of hazard closer to the site dominate. Larger, more distant earthquakes contribute more significantly to hazard for 1.0-sec SA than for 0.2-sec SA. Additional maps of geographically deaggregated seismic hazard are available on the Internet for 120 cities in the conterminous United States (http://geohazards. cr.usgs.gov/eq/) for 1-sec SA and for 0.2-sec SA with a 2% PE in 50 yr. Examination of these maps of hazard contributions enables the investigator to determine the distance and azimuth to predominant sources, and their magnitudes. This information can be used to generate scenario earthquakes and corresponding time histories for seismic design and retrofit. Where fault density is lower than deaggregation cell dimensions, we can identify specific faults that contribute significantly to the seismic hazard at a given site. Detailed fault information enables investigators to include rupture information such as source directivity, radiation pattern, and basin-edge effects into their scenario earthquakes used in engineering analyses.

Bulletin of the Seismological Society of America↗
USGS1994

Airborne remote sensing for geology and the environment; present and future

In 1988, a group of leading experts from government, academia, and industry attended a workshop on airborne remote sensing sponsored by the U.S. Geological Survey (USGS) and hosted by the Branch of Geophysics. The purpose of the workshop was to examine the scientific rationale for airborne remote sensing in support of government earth science in the next decade. This report has arranged the six resulting working-group reports under two main headings: (1) Geologic Remote Sensing, for the reports on geologic mapping, mineral resources, and fossil fuels and geothermal resources; and (2) Environmental Remote Sensing, for the reports on environmental geology, geologic hazards, and water resources. The intent of the workshop was to provide an evaluation of demonstrated capabilities, their direct extensions, and possible future applications, and this was the organizational format used for the geologic remote sensing reports. The working groups in environmental remote sensing chose to present their reports in a somewhat modified version of this format. A final section examines future advances and limitations in the field. There is a large, complex, and often bewildering array of remote sensing data available. Early remote sensing studies were based on data collected from airborne platforms. Much of that technology was later extended to satellites. The original 80-m-resolution Landsat Multispectral Scanner System (MSS) has now been largely superseded by the 30-m-resolution Thematic Mapper (TM) system that has additional spectral channels. The French satellite SPOT provides higher spatial resolution for channels equivalent to MSS. Low-resolution (1 km) data are available from the National Oceanographic and Atmospheric Administration's AVHRR system, which acquires reflectance and day and night thermal data daily. Several experimental satellites have acquired limited data, and there are extensive plans for future satellites including those of Japan (JERS), Europe (ESA), Canada (Radarsat), and the United States (EOS). There are currently two national airborne remote sensing programs (photography, radar) with data archived at the USGS' EROS Data Center. Airborne broadband multispectral data (comparable to Landsat MSS and TM but involving several more channels) for limited geographic areas also are available for digital processing and analysis. Narrow-band imaging spectrometer data are available for some NASA experiment sites and can be acquired for other locations commercially. Remote sensing data and derivative images, because of the uniform spatial coverage, availability at different resolutions, and digital format, are becoming important data sets for geographic information system (GIS) analyses. Examples range from overlaying digitized geologic maps on remote sensing images and draping these over topography, to maps of mineral distribution and inferred abundance. A large variety of remote sensing data sets are available, with costs ranging from a few dollars per square mile for satellite digital data to a few hundred dollars per square mile for airborne imaging spectrometry. Computer processing and analysis costs routinely surpass these expenses because of the equipment and expertise necessary for information extraction and interpretation. Effective use requires both an understanding of the current methodology and an appreciation of the most cost-effective solution.

Bulletin↗