Results for “Engineering Analysis” — Page 29

USGS2019

Relaxation response of critically stressed macroscale surficial rock sheets

Rock environments both underground and on Earth’s surface show indications of energetic macroscale fracture. In tunnels and excavations, these manifest as rockbursts—energetic explosions of rock that can damage engineering projects, and may pose ongoing financial and safety risk as rock stresses adjust during post-failure relaxation. In natural settings at the surface, evidence for rockbursts exist in the form of tent-like structures of ruptured exfoliation sheets, but few direct observations of such events exist, precluding the analysis of how natural rock formations may evolve after rupture. Here we investigate the post-failure evolution of a granitic rock dome following rapid fracture events (i.e., surficial rockbursts) that occurred in California, USA during 2014–2016. Building upon previous work that showed a thermal stress origin for the observed fracturing, we investigate the return to background stress conditions (i.e., stress relaxation) observed in both short- (week, month) and long-term (multi-year) rock deformation trends. Acoustic emissions, deformation, and environmental monitoring data indicate that partially detached rock sheets forming the surface of the dome undergo fracture aperture closing during cooling periods, concurrent with reduction of rock stress by the source of forcing (i.e., thermal stress). However, with sufficient critical and/or subcritical fracture, our observations also show that rock sheets can become decoupled from the source of stress, resulting in a long-term return to background stress conditions. Our results provide insight into the cyclic and likely ephemeral nature of rock fracture in surficial rock domes, as well as in underground rockburst environments.

Rock Mechanics and Rock Engineering↗

USGS2011

USGS remote sensing coordination for the 2010 Haiti earthquake

In response to the devastating 12 January 2010, earthquake in Haiti, the US Geological Survey (USGS) provided essential coordinating services for remote sensing activities. Communication was rapidly established between the widely distributed response teams and data providers to define imaging requirements and sensor tasking opportunities. Data acquired from a variety of sources were received and archived by the USGS, and these products were subsequently distributed using the Hazards Data Distribution System (HDDS) and other mechanisms. Within six weeks after the earthquake, over 600,000 files representing 54 terabytes of data were provided to the response community. The USGS directly supported a wide variety of groups in their use of these data to characterize post-earthquake conditions and to make comparisons with pre-event imagery. The rapid and continuing response achieved was enabled by existing imaging and ground systems, and skilled personnel adept in all aspects of satellite data acquisition, processing, distribution and analysis. The information derived from image interpretation assisted senior planners and on-site teams to direct assistance where it was most needed.

Photogrammetric Engineering and Remote Sensing↗

USGS2012

Evaluation of long-term gas hydrate production testing locations on the Alaska North Slope

The results of short-duration formation tests in northern Alaska and Canada have further documented the energy-resource potential of gas hydrates and have justified the need for long-term gas-hydrate-production testing. Additional data acquisition and long-term production testing could improve the understanding of the response of naturally occurring gas hydrate to depressurization-induced or thermal-, chemical-, or mechanical-stimulated dissociation of gas hydrate into producible gas. The Eileen gashydrate accumulation located in the Greater Prudhoe Bay area in northern Alaska has become a focal point for gas-hydrate geologic and production studies. BP Exploration (Alaska) Incorporated and ConocoPhillips have each established research partnerships with the US Department of Energy to assess the production potential of gas hydrates in northern Alaska. A critical goal of these efforts is to identify the most suitable site for production testing. A total of seven potential locations in the Prudhoe Bay, Kuparuk River, and Milne Point production units were identified and assessed relative to their suitability as a long-term gas-hydrate-production test sites. The test-site-assessment criteria included the analysis of the geologic risk associated with encountering reservoirs for gas-hydrate testing. The site-selection process also dealt with the assessment of the operational/logistical risk associated with each of the potential test sites. From this review, a site in the Prudhoe Bay production unit was determined to be the best location for extended gas-hydrate-production testing. The work presented in this report identifies the key features of the potential test site in the Greater Prudhoe Bay area and provides new information on the nature of gas-hydrate occurrence and the potential impact of production testing on existing infrastructure at the most favorable sites. These data were obtained from well-log analysis, geological correlation and mapping, and numerical simulation.

Alaska↗

USGS1992

US GeoData

US GeoData tapes are computer tapes which contain cartographic data in digital form. The 1:2,000,000-scale data are available in two forms. The graphic form can be used to generate computer-plotted maps. The content and scale of the maps can be varied to meet your needs. The topologically-structured form of US GeoData is suitable for input to geographic information systems for use in spatial analysis and geographic studies. Both forms must be used in conjunction with appropriate software. US GeoData tapes offer convenience, accuracy, flexibility, and cost effectiveness to many map users. Business, industry, and government users who are involved in network planning and analysis, transportation, demography, land use, or any activity where data can be related to, or plotted on a map will find US GeoData a valuable resource.

General Information Product↗

USGS2003

Tree islands of the Florida Everglades - A disappearing resource

Until recently, the timing and cause of tree island formation have been poorly understood, with estimates of initial tree-island development as early as thousands of years ago to as recently as the last few decades. To increase our knowledge about the origins of these features, sediment cores were collected on and around tree islands. These cores were dated using radioisotopic techniques, including carbon-14 dating, which provides reliable dates from ~40,000 to ~300 years ago, and lead-210 dating, which provides age models for the last century. These age models were paired with vegetational reconstruction based on pollen analysis from cores to identify the timing of tree-island formation and assess past tree-island response to hydrologic changes in the 20th century.

Florida↗

USGS2008

Site characterization of Italian strong motion recording stations

A dataset of site conditions at 101 Italian ground motion stations with recorded motions has been compiled that includes geologic characteristics and seismic velocities. Geologic characterization is derived principally from local geologic investigations by ENEL that include detailed mapping and cross sections. For sites lacking such detailed geologic characterization, the geology maps of the by Servizio Geologico d'Italia are used. Seismic velocities are extracted from the literature and the files of consulting engineers, geologists and public agencies for 33 sites. Data sources utilized include post earthquake site investigations (Friuli and Irpinia events), microzonation studies, and miscellaneous investigations performed by researchers or consulting engineers/geologists. Additional seismic velocities are measured by the authors using the controlled source spectral analysis of surface waves (SASW) method for 18 sites that recorded the 1997–1998 Umbria Marche earthquake sequence. The compiled velocity measurements provide data for 51 of the 101 sites. For the remaining sites, the average seismic velocity in the upper 30 m (V s30 ) "> (V s30 ) is estimated using a hybrid approach. For young Quaternary alluvium, V s30 "> 𝑉 s30 an existing empirical relationship for California sites by Wills and Clahan (2006) is used, which we justify by validating this relationship against Italian data. For Tertiary Limestone and Italian Mesozoic rocks, empirical estimates of V s30 "> 𝑉 s30 are developed using the available data.

Conference Paper↗

USGS2007

Analysis of the Interstate 10 Twin Bridge’s collapse during Hurricane Katrina: Chapter 3D in Science and the storms-the USGS response to the hurricanes of 2005

The Interstate 10 Twin Span Bridge over Lake Pontchartrain north of New Orleans, La., was rendered completely unusable by Hurricane Katrina. The cause of the collapse of the bridges generated great interest among hydrologists and structural engineers as well as among the general public. What made this case study even more important was the fact that two nearby bridges sustained the effects of the same storm surge and suffered only light damage. Lessons learned from this investigation are invaluable to maintaining the safety of many of the Nation's coastal and river-crossing bridges.

Louisiana↗

USGS1985

Analysis of survival data from telemetry projects

Telemetry techniques can be used to study the survival rates of animal populations and are particularly suitable for species or settings for which band recovery models are not. Statistical methods for estimating survival rates and parameters of survival distributions from observations of radio-tagged animals will be described. These methods have been applied to medical and engineering studies and to the study of nest success. Estimates and tests based on discrete models, originally introduced by Mayfield, and on continuous models, both parametric and nonparametric, will be described. Generalizations, including staggered entry of subjects into the study and identification of mortality factors will be considered. Additional discussion topics will include sample size considerations, relocation frequency for subjects, and use of covariates.

Book chapter↗

USGS2007

Application of acoustic doppler velocimeters for streamflow measurements

The U.S. Geological Survey (USGS) principally has used Price AA and Price pygmy mechanical current meters for measurement of discharge. New technologies have resulted in the introduction of alternatives to the Price meters. One alternative, the FlowTracker acoustic Doppler velocimeter, was designed by SonTek/YSI to make streamflow measurements in wadeable conditions. The device measures a point velocity and can be used with standard midsection method algorithms to compute streamflow. The USGS collected 55 quality-assurance measurements with the FlowTracker at 43 different USGS streamflow-gaging stations across the United States, with mean depths from 0.05to0.67m, mean velocities from 13 to 60 cm/s, and discharges from 0.02 to 12.4m3/s. These measurements were compared with Price mechanical current meter measurements. Analysis of the comparisons shows that the FlowTracker discharges were not statistically different from the Price meter discharges at a 95% confidence level. ?? 2007 ASCE.

Journal of Hydraulic Engineering↗

USGS2018

Structural design of Kaohsiung Stadium, Taiwan

This paper presents an outline description of the structural design of the main stadium for the World Games held in Kaohsiung City, Taiwan, in 2009. Three new design concepts, unseen in previous stadiums, were proposed and realized: “an open stadium”, “an urban park”, and “a spiral continuous form”. Based on the open stadium concept, simple cantilever trusses in the roof structure were arranged in a delicate rhythm, and a so-called oscillating hoop of steel tubes was wound around the top and bottom surfaces of a group of cantilever trusses to form a continuous spiral form. Also, at the same time by clearly grouping the structural elements of the roof structure, the dramatic effect of the urban park was highlighted by unifying the landscape and the spectator seating area to form the stadium facade. This paper specifically reports on the overview of the building, concepts of structural design, structural analysis of the roof, roof design, foundation design, and an outline of the construction.

Kaohsiung City↗

USGS2003

Cartographic services contract...for everything geographic

The U.S. Geological Survey's (USGS) Cartographic Services Contract (CSC) is used to award work for photogrammetric and mapping services under the umbrella of Architect-Engineer (A&E) contracting. The A&E contract is broad in scope and can accommodate any activity related to standard, nonstandard, graphic, and digital cartographic products. Services provided may include, but are not limited to, photogrammetric mapping and aerotriangulation; orthophotography; thematic mapping (for example, land characterization); analog and digital imagery applications; geographic information systems development; surveying and control acquisition, including ground-based and airborne Global Positioning System; analog and digital image manipulation, analysis, and interpretation; raster and vector map digitizing; data manipulations (for example, transformations, conversions, generalization, integration, and conflation); primary and ancillary data acquisition (for example, aerial photography, satellite imagery, multispectral, multitemporal, and hyperspectral data); image scanning and processing; metadata production, revision, and creation; and production or revision of standard USGS products defined by formal and informal specification and standards, such as those for digital line graphs, digital elevation models, digital orthophoto quadrangles, and digital raster graphics.

Fact Sheet↗

USGS2022

Analysis of surface water trends for the conterminous United States using MODIS satellite data, 2003–2019

