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At least 1,333 records · Page 74Linked to original sources

P wave crustal velocity structure in the greater Mount Rainier area from local earthquake tomography

We present results from a local earthquake tomographic imaging experiment in the greater Mount Rainier area. We inverted P wave arrival times from local earthquakes recorded at permanent and temporary Pacific Northwest Seismograph Network seismographs between 1980 and 1996. We used a method similar to that described by Lees and Crosson [1989], modified to incorporate the parameter separation method for decoupling the hypocenter and velocity problems. In the upper 7 km of the resulting model there is good correlation between velocity anomalies and surface geology. Many focal mechanisms within the St. Helens seismic zone have nodal planes parallel to the epicentral trend as well as to a north-south trending low-velocity trough, leading us to speculate that the trough represents a zone of structural weakness in which a moderate ( M 6.5–7.0) earthquake could occur. In contrast, the western Rainier seismic zone does not correlate in any simple way with anomaly patterns or focal mechanism fault planes, leading us to infer that it is less likely to experience a moderate earthquake. A ∼10 km-wide low-velocity anomaly occurs 5 to 18 km beneath the summit of Mount Rainier, which we interpret to be a signal of a region composed of hot, fractured rock with possible small amounts of melt or fluid. No systematic velocity pattern is observed in association with the southern Washington Cascades conductor. A midcrustal anomaly parallels the Olympic-Wallowa lineament as well as several other geophysical trends, indicating that it may play an important role in regional tectonics.

Journal of Geophysical Research B: Solid Earth↗

A system design for implementing advanced feature descriptions for a map knowledge base

A prototype system to explore Linked Data that semantically integrates geospatial data in various formats from different publication sources with data from The National Map of the U.S. Geological Survey is presented. The focus is on accessing advanced feature descriptions for data from The National Map with data coreferenced from other sources. The prototype uses Geoserver to access The National Map data, which are converted to Resource Description Framework triples using Karma and stored in the Marmotta triplestore. Marmotta uses a Postgres relational database as a backend for the project and queries to the Marmotta triplestore are converted to structured query language and executed by Postgres. Triples retrieved are linked with same_as relationships to external data sources. The links to these sources provide additional attributes and relationships of the data from The National Map. Visualization of the results is provided using Leaflet and workflows for all parts of the system are defined. A use case for the system is provided to access structures and names information from The National Map for the Washington, D.C., area and link these to Geonames data, with visualization of the graphical and tabular results.

Scientific Investigations Report↗

Comparison of flood lavas on Earth and Mars

Flood lavas, by definition, cover vast areas in great sheets of lava, without the construction of major edifices (e.g., Geikie, 1880; Washington, 1922; Tyrrell, 1937; Self et al ., 1997). The flat terrain that flood lavas produce has led to the term “plateau volcanism” to be used as a synonym for flood volcanism. In addition, the classic erosion pattern of flood lavas leaves a series of topographic steps. Thus many flood basalt provinces are known as “traps” from the Scandinavian word for steps. Plateau volcanism transitions to “plains” volcanism when low shields become common (Greeley and King, 1977). It is not surprising that these large-volume eruptions are usually composed of the most common of volcanic rocks: basalt. Thus, the term “flood basalt” is often used interchangeably with “flood volcanism.” However, there can be interesting and significant compositional variability within flood “basalt” provinces. The most general term to describe all large-volume volcanism is “Large Igneous Province” (LIP) (e.g., Coffin and Eldholm, 1994). LIPs represent a major geologic event with significant repercussions on the interior of a planetary body. The extraction of such large volumes of magma can alter the thermal state of the mantle, indicate major changes in the convection patterns within the mantle, and lead to geochemical evolution of the mantle on a regional scale (e.g., Coffin and Eldholm, 1994 and references therein). Flood lavas also alter the face of a planet for geologically significant time.

