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At least 649 records · Page 36Linked to original sources
USGS1984

Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste: Part I, Introduction and guidelines

The U.S. Geological Survey's program for geologic and hydrologic evaluation of physiographic provinces to identify areas potentially suitable for locating repository sites for disposal of high-level nuclear wastes was announced to the Governors of the eight States in the Basin and Range Province on May 5, 1981. Representatives of Arizona, California, Idaho, New Mexico, Nevada, Oregon, Texas, and Utah, were invited to cooperate with the Federal Government in the evaluation process. Each Governor was requested to nominate an Earth scientist to represent the State in a province working group composed of State and U.S. Geological Survey representatives. This report, Part I of a three-part report, provides the background, introduction and scope of the study. This part also includes a discussion of geologic and hydrologic guidelines that will be used in the evaluation process and illustrates geohydrologic environments and the effect of individual factors in providing multiple natural barriers to radionuclide migration. Part II is a reconnaissance characterization of the geologic and hydrologic factors to be used in the initial screening of the Basin and Range Province. Part III will be the initial evaluation of the Province and will identify regions that appear suitable for further study. The plan for study of the Province includes a stepwise screening process by which successively smaller land units are considered in increasing detail. Each step involves characterization of the geology and hydrology and selection of subunits for more intensive characterization. Selection of subunits for further study is by evaluation of geologic and hydrologic conditions following a set of guidelines. By representation on the Province Working Group, the States participate in a consultation and review role in: (1) Establishing geologic and hydrologic guidelines, and (2) characterizing and evaluating the Province. The States also participate in compilation of geologic and hydrologic data used in characterizing the Province. The current (1983) needs for a high-level radioactive waste repository include: (1) Disposal in a mined repository; (2) retrievability of the waste for as much as 50 years; and (3) confidence of isolation of the waste from the accessible environment. Isolation of the waste needs to be assured using geologic and hydrologic conditions that: (1) Minimize risk of inadvertent future intrusions by man; (2) minimize the possibility of disturbance by processes that would expose the waste or increase its mobility; and (3) provide a system of natural barriers to the migration of waste by ground water. The guidelines adopted by the Province Working Group are designed to provide a standard with which these conditions can be compared. The guidelines can be grouped into four principal categories: (1) Potential host media, (2) ground-water conditions, (3) tectonic conditions, and. (4) occurrence of natural resources. Ideally the host medium constitutes the first natural barrier to migration of radionculides. The host medium ideally should be a rock type that prevents or retards dissolution and transport of radionuclides. Rocks in both the saturated and unsaturated zones may have desirable characteristics for host media. Rocks-other than the host-in the ground-water flow path from the repository ideally should be major barriers to radionuclide migration. Confining beds of low permeability might be present to retard the rate of flow between more permeable beds. Additionally, sorption of radionuclides by materials such as clays and zeolites in the flow path can further retard the flow of radionuclides by several orders of magnitude. Tectonic conditions in an area should not present a probable cause for exhumation or increased mobility of radioactive waste. Natural resources are a factor for consideration because of the problem of future human intrusion and exposure to radioactivity in the quest for minerals, oil, gas, water, and geothermal resources. The ultimate evaluation of the suitability of a geohydrologic environment for developing a mined repository needs to assess all geologic and hydrologic characteristics and their interaction in providing confidence that a geohydrologic environment will effectively isolate radionuclides from human access. Several hypothetical settings with typical geohydrologic conditions in the Basin and Range Province are used to illustrate the effect of multiple barriers in the isolation of radionuclides.

Arizona, California, Idaho, Nevada, New Mexico, Or↗
USGS2015

Upstream factors affecting Tualatin River algae—Tracking the 2008 Anabaena algae bloom to Wapato Lake, Oregon

Significant Findings A large bloom that included floating mats of the blue-green algae Anabaena flos-aquae occurred in the lower 20 miles of the Tualatin River in northwestern Oregon between July 7 and July 17, 2008. The floating bloom was deemed a hazard to recreational users of the river due to the potential production of algal toxins (anatoxin- a and microcystin), and a public health advisory was posted for the lower 10.8 miles of the river by the Oregon Department of Human Services for July 12–25, 2008. The bloom caused nuisance taste and odor issues and required modified drinking-water treatment techniques where water was withdrawn for municipal uses in the upper reaches of the Tualatin River, some 46 miles upstream of the worst algae problems. Using water sample data from Clean Water Services and the Joint Water Commission, and continuous and discrete monitoring data from the U.S. Geological Survey, the source of the anomalous water-quality conditions and the likely source of the Anabaena bloom was traced upstream to discharges from the Wapato Lake agricultural area near Gaston, Oregon, in the upper part of the watershed near river mile 60. The Wapato Lake algae bloom occurred as standing water remained on the lakebed far longer than normal—into early summer. A failure of the levee on the edge of Wapato Lake in December 2007 caused by heavy rainfall and high water in the canal outside the levee inundated the lakebed to a depth of 7–9 feet, storing thousands of acre-feet more water than its normal winter volume. The water could not be pumped out until the levee was repaired or river levels receded, thus delaying drainage of the lake until summer and facilitating the bloom. In normal summers, the lower Tualatin River grows a moderate crop of algae that responds strongly to streamflow (residence time), light available for photosynthesis, and phosphorus concentrations. In 2008, however, inoculation of the river with phytoplankton and zooplankton discharged from Wapato Lake some 30 miles upstream of the lower, pooled reach of the river demonstrated the importance of upstream factors on plankton communities and water-quality conditions in the Tualatin River. The Wapato Lake algae bloom of July 2008 provided useful information and lessons for agencies managing public health, wetlands, agricultural activities, and water quality in the Tualatin River basin and similar river basins elsewhere. The results and insights derived from this study can be used to enhance future monitoring and data collection strategies designed to improve water quality and plankton models and better predict dissolved-oxygen concentrations in the lower Tualatin River.

Oregon↗
USGS1936

Nodular, orbicular, and banded chromite in northern California

IN I930 Mr. A. F. Duggleby gave me a specimen of orbicular chromite from the Octopus claim, in Siskiyou County, Calif., showing two generations of chromite, one older than the associated olivine and one younger. In November, I93I, I examined briefly a number of deposits in northern California, in search for chromite showing similar and related textures. Some of the more unusual and genetically significant occurrences are described in this paper. Most of the chromite localities here described are in Siskiyou County, northern California. Localities I and 2 are in the Seiad Quadrangle, where a belt of chromite-bearing dunite, striking northwest, extends from McGuffy Creek, near Scott Bar, into Oregon. Other deposits are in southern Siskiyou, Shasta, and Trinity Counties.

Economic Geology↗
USGS2023

A survey of non-USGS continuous streamflow gaging networks in the Pacific Northwest

Extensive streamflow data sources exist beyond the largest streamflow data provider in the United States, the U.S. Geological Survey. We developed and distributed a survey to about 300 individuals and organizations that collect streamflow data across the Pacific Northwest (Idaho, Oregon, Washington). We received 100 responses with 56% of those sufficiently complete to include in the analysis. From these responses, there are about 2000 streamflow monitoring locations in the region beyond the USGS monitoring network. The duration of record for gages is related to the size of the streamflow gaging network, with small and large networks generally operating monitoring locations for less than 5 years and more than 10 years, respectively. Quality assurance and quality control are variable across organizations, with 41% of respondents having at least two review steps and 13% that audit their data for long-term consistency. Results of this survey begin to establish the differing capabilities of large and small stream gaging networks and highlight how supporting the overall quality streamflow data collection and management within the water resources community will improve our ability to harmonize these datasets in the future.

Idaho, Montana, Nevada, Oregon, Washington, Wyomin↗
USGS2012

Occurrence of pesticides in water and sediment collected from amphibian habitats located throughout the United States, 2009-10

Water and bed-sediment samples were collected by the U.S. Geological Survey (USGS) in 2009 and 2010 from 11 sites within California and 18 sites total in Colorado, Georgia, Idaho, Louisiana, Maine, and Oregon, and were analyzed for a suite of pesticides by the USGS. Water samples and bed-sediment samples were collected from perennial or seasonal ponds located in amphibian habitats in conjunction with research conducted by the USGS Amphibian Research and Monitoring Initiative and the USGS Toxic Substances Hydrology Program. Sites selected for this study in three of the states (California, Colorado, and Orgeon) have no direct pesticide application and are considered undeveloped and remote. Sites selected in Georgia, Idaho, Louisiana, and Maine were in close proximity to either agricultural or suburban areas. Water and sediment samples were collected once in 2009 during amphibian breeding seasons. In 2010, water samples were collected twice. The first sampling event coincided with the beginning of the frog breeding season for the species of interest, and the second event occurred 10-12 weeks later when pesticides were being applied to the surrounding areas. Additionally, water was collected during each sampling event to measure dissolved organic carbon, nutrients, and the fungus, Batrachochytrium dendrobatidis , which has been linked to amphibian declines worldwide. Bed-sediment samples were collected once during the beginning of the frog breeding season, when the amphibians are thought to be most at risk to pesticides. Results of this study are reported for the following two geographic scales: (1) for a national scale, by using data from the 29 sites that were sampled from seven states, and (2) for California, by using data from the 11 sampled sites in that state. Water samples were analyzed for 96 pesticides by using gas chromatography/mass spectrometry. A total of 24 pesticides were detected in one or more of the 54 water samples, including 7 fungicides, 10 herbicides, 4 insecticides, 1 synergist, and 2 pesticide degradates. On a national scale, aminomethylphosphonic acid (AMPA), the primary degradate of the herbicide glyphosate, which is the active ingredient in Roundup®, was the most frequently detected pesticide in water (16 of 54 samples) followed by glyphosate (8 of 54 samples). The maximum number of pesticides observed at a single site was nine compounds in a water sample from a site in Louisiana. The maximum concentration of a pesticide or degradate observed in water was 2,880 nanograms per liter of clomazone (a herbicide) at a site in Louisiana. In California, a total of eight pesticides were detected among all of the low and high elevation sites; AMPA was the most frequently detected pesticide, but glyphosate was detected at the highest concentrations (1.1 micrograms per liter). Bed-sediment samples were analyzed for 94 pesticides by using accelerated solvent extraction, gel permeation chromatography for sulfur removal, and carbon/alumina stacked solid-phase extraction cartridges to remove interfering sediment matrices. In bed sediment, 22 pesticides were detected in one or more of the samples, including 9 fungicides, 3 pyrethroid insecticides, p,p' -dichlorodiphenyltrichloroethane ( p,p' -DDT) and its major degradates, as well as several herbicides. Pyraclostrobin, a strobilurin fungicide, and bifenthrin, a pyrethroid insecticide, were detected most frequently. Maximum pesticide concentrations ranged from less than their respective method detection limits to 1,380 micrograms per kilogram (tebuconazole in California). The number of pesticides detected in samples from each site ranged from zero to six compounds. The sites with the greatest number of pesticides were in Maine and Oregon with six pesticides detected in one sample from each state, followed by Georgia with four pesticides in one sample. For California, a total of 10 pesticides were detected among all sites, and 4 pesticides were detected at both low and high elevation sites; tebuconazole and pyraclostrobin were the two most frequently detected pesticides in California. For the other six selected states, the most frequently detected pesticides in bed sediment were pyraclostrobin (detected in 17 of 42 samples), bifenthrin (detected in 14 of 42 samples), and tebuconazole (detected in 10 of 42 samples). The fungus, Batrachochytrium dendrobatidis (Bd), was detected in water samples in sites from four of the seven states during 2009 and 2010, and the number of zoospore equivalents per liter of water in samples where Bd was detected ranged from 1.6 to 343. Bd was not detected in water samples from sites in Georgia, Louisiana, and Oregon.

Data Series↗
USGS2005

The Columbia River Research Laboratory

The U.S. Geological Survey's Columbia River Research Laboratory (CRRL) was established in 1978 at Cook, Washington, in the Columbia River Gorge east of Portland, Oregon. The CRRL, as part of the Western Fisheries Research Center, conducts research on fishery issues in the Columbia River Basin. Our mission is to: 'Serve the public by providing scientific information to support the stewardship of our Nation's fish and aquatic resources...by conducting objective, relevant research'.

Washington↗
USGS2025

Assessment of western Oregon debris-flow hazards in burned and unburned environments

