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At least 883 records · Page 49Linked to original sources

USGS2005

Simulating reservoir leakage in ground-water models

Leakage to ground water resulting from the expansion and contraction of reservoirs cannot be easily simulated by most ground-water flow models. An algorithm, entitled the Reservoir Package, was developed for the United States Geological Survey (USGS) three-dimensional finite-difference modular ground-water flow model MODFLOW. The Reservoir Package automates the process of specifying head-dependent boundary cells, eliminating the need to divide a simulation into many stress periods while improving accuracy in simulating changes in ground-water levels resulting from transient reservoir stage. Leakage between the reservoir and the underlying aquifer is simulated for each model cell corrresponding to the inundated area by multiplying the head difference between the reservoir and the aquifer with the hydraulic conductance of the reservoir-bed sediments.

Groundwater↗

USGS2010

GSD-1G and MPI-DING Reference Glasses for In Situ and Bulk Isotopic Determination

This paper contains the results of an extensive isotopic study of United States Geological Survey GSD-1G and MPI-DING reference glasses. Thirteen different laboratories were involved using high-precision bulk (TIMS, MC-ICP-MS) and microanalytical (LA-MC-ICP-MS, LA-ICP-MS) techniques. Detailed studies were performed to demonstrate the large-scale and small-scale homogeneity of the reference glasses. Together with previously published isotopic data from ten other laboratories, preliminary reference and information values as well as their uncertainties at the 95% confidence level were determined for H, O, Li, B, Si, Ca, Sr, Nd, Hf, Pb, Th and U isotopes using the recommendations of the International Association of Geoanalysts for certification of reference materials. Our results indicate that GSD-1G and the MPI-DING glasses are suitable reference materials for microanalytical and bulk analytical purposes. Ce document contient les r??sultats d'une importante ??tude isotopique des verres de r??f??rence USGS GSD-1G et MPI-DING. Treize laboratoires diff??rents ont particip?? au travers de techniques analytiques de haute pr??cision travaillant soit sur ??chantillon total (TIMS, MC-ICP-MS) soit par microanalyse ??in situ?? (LA-MC-ICP-MS, LA-ICP-MS). ?? 2010 The Authors. Geostandards and Geoanalytical Research ?? 2010 International Association of Geoanalysts.

Geostandards and Geoanalytical Research↗

USGS2007

Water level fluctuations in an urban pond: Climatic or anthropogenic impact?

In 1996, the Illinois State Geological Survey began an investigation of fluctuating water levels in a pond in Cary, Illinois. The cause of the fluctuations appeared to be ground water discharge into a storm sewer recently installed by the Illinois Department of Transportation. However, analysis of climatic data provided an equally likely explanation of the fluctuations. Distinguishing the effect of climatic variations from the effect of the storm sewer was hampered by the lack of antecedent ground water and surface water data. In similar settings, it is recommended that ground water and surface water data be collected prior to initiating any infrastructure improvements.

Illinois↗

USGS2011

Characterization of the Sonoran desert as a radiometric calibration target for Earth observing sensors

To provide highly accurate quantitative measurements of the Earth's surface, a comprehensive calibration and validation of the satellite sensors is required. The NASA Moderate Resolution Imaging Spectroradiometer (MODIS) Characterization Support Team, in collaboration with United States Geological Survey, Earth Resources Observation and Science Center, has previously demonstrated the use of African desert sites to monitor the long-term calibration stability of Terra MODIS and Landsat 7 (L7) Enhanced Thematic Mapper plus (ETM+). The current study focuses on evaluating the suitability of the Sonoran Desert test site for post-launch long-term radiometric calibration as well as cross-calibration purposes. Due to the lack of historical and on-going in situ ground measurements, the Sonoran Desert is not usually used for absolute calibration. An in-depth evaluation (spatial, temporal, and spectral stability) of this site using well calibrated L7 ETM+ measurements and local climatology data has been performed. The Sonoran Desert site produced spatial variability of about 3 to 5% in the reflective solar regions, and the temporal variations of the site after correction for view-geometry impacts were generally around 3%. The results demonstrate that, barring the impacts due to occasional precipitation, the Sonoran Desert site can be effectively used for cross-calibration and long-term stability monitoring of satellite sensors, thus, providing a good test site in the western hemisphere.

