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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 19 recordsLinked to original sources
USGS2008

Liquefaction hazard maps for three earthquake scenarios for the communities of San Jose, Campbell, Cupertino, Los Altos, Los Gatos, Milpitas, Mountain View, Palo Alto, Santa Clara, Saratoga, and Sunnyvale, Northern Santa Clara County, California

Maps showing the probability of surface manifestations of liquefaction in the northern Santa Clara Valley were prepared with liquefaction probability curves. The area includes the communities of San Jose, Campbell, Cupertino, Los Altos, Los Gatos Milpitas, Mountain View, Palo Alto, Santa Clara, Saratoga, and Sunnyvale. The probability curves were based on complementary cumulative frequency distributions of the liquefaction potential index (LPI) for surficial geologic units in the study area. LPI values were computed with extensive cone penetration test soundings. Maps were developed for three earthquake scenarios, an M7.8 on the San Andreas Fault comparable to the 1906 event, an M6.7 on the Hayward Fault comparable to the 1868 event, and an M6.9 on the Calaveras Fault. Ground motions were estimated with the Boore and Atkinson (2008) attenuation relation. Liquefaction is predicted for all three events in young Holocene levee deposits along the major creeks. Liquefaction probabilities are highest for the M7.8 earthquake, ranging from 0.33 to 0.37 if a 1.5-m deep water table is assumed, and 0.10 to 0.14 if a 5-m deep water table is assumed. Liquefaction probabilities of the other surficial geologic units are less than 0.05. Probabilities for the scenario earthquakes are generally consistent with observations during historical earthquakes.

Open-File Report↗
USGS1965

Water resources appraisal of the Anchorage area, Alaska

At the present, water use in the Anchorage area amounts to about 21 mgd (million gallons per day); of this amount ground water accounts for about 10 mgd. By 1980, 60 mgd may be required to meet the demand. The greatest potential problem is overpumping the ground-water reservoir resulting in excessive declines in water levels, which, in turn, might lead to salt-water intrusion. A well-laid plan for conjunctive use of surface and ground water seems to be the most promising means of supplying the expected need of 60 mgd, and of preventing saltwater intrusion of the aquifers. Total inflow into the Anchorage hydrologic system amounts to about 180 mgd. Of this amount Ship and South Fork Campbell Creeks contribute about 130 mgd, North Fork Campbell Creek and other streams contribute an estimated 24 mgd, and precipitation and ground-water inflow contribute an estimated 26 mgd. Of the total outflow, which must be equivalent to the inflow, Ship and Chester Creeks contribute about 94 mgd, Campbell Creek about 25 mgd, and ground-water pumpage contributes an assumed amount of approximately 10 mgd. The difference of 50 mgd between inflow and outflow presumably is accounted for; by submarine discharge beneath Cook Inlet and evapotranspiration. Surface and subsurface storage of excess stream discharge during periods of high flow can overcome the problem of water shortages during periods of greatest demand. Surface storage can be accomplished by construction of an additional dam on Ship Creek. Natural ground-water storage can be supplemented by spreading techniques to increase the amount of ground-water recharge. Additional recharge can be provided by returning air-conditioning water to the aquifer through recharge wells. Recharge along the coastline would be a means of maintaining a fresh-water barrier against salt-water intrusion. The area with the greatest potential for ground-water development is along Ship Creek east and north of Mountain View. The alluvial fan east of Mountain View seems favorable for installation of deep wells; and withdrawal of ground water in this area is not likely to result in salt-water intrusion. Similar favorable conditions exist in the alluvial fan areas of North and South Forks Campbell Creek. Infiltration galleries in alluvial deposits along Ship Creek are a relatively inexpensive and convenient means of withdrawing water. To plan for orderly and economical development of the Anchorage area's water resources, geologic and hydrologic studies are needed. An expanded network of stream-gaging stations and observation wells is needed. Deep wells near the coastline are needed to monitor any changes in chemical quality of ground water that would indicate impending salt-water intrusion. Borehole geophysical studies and pumping tests are needed to define the boundaries and hydraulic characteristics of the aquifers. The primary goal of these and other supplementing studies would be to provide the information needed to construct an electric-analog model of the Anchorage hydrologic system. Such a model would provide a means of assessing quantitatively alternative methods of water development.

Alaska↗
USGS1954

Reconnaissance for radioactive deposits in the Hyder district, southeastern Alaska, 1949

Radioactivity reconnaissance during 1949 in the Hyder district, southeastern Alaska, revealed that radioactive material is widely distributed on the Mountain View property. However, no uranium deposits of commercial value were found in the restricted parts of the district covered by this investigation. Anomalous radioactivity was detected at a number of localities on the Mountain View property, but the source could not be determined at all sites. The most highly radioactive unconcentrated vein sample collected Sn 1949 contained 0.049 percent equivalent uranium, and the most Intensely radioactive vein-material concentrate (specific gravity greater than 2.89) contained 0.398 percent equivalent uranium. Both samples are from the Skookum tunnel on the Mountain View property. The radioactive material on the properties Investigated in the Hyder district appears to be chiefly uranium which occurs In an unidentified, highly radioactive, opaque mineral and, also, in trace amounts in the sulfides of the vein deposits. Some of the radioactive material, however, occurs as disseminated deposits In the Igneous rocks of the district and, also, to a minor extent as thin secondary coatings on fracture surfaces in veins and rocks.

Alaska↗
USGS2015

Evaluation of mercury in rainbow trout collected from Duck Valley Indian Reservation reservoirs, southwestern Idaho and northern Nevada, 2007, 2009, and 2013

The U.S. Geological Survey, in cooperation with the Shoshone-Paiute Tribes of the Duck Valley Indian Reservation, analyzed mercury (Hg) concentration in rainbow trout ( Oncorhynchus mykiss ) collected from three reservoirs on the reservation (Mountain View, Lake Billy Shaw, and Sheep Creek) during sampling events in 2007, 2009, and 2013, to determine the risk of Hg exposure to Tribal members and the general public. Mercury concentration in predatory fish tends to increase with fish length, and this tendency was true for rainbow trout in the reservoirs on the reservation (r 2 = 0.44–0.70). Mean (average) and median Hg concentrations in fish tissue were determined for each reservoir for each sample year. All Hg concentrations were less than the U.S. Environmental Protection Agency’s water-quality criterion of 0.30 milligram per kilogram (mg/kg wet weight [ww]) and the Idaho Department of Environmental Quality’s reasonable potential to exceed threshold of 0.24 mg/kg. Idaho Department of Health and Welfare toxicologists determined that the Hg concentrations in rainbow trout in this study would not warrant a fish-consumption advisory for this species. Throughout this report, statistical findings with a p -value of less than 0.05 are referred to as “significant.” Mean Hg concentrations in fish-tissue samples collected from Mountain View Reservoir were higher in 2007 (0.12 mg/kg ww) than in 2009 and 2013 (0.07 and 0.06 mg/kg ww, respectively), indicating a significant mean decrease. Mean Hg concentrations in fish-tissue samples collected from Lake Billy Shaw showed no significant differences among sample years (2007, 0.12 mg/kg ww; 2009, 0.07 mg/kg ww; 2013, 0.09 mg/kg ww). Mean Hg concentrations in fish-tissue samples collected from Sheep Creek Reservoir significantly increased in 2013 (0.10 mg/kg ww) from concentrations in 2007 and 2009 (0.06 and 0.05 mg/kg ww, respectively). These temporal and spatial variations are not unexpected, as each body of water may differ in the factors and conditions affecting the rate of methylation and demethylation. Coupled with the dynamic put-and-take fishery, the outcomes reflect the system complexities among reservoirs despite their fairly close proximity to one another. The influence of these other factors is evident when the analysis of atmospheric Hg deposition at Mercury Deposition Network site NV02 in northern Nevada showed no significant linear trend in wet Hg deposition rates for 2003–2013 (average 3.02 micrograms per square meter).

Idaho, Nevada↗
USGS1949

Chromite deposits near Seiad and McGuffy Creeks, Siskiyou County, California

The chromite deposits described in this report are in northcentral Siskiyou County, Calif. They are in two long tabular masses of peridotite which lie end to end and trend northnorthwest across the valley of the Klamath River. The Seiad Creek-Red Butte mass extends 10 miles north of the river and the Hamburg-McGuffy Creek mass 8 miles south. The outcrops of both are from 1 to 2 miles wide. The rocks that bound the peridotite on the east are thoroughly reconstructed schist and those bordering it to the west are less-metamorphosed volcanic and sedimentary rocks. The schists have been considered to be pre-Cambrian age, whereas the rocks to the west are probably of early Triassic age. Strictly speaking, the chromite-bearing masses are complex bodies of ultramafic rock consisting mainly of dunite but also containing saxonite, lherzolite, pyroxeni,te and hornblendite (listed in order of abundance). Only the dunite contains chromite ore. The tabular peridotite masses lie parallel to planar structures in the older rocks, but in their internal make-up no large- scale structural pattern has been recognized. The most con- spicuous internal structure is the linear arrangement of the chromite-rich schlieren in the ore-bearing parts of the peri- dotite. A typical ore body may include parts made up of evenly disseminated chromite; the richest and largest bodies, however, are made up of concentrated, closely spaced chromite schlieren of different size, shape, and richness. Some schlieren contain 80 to 95 percent of chromite, but most of them contain 25 percent or less, and the ore must be concentrated to yield a marketable product. Chromite is composed of chromic oxide, alumina, ferric oxide, ferrous oxide, and magnesia in different proportions. Hence the ~bromic-oxide content of pure chromites differ. It is consistently high for the chromite from this area as it ranges from 55 to 58 percent. The iron content is likewise consistently high, ranging from 14 to 21 percent. The total reserves of indicated and inferred ore as of May 1945 were 274,500 short tons, which would average 8 percent Cr 2 O 3 . The Seiad Creek mine (Mountain View group) contained the largest deposit; reserves amounted to 212,000 short tons. The McGuffy Creek mine contained 50,000 short tons of indicated and inferred ore. Four other deposits, the Emma Bell, Kangaroo, Mountain, Fairview, and Ladd, contain a few thousand tons of ore each.

California↗
USGS2021

Origin of the J-M Reef and Lower Banded series, Stillwater Complex, Montana, USA

The origin and parental magma for layered cumulates in the Lower Banded series (LBS) and the J-M Reef Pd-Pt deposit of the Stillwater Complex remains poorly constrained. We present whole-rock lithogeochemistry and mineral chemistry from LBS rocks collected from drill holes and surface samples from the Mountain View area of the complex that in total span nearly the entirety of the LBS stratigraphy. Excess S, Pt, and Pd in the noritic and gabbronoritic cumulates of the LBS indicate that small amounts of high tenor sulfide liquid generated at very low degrees of sulfide oversaturation were ubiquitous parts of the cumulate assemblage. We show that a simple two-stage thermodynamic model of assimilation-batch crystallization of a komatiitic parental magma in the lower crust, produces a close match to a common suite of fine-grained gabbronorite dikes and sills that intrude both the complex and its footwall. After fractionating ultramafic cumulates in the lower crust, the model contaminated komatiitic liquid produces upper crustal cumulates by batch crystallization en route to or at the level of the intrusion. The modeled rocks have compositions and mineral assemblages closely resembling pyroxenite of the Bronzitite zone and both norite and gabbronorite cumulates in the lower LBS. The trends from the Bronzitite zone through Norite zone I and Gabbronorite zone I can be understood as the result of deposition of crystals from successive batches of the same contaminated parental magma, with an upward trend toward greater amounts of cooling before the separation of crystals from liquid. The olivine-bearing suite of Olivine-bearing zone I, which includes the J-M Reef, can be modeled by partial remelting of the same norite and gabbronorite cumulates due to a temporarily increased flux of hot, moderately less contaminated LBS parental magma that infiltrated partially molten cumulates because its density exceeded that of the interstitial liquid. This model suggests that infiltration of hot Mg-rich parental liquid into moderately PGE-enriched footwall cumulates may be fundamental to the formation of the extremely high tenor sulfide mineralization in the J-M Reef ore zone, and perhaps other reef-type deposits worldwide. The same metal tenors that would require silicate/sulfide mass ratios (i.e., R-factors) of 10 5 to 10 6 in a single stage of equilibration would be attained during this second stage of interaction by the incremental infiltration and passage of LBS parental magma through previously sulfide saturated cumulate mush.

Montana↗
USGS2016

Radiocarbon dates for lava flows from northeast rift zone of Mauna Loa Volcano, Hilo 7 1/2 minute quadrangle, Island of Hawaii

Twenty-eight 14 C analyses are reported for carbonized roots and other plant material collected from beneath 15 prehistoric lava flows erupted from the northeast rift zone (NERZ) of Mauna Loa Volcano (ML) utilizing the recovery techniques of Lockwood and Lipman (1980). Most samples were collected from the Hilo 7 1/2’ quadrangle during field work for a geologic map of that quadrangle (Buchanan-Banks, unpub data); a few sample sites are located in adjacent quadrangles: Piihonua to the west and Mountain View to the south. Altitudes are given in English units as well as metric to facilitate locating sites on USGS topographic maps.