In the steep and mountainous environment of western Oregon, debris flows pose a considerable threat to property, infrastructure and life. Wildfire is commonly known to increase the susceptibility of steep slopes to debris flows, but the extent of this process in the western Cascades is not well understood. The US Geological Survey (USGS) currently estimates postfire debris-flow likelihood and triggering rainfall thresholds using a model calibrated to a southern California inventory of debris flows generated by excess runoff within the first year after fire. Because of a lack of available data, this model has not been tested in western Oregon, or in locations where postfire debris flows initiate via other mechanisms (e.g., shallow landslides or in-channel failures). Using repeat field observations and aerial imagery, we developed two new debris-flow inventories within and adjacent to the perimeters of five 2020 wildfires in western Oregon: Archie Creek, Holiday Farm, Beachie Creek, Lionshead and Riverside. The first inventory focuses on postfire debris flows (2020–2022); the second focuses on debris flows prior to fires (1995–2020). Our inventories of prefire and postfire debris flows were used to document initiation mechanisms in Oregon's western Cascades and to evaluate the effects of wildfire. We found that wildfire changed the distribution of debris-flow initiation mechanisms in the western Cascades. After the wildfires, annual rates of runoff-generated debris flows increased by 22% and the number of shallow landslide-initiated debris flows decreased by 17% relative to before the wildfires. Despite this shift, shallow landsliding was the dominant debris-flow initiation mechanism in both unburned and burned environments. We found the performance of the current USGS debris-flow likelihood model was degraded relative to other previously tested locations across the intermountain western United States. Our results highlight the need for improved postfire hazard assessment in western Oregon based on regional model calibration that is tuned to the dominant debris-flow initiation mechanisms.

Oregon↗
USGS1999

Three-dimensional velocity structure of Siletzia and other accreted terranes in the Cascadia forearc of Washington

Eocene mafic crust with high seismic velocities underlies much of the Oregon and Washington forearc and acts as a backstop for accretion of marine sedimentary rocks from the obliquely subducting Juan de Fuca slab. Arc-parallel migration of relatively strong blocks of this terrane, known as Siletzia, focuses upper crustal deformation along block boundaries, which are potential sources of earthquakes. In a three-dimensional velocity model of coastal Washington, we have combined surface geology, well data, and travel times from earthquakes and controlled source seismic experiments to resolve the major boundaries of the Siletz terrane with the adjacent accreted sedimentary prism and volcanic arc. In southern Washington and northern Oregon the Siletz terrane appears to be a thick block (???20 km) that extends west of the coastline and makes a high-angle contact with the offshore accreted sedimentary prism. On its east flank the high-velocity Siletz terrane boundary coincides with an en echelon zone of seismicity in the arc. In northern Washington the western edge of Siletzia makes a lower-angled, fault-bound contact with the accretionary prism. In addition, alternating, east-west trending uplifts and downwarps of the Siletz terrane centered on the antiformal Olympic Mountains may reflect focusing of north-south compression in the northern part of the Siletz terrane. This compressional strain may result from northward transport and clockwise rotation of the Siletz terrane into the relatively fixed Canadian Coast Mountains restraining bend along the coast.

Oregon, Washington↗
USGS2004

Reconnaissance of chemical and biological quality in the Owyhee River from the Oregon State line to the Owyhee Reservoir, Oregon, 2001–02

The Owyhee River drains an extremely rugged and sparsely populated landscape in northern Nevada, southwestern Idaho, and eastern Oregon. Most of the segment between the Oregon State line and Lake Owyhee is part of the National Wild and Scenic Rivers System, and few water-quality data exist for evaluating environmental impacts. As a result, the U.S. Geological Survey, in cooperation with the Bureau of Land Management, assessed this river segment to characterize chemical and biological quality of the river, identify where designated beneficial uses are met and where changes in stream quality occur, and provide data needed to address activities related to environmental impact assessments and Total Maximum Daily Loads. Water-quality issues identified at one or more sites were water temperature, suspended sediment, dissolved oxygen, pH, nutrients, trace elements, fecal bacteria, benthic invertebrate communities, and periphyton communities. Generally, summer water temperatures routinely exceeded Oregon's maximum 7-day average criteria of 17.8 degrees Celsius. The presence of few coldwater taxa in benthic invertebrate communities supports this observation. Suspended-sediment concentrations during summer base flow were less than 10 milligrams per liter (mg/L). Dissolved solids concentrations ranged from 46 to 222 mg/L, were highest during base flow, and tended to increase in a downstream direction. Chemical compositions of water samples indicated that large proportions of upland-derived water extend to the lower reaches of the study area during spring runoff. Dissolved fluoride and arsenic concentrations were highest during base flow and may be a result of geothermal springs discharging to the river. No dissolved selenium was detected. Upstream from the Rome area, spring runoff concentrations of suspended sediment ranged from 0 to 52 mg/L, and all except at the Three Forks site were typically below 20 mg/L. Stream-bottom materials from the North Fork Owyhee River, an area with no mines, were enriched with nine trace elements, which indicates that this basin may be a natural source of these elements. Near Rome, the part of the study area not included in the National Wild and Scenic Rivers System, land-use impacts resulted in elevated populations of Escherichia coli bacteria ( E. coli ) during base flow and elevated concentrations of nitrogen and phosphorus during spring runoff. Sites in this area had the highest numbers of benthic invertebrates; the fewest Ephemeroptera, Plecoptera, and Trichoptera taxa; and the highest Hilsenhoff Biotic Index scores. These results suggest degraded stream quality. Periphyton communities at sites in this area approached nuisance levels and could cause significant dissolved oxygen depletions and pH values that exceed Oregon's recommended criteria. Stream-bottom materials from Jordan Creek were enriched with mercury and manganese, which probably were ultimately caused by past mining in that basin. Below Crooked Creek, elevated suspended sediment concentrations (142 mg/L), phosphorus concentrations (0.23 mg/L), and E. coli populations (370 most probable number per 100 milliliters) during the largest spring runoff event could be the result of inputs at the lower end of Jordan Valley and (or) inputs from Crooked Creek. The New Zealand Mud Snail, a highly competitive gastropod introduced to the Snake River in the 1980s, was collected just downstream from the Crooked Creek confluence.

Idaho;Nevada;Oregon↗
USGS1993

Geomorphic observations of rivers in the Oregon Coast Range from a regional reconnaissance perspective

Changes in long profile, gradient, gradient index, pseudo-hypsometric integral, valley incision, and sinuosity fractal dimension for rivers in western Oregon were studied to determine their usefulness in assessing an hypothesis of differential uplift within the Coast Range. All data were gathered from topographic quadrangles and geologic maps, and so the results of this paper are limited to the description of river forms with only limited interpretations. Rivers were naturally divided into three groups, those in the western Coast Range, the eastern Coast Range, and the Klamath and Cascade Ranges, and differences in river morphometry were generalized. Rivers in the western Coast Range had more divergent characteristics, whereas those in the other groups were more similar within each group. For example, long profiles of western Coast Range rivers had diverse forms, but in the other groups, long profiles were similar within the group. Pseudo-hypsometric integrals had a wide scatter in the western Coast Range, but in the other ranges, the pseudo-hypsometric integral was more narrowly defined. Valley entrenchment and high sinuosity were common in the western Coast Range, and were less visible in the eastern Coast Range. These regional generalizations do not hold for the central Coast Range near 44.5°N where the Yaquina and Marys Rivers are located. In the eastern Coast Range, the Marys River is unique in that it has a convex bulge in its long profile, does not have an increasing valley-floor width to valley height ratio downstream, and has a high sinuosity fractal dimension. In the western Coast Range, the Yaquina River is unique in that it has a smoothly decreasing long profile, has a very low pseudo-hypsometric integral, and does not have a decreasing valley-floor width to valley height ratio downstream. There may be many explanations for these observations, but these observations are also consistent with tectonic interpretations that the central western Coast Range is the locus of synclinal tilting and that the entire Oregon coast is experiencing landward tilting and uplift.

Geomorphology↗
USGS2012

Watershed scale response to climate change--Sprague River Basin, Oregon

General Circulation Model simulations of future climate through 2099 project a wide range of possible scenarios. To determine the sensitivity and potential effect of long-term climate change on the freshwater resources of the United States, the U.S. Geological Survey Global Change study, "An integrated watershed scale response to global change in selected basins across the United States" was started in 2008. The long-term goal of this national study is to provide the foundation for hydrologically based climate change studies across the nation. Fourteen basins for which the Precipitation Runoff Modeling System has been calibrated and evaluated were selected as study sites. Precipitation Runoff Modeling System is a deterministic, distributed parameter watershed model developed to evaluate the effects of various combinations of precipitation, temperature, and land use on streamflow and general basin hydrology. Output from five General Circulation Model simulations and four emission scenarios were used to develop an ensemble of climate-change scenarios for each basin. These ensembles were simulated with the corresponding Precipitation Runoff Modeling System model. This fact sheet summarizes the hydrologic effect and sensitivity of the Precipitation Runoff Modeling System simulations to climate change for the Sprague River Basin near Chiloquin, Oregon.