Sonoran Desert↗

USGS2013

Landsat Data Continuity Mission, now Landsat-8: six months on-orbit

The Landsat Data Continuity Mission (LDCM) with two pushbroom Earth-imaging sensors, the Operational Land Imager (OLI) and the Thermal InfraRed Sensor (TIRS), was launched on February 11, 2013. Its on-orbit check out period or commissioning phase lasted about 90 days. During this phase the spacecraft and its instruments were activated, operationally tested and their performance verified. In addition, during this period, the spacecraft was temporarily placed in an intermediary orbit where it drifted relative to the Landsat-7 spacecraft, providing near simultaneous imaging for about 3 days, allowing data comparison and cross calibration. After this tandem-imaging period, LDCM was raised to its final altitude and placed in the position formerly occupied by Landsat-5, i.e., 8 days out of phase with Landsat-7, with about a 10:10 AM equatorial crossing time. At the end of commissioning, the satellite was transferred to the United States Geological Survey (USGS), officially renamed Landsat-8 and declared operational. Data were made available to the public beginning May 31, 2013. The performance of the satellite and two instruments has generally been excellent as evidenced in the quality of the distributed data products. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Conference Paper↗

USGS2010

An overview of the Landsat Data Continuity Mission

The Landsat Data Continuity Mission (LDCM) is the follow-on mission to Landsat 7 and will be the eighth mission in the Landsat series. The mission is in development via an interagency partnership between the National Aeronautics and Space Administration (NASA) and the Department of Interior (DOI) / United States Geological Survey (USGS). The LDCM satellite will carry two earth-observing sensors, the Operational Land Imager (OLI) to collect image data for nine spectral bands in the reflective portion of the spectrum and the Thermal Infrared Sensor (TIRS) to collect coincident image data for two thermal spectral bands. The LDCM ground segment will control the satellite and will receive, process, archive, and distribute the science data collected by the OLI and TIRS instruments. The USGS Earth Resources Observation & Science Center (EROS) will distribute LDCM data products at no cost to requestors. The mission objective is to continues the Landsat program's collection, archive, and distribution of multispectral imagery affording global, synoptic, and repetitive coverage of the Earth's land surfaces at a scale where natural and human-induced changes can be detected, differentiated, characterized, and monitored over time. The LDCM launch readiness date is currently December, 2012.

Conference Paper↗

USGS2019

Walk in the footsteps of the Apollo astronauts: A field guide to northern Arizona astronaut training sites

Every astronaut who walked on the Moon trained in Flagstaff, AZ. In the early 1960s, scientists at the newly formed United States Geological Survey (USGS) Branch of Astrogeology led this training, teaching geologic principals and field techniques to the astronaut crews. USGS scientists and engineers also developed and tested scientific instrument prototypes, and communication and transportation technologies that would aid in lunar exploration. Astronomers and cartographers based at the USGS and Lowell Observatory, using telescopes at Lowell Observatory and the U.S. Naval Observatory, also played a key role, preparing lunar navigation charts and landing site maps. This historical / educational field trip will take participants along a historical path to some of the key sites where the Apollo astronauts trained. Field trip participants will see: (1) Grover, the geologic rover simulator on which the Apollo astronauts trained, which is on display at the USGS Astrogeology Science Center; (2) Telescopes at Lowell Observatory used to map the lunar surface, as well as some of the original airbrushed maps; (3) the Bonito Lava Flow training area at Sunset Crater Volcano National Monument; (4) the Cinder Lake crater field, which was created in 1967 to simulate the lunar landscape for training astronauts and testing equipment; and (5) Meteor Crater, the best-preserved exposed impact crater on Earth. During this field trip, as we celebrate the 50th anniversary of one of the most remarkable events and most significant achievements in the history of humankind, we hope that the sites we visit will connect participants with the experiences of the astronauts, and the excitement and inspiration of the origins of human space exploration. We also hope to communicate the historical significance of these sites, facilitate continued visitation of the sites (e.g. through class field trips), and educate the broader scientific and science education communities about the role that Flagstaff scientists and engineers played in the Apollo expeditions to the Moon.

Arizona↗

USGS2023

Modeling fluvial sediment plumes: Impacts to coral reefs

To help guide watershed restoration to reduce the impacts to adjacent coral reefs, the United States Geological Survey and Deltares acquired and analyzed oceanographic and sedimentologic data off 5 West Maui watersheds to calibrate and validate physics-based, numerical hydrodynamic and sediment transport models of the study area. The results indicated sheltered sites are impacted by terrestrial sediment from single stream mouths, with most of the sediment delivered within hours of a flood event. Once this sediment enters the nearshore, it settles out and remains on the reef for a prolonged period. In contrast, the coral reefs along “open” sections of coastline are more exposed to waves and terrestrial sediment from multiple stream sources and the terrestrial sediment can rarely settle but instead remains in suspension, causing turbidity. These analyses underscore the importance of understanding how hydro-dynamics can lead to different sediment dynamics on coral reefs in the same region.

