Conference Papers
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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse almost 5,000 conference papers authored by our scientists and refine search by topic, location, year, and advanced search.
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Rarity and diversity in forest ant assemblages of Great Smoky Mountains National Park
We report on a systematic survey of the ant fauna occurring in hardwood forests in the Great Smoky Mountains National Park. At 22-mixed hardwood sites, we collected leaf-litter ant species using Winkler samplers. At eight of those sites, we also collected ants using pitfall and Malaise traps. In total, we collected 53 ant species. As shown in other studies, ant species richness tended to decline w
Authors
J.-P. Lessard, R.R. Dunn, C.R. Parker, N.J. Sanders
Regional beach/cliff system dynamics along the california coast
The coast of California is comprised of both sandy shorelines and cliffed coastline, and in many areas these features spatially coincide. In order to better understand the regional trends of change along the California coast, the U.S. Geological Survey is quantifying both sandy shoreline change and coastal cliff retreat for the state. The resulting database was used to examine the dynamics of the
Authors
C.J. Hapke, Don Reid
Regional dynamics of grassland change in the western Great Plains
This paper examines the contemporary land-cover changes in two western Great Plains ecoregions between 1973 and 2000. Agriculture and other land uses can have a substantial effect on grassland cover that varies regionally depending on the primary driving forces of change. In order to better understand change, the rates, types, and causes of land conversion were examined for 1973, 1980, 1986, 1992,
Authors
M.A. Drummond
Remaining uncertainties in the use of Rn-222 as a quantitative tracer of submarine groundwater discharge
Research performed in many locations over the past decade has shown that radon is an effective tracer for quantifying submarine groundwater discharge (SGD). The technique works because both fresh and saline groundwaters acquire radon from the subterranean environment and display activities that are typically orders of magnitude greater than those found in coastal seawaters. However, some uncertain
Authors
W. C. Burnett, I.R. Santos, Y. Weinstein, P.W. Swarzenski, B. Herut
Risk-targeted versus current seismic design maps for the conterminous United States
The probabilistic portions of the seismic design maps in the NEHRP Provisions (FEMA, 2003/2000/1997), and in the International Building Code (ICC, 2006/2003/2000) and ASCE Standard 7-05 (ASCE, 2005a), provide ground motion values from the USGS that have a 2% probability of being exceeded in 50 years. Under the assumption that the capacity against collapse of structures designed for these "uniform
Authors
Nicolas Luco, Bruce R. Ellingwood, Ronald O. Hamburger, John D. Hooper, Jeffrey K. Kimball, Charles A. Kircher
SAR measurements of surface displacements at Augustine Volcano, Alaska from 1992 to 2005
Augustine volcano is an active stratovolcano located at the southwest of Anchorage, Alaska. Augustine volcano had experienced seven significantly explosive eruptions in 1812, 1883, 1908, 1935, 1963, 1976, and 1986, and a minor eruption in January 2006. We measured the surface displacements of the volcano by radar interferometry and GPS before and after the eruption in 2006. ERS-1/2, RADARSAT-1 and
Authors
C.-W. Lee, Z. Lu, Oh-Ig Kwoun
Scale independence of décollement thrusting
Orogen-scale décollements (detachment surfaces) are an enduring subject of investigation by geoscientists. Uncertainties remain as to how crustal convergence processes maintain the stresses necessary for development of low-angle fault surfaces above which huge slabs of rock are transported horizontally for tens to hundreds of kilometers. Seismic reflection profiles from the southern Appalachian cr
Authors
John H. McBride, Andre J. M. Pugin, Robert D. Hatcher
Seasonal fish community variation in headwater mangrove creeks in the southwestern everglades: An examination of their role as dry-down refuges
The connectivity between the fish community of estuarine mangroves and that of freshwater habitats upstream remains poorly understood. In the Florida Everglades, mangrove-lined creeks link freshwater marshes to estuarine habitats downstream and may act as dry-season refuges for freshwater fishes. We examined seasonal dynamics in the fish community of ecotonal creeks in the southwestern region of E
Authors
Jennifer S. Rehage, W.F. Loftus
Sensitivity of high-frequency Rayleigh-wave data revisited
Rayleigh-wave phase velocity of a layered earth model is a function of frequency and four groups of earth properties: P-wave velocity, S-wave velocity (Vs), density, and thickness of layers. Analysis of the Jacobian matrix (or the difference method) provides a measure of dispersion curve sensitivity to earth properties. Vs is the dominant influence for the fundamