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At least 91 records · Page 5Linked to original sources
USGS2008

ShakeCast: Automating and improving the use of shakemap for post-earthquake deeision-making and response

When a potentially damaging earthquake occurs, utility and other lifeline managers, emergency responders, and other critical users have an urgent need for information about the impact on their particular facilities so they can make appropriate decisions and take quick actions to ensure safety and restore system functionality. ShakeMap, a tool used to portray the extent of potentially damaging shaking following an earthquake, on its own can be useful for emergency response, loss estimation, and public information. However, to take full advantage of the potential of ShakeMap, we introduce ShakeCast. ShakeCast facilitates the complicated assessment of potential damage to a user's widely distributed facilities by comparing the complex shaking distribution with the potentially highly variable damageability of their inventory to provide a simple, hierarchical list and maps of structures or facilities most likely impacted. ShakeCast is a freely available, post-earthquake situational awareness application that automatically retrieves earthquake shaking data from ShakeMap, compares intensity measures against users' facilities, sends notifications of potential damage to responsible parties, and generates facility damage maps and other Web-based products for both public and private emergency managers and responders. ?? 2008, Earthquake Engineering Research Institute.

Earthquake Spectra↗
USGS2024

Dam removal cost databases and drivers

The United States (U.S.) has over 90,000 dams listed in the National Inventory of Dams that provide vital infrastructure to support water management for municipal and industrial uses including irrigation, hydropower, flood control, navigation, recreation, and habitat, among other uses (NID 2023). The Bureau of Reclamation (Reclamation) and U.S. Army Corps of Engineers (USACE) operate and maintain approximately 489 and 740 dams, respectively, as well as associated structures which provide flood risk management, navigation, water supply, hydropower, environmental stewardship, fish and wildlife conservation, and recreation benefits. As dams age, structural and operational maintenance investments increase until a time when decisions on whether to rehabilitate, replace, or decommission the dam need to be made. While most dams continue to provide important value even with maintenance requirements, at least 2,000 dams have been removed in the U.S. during the past 110 years, with an upward trend in the last few decades (American Rivers 2023). Decommissioning a dam may be considered when the purpose of the dam is no longer needed or other factors such as dam safety, fish passage, recreation safety, or river restoration goals take higher priority and are more economically feasible for the dam owner long-term. Dam safety programs, river restoration programs, and asset class management programs need cost estimating methods to consider dam decommissioning when appropriate. Traditional cost estimating approaches in planning stages focus mainly on dam removal construction and may leave out or have uncertainty on important complexities that can have substantial effects on total costs and be critical for project success. As the numbers of dam removal case studies increase, a growing set of cost data has become available (Duda et al. 2023a; Tullos and Bountry 2023; American Rivers 2022). However, total costs vary over five orders of magnitude for similar size dams, and it was unclear why. We evaluated three sets of cost data that had varying level of details regarding elements contributing to dam removal costs reported by project managers working on the dam removal studies and construction means and methods. We created planning-level cost estimating tools to assist with projects needing to consider the dam removal alternative: (1) new databases of case studies (Duda et al. 2023a; Tullos and Bountry 2023); (2) scoping questions to help determine if complexity cost drivers will be present; (3) machine learning based regression trees to estimate a potential cost range; and (4) a Computation Guide for Cost Estimating that can be used to inform discussions on potential dam removal cost items, quantities, and unit costs (appendix A). The collected data showed that dam height is important but is not a reliable predictor of the removal cost without considering other elements. However, knowing some basic characteristics about the average annual flow and geographic location of the dam site, in addition to dam size, can improve the ability to use past case studies for planning-level cost estimating. By additionally incorporating scoping questions related to sediment removal, mitigation, or other infrastructure, the likelihood of complexity cost drivers and the initial uncertainty of a cost estimate can be further reduced especially for small dams. Applying the Computation Guide for Cost Estimating requires more robust information but helps users reduce cost uncertainty. This step further refines the dam removal objective, removal approach (partial or full; phased or instantaneous), engineering design, construction means and methods, quantities, and unit costs, and results in a quantitative cost estimate.

Final Report↗
USGS2011

Indigenous observations of climate change in the Lower Yukon River Basin, Alaska

Natural science climate change studies have led to an overwhelming amount of evidence that the Arctic and Subarctic are among the world's first locations to begin experiencing climate change. Indigenous knowledge of northern regions is a valuable resource to assess the effects of climate change on the people and the landscape. Most studies, however, have focused on coastal Arctic and Subarctic communities with relatively little focus on inland communities. This paper relates the findings from fieldwork conducted in the Lower Yukon River Basin of Alaska in the spring of 2009. Semi-structured interviews were conducted with hunters and elders in the villages of St. Mary's and Pitka's Point, Alaska to document observations of climate change. This study assumes that scientific findings and indigenous knowledge are complementary and seeks to overcome the false dichotomy that these two ways of knowing are in opposition. The observed changes in the climate communicated by the hunters and elders of St. Mary's and Pitka's Point, Alaska are impacting the community in ways ranging from subsistence (shifting flora and fauna patterns), concerns about safety (unpredictable weather patterns and dangerous ice conditions), and a changing resource base (increased reliance on fossil fuels). Here we attempt to address the challenges of integrating these two ways of knowing while relating indigenous observations as described by elders and hunters of the study area to those described by scientific literature.

Human Organization↗
USGS2007

Risk-targeted versus current seismic design maps for the conterminous United States

The probabilistic portions of the seismic design maps in the NEHRP Provisions (FEMA, 2003/2000/1997), and in the International Building Code (ICC, 2006/2003/2000) and ASCE Standard 7-05 (ASCE, 2005a), provide ground motion values from the USGS that have a 2% probability of being exceeded in 50 years. Under the assumption that the capacity against collapse of structures designed for these "uniformhazard" ground motions is equal to, without uncertainty, the corresponding mapped value at the location of the structure, the probability of its collapse in 50 years is also uniform. This is not the case however, when it is recognized that there is, in fact, uncertainty in the structural capacity. In that case, siteto-site variability in the shape of ground motion hazard curves results in a lack of uniformity. This paper explains the basis for proposed adjustments to the uniform-hazard portions of the seismic design maps currently in the NEHRP Provisions that result in uniform estimated collapse probability. For seismic design of nuclear facilities, analogous but specialized adjustments have recently been defined in ASCE Standard 43-05 (ASCE, 2005b). In support of the 2009 update of the NEHRP Provisions currently being conducted by the Building Seismic Safety Council (BSSC), herein we provide examples of the adjusted ground motions for a selected target collapse probability (or target risk). Relative to the probabilistic MCE ground motions currently in the NEHRP Provisions, the risk-targeted ground motions for design are smaller (by as much as about 30%) in the New Madrid Seismic Zone, near Charleston, South Carolina, and in the coastal region of Oregon, with relatively little (<15%) change almost everywhere else in the conterminous U.S.

Conference Paper↗
USGS2024

Current and projected flood exposure for Alaska coastal communities

Globally, coastal communities experience flood hazards that are projected to worsen from climate change and sea level rise. The 100-year floodplain or record flood are commonly used to identify risk areas for planning purposes. Remote communities often lack measured flood elevations and require innovative approaches to estimate flood elevations. This study employs observation-based methods to estimate the record flood elevation in Alaska communities and compares results to elevation models, infrastructure locations, and sea level rise projections. In 46 analyzed communities, 22% of structures are located within the record floodplain. With sea level rise projections, this estimate increases to 30–37% of structures by 2100 if structures remain in the same location. Flood exposure is highest in western Alaska. Sea level rise projections suggest northern Alaska will see similar flood exposure levels by 2100 as currently experienced in western Alaska. This evaluation of record flood height, category, and history can be incorporated into hazard planning documents, providing more context for coastal flood exposure than previously existed for Alaska. This basic flood exposure method is transferable to other areas with similar mapping challenges. Identifying current and projected hazardous zones is essential to avoid unintentional development in floodplains and improve long-term safety.

Alaska↗
USGS2014

Evaluation of juvenile salmonid behavior near a prototype weir box at Cowlitz Falls Dam, Washington, 2013

Collection of juvenile salmonids at Cowlitz Falls Dam is a critical part of the effort to restore salmon in the upper Cowlitz River because the majority of fish that are not collected at the dam pass downstream and enter a large reservoir where they become landlocked and lost to the anadromous fish population. However, the juvenile fish collection system at Cowlitz Falls Dam has failed to achieve annual collection goals since it first began operating in 1996. Since that time, numerous modifications to the fish collection system have been made and several prototype collection structures have been developed and tested, but these efforts have not substantially increased juvenile fish collection. Studies have shown that juvenile steelhead (Oncorhynchus mykiss), coho salmon (Oncorhynchus kisutch), and Chinook salmon (Oncorhynchus tshawytscha) tend to locate the collection entrances effectively, but many of these fish are not collected and eventually pass the dam through turbines or spillways. Tacoma Power developed a prototype weir box in 2009 to increase capture rates of juvenile salmonids at the collection entrances, and this device proved to be successful at retaining those fish that entered the weir. However, because of safety concerns at the dam, the weir box could not be deployed near a spillway gate where the prototype was tested, so the device was altered and re-deployed at a different location, where it was evaluated during 2013. The U.S. Geological Survey conducted an evaluation using radiotelemetry to monitor fish behavior near the weir box and collection flumes. The evaluation was conducted during April–June 2013. Juvenile steelhead and coho salmon (45 per species) were tagged with a radio transmitter and passive integrated transponder (PIT) tag, and released upstream of the dam. All tagged fish moved downstream and entered the forebay of Cowlitz Falls Dam. Median travel times from the release site to the forebay were 0.8 d for steelhead and 1.2 d for coho salmon. Most fish spent several days in the dam forebay; median forebay residence times were 4.4 d for juvenile steelhead and 5.7 d for juvenile coho salmon. A new radio transmitter model was used during the study period. The transmitter had low detection probabilities on underwater antennas located within the collection system, which prevented us from reporting performance metrics (discovery efficiency, entrance efficiency, retention efficiency) that are traditionally used to evaluate fish collection systems. Most tagged steelhead (98 percent) and coho salmon (84 percent) were detected near the weir box or collection flume entrances during the study period; 39 percent of tagged steelhead and 55 percent of tagged coho salmon were detected at both entrances. Sixty-three percent of the tagged steelhead that were detected at both entrances were first detected at the weir box, compared to 52 percent of the coho salmon. Twelve steelhead and 15 coho salmon detected inside the weir box eventually left the device and were collected in collection flumes or passed the dam. Overall, collection rates were relatively high during the study period. Sixty-five percent of the steelhead and 80 percent of the coho salmon were collected during the study, and most of the remaining fish passed the dam and entered the tailrace (24 percent of steelhead; 13 percent of coho salmon). The remaining 11 percent of steelhead and 7 percent of coho salmon did not pass the dam while their transmitters were operating. We were able to confirm collection of tagged fish at the fish facility using three approaches: (1) detection of radio transmitters in study fish; (2) detection of PIT-tags in study fish; (3) observation of study fish by staff at the fish facility. Data from all three methods were used to develop a multistate mark-recapture model that estimated detection probabilities for the various monitoring methods. These estimates then were used to describe the percent of tagged fish that were collected through the weir box and collection flumes. Detection probabilities of PIT-tag antennas in the collection flumes were 0.895 for juvenile steelhead and 0.881 for juvenile coho salmon, although radiotelemetry detection probabilities were 0.654 and 0.646 for the two species, respectively. The multistate model estimates showed that all steelhead and most coho salmon (94.5 percent) that were collected at the dam entered the collection system through the flumes rather than through the weir box. None of the tagged steelhead and only 5.5 percent of the tagged coho salmon were collected through the weir box. These data show that juvenile steelhead and coho salmon collection rates were much higher through the collection flumes than through the weir box. Low detection probabilities of tagged fish in the fish collection system resulted in uncertainty for some aspects of our evaluation. Missing detection records within the collection system for fish that were known to have been collected resulted in four tagged steelhead and seven tagged coho salmon being removed from the dataset, which was used to assess discovery rates of the weir box and collection flumes. However, the multistate model allowed us to provide unbiased estimates of the percentage of tagged fish that were collected through each route, and these data showed that few fish were collected through the weir box. Overall, the fish collection system performed reasonably well in collecting juvenile steelhead and coho salmon during the 2013 collection season. Fish collection efficiency estimates from the Washington Department of Fish and Wildlife showed that steelhead collection efficiency was slightly higher than the 10-year average (46 percent compared to 42 percent), whereas coho salmon collection efficiency was more than twice as high as the 10-year average (63 percent compared to 30 percent). However, the performance of the weir box was poor because most fish were collected through the collection flumes.

Washington↗
USGS2008

Protocol for Monitoring Fish Assemblages in Pacific Northwest National Parks

Rivers and streams that drain from Olympic, Mount Rainier, and North Cascades National Parks are among the most protected corridors in the lower 48 States, and represent some of the largest tracts of contiguous, undisturbed habitat throughout the range of several key fish species of the Pacific Northwest. These watersheds are of high regional importance as freshwater habitat sanctuaries for native fish, where habitat conditions are characterized as having little to no disturbance from development, channelization, impervious surfaces, roads, diversions, or hydroelectric projects. Fishery resources are of high ecological and cultural importance in Pacific Northwest National Parks, and significantly contribute to economically important recreational, commercial, and tribal fisheries. This protocol describes procedures to monitor trends in fish assemblages, fish abundance, and water temperature in eight rivers and five wadeable streams in Olympic National Park during summer months, and is based on 4 years of field testing. Fish assemblages link freshwater, marine, and terrestrial ecosystems. They also serve as focal resources of national parks and are excellent indicators of ecological conditions of rivers and streams. Despite the vital importance of native anadromous and resident fish populations, there is no existing monitoring program for fish assemblages in the North Coast and Cascades Network. Specific monitoring objectives of this protocol are to determine seasonal and annual trends in: (1) fish species composition, (2) timing of migration of adult fish, (3) relative abundance, (4) age and size structure, (5) extent of non-native and hatchery fish, and (6) water temperature. To detect seasonal and annual trends in fish assemblages in reference sites, we rely on repeated and consistent annual sampling at each monitoring site. The general rationale for the repeated sampling of reference sites is to ensure that we account for the high interannual variability in fish movements and abundances in rivers. One underlying assumption is that the monitoring program is designed in perpetuity, and consequently our capability to detect trends substantially increases with time. The protocol describes sampling designs, methods, training procedures, safety considerations, data management, data analysis, and reporting. The allocation of sampling effort represents a balance between ecological considerations, a sound monitoring approach, and practical limitations caused by logistical constraints and a limited annual budget of $55,000. The widespread declines of native fish species in western North America highlights the importance and urgency of understanding trends in fish assemblages from undisturbed habitats. Seasonal and annual trends in fish assemblages will provide insights at the individual, population, and assemblage level. This protocol will allow managers to detect increases and decreases in abundance of priority management species, and occurrence of non-native, hatchery, and federally listed fish. The detection of trends in fish assemblages will allow for specific management actions that may include: implementation of more appropriate fishing regulations, evaluation of existing hatchery releases, control of non-native fish species, and prioritization of habitat restoration projects. Dissemination and communication of scientific findings on North Coast and Cascades Network fish assemblages will be a core product of this protocol, which will have much relevance to decision makers, park visitors, researchers, and educators.

Techniques and Methods↗
USGS2024

Effective site coefficients for the 2024 International Building Code (IBC)

The U.S. National Seismic Hazard Models (NSHMs), developed by the U.S. Geological Survey (USGS), have long been the scientific foundation of seismic design guidelines and have been used to compute design ground motions for construction of new buildings and retrofit of existing buildings in the United States and its territories. The 2018 NSHM is adopted by the 2024 International Building Code (IBC). Prior to the 2018 NSHM update, hazard calculations were required only at one reference site condition defined by V S30 =760 m/s (where V S30 is the time-averaged shear wave velocity from the surface to a depth of 30 m) and three periods (peak ground acceleration, PGA, and pseudo spectral accelerations at periods of 0.2 and 1 s, S s and S 1 ). Site coefficients, F PGA , F a , and F v , were then defined by the Building Seismic Safety Council (BSSC) Provisions Update Committee (PUC) in the site-specific procedures of National Earthquake Hazard Reduction Program (NEHRP) Recommended Seismic Provisions to calculate ground motions for other site classes with different V S30 values at the given periods. The design ground motions at other periods were then estimated using a generic spectral shape that was also defined by the BSSC PUC in NEHRP provisions. In recent years, the engineering community has realized there were deficiencies with the F a and F v site coefficients and the generic spectral shape. To avoid potentially dangerous underestimations of design ground motions for long period structures on soft site conditions in high seismicity regions, the BSSC PUC recommended the use of multi-period response spectra (MPRS) in 2017. As a result, the USGS produced multi-period and multi-V S30 response spectral values in the 2018 NSHM for calculations of design ground motions and the site coefficients F a and F v were eliminated from the 2020 NEHRP Provisions. As these site coefficients were widely used inside and outside of the United States, in this study we back-calculate the “effective” site coefficients F a,eff , and F v,eff by comparing MPRS for various site classes with the MPRS for the reference site condition, and discuss the changes that are observed in the 2024 IBC compared to its previous version in 2021. The effective site coefficients are presented for test site locations and their dependence on various factors including period, ground motion intensity, and regional models are discussed. Ratio maps between the new effective site coefficients and the old ones are then presented for soft site classes and for short and long periods. For soft site classes at short periods, the new effective site coefficients are lower than the old site coefficients for high seismicity regions and higher for low seismicity regions. As it was expected, for soft site classes at long periods and high seismicity regions, the new effective site coefficients are much larger than the old site coefficients without imposing the 50% increase as a penalty that was suggested in the 2021 IBC, whereas they could be much smaller if the 50% increase would have been imposed particularly around New Madrid and Charleston high seismicity regions. For low seismicity regions, the long period effective site coefficients can be smaller or larger by 20% compared to the 2021 IBC coefficients.

Conference Paper↗
USGS2015

Re-colonization by common eiders Somateria mollissima in the Aleutian Archipelago following removal of introduced arctic foxes Vulpes lagopus

Islands provide refuges for populations of many species where they find safety from predators, but the introduction of predators frequently results in elimination or dramatic reductions in island-dwelling organisms. When predators are removed, re-colonization for some species occurs naturally, and inter-island phylogeographic relationships and current movement patterns can illuminate processes of colonization. We studied a case of re-colonization of common eiders Somateria mollissima following removal of introduced arctic foxes Vulpes lagopus in the Aleutian Archipelago, Alaska. We expected common eiders to resume nesting on islands cleared of foxes and to re-colonize from nearby islets, islands, and island groups. We thus expected common eiders to show limited genetic structure indicative of extensive mixing among island populations. Satellite telemetry was used to record current movement patterns of female common eiders from six islands across three island groups. We collected genetic data from these and other nesting common eiders at 14 microsatellite loci and the mitochondrial DNA control region to examine population genetic structure, historical fluctuations in population demography, and gene flow. Our results suggest recent interchange among islands. Analysis of microsatellite data supports satellite telemetry data of increased dispersal of common eiders to nearby areas and little between island groups. Although evidence from mtDNA is suggestive of female dispersal among island groups, gene flow is insufficient to account for recolonization and rapid population growth. Instead, near-by remnant populations of common eiders contributed substantially to population expansion, without which re-colonization would have likely occurred at a much lower rate. Genetic and morphometric data of common eiders within one island group two and three decades after re-colonization suggests reduced movement of eiders among islands and little movement between island groups after populations were re-established. We predict that re-colonization of an island group where all common eiders are extirpated could take decades.

Alaska↗
USGS1981

Research and development program; Conservation Division Outer Continental Shelf oil and gas operations; Technical report 1981

As a result of recommendations several years ago from the National Academy of Sciences, the University of Oklahoma, and the National Aeronautics and Space Administration (NASA), the U.S. Geological Survey has embarked upon a program of research and development to provide the technological insights needed for its regulatory operations offshore—operations which provide assurances to the public for safety and for the prevention of pollution in oil and gas drilling and production. These clear objectives are, therefore, those of the research program, not the economics of operations, which are of concern to industry. The Program is a contract research program and is an integral part of the Conservation Division. It is a focal point for deriving possible solutions from the university community, private industry, and the Federal laboratory system for identified offshore operational problems. This vast interdisciplinary body of science and technology provides the kind of research needed by the Division in its Outer Continental Shelf (OCS) operations which involve such problematic areas as structural dynamics, fluid flow, and geotechnology. The Program encourages innovation and creativity which can be accomplished only by talented scientists and engineers who are dedicated to man's endeavor to make breakthroughs in science and technology. Because the Division's mission is operational, in a sense like the U.S. Navy, the R&D Program must progress in a timely manner even though technological advances cannot really be scheduled. As the Navy's Office of Naval Research (ONR) has so successfully coped with the seeming dichotomy of anticipating the occurrence of innovations, so must the Conservation Division. Thus, USGS, like ONR, makes use of the unsolicited proposal and the best effort contract to accomplish its objectives. Good science and technology can only be accomplished when several variables converge: a talented investigator doing his own research, which happens to coincide with our needs, availability of resources, time scales, etc. Our task is to "beat the bushes" so that these people come to us with their innovative ideas and concepts. They have done so by learning of our interests through announcements of the Program in the Federal Register, reading reports which emanate from the Program, and by attending our seminars.