Satellite imagery is commonly used to map surface water extents over time, but many approaches yield discontinuous records resulting from cloud obstruction or image archive gaps. We applied the Dynamic Surface Water Extent (DSWE) model to downscaled (250-m) daily Moderate Resolution Imaging Spectroradiometer (MODIS) data in Google Earth Engine to generate monthly surface water maps for the conterminous United States (US) from 2003 through 2019. The aggregation of daily observations to monthly maps of maximum water extent produced records with diminished cloud and cloud shadow effects across most of the country. We used the continuous monthly record to analyze spatiotemporal surface water trends stratified within Environmental Protection Agency Ecoregions. Although not all ecoregion trends were significant ( p < 0.05), results indicate that much of the western and eastern US underwent a decline in surface water over the 17-year period, while many ecoregions in the Great Plains had positive trends. Trends were also generated from monthly streamgage discharge records and compared to surface water trends from the same ecoregion. These approaches agreed on the directionality of trend detected for 54 of 85 ecoregions, particularly across the Great Plains and portions of the western US, whereas trends were not congruent in select western deserts, the Great Lakes region, and the southeastern US. By describing the geographic distribution of surface water over time and comparing these records to instrumented discharge data across the conterminous US, our findings demonstrate the efficacy of using satellite imagery to monitor surface water dynamics and supplement traditional instrumented monitoring.

Water Resources Research↗

USGS2011

Near-surface shear-wave velocity measurements in unlithified sediment

S-wave velocity can be directly correlated to material stiffness and lithology making it a valuable physical property that has found uses in construction, engineering, and environmental projects. This study compares different methods for measuring S-wave velocities, investigating and identifying the differences among the methods' results, and prioritizing the different methods for optimal S-wave use at the U. S. Army's Yuma Proving Grounds YPG. Multichannel Analysis of Surface Waves MASW and S-wave tomography were used to generate S-wave velocity profiles. Each method has advantages and disadvantages. A strong signal-to-noise ratio at the study site gives the MASW method promising resolution. S-wave first arrivals are picked on impulsive sledgehammer data which were then used for the tomography process. Three-component downhole seismic data were collected in-line with a locking geophone, providing ground truth to compare the data and to draw conclusions about the validity of each data set. Results from these S-wave measurement techniques are compared with borehole seismic data and with lithology data from continuous samples to help ascertain the accuracy, and therefore applicability, of each method. This study helps to select the best methods for obtaining S-wave velocities for media much like those found in unconsolidated sediments at YPG. ?? 2011 Society of Exploration Geophysicists.

SEG Technical Program Expanded Abstracts↗

USGS2015

Quantification of shoreline change along Hatteras Island, North Carolina: Oregon Inlet to Cape Hatteras, 1978-2002, and associated vector shoreline data

Shoreline change spanning twenty-four years was assessed along the coastline of Cape Hatteras National Seashore, at Hatteras Island, North Carolina. The shorelines used in the analysis were generated from georeferenced historical aerial imagery and are used to develop shoreline change rates for Hatteras Island, from Oregon Inlet to Cape Hatteras. A total of 14 dates of aerial photographs ranging from 1978 through 2002 were obtained from the U.S. Army Corp of Engineers Field Research Facility in Duck, North Carolina, and scanned to generate digital imagery. The digital imagery was georeferenced and high water line shorelines (interpreted from the wet/dry line) were digitized from each date to produce a time series of shorelines for the study area. Rates of shoreline change were calculated for three periods: the full span of the time series, 1978 through 2002, and two approximately decadal subsets, 1978–89 and 1989–2002.

North Carolina↗

USGS1989

GEOS seismograms recorded for aftershocks of the earthquakes of December 7, 1988, near Spitak, Armenia SSR, during the time period 26 December 1988 14:00 through 29 December 1988 (UTC)

The earthquakes of December 7, 1988, near Spitak, Armenia SSR, serve as another grim reminder of the serious hazard that earthquakes pose throughout the world. We extend our heartfelt sympathies to the families of the earthquake victims and intend that our cooperative scientific endeavours will help reduce losses in future earthquakes. Only through a better understanding of earthquake hazards can earthquake losses be reduced for all peoples in seismically active regions of the world. The tragic consequences of these earthquakes remind scientists and public officials alike of their urgent responsibilities to understand and mitigate the effects of earthquakes. On behalf of the U.S. Geological Survey, I would like to express appreciation to our Soviet colleagues for their kind invitation to participate in joint scientific and engineering studies. Without their cooperation and generous assistance, the conduct of these studies would not have been possible. This report provides seismologic and geologic data collected during the time period December 21, 1988, through February 2, 1989. These data are presented in their entirety to expedite analysis of the data set for inferences regarding hazard mitigation actions, applicable not only in Armenia but other regions of the world exposed to high seismic risk.