Oregon↗
USGS2007

Total dissolved gas and water temperature in the lower Columbia River, Oregon and Washington, 2007: Quality-assurance data and comparison to water-quality standards

Significant Findings When water is released through the spillways of dams, air is entrained in the water, increasing the downstream concentration of dissolved gases. Excess dissolved-gas concentrations can have adverse effects on freshwater aquatic life. The U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers, collected dissolved-gas and water-temperature data at eight sites on the lower Columbia River in 2007. Significant findings from the data include: From early July to mid-September 2007, water temperatures were above 20°C (degrees Celsius) at each of the eight lower Columbia River sites. According to the Oregon temperature standard, the 7-day average maximum temperature of the lower Columbia River should not exceed 20°C; Washington regulations state that the 1-day maximum should not exceed 20°C due to human activities. Most in-situ field checks of total-dissolved-gas sensors with a secondary standard were within ± (plus or minus) 1% saturation after 3 to 4 weeks of deployment in the river. All of the field checks of barometric pressure were within ±2.5 millimeter of mercury of a secondary standard, and water-temperature field checks were all within ±0.2 °C. For the eight monitoring sites in water year 2007, an average of 99.5% of the total-dissolved-gas data were received in real time by the USGS satellite downlink and were within 1% saturation of the expected value on the basis of calibration data, replicate quality-control measurements in the river, and comparison to ambient river conditions at adjacent sites. Data received from the sites ranged from 97.9% to 100.0% complete.

Lower Columbia River↗
USGS2002

Influence of fluvial processes on the quaternary geologic framework of the continental shelf, North Carolina, USA

Digital, single-channel, high-resolution seismic reflection profiles were acquired from the insular continental shelf of North Carolina, USA along a data grid extending from Oregon Inlet northward 48 km to Duck, North Carolina and from the nearshore zone seaward approximately 28 km (total surveyed area= 1334 km2). These data were processed and interpreted to delineate principal reflecting horizons and develop a three-dimensional seismic stratigraphic framework for the continental shelf that was compared to stratigraphic data from the shoreward back-barrier (estuarine) and barrier island system. Six principal reflecting horizons (designated R0 through R5) were present within the upper 60 m of the shelf stratigraphic succession. Three-dimensional mapping of reflector R1 demonstrated its origin from fluvial incision of the continental shelf during an episode (or episodes) of lowered sea-level. Fluvial processes during development of reflector R1 were responsible for extensive reworking and re-deposition of sediment throughout most of the northern half of the study area. Five seismic stratigraphic units (designated S1 through S5) were tentatively correlated with depositional sequences previously identified from the North Carolina back-barrier (estuarine) and barrier island system. These five stratigraphic units span the Quaternary Period (S1 = early Holocene; S2 = 51-78 ka; S3 = 330-530 ka; S4 = 1.1-1.8 Ma; S5 = earliest Pleistocene). Unit S1 is composed of fine-grained fluvial/estuarine sediment that back-filled incised streams during early Holocene sea-level rise. The four other stratigraphic units (S2-S5) display tabular depositional geometries, low total relief, and thicken toward the east-southeast as their basal reflectors dip gently between 0.41 m km-1 (0.02??) and 0.54 m km-1 (0.03??). Knowledge of the three-dimensional subsurface stratigraphic architecture of the continental shelf enhances understanding of the development of shelf depositional successions and provides a framework for development of better Quaternary sea-level data, especially offshore North Carolina where such data are sparse. ?? 2002 Elsevier Science B.V. All rights reserved.

Marine Geology↗
USGS2025

ShakeAlert® version 3: Expected performance in large earthquakes

The ShakeAlert earthquake early warning (EEW) system partners along with U.S. Geological Survey (USGS) licensed operators deliver EEW alerts to the public and trigger automated systems when a significant earthquake is expected to impact California, Oregon, or Washington. ShakeAlert’s primary goal is to provide usable warning times before the arrival of damaging shaking. EEW is most likely to achieve this goal in large‐magnitude earthquakes. In recent years, ShakeAlert has gone through a series of upgrades to its underlying scientific algorithms aimed at improved performance during large earthquakes. Version 3 of this software recently went live in the production system and includes improvements to all algorithms. The main seismic algorithms that detect an earthquake and characterize its location, magnitude, and fault rupture orientation are faster than older versions. Other key changes include: using real‐time geodetic data to characterize the magnitude growth in large earthquakes; the introduction of an alert pause procedure to compromise between speed near the epicenter and improved accuracy at larger distances; and the inclusion of a nonergodic site‐response model in the ground‐motion predictions. ShakeAlert has achieved its primary goal of usable warning times before strong shaking at some locations in real‐time operations in recent M 6 earthquakes. Using offline tests, we demonstrate usable warning times are possible for many sites with peak shaking values of modified Mercalli intensity (MMI) 7–8 in M 7+ earthquakes and also for many MMI 8–9 sites in M 8+ earthquakes. ShakeAlert partners use a variety of MMI and magnitude thresholds in deciding when to alert their users within bounds set by the USGS. Our study shows that there is room to raise the magnitude thresholds up to about M 5.5 without adversely affecting performance in large earthquakes. The ground‐motion criteria are more complex owing to a significant drop‐off in warning times between the MMI 4 and 5 levels of predicted shaking. However, widely used ShakeAlert products, such as the MMI 3 and 4 contour products, can provide sufficiently long warning times before strong shaking in moderate‐to‐great earthquakes to enable a range of protective actions.