Open-File Report↗
USGS2007

The National Map - Orthoimagery Layer

Many Federal, State, and local agencies use a common set of framework geographic information databases as a tool for economic and community development, land and natural resource management, and health and safety services. Emergency management and homeland security applications rely on this information. Private industry, nongovernmental organizations, and individual citizens use the same geographic data. Geographic information underpins an increasingly large part of the Nation's economy. The U.S. Geological Survey (USGS) is developing The National Map to be a seamless, continually maintained, and nationally consistent set of online, public domain, framework geographic information databases. The National Map will serve as a foundation for integrating, sharing, and using data easily and consistently. The data will be the source of revised paper topographic maps. The National Map includes digital orthorectified imagery; elevation data; vector data for hydrography, transportation, boundary, and structure features; geographic names; and land cover information.

Fact Sheet↗
USGS1996

Summary of hydrogeologic controls on ground-water flow at the Nevada Test Site, Nye County, Nevada

The underground testing of nuclear devices has generated substantial volumes of radioactive and other chemical contaminants below ground at the Nevada Test Site (NTS). Many of the more radioactive contaminants are highly toxic and are known to persist in the environment for thousands of years. In response to concerns about potential health hazards, the U.S. Department of Energy, under its Environmental Restoration Program, has made NTS the subject of a long-term investigation. Efforts supported through the U.S. Department of Energy program will assess whether byproducts of underground testing pose a potential hazard to the health and safety of the public and, if necessary, will evaluate and implement steps to remediate any of the identified dangers. Test-generated contaminants have been introduced over large areas and at variable depths above and below the water table throughout NTS. Evaluating the risks associated with these byproducts of underground testing presupposes a knowledge of the source, transport, and potential receptors of these contaminants. Ground-water flow is the primary mechanism by which contaminants can be transported significant distances away from the initial point of injection. Flow paths between contaminant sources and potential receptors are separated by remote areas that span tens of miles. The diversity and structural complexity of the rocks along these flow paths complicates the hydrology of the region. Although the hydrology has been studied in some detail, much still remains uncertain about flow rates and directions through the fractured-rock aquifers that transmit water great distances across this arid region. Unique to the hydrology of NTS are the effects of underground testing, which severely alter local rock characteristics and affect hydrologic conditions throughout the region. Any assessment of the risk must rely in part on the current understanding of ground-water flow, and the assessment will be only as good as the understanding itself. This report summarizes what is known and inferred about ground-water flow throughout the NTS region. The report identifies and updates what is known about some of the major controls on ground-water flow, highlights some of the uncertainties in the current understanding, and prioritizes some of the technical needs as related to the Environmental Restoration Program. An apparent deficiency in the current understanding is a lack of knowledge about flow directions and rates away from major areas of testing. Efforts are necessary to delineate areas of downgradient flow and to identify factors that constrain and control flow within these areas. These efforts also should identify the areas most critical to gaining detailed understanding and to establishing long-term monitoring sites necessary for effective remediation.

Nevada↗
USGS2023

Modeling non-structural strategies to reduce pedestrian evacuation times for mitigating local tsunami threats in Guam

Reducing the potential for loss of life from local tsunamis is challenging for emergency managers given the need for self-protective behavior of at-risk individuals within brief windows of time to evacuate. There has been considerable attention paid to discussing the use of tsunami vertical-evacuation structures for areas where there may be insufficient time to evacuate. This strategy may not be feasible or needed for at-risk populations in island communities for multiple reasons. We examine the influence of three non-structural interventions (reducing departure delays, increasing travel speeds, and managing vegetation to create new paths) that may improve the evacuation potential for at-risk individuals in island communities and use the United States territory of Guam as our case study. We model pedestrian travel times out of a modeled inundation zone for a local tsunami generated by a M w 8.3 earthquake within the Mariana subduction zone. Evacuation-modeling results indicate that reducing departure delays has a larger impact than increasing travel speeds or creating evacuation corridors through heavy brush on reducing the number of at-risk individuals with insufficient time to evacuate. Travel times to safety are less than wave-arrival times for almost all at-risk individuals in the tsunami-hazard zone if one assumes all three interventions are implemented.