Book chapter↗

Atmospheric Deposition and Surface-Water Chemistry in Mount Rainier and North Cascades National Parks, U.S.A., Water Years 2000 and 2005-2006

High-elevation aquatic ecosystems in Mount Rainier and North Cascades National Parks are highly sensitive to atmospheric deposition of nitrogen and sulfur. Thin, rocky soils promote fast hydrologic flushing rates during snowmelt and rain events, limiting the ability of basins to neutralize acidity and assimilate nitrogen deposited from the atmosphere. Potential effects of nitrogen and sulfur deposition include episodic or chronic acidification of terrestrial and aquatic ecosystems. In addition, nitrogen deposition can cause eutrophication of water bodies and changes in species composition in lakes and streams. This report documents results of a study performed by the U.S. Geological Survey, in cooperation with the National Park Service, of the effects of atmospheric deposition of nitrogen and sulfur on surface-water chemistry in Mount Rainier and North Cascades National Parks. Inorganic nitrogen in wet deposition was highest in the vicinity of North Cascades National Park, perhaps due to emissions from human sources and activities in the Puget Sound area. Sulfur in wet deposition was highest near the Pacific coast, reflecting the influence of marine aerosols. Dry deposition generally accounted for less than 30 percent of wet plus dry inorganic nitrogen and sulfur deposition, but occult deposition (primarily fog) represents a potentially substantial unmeasured component of total deposition. Trend analyses indicate inorganic nitrogen in wet deposition was relatively stable during 1986-2005, but sulfur in wet deposition declined substantially during that time, particularly after 2001, when emissions controls were added to a large powerplant in western Washington. Surface-water sulfate concentrations at the study site nearest the powerplant showed a statistically significant decrease between 2000 and 2005-06, but there was no statistically significant change in alkalinity, indicating a delayed response in surface-water alkalinity. Seasonal patterns in surface-water chemistry and streamflow are strongly influenced by melting of seasonal snowpacks, which release large amounts of dilute, slightly acidic water to terrestrial and aquatic ecosystems during spring snowmelt. Concentrations of sulfate, alkalinity, and base cations in surface water declined rapidly during snowmelt, then gradually recovered during summer and fall. Preferential elution of acidic solutes from the snowpack at the beginning of snowmelt may cause episodic acidification in small alpine streams; evidence is provided by a stream sample collected at one of the sites during spring 2006 that was acidic (pH = 4.8, alkalinity = -18 microequivalents per liter) and had high concentrations of nitrate and sulfate and low concentrations of weathering products. Rain-on-snow events caused sharp declines in specific conductance, which was measured continuously using an in-stream sensor. A strong correlation was observed between measured specific conductance and measured alkalinity (r2 = 0.76), permitting estimation of alkalinity from specific-conductance data using a regression equation. Estimated alkalinity declined by an order of magnitude during the rain-on-snow events, in one case to 8 microequivalents per liter. Actual declines in alkalinity might be greater because the regression equation accounts only for dilution effects; at low concentrations, the relation between specific conductance and alkalinity is likely to be nonlinear and have a negative intercept (negative alkalinity). Thus, episodic acidification is possible during rain-on-snow events. The scale of episodic acidification is unknown, but if it occurs, it could have detrimental effects on aquatic life and amphibians. Historical lake-survey data indicate that most lakes are oligotrophic and have low nitrogen and phosphorus concentrations. Nitrogen limitation is more common in lakes in Mount Rainier National Park than in North Cascades National Park due to higher nitrate concentrations at North Cascades. T

Scientific Investigations Report↗

SHRIMP U-Pb dating of recurrent Cryogenian and Late Cambrian-Early Ordovician alkalic magmatism in central Idaho: Implications for Rodinian rift tectonics

Composite alkalic plutonic suites and tuffaceous diamictite, although discontinuously exposed across central Idaho in roof pendants and inliers within the Idaho batholith and Challis volcanic-plutonic complex, define the >200-km-long northwest-aligned Big Creek-Beaverhead belt. Sensitive highresolution ion microprobe (SHRIMP) U-Pb zircon dates on these igneous rocks provide direct evidence for the orientation and location of the Neoproterozoic-Paleozoic western Laurentian rift margin in the northern U.S. Cordillera. Dating delimits two discrete magmatic pulses at ca. 665-650 Ma and 500-485 Ma at the western and eastern ends, respectively, of this belt. Together with the nearby 685 Ma volcanic rocks of the Edwardsburg Formation, there is a 200 Ma history of recurrent extensional magmatic pulses along the belt. A similar history of recurrent uplift is reflected in the stratigraphic record of the associated miogeoclinal and cratonal platform basins, suggesting that the Big Creek-Beaverhead belt originated as a border fault during continental rift events. The magmatic belt is paired with the recurrently emergent Lemhi Arch and narrow miogeoclinal facies belts and it lies inboard of a northwest-striking narrow zone of thinned continental crust. These features define a northeast-extending upper-plate extensional system between southeast Washington and southeast Idaho that formed a segment of the Neoproterozoic-Paleozoic miogeocline. This segment was flanked on the north by the St. Mary-Moyie transform zone (south of a narrow southern Canadian upper-plate margin) and on the south by the Snake River transfer zone (north of a broad Great Basin lower-plate margin). These are the central segments of a zigzagshaped Cordilleran rift system of alternating northwest-striking extensional zones offset by northeast-striking transfers and transforms. The data substantiate polyphase rift and continental separation events that included (1) pre-and syn-Windermere rifting, (2) Windermere margin subsidence, (3) late Ediacaran-Cambrain rifting, and (4) welldeveloped late Ediacaran-Devonian passive margin subsidence and deposition. Timing and geometries support synchronous but opposing divergence along Cordilleran and Atlantic rifts with a junction in Southern California-Sonora. ?? 2010 Geological Society of America.

Geological Society of America Bulletin↗

A hydrologic network supporting spatially referenced regression modeling in the Chesapeake Bay watershed

The U.S. Geological Survey has developed a methodology for statistically relating nutrient sources and land-surface characteristics to nutrient loads of streams. The methodology is referred to as SPAtially Referenced Regressions On Watershed attributes (SPARROW), and relates measured stream nutrient loads to nutrient sources using nonlinear statistical regression models. A spatially detailed digital hydrologic network of stream reaches, stream-reach characteristics such as mean streamflow, water velocity, reach length, and travel time, and their associated watersheds supports the regression models. This network serves as the primary framework for spatially referencing potential nutrient source information such as atmospheric deposition, septic systems, point-sources, land use, land cover, and agricultural sources and land-surface characteristics such as land use, land cover, average-annual precipitation and temperature, slope, and soil permeability. In the Chesapeake Bay watershed that covers parts of Delaware, Maryland, Pennsylvania, New York, Virginia, West Virginia, and Washington D.C., SPARROW was used to generate models estimating loads of total nitrogen and total phosphorus representing 1987 and 1992 land-surface conditions. The 1987 models used a hydrologic network derived from an enhanced version of the U.S. Environmental Protection Agency's digital River Reach File, and course resolution Digital Elevation Models (DEMs). A new hydrologic network was created to support the 1992 models by generating stream reaches representing surface-water pathways defined by flow direction and flow accumulation algorithms from higher resolution DEMs. On a reach-by-reach basis, stream reach characteristics essential to the modeling were transferred to the newly generated pathways or reaches from the enhanced River Reach File used to support the 1987 models. To complete the new network, watersheds for each reach were generated using the direction of surface-water flow derived from the DEMs. This network improves upon existing digital stream data by increasing the level of spatial detail and providing consistency between the reach locations and topography. The hydrologic network also aids in illustrating the spatial patterns of predicted nutrient loads and sources contributed locally to each stream, and the percentages of nutrient load that reach Chesapeake Bay.

Environmental Monitoring and Assessment↗

Wind River watershed restoration. Annual report. November 2011 through October 2012

Introduction This report summarizes work by U.S. Geological Survey’s Columbia River Research Laboratory (USGS-CRRL) in the Wind River subbasin, from November 2011 through October 2012. Funding was provided by Bonneville Power Administration (BPA) under contract 55275. The primary focus of USGS activities during this time was tagging of parr steelhead Oncorhynchus mykiss with Passive Integrated Transponder (PIT) tags, and establishing a network of instream PIT tag interrogation systems (PTIS). The PIT-tagged parr steelhead will provide movement and life history data through recapture events and detections at instream PTIS systems, will contribute to estimates of adult steelhead returning to the Wind River, and aid in the evaluation of the removal of Hemlock Dam on Trout Creek steelhead populations. The Wind River Watershed project (BPA Project Number 1998-019-00) is a collaborative effort to restore wild steelhead in the Wind River, WA. The four partner agencies are the U.S. Forest Service (USFS), Washington Department of Fish and Wildlife (WDFW), USGS-CRRL, and Underwood Conservation District (UCD). This partnership was established in the early 1990s with support from BPA, and has continued to conduct extensive habitat, research, monitoring, and coordination activities across the subbasin. The project works at multiple levels to identify and characterize key limiting habitat factors in the Wind River; restore degraded habitats and watershed processes; document fish populations, life histories, and interactions; investigate efficacy of restoration actions; and to share information across agency and non-agency boundaries. Long-term research in the Wind River has focused on assessments of steelhead/rainbow trout populations, relationships with introduced populations of spring Chinook salmon O. tshawytscha and brook trout Salvelinus fontinalis , and effects of habitat variables and habitat restoration on fish productivity. During the period covered by this report, we PIT tagged steelhead parr in headwater sections of the subbasin (Figure 1), maintained a PTIS in Trout Creek, installed a PTIS in the Wind River, and installed smaller scale PTISs in Trapper Creek, Paradise Creek, and the Wind River upstream of Paradise Creek (Figure 2). Additionally we maintained thermologgers to collect water temperature data near the PIT tagging sites. A statement of work (SOW) was submitted to BPA in October 2011 that outlined work to be performed by USGS-CRRL. The SOW was organized by Work Element (WE), with each describing a research task. This report summarizes the progress completed under each WE.

Washington↗

Low-flow characteristics of streams in the Puget Sound region, Washington

Periods of low streamflow are usually the most critical factor in relation to most water uses. The purpose of this report is to present data on low-flow characteristics of streams in the Puget Sound region, Washington, and to briefly explain some of the factors that influence low flow in the various basins. Presented are data on low-flow frequencies of streams in the Puget Sound region, as gathered at 150 gaging stations. Four indexes were computed from the flow-flow-frequency curves and were used as a basis to compare the low-flow characteristics of the streams. The indexes are the (1) low-flow-yield index, expressed in unit runoff per square mile; (2) base-flow index, or the ratio of the median 7-day low flow to the average discharge; (3) slope index, or slope of annual 7-day low-flow-frequency curve; and (4) spacing index, or spread between the 7-day and 183-day low-flow-frequency curves. The indexes showed a wide variation between streams due to the complex interrelation between climate, topography, and geology. The largest low-flow-yield indexes determined--greater than 1.5 cfs (cubic feet per second) per square mile--were for streams that head at high altitudes in the Cascade and Olympic Mountains and have their sources at glaciers. The smallest low-flow-yield indexes--less than 0.5 cfs per square mile--were for the small streams that drain the lowlands adjacent to Puget Sound. Indexes between the two extremes were for nonglacial streams that head at fairly high altitudes in areas of abundant precipitation. The base-flow index has variations that can be attributed to a basin's hydrogeology, with very little influence from climate. The largest base-flow indexes were obtained for streams draining permeable unconsolidated glacial and alluvial sediments in parts of the lowlands adjacent to Puget Sound. Large volume of ground water in these materials sustain flows during late summer. The smallest indexes were computed for streams draining areas underlain by relatively impermeable igneous, sedimentary, and metamorphic rocks or by relatively impermeable glacial till. Melt water from snow and ice influences the index for streams which originate at glaciers, and result in fairly large indexes--0.25 or greater. The slope index is influenced principally by the character of the geologic materials that underlie the basin. The largest slope indexes were computed for small streams that drain areas underlain by compact glacial till or consolidated sedimentary rocks. In contrast, lowland streams that flow through areas underlain by unconsolidated alluvia and glacial deposits have the smallest indexes. Small slope indexes also are characteristic of glacial streams and show the moderating effect of the snow and ice storage in the high mountain basins. The spacing indexes are similar to the slope indexes in that they are affected by the character of the geologic materials underlying a basin. The largest spacing indexes are characteristic of small streams whose basins are underlain by glacial till or by consolidated sedimentary rocks. The smallest indexes were computed for some lowland streams draining areas underlain by permeable glacial and alluvial sediments. The indexes do not appear to have a definite relation to each other. The low-flow-yield indexes are not related to either the slope or spacing indexes because snow and ice storage has a great influence on the low-flow-yield index, while the character of the geologic materials influences the slope and spacing indexes. A relation exists between the slope and spacing indexes but many anomalies occur that cannot be explained by the geology of the basins.

Open-File Report↗

The National Assessment of Shoreline Change: A GIS compilation of vector shorelines and associated shoreline change data for the sandy shorelines of the California coast

Introduction The Coastal and Marine Geology Program of the U.S. Geological Survey has generated a comprehensive data clearinghouse of digital vector shorelines and shoreline change rates for the sandy shoreline along the California open coast. These data, which are presented herein, were compiled as part of the U.S. Geological Survey's National Assessment of Shoreline Change Project. Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information including rates and trends of shoreline migration. There is also a critical need for shoreline change data that is consistent from one coastal region to another. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, and internally consistent updates of shorelines and shoreline change rates can be made at a National Scale. This data compilation for open-ocean, sandy shorelines of the California coast is one in a series that already includes the Gulf of Mexico and the Southeast Atlantic Coast (Morton et al., 2004; Morton et al., 2005) and will eventually cover Washington, Oregon, and parts of Hawaii and Alaska. Short- and long-term shoreline change evaluations are determined by comparing the positions of three historical shorelines digitized from maps, with a modern shoreline derived from LIDAR (light detection and ranging) topographic surveys. Historical shorelines generally represent the following time-periods: 1850s-1880s, 1920s-1930s, and late 1940s-1970s. The most recent shoreline is from data collected between 1997 and 2002. Long-term rates of change are calculated by linear regression using all four shorelines. Short-term rates of change are end-point rate calculations using the two most recent shorelines. Please refer to our full report on shoreline change of the California coastline at http://pubs.usgs.gov/of/2006/1219/ for additional information regarding methods and results (Hapke et al., 2006). Data in this report are organized into downloadable layers by region (Northern, Central and Southern California) and are provided as vector datasets with metadata. Vector shorelines may represent a compilation of data from one or more sources and these sources are included in the dataset metadata. This project employs the Environmental Systems Research Institute's (ESRI) ArcGIS as it's GIS mapping tool and contains several data layers (shapefiles) that are used to create a geographic view of the California Coast. These vector data form a basemap comprised of polygon and line themes that include a U.S. coastline (1:80,000), U.S. cities, and state boundaries.