Open-File Report↗

USGS1989

GEOS seismograms for aftershocks of the earthquakes of December 7, 1988, near Spitak, Armenia SSR, during the time period 30 December 1988 14:00 through 2 January 1989 (UTC): Chapter D in Results and data from seismologic and geologic studies following earthquakes of December 7, 1988, near Spitak, Armenia SSR (Open-File Report 89-163)

The earthquakes of December 7, 1988, near Spitak, Armenia SSR, serve as another grim reminder of the serious hazard that earthquakes pose throughout the world. We extend our heartfelt sympathies to the families of the earthquake victims and intend that our cooperative scientific endeavours will help reduce losses in future earthquakes. Only through a better understanding of earthquake hazards can earthquake losses be reduced for all peoples in seismically active regions of the world. The tragic consequences of these earthquakes remind scientists and public officials alike of their urgent responsibilities to understand and mitigate the effects of earthquakes. On behalf of the U.S. Geological Survey, I would like to express appreciation to our Soviet colleagues for their kind invitation to participate in joint scientific and engineering studies. Without their cooperation and generous assistance, the conduct of these studies would not have been possible. This report provides seismologic and geologic data collected during the time period December 21, 1988, through February 2, 1989. These data are presented in their entirety to expedite analysis of the data set for inferences regarding hazard mitigation actions, applicable not only in Armenia but other regions of the world exposed to high seismic risk

Spitak↗

USGS1989

GEOS seismograms recorded for aftershocks of the earthquakes of December 7, 1988, near Spitak, Armenia SSR, during the time period 3 January 1989 through 2 February 1988 (UTC)

The earthquakes of December 7, 1988, near Spitak, Armenia SSR, serve as another grim reminder of the serious hazard that earthquakes pose throughout the world. We extend our heartfelt sympathies to the families of the earthquake victims and intend that our cooperative scientific endeavours will help reduce losses in future earthquakes. Only through a better understanding of earthquake hazards can earthquake losses be reduced for all peoples in seismically active regions of the world. The tragic consequences of these earthquakes remind scientists and public officials alike of their urgent responsibilities to understand and mitigate the effects of earthquakes. On behalf of the U.S. Geological Survey, I would like to express appreciation to our Soviet colleagues for their kind invitation to participate in joint scientific and engineering studies. Without their cooperation and generous assistance, the conduct of these studies would not have been possible. This report provides seismologic and geologic data collected during the time period December 21, 1988, through February 2, 1989. These data are presented in their entirety to expedite analysis of the data set for inferences regarding hazard mitigation actions, applicable not only in Armenia but other regions of the world exposed to high seismic risk

Open-File Report↗

USGS1977

Techniques for estimating magnitude and frequency of floods in Minnesota

Estimating relations have been developed to provide engineers and designers with improved techniques for defining flow-frequency characteristics to satisfy hydraulic planning and design requirements. The magnitude and frequency of floods up to the 100-year recurrence interval can be determined for most streams in Minnesota by methods presented. By multiple regression analysis, equations have been developed for estimating flood-frequency relations at ungaged sites on natural flow streams. Eight distinct hydrologic regions are delineated within the State with boundaries defined generally by river basin divides. Regression equations are provided for each region which relate selected frequency floods to significant basin parameters. For main-stem streams, graphs are presented showing floods for selected recurrence intervals plotted against contributing drainage area. Flow-frequency estimates for intervening sites along the Minnesota River, Mississippi River, and the Red River of the North can be derived from these graphs. Flood-frequency characteristics are tabulated for 201 paging stations having 10 or more years of record.

Minnesota↗