Conference Paper↗

USGS2011

An overview of the petroleum geology of the Arctic

Nine main petroleum provinces containing recoverable resources totalling 61 Bbbl liquids+269 Bbbloe of gas are known in the Arctic. The three best known major provinces are: West Siberia–South Kara, Arctic Alaska and Timan–Pechora. They have been sourced principally from, respectively, Upper Jurassic, Triassic and Devonian marine source rocks and their hydrocarbons are reservoired principally in Cretaceous sandstones, Triassic sandstones and Palaeozoic carbonates. The remaining six provinces except for the Upper Cretaceous–Palaeogene petroleum system in the Mackenzie Delta have predominantly Mesozoic sources and Jurassic reservoirs. There are discoveries in 15% of the total area of sedimentary basins ( c. 8×10 6 km 2 ), dry wells in 10% of the area, seismic but no wells in 50% and no seismic in 25%. The United States Geological Survey estimate yet-to-find resources to total 90 Bbbl liquids+279 Bbbloe gas, with four regions – South Kara Sea, Alaska, East Barents Sea, East Greenland – dominating. Russian estimates of South Kara Sea and East Barents Sea are equally positive. The large potential reflects primarily the large undrilled areas, thick basins and widespread source rocks.

Geological Society Memoir↗

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↗

USGS2020

Multi-region assessment of pharmaceutical exposures and predicted effects in USA wadeable urban-gradient streams

Human-use pharmaceuticals in urban streams link aquatic-ecosystem health to human health. Pharmaceutical mixtures have been widely reported in larger streams due to historical emphasis on wastewater-treatment plant (WWTP) sources, with limited investigation of pharmaceutical exposures and potential effects in smaller headwater streams. In 2014–2017, the United States Geological Survey measured 111 pharmaceutical compounds in 308 headwater streams (261 urban-gradient sites sampled 3–5 times, 47 putative low-impact sites sampled once) in 4 regions across the US. Simultaneous exposures to multiple pharmaceutical compounds (pharmaceutical mixtures) were observed in 91% of streams (248 urban-gradient, 32 low-impact), with 88 analytes detected across all sites and cumulative maximum concentrations up to 36,142 ng/L per site. Cumulative detections and concentrations correlated to urban land use and presence/absence of permitted WWTP discharges, but pharmaceutical mixtures also were common in the 75% of sampled streams without WWTP. Cumulative exposure-activity ratios (EAR) indicated widespread transient exposures with high probability of molecular effects to vertebrates. Considering the potential individual and interactive effects of the detected pharmaceuticals and the recognized analytical underestimation of the pharmaceutical-contaminant (unassessed parent compounds, metabolites, degradates) space, these results demonstrate a nation-wide environmental concern and the need for watershed-scale mitigation of in-stream pharmaceutical contamination.

Alabama, California, Connecticut, Georgia, Delawar↗

USGS2012

Estimating pole/zero errors in GSN-IRIS/USGS network calibration metadata

Mapping the digital record of a seismograph into true ground motion requires the correction of the data by some description of the instrument's response. For the Global Seismographic Network (Butler et al., 2004), as well as many other networks, this instrument response is represented as a Laplace domain pole–zero model and published in the Standard for the Exchange of Earthquake Data (SEED) format. This Laplace representation assumes that the seismometer behaves as a linear system, with any abrupt changes described adequately via multiple time-invariant epochs. The SEED format allows for published instrument response errors as well, but these typically have not been estimated or provided to users. We present an iterative three-step method to estimate the instrument response parameters (poles and zeros) and their associated errors using random calibration signals. First, we solve a coarse nonlinear inverse problem using a least-squares grid search to yield a first approximation to the solution. This approach reduces the likelihood of poorly estimated parameters (a local-minimum solution) caused by noise in the calibration records and enhances algorithm convergence. Second, we iteratively solve a nonlinear parameter estimation problem to obtain the least-squares best-fit Laplace pole–zero–gain model. Third, by applying the central limit theorem, we estimate the errors in this pole–zero model by solving the inverse problem at each frequency in a two-thirds octave band centered at each best-fit pole–zero frequency. This procedure yields error estimates of the 99% confidence interval. We demonstrate the method by applying it to a number of recent Incorporated Research Institutions in Seismology/United States Geological Survey (IRIS/USGS) network calibrations (network code IU).

Bulletin of the Seismological Society of America↗

USGS2018

Evaluation of ground motion models for USGS seismic hazard forecasts: Induced and tectonic earthquakes in the Central and Eastern U.S.