California↗

Evaluation of sockeye salmon after passage through an innovative upstream fish-passage system at Cle Elum Dam, Washington, 2017

Executive Summary The Bureau of Reclamation (Reclamation) and the Washington State Department of Ecology (Ecology), working with the Yakima River Basin Water Enhancement Project Workgroup (composed of representatives of the Yakama Nation; Federal, State, county, and city governments; environmental organizations; and irrigation districts), developed the Yakima Basin Integrated Plan (Integrated Plan). The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima Basin to be implemented over a 30-year period. The Integrated Plan includes seven elements: Reservoir fish passage, Structural and operational changes to existing facilities, Surface water storage, Groundwater storage, Habitat/watershed protection and enhancement, Enhanced water conservation, and Market reallocation. The first listed element, reservoir fish passage, will be expensive and take many years to accomplish. Reclamation and Ecology decided to look at new and innovative means to provide passage that could help reduce project cost and construction timing while maintaining survival rates of traditional upstream passage facilities. Reclamation contracted with the U.S. Geological Survey to do a study to evaluate the outcome of passage through one innovative fish-passage system at Cle Elum Dam, the first Integrated Plan reservoir fish-passage project being implemented.

Washington↗

Summary of suspended-sediment data for streams draining the Chesapeake Bay Watershed, water years 1952-2002

U.S. Geological Survey suspended-sediment data from 1952 to 2002 from selected stream-gaging stations draining the nontidal parts of the Chesapeake Bay Watershed were summarized to identify areas in the Watershed with high suspended-sediment loads, yields, and concentrations. The suspended-sediment load data were separated into two periods, 1952?1984 and 1985?2001. In 1985, the Chesapeake Bay Program began recommending sediment regulations, so 1985 represents an important break in the data. The instantaneous suspended-sediment concentration data were examined for the period 1985?2002. Suspended-sediment load data collected from 43 stations from 1952?1984, with a minimum of 3 years of record, indicated that the two highest average annual suspended-sediment loads were for stations on the main stem of the Potomac and Susquehanna Rivers. The highest average annual sediment yields and discharge-weighted sediment concentrations were for streams draining the metropolitan Washington, D.C. area, possibly related to urbanization. Data from 1985 through 2001 that were collected from 35 stations with a minimum of 3 years of record showed that the highest average annual suspended-sediment loads were also on the main stem of the Potomac and Susquehanna Rivers. Four of the six highest average annual sediment yields and discharge-weighted sediment concentrations for 1985?2001 were for stations draining to the Conestoga River, a tributary of the Susquehanna River. Examination of percentiles (10th, 50th, and 90th) of instantaneous suspended-sediment concentrations for 51 stations with a minimum of 3 years of data and at least 10 samples in a year indicated that streams that drain to the Conestoga River had the highest suspended-sediment concentrations. Sediment-transport curves for the 51 stations were separated into classes by drainage-area size. Five of the eight drainage-area classes showed that streams draining the Susquehanna River Basin had the highest suspended-sediment concentrations. Three of the Susquehanna River Basin drainage-area classes were in the Conestoga River Basin. Agriculture is the dominant land use in the Conestoga River Basin and may be an important source of sediment leading to the high sediment yields and instantaneous suspended-sediment concentrations, but further research is needed to quantify the importance of agriculture in relation to other sources of sediment in the Conestoga River Basin.

Scientific Investigations Report↗

Controls on ground-water chemistry in the Horse Heaven Hills, south-central Washington

Miocene basaltic aquifers are the source of domestic and municipal water, and about 20,000 acre-feet of irrigation water annually, in the Horse Heaven Hills in south-central Washington State. Groundwater chemical variations derive from the hydraulic characteristics is of the geohydrologic system, from groundwater basalt reactions, and from irrigation. Some dissolved species concentrations increase with residence time; others decrease. Recharge area groundwaters are calcium magnesium sodium bicarbonate waters with sodium-adsorption ratios (SAR's) less than 1.0. They evolve to sodium potassium bicarbonate waters with SAR 's as high as 17. Glassy and cryptocrystalline phases of the basalt are the main sources of dissolved sodium. They dissolve by silicate hydrolysis in carbon dioxide charged waters that recharge the aquifer system. Dissolved silicon, iron, and aluminum concentrations are controlled by the solubilities of amorphous secondary alteration products, which order to silica phases, oxyhydroxides, and smectite. Carbonate mineral precipitation is induced by increasing pH from the hydrolysis reaction. Sodium and potassium concentrations increase until clinoptilolite saturation is reached and precipitation begins. Deviations from the general variation patterns are due to localized geologic structures which distort the groundwater flow system, and to the irrigation use of Columbia River water. (USGS)

Water-Resources Investigations Report↗

Origin of two clay-mineral facies of the Potomac Group (Cretaceous) in the Middle Atlantic States

Sedimentary clay that crops out in the coastal plains of New Jersey, Delaware, the part of Maryland north and east of Washington, B.C., and the northeast half of Washington, D.C., in the nonmarine Cretaceous Potomac Group is predominantly kaolinite and illite. In contrast, in part of southeastern Maryland, the southwest half of Washington, D.C., and most of eastern Virginia, Potomac Group clay is predominantly montmorillonite. Kaolinite and illite were probably derived by intense acid weathering of metamorphic and granitic rocks to the west during the Cretaceous and were deposited in a well-drained basin. Montmorillonite was most likely produced by deep weathering of a mainly granitic source. Poor drainage and alkaline surface- and ground-water conditions probably accompanied the production, transportation, deposition, and burial of the montmorillonite. Kaolinization of the montmorillonite is taking place now at the surface in northern Virginia.

Delaware, Maryland, New Jersey, Pennsylvania, Virg↗

Active tectonics of the Seattle fault and central Puget sound, Washington - Implications for earthquake hazards

We use an extensive network of marine high-resolution and conventional industry seismic-reflection data to constrain the location, shallow structure, and displacement rates of the Seattle fault zone and crosscutting high-angle faults in the Puget Lowland of western Washington. Analysis of seismic profiles extending 50 km across the Puget Lowland from Lake Washington to Hood Canal indicates that the west-trending Seattle fault comprises a broad (4–6 km) zone of three or more south-dipping reverse faults. Quaternary sediment has been folded and faulted along all faults in the zone but is clearly most pronounced along fault A, the northernmost fault, which forms the boundary between the Seattle uplift and Seattle basin. Analysis of growth strata deposited across fault A indicate minimum Quaternary slip rates of about 0.6 mm/yr. Slip rates across the entire zone are estimated to be 0.7–1.1 mm/yr.

Washington↗

A compendium of P- and S-wave velocities from surface-to-borehole logging; summary and reanalysis of previously published data and analysis of unpublished data

For over 28 years, the U.S. Geological Survey (USGS) has been acquiring seismic velocity and geologic data at a number of locations in California, many of which were chosen because strong ground motions from earthquakes were recorded at the sites. The method for all measurements involves picking first arrivals of P- and S-waves from a surface source recorded at various depths in a borehole (as opposed to noninvasive methods, such as the SASW method [e.g., Brown et al., 2002]). The results from most of the sites are contained in a series of U.S. Geological Survey Open-File Reports (see References). Until now, none of the results have been available as computer files, and before 1992 the interpretation of the arrival times was in terms of piecemeal interval velocities, with no attempt to derive a layered model that would fit the travel times in an overall sense (the one exception is Porcella, 1984). In this report I reanalyze all of the arrival times in terms of layered models for P- and for S-wave velocities at each site, and I provide the results as computer files. In addition to the measurements reported in the open-file reports, I also include some borehole results from other reports, as well as some results never before published. I include data for 277 boreholes (at the time of this writing; more will be added to the web site as they are obtained), all in California (I have data from boreholes in Washington and Utah, but these will be published separately). I am also in the process of interpreting travel time data obtained using a seismic cone penetrometer at hundreds of sites; these data can be interpreted in the same way of those obtained from surface-to-borehole logging. When available, the data will be added to the web site (see below for information on obtaining data from the World Wide Web (WWW)). In addition to the basic borehole data and results, I provide information concerning strong-motion stations that I judge to be close enough to the boreholes that the borehole velocity models can be used as the velocity models beneath the stations.