Guam↗
USGS2000

GPS in dynamic monitoring of long-period structures

Global Positioning System (GPS) technology with high sampling rates (??? 10 samples per second) allows scientifically justified and economically feasible dynamic measurements of relative displacements of long-period structures-otherwise difficult to measure directly by other means, such as the most commonly used accelerometers that require post-processing including double integration. We describe an experiment whereby the displacement responses of a simulated tall building are measured clearly and accurately in real-time. Such measurements can be used to assess average drift ratios and changes in dynamic characteristics, and therefore can be used by engineers and building owners or managers to assess the building performance during extreme motions caused by earthquakes and strong winds. By establishing threshold displacements or drift ratios and identifying changing dynamic characteristics, procedures can be developed to use such information to secure public safety and/or take steps to improve the performance of the building. Published by Elsevier Science Ltd.

Soil Dynamics and Earthquake Engineering↗
USGS1969

Seismic environment of the Burro Flats site, Ventura County, California: a brief, limited literature review

A limited review of available literature suggests that the maximum horizontal ground acceleration at the Burro Flats site from earthquakes in the region could range from less than 0.1 to 0.49 g. A magnitude 8 earthquake on the nearby San Andreas fault could produce ground acceleration in the range 0.18 to 0.31 g, and an expectable larger earthquake on that fault could produce larger accelerations. Ground motion from possible smaller but closer earthquakes ranges up to 0.49 g for an earthquake of magnitude 6.5 on the adjacent "Burro Flats fault". Estimation of these accelerations is dependent on determining the geologic environment of the site, the appropriate earthquake magnitudes to be assigned significant faults in that environment, and the attenuation of shaking between the earthquake epicenters and the site. The site lies within a tectonically active region--the historically active San Andreas fault is only 34 miles to the northeast, and lesser faults showing evidence of late Quaternary displacement are located closer to the site. Evidence for youthfulness of these lesser faults varies, and except for the active Newport-Inglewood zone and the Santa Ynez fault, they qualify as possible but as yet-unproven active faults. All known faults with appropriate length to site-distance ratios that are reasonably classed as late Quaternary faults are discussed, and are included as potential earthquake generators. Earthquakes of appropriate magnitude to be assigned to each fault are determined by assuming rupture in one event of half the map length of the fault, and applying relations (determined by several authors) between earthquake magnitude and rupture length in historic events to determine magnitudes. These magnitudes are, for the purposes of this brief review, probably reasonable estimates of the capabilities of each fault, although earthquakes of larger magnitude are possible. Accelerations are then determined by assuming earthquakes of the above determined magnitude placed at the closest point to the site on the fault trace, and applying attenuation curves of three different authors. Considerable uncertainty is inherent in the rough estimates of seismic accelerations made herein, for they are dependent on a chain of judgments, each of which, in itself, is uncertain. Present knowledge of the geology of the region is incomplete, so that geometry and structural relations of the faults are in part uncertain, and much evidence bearing on the youth of the faults has yet to be gathered and evaluated. Estimation of earthquake magnitude is also uncertain, and even assuming that approximate magnitude is known rather than estimated from fault length, estimates of maximum ground acceleration may differ greatly depending on the authority used. Further consideration of ground acceleration at the site might refine the estimates made herein and resolve the apparent contradictions between the authorities cited. Attention to frequency and duration of strong shaking would also be appropriate. This study was undertaken at the request of A. J. Pressesky, Assistant Director for Nuclear Safety, Division of Reactor-Development and Technology, U.S. Atomic Energy Commission, in March, 1969. It is based on a brief review of pertinent literature to which the authors had immediate access during the few weeks (April-May, 1969) available for report preparation. Because the report is limited both in scope and thoroughness, it must be considered no more than a first estimate of the tectonic and seismic environment of the Burro Flats site, and should not be considered sufficient, in itself, as a basis for design. The report is intended, however, to indicate the breadth of inquiry that is necessary in the consideration of ground acceleration at sites in California, and to indicate the incomplete status of geologic mapping and other geologic studies in the region. The report describes the tectonic environment of the Burro Flats site, discusses 10 pertinent faults individually, and presents possible earthquake magnitudes for those faults and resultant potential ground accelerations at the site.