Ground motion model (GMM) selection and weighting introduces a significant source of uncertainty in United States Geological Survey (USGS) seismic hazard models. The increase in moderate moment magnitude induced earthquakes (Mw 4 to 5.8) in Oklahoma and Kansas since 2009, due to increased wastewater injection related to oil and gas production (Keranen et al., 2013; 2014; Weingarten et al., 2015; McNamara et al., 2015a), provides useful near-source (< 40 km) instrumental ground-motion observations for comparisons between central and eastern US (CEUS) induced (Rennolet et al., 2017) and tectonic (Goulet et al., 2014) earthquakes. In this study, we evaluate over 50 GMMs using two well-established probabilistic scoring methods: log likelihood (LLH) (Scherbaum et al., 2004; 2009) and multivariate LLH (MLLH) (Mak et al., 2017). The LLH approach compares the mean and standard deviation (σ) of the observed and modeled ground motions. The MLLH approach advances the LLH method by considering the variability (φ,τ) of multiple correlated variables namely intra- (within) and inter- (between) event residuals. For the probabilistic scoring GMM evaluation methods (LLH, MLLH), we compute horizontal component peak ground acceleration (PGA) and 1s period pseudo spectral acceleration (PSA1.0) total residuals using GMM software (nshmp-haz) recently implemented by the USGS National Seismic Hazard Model Project (NSHMP). We observe from LLH and MLLH scores that: 1) newer GMMs with lower standard deviations (σ,φ,τ) score better than older GMMs with higher published uncertainty; 2) 2014 CEUS GMMs score better for CEUS tectonic earthquakes than induced earthquakes; 3) NGA-West2, G17 and A15 GMMs score well for CEUS induced earthquake ground motions; and 4) NGA-East GMMs score well for CEUS tectonic earthquake ground motions. We also use the LLH and MLLH scores to evaluate GMM weights applied in past USGS seismic hazard forecasts and to inform weighting of GMMs in future seismic hazard forecasts.

Bulletin of the Seismological Society of America↗

USGS2025

Seismic moment and local magnitude scales in Ridgecrest, CA from the SCEC/USGS Community Stress Drop Validation Study

We illustrate the systematic difference between moment magnitude and local magnitude caused by underlying earthquake source physics, using seismic moments submitted to the Statewide California Earthquake Center/United States Geological Survey Community Stress Drop Validation Study 2019 Ridgecrest data set. While the relationship between seismic moment and moment magnitude ( M or M w ) of log 10 ( M 0 ) ~ 1.5* M is uniformly valid for all earthquake sizes by definition (Hanks and Kanamori, 1979), the relationship between local magnitude M L and moment is itself magnitude dependent. For moderate events, ~3< M < ~6, M and M L are coincident; for earthquakes smaller than ~3, M L ~ 1.0 log 10 M 0 (Hanks and Boore, 1984). This is a physical consequence of the corner frequency fc becoming larger than the upper frequency of observation and implies that M L and M differ systematically by a factor of 1.5 for these small events. While this idea is not new, we propose a new, continuous relationship between local magnitude and moment, for magnitudes 2 to 6 which extrapolates to smaller and larger magnitudes, applicable to southern California specific to the Ridgecrest region. We make use of the plethora of seismic moments as submitted by many participants of the Community Stress Drop study, compared to the Southern California Seismic Network (SCSN) catalog magnitudes. Overall, the seismic moments in the Community Study recover moment magnitude well, so we use our new M L - M 0 to convert M L to M , refining the SCSN operational M Lr scale. This systematic difference of 50% in slope between local and moment magnitude at small magnitudes has implications for spectral stress drop estimates, earthquake ground motion modeling, as well as other magnitude scales and earthquake occurrence statistics.

California↗

USGS2025

A scientific vision and roadmap for earthquake rupture forecast developments, a USGS perspective

We articulate a scientific vision and roadmap for the development of improved Earthquake Rupture Forecast models, which are one of the two main modeling components used in modern seismic hazard and risk analysis. One primary future objective is to provide fully time-dependent models that include both elastic rebound and spatiotemporal clustering nationwide, which is particularly important for shorter-term hazard and risk considerations (e.g., earthquake insurance products). We also discuss the importance and perennial challenges associated with quantifying epistemic uncertainties, including those associated with deformation-model slip rates, un-quantified sampling errors with respect to off-fault seismicity, and any spatial covariances. The need for more physics-based approaches is also emphasized, as is the benefit of adding model valuation (quantifying usefulness) to our verification and validation protocols. Given the multidisciplinary and system-level nature of this activity, modular design is critical. Future updates will also draw from best-available science by both the United States Geological Survey and the external community. The primary goal of this paper is to highlight plans that guide research and facilitate community engagement with model development, especially with respect to lowering the entry barrier for early career scientists and engineers. The paper is written so readers can focus on the sections that interest them most (see table of contents), with the Introduction and Discussion providing a stand-alone overview and summary.