Radiocarbon↗
USGS2002

Using dye-tracing and chemical analyses to determine effects of a wastewater discharge to Jam Up Creek on water quality of Big Spring, southeastern Missouri, 2001

On July 5, 2001, approximately 50,000 gallons of partially treated wastewater was accidentally discharged from the Mountain View wastewater-treatment plant in Howell County, Missouri, into nearby Jam Up Creek. The creek is a tributary of the Jacks Fork, a recreational stream administered by the National Park Service (NPS) as part of the Ozark National Scenic Riverways in southeastern Missouri.

Fact Sheet↗
USGS2002

Abstracts for the symposium on the application of neural networks to the earth sciences

Artificial neural networks are a group of mathematical methods that attempt to mimic some of the processes in the human mind. Although the foundations for these ideas were laid as early as 1943 (McCulloch and Pitts, 1943), it wasn't until 1986 (Rumelhart and McClelland, 1986; Masters, 1995) that applications to practical problems became possible. It is the acknowledged superiority of the human mind at recognizing patterns that the artificial neural networks are trying to imitate with their interconnected neurons. Interconnections used in the methods that have been developed allow robust learning. Capabilities of neural networks fall into three kinds of applications: (1) function fitting or prediction, (2) noise reduction or pattern recognition, and (3) classification or placing into types. Because of these capabilities and the powerful abilities of artificial neural networks, there have been increasing applications of these methods in the earth sciences. The abstracts in this document represent excellent samples of the range of applications. Talks associated with the abstracts were presented at the Symposium on the Application of Neural Networks to the Earth Sciences: Seventh International Symposium on Mineral Exploration (ISME–02), held August 20–21, 2002, at NASA Moffett Field, Mountain View, California. This symposium was sponsored by the Mining and Materials Processing Institute of Japan (MMIJ), the U.S. Geological Survey, the Circum-Pacific Council, and NASA. The ISME symposia have been held every two years in order to bring together scientists actively working on diverse quantitative methods applied to the earth sciences. Although the title, International Symposium on Mineral Exploration, suggests exclusive focus on mineral exploration, interests and presentations have always been wide-ranging—abstracts presented here are no exception.

Open-File Report↗
USGS1958

Ground water in the alluvial deposits of the Washita River and its tributaries in Oklahoma

Physical features.--The Washita River heads in the Texas Panhandle, in Hemphill, Roberts, and Wheeler Counties. It flows generally east-southeastward through southwestern and south-central Oklahoma to its confluence with the Red River above Denison, Texas, at a point about 4 miles northwest of Cartwright, Oklahoma. That point of confluence is now beneath the waters of Lake Texoma, into which the river flows near Tishomingo in southern Johnston County. The average gradient of the Washita River is about 3.7 feet per mile, beginning with an elevation of about 2,800 feet at its source, and ending with an elevation of about 510 feet at its mouth. The river is about 626 miles in length. The total area of the Washita River drainage basin is about 7,945 square miles, of which about 463 square miles is in Texas. The 7,482 square miles of the basin in Oklahoma is in the 17 counties of Roger Mills, Beckham, Comanche, Grady, Stephens, McClain, Custer, Washita, Caddo, Kiowa, Garvin, Carter, Bryan, Murray, Pontotoc, Johnston and Marshall. The river has a winding, sinuous course. In some reaches, such as near Anadarko, it flows in broad meanders 3 or 4 miles across which have incised the bedrock. Throughout its course in Oklahoma the river meanders within its alluvial valley, so that the valley is much shorter than the river channel. In Texas and at the western edge of Oklahoma the Washita flows in a valley cut in rocks of the High Plains; much of the coarse gravel and sand of the alluvium is derived from these rocks. About nine-tenths of the Oklahoma portion of the valley, from western Roger Mills County to near Davis in northern Murray County, is cut in Permian redbeds. These red beds consist largely of shale, siltstone, and fine-grained sandstone. In the western part of the basin, down to about Mountain View in northeastern Kiowa County, they contain irregular layers of gypsum. The gypsum locally forms steep valley walls, such as those along State Highway 152 east of Cordell. (available as photostat copy only)

Open-File Report↗