Bulletin of the Seismological Society of America↗
USGS1977

Ground-water data for the Drewsey Resource Area, Harney and Malheur counties, Oregon

Appraisals of the resources of selected management areas in eastern Oregon are being made by the U.S. Bureau of Land Management. To provide needed hydrologic information the Bureau of Land Management requested the U.S. Geological Survey Water Resources Division to inventory ground-water data for the Drewsey Resource Area. Included in this report are well data, drillers ' lithologic logs, hydrographs, a summary of observation-well data, and chemical analyses of ground water. (Woodard-USGS)

Open-File Report↗
USGS1978

U.S. Geological Survey offshore program of resource and geo-environmental studies and topical investigations, Pacific-Arctic region

The Geological Survey's marine geology investigations in the Pacific-Arctic area are presented in this report in the context of the underlying socio-economic problem of expanding the domestic production of oil and gas and other mineral and hard- and soft-rock resources while maintaining acceptable standards in the marine environment. The primary mission of the Survey 's Pacific-Arctic Branch of Marine Geology is to provide scientifically interpreted information about the (1) resource potential, (2) geo-environmental setting, and (3) overall geologic characteristics of the continental margins (that is, the continental shelf, slope and rise) and adjacent deeper water and shallower coastal areas off California, Oregon, Washington, Alaska and Hawaii and also, where it is of interest to the U.S. Government, more remote deep-sea areas of the Pacific-Arctic realm.

Open-File Report↗
USGS1990

The Pacific Northwest; linkage between earthquake and volcano hazards

AS the title of the magazine Earthquake and Volcanoes suggests, these two geological phenomena are often closely associated. Earthquakes frequently precede volcanic eruptions, and volcanoes are often sources of small to intermediate size earthquakes resulting from the movement of magma within the volcano's plumbing system. In the Pacific Northwest, the association between earthquakes and volcanoes is much more fundamental- they both arise from the same large-scale interaction between two plates of the Earth's crust. The oceanic Juan de Fuca plate is being shoved beneath the edge of the continental North American plate in the process known as subduction. The result is the Cascade chain of volcanoes, the potential for very large earthquakes along the coastal margin, and the generation of stresses that produce other regional earthquakes. The Pacific Northwest (Oregon, Washington, and northern California) is experiencing rapid industrial and population growth. The same conditions that make the region attractive- close proximity to both mountains and oceans, volcanoes and spectacular inland waters- also present significant geologic hazards that are easily overlooked in the normal timetable of human activities. The catastrophic eruption of Mount St. Helens 10 years ago serves as a dramatic reminder of the forces of nature that can be unleashed through volcanism. other volcanoes such as mount Rainier, a majestic symbol of Washington, or Mount hood in Oregon, lie closer to population centers and could present far greater hazards should they become active. Earthquakes may affect even larger regions, prodcuging more cumulative damage.

Pacific Northwest↗
USGS2001

Data-collection methods, quality-assurance data, and site considerations for total dissolved gas monitoring, lower Columbia River, Oregon and Washington, 2000

Excessive total dissolved gas pressure can cause gas-bubble trauma in fish downstream from dams on the Columbia River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey collected data on total dissolved gas pressure, barometric pressure, water temperature, and probe depth at eight stations on the lower Columbia River from the John Day forebay (river mile 215.6) to Camas (river mile 121.7) in water year 2000 (October 1, 1999, to September 30, 2000). These data are in the databases of the U.S. Geological Survey and the U.S. Army Corps of Engineers. Methods of data collection, review, and processing, and quality-assurance data are presented in this report.

Oregon, Washington↗