California↗

Nickel-gold ore of the mackinaw mine, Snohomish County, Washington

The Mackinaw mine ore is of an unusual or unique type, consisting chiefly of niccolite, maucherite, pentlandite, chalcopyrite, cubanite, and magnetite in an altered peridotite. Valleriite, gold and sphalerite are minor primary minerals; chalcocite and violarite or bravoite are supergene minerals. Pyrrhotite and pyrite are absent. From the textural relations it is inferred that a complex copper-nickel-iron sulfide was deposited early. On cooling, the sulfide unmixed into two different complex sulfides, one of which in turn unmixed into chalcopyrite and cubanite, the other into chalcopyrite and pentlandite. The latter exsolution relationship has not been previously reported. Valleriite either exsolved from, or replaced, chalcopyrite. Late solutions altered the niccolite to maucherite, and introduced gold and magnetite. The gold is almost always with maucherite.

Washington↗

MAS/MILS Arc/Info point coverage for the western U.S. (excluding Hawaii)

The U.S. Geological Survey has two international and one regional digital database that contains information on mineral properties. This report describes the conversion of selected data from one of the international databases - MAS/MILS (Mineral Availability System/Mineral Industry Location System) - into a spatial data product. The MAS/MILS database, obtained from the U.S. Bureau of Mines (USBM) upon its closure, contains over 221,000 records of mineral properties and processing facilities throughout the world. However, the majority of the records in the database are of sites located in the western U.S. This is due to the extensive mineral activity that has occurred in the West, and the work done by mineral professionals in the Western, Alaska, and Intermountain Field Operations Centers of the USBM. The purpose of this project was to create a spatial coverage of the western U.S. containing mineral resource information. This coverage includes information for the states of Alaska, Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. For this report, locations from MAS/MILS were converted to a point coverage using a geographic information system (GIS). All work was done using Arc/Info v. 7.0.4. There are 128,441 points in the coverage.

Alaska, Arizona, California, Colorado, Idaho, Mont↗

Water-level surface in the Chicot equivalent aquifer system in southeastern Louisiana, 2009

The Chicot equivalent aquifer system is an important source of freshwater in southeastern Louisiana. In 2005, about 47 million gallons per day (Mgal/d) were withdrawn from the Chicot equivalent aquifer system in East Baton Rouge, East Feliciana, Livingston, Tangipahoa, St. Helena, St. Tammany, Washington, and West Feliciana Parishes. Concentrated withdrawals exceeded 5 Mgal/d in Bogalusa, the city of Baton Rouge, and in northwestern East Baton Rouge Parish. In the study area, about 30,000 wells screened in the Chicot equivalent aquifer system were registered with the Louisiana Department of Transportation and Development (LaDOTD). These wells were constructed for public-supply, industry, irrigation, and domestic uses. Most of the wells were registered as domestic-use wells and are small-diameter, low-yielding wells. Total withdrawal from the Chicot equivalent aquifer system for domestic use was estimated to be 12 Mgal/d in 2005. This report documents the 2009 water-level surface of the Chicot equivalent aquifer system in southeastern Louisiana. The report also shows differences in water-level measurements for the years 1991 and 2009 at selected sites. Understanding changes and trends in water levels is important for continued use, planning, and management of groundwater resources. The U.S. Geological Survey, in cooperation with the Louisiana Department of Transportation and Development, conducted this study of the water-level surface of the Chicot equivalent aquifer system as part of an ongoing effort to monitor groundwater levels in aquifers in Louisiana.

Louisiana↗