California↗
USGS2018

Spatial, road geometric, and biotic factors associated with Barn Owl mortality along an interstate highway

Highway programs typically focus on reducing vehicle collisions with large mammals because of economic or safety reasons while overlooking the millions of birds that die annually from traffic. We studied wildlife‐vehicle collisions along an interstate highway in southern Idaho, USA, with among the highest reported rates of American Barn Owl Tyto furcata road mortality. Carcass data from systematic and ad hoc surveys conducted in 2004–2006 and 2013–2015 were used to explore the extent to which spatial, road geometric, and biotic factors explained Barn Owl‐vehicle collisions. Barn Owls outnumbered all other identified vertebrate species of roadkill and represented > 25% of individuals and 73.6% of road‐killed birds. At a 1‐km highway segment scale, the number of dead Barn Owls decreased with increasing numbers of human structures, cumulative length of secondary roads near the highway, and width of the highway median. Number of dead Barn Owls increased with higher commercial average annual daily traffic (CAADT), small mammal abundance index, and with grass rather than shrubs in the roadside verge. The small mammal abundance index was also greater in roadsides with grass versus mixed shrubs, suggesting that Barn Owls may be attracted to grassy portions of the highway with more abundant small mammals for hunting prey. When assessed at a 3‐km highway segment scale, the number of dead Barn Owls again increased with higher CAADT as well as with greater numbers of dairy farms. At a 5‐km scale, number of dead Barn Owls increased with greater percentage of cropland near the highway. While human conversion of the environment from natural shrub‐steppe to irrigated agriculture in this region of Idaho has likely enhanced habitat for Barns Owls, it simultaneously has increased risk for owl‐vehicle collisions where an interstate highway traverses the altered landscape. We review some approaches for highway mitigation and suggest that reducing wildlife‐vehicle collisions involving Barn Owls may contribute to the persistence of this species.

Idaho↗
USGS2012

Community variations in population exposure to near-field tsunami hazards as a function of pedestrian travel time to safety

Efforts to characterize population exposure to near-field tsunami threats typically focus on quantifying the number and type of people in tsunami-hazard zones. To develop and prioritize effective risk-reduction strategies, emergency managers also need information on the potential for successful evacuations and how this evacuation potential varies among communities. To improve efforts to properly characterize and differentiate near-field tsunami threats among multiple communities, we assess community variations in population exposure to tsunamis as a function of pedestrian travel time to safety. We focus our efforts on the multiple coastal communities in Grays Harbor and Pacific Counties (State of Washington, USA), where a substantial resident and visitor population is threatened by near-field tsunamis related to a potential Cascadia subduction zone earthquake. Anisotropic, path-distance modeling is conducted to estimate travel times to safety and results are merged with various population data, including residents, employees, public venues, and dependent-care facilities. Results suggest that there is substantial variability among communities in the number of people that may have insufficient time to evacuate. Successful evacuations may be possible in some communities assuming slow-walking speeds, are plausible in others if travel speeds are increased, and are unlikely in another set of communities given the large distances and short time horizon. Emergency managers can use these results to prioritize the location and determine the most appropriate type of tsunami risk-reduction strategies, such as education and training in areas where evacuations are plausible and vertical-evacuation structures in areas where they are not.

Washington↗
USGS2026

RoadxStr user’s guide—For collection of road-stream crossing assessment field observations

Intersections of drainage networks and road networks represent a critical nexus between natural waterways and human infrastructure. Managing these systems involves decisions related to management of infrastructure, hydrologic and geomorphic processes, and ecological connectivity. Interactions among these systems influence multiple values, including the intactness of transportation networks, public safety, water quality, and ecosystem function that collectively amount to billions of dollars. Despite the importance of road-stream crossings, there are countless gaps in knowing where and what they are. These gaps limit the degree to which managers can inventory and assess stream and road networks to inform decisions. To address this first-level need, we developed RoadxStr (road-stream crossings): a survey tool that effectively characterizes road-stream crossings across the full stream and drainage network. This document describes the RoadxStr Field Form, available within a mobile application, which is designed for rapid and standardized data collection involving assessment of a road-stream crossing, including the road, crossing structure(s), and the nearby hydrologic channel. This document provides instructions on how to (1) access and download the RoadxStr Field Form within the mobile application service and (2) use and complete a RoadxStr Field Form survey.

Techniques and Methods↗