Bulletin of the Seismological Society of America↗

USGS2022

Revised earthquake geology inputs for the central and eastern United States and southeast Canada for the 2023 National Seismic Hazard Model

It has been nearly a decade since updates to seismic and fault sources in the central and eastern United States (CEUS) were last assessed for the 2012 Central and Eastern United States Seismic Source Characterization for nuclear facilities (CEUS-SSCn) and 2014 United States Geological Survey National Seismic Hazard Model (NSHM) for the conterminous U.S. In advance of the 2023 NSHM update, we created 3 related geospatial databases to summarize and characterize new fault source information for the CEUS. These include fault section, fault-zone polygon, and earthquake geology (fault slip rate, earthquake recurrence intervals) databases which document updates to fault parameters used in prior seismic hazard models in this region. The 2012 CEUS-SSCn and 2014 NSHM fault models served as a foundation, as we revised and added fault sources where new published studies documented significant changes to our understanding of fault location, geometry, or activity. We added 9 new fault sections that meet the criteria of (1) a length ≥7 km, (2) evidence of recurrent Quaternary tectonic activity, and (3) documentation that is publicly available in a peer-reviewed source. The prior CEUS models only included 6 fault sections (sources) and 10 fault-zone polygons (previously called repeating large magnitude earthquake (RLME) polygons). The revised databases include 15 fault sections and 10 fault zone polygons. Updates to the faults constitute a 150% increase in fault sections, but no change in the number of fault-zone polygons, although some fault-zone polygons differ from RLME polygons used in prior models. No faults were removed from past models. Several seismic zones and suspected faults were evaluated but not included in this update due to a lack of information about fault location, geometry, or recurrent Quaternary activity. These updates to the fault sections, fault-zone polygons, and earthquake geology databases will inform fault geometry and activity rates of CEUS sources during the 2023 NSHM implementation.

Seismological Research Letters↗

USGS1985

A seismic-refraction profile across the San Andreas, Sargent, and Calaveras faults, west-central California

In 1981, the United States Geological Survey recorded a seismic-refraction profile across the southern Santa Cruz Mountains in west-central California to examine the shallow velocity structure of this seismogenic region. This 40-km-long profile, which consisted of three shotpoints, extended northeastward from near Watsonville, California, to Coyote Lake, crossing the San Andreas, Sargent, and Calaveras faults. This entire region is characterized by a highly heterogeneous upper crust. West of Watsonville, 1 km of alluvium with a velocity of 2.12 km/sec overlies a basement with a velocity 5.45 km/sec. The abrupt deepening of basement by 1.5 km just east of Watsonville at a subsurface fault suggests that the Zayante fault to the north and the Vergeles fault to the south are connected. The Tertiary sediment at the San Andreas fault is 2.5 km thick and has a velocity of 3.34 km/sec. The San Andreas fault is not marked by any distinctive seismic velocity features, whereas a 1-km-wide low velocity zone is found at both the Sargent and Calaveras faults. East of the Sargent fault, the basement surface forms a broad anticlinal structure, with velocities ranging from 5.4 to 6.0 km/sec. From the anticlinal crest, basement dips to the east beneath the Santa Clara Valley and reaches a maximum depth of 1 km on the east side; the overlying alluvium has a velocity of 2.7 km/sec. At the crest of the basement anticlinal structure, a vertical low-velocity zone coincident with exposed serpentine provides strong evidence of faulting.

California↗

USGS2011

8 March 2010 Elazığ-Kovancilar (Turkey) Earthquake: observations on ground motions and building damage

An earthquake of M W = 6.1 occurred in the Elazığ region of eastern Turkey on 8 March 2010 at 02:32:34 UTC. The United States Geological Survey (USGS) reported the epicenter of the earthquake as 38.873°N-39.981°E with a focal depth of 12 km. Forty-two people lost their lives and 137 were injured during the event. The earthquake was reported to be on the left-lateral strike-slip east Anatolian fault (EAF), which is one of the two major active fault systems in Turkey. Teams from the Earthquake Engineering Research Center of the Middle East Technical University (EERC-METU) visited the earthquake area in the aftermath of the mainshock. Their reconnaissance observations were combined with interpretations of recorded ground motions for completeness. This article summarizes observations on building and ground damage in the area and provides a discussion of the recorded motions. No significant observations in terms of geotechnical engineering were made.

Seismological Research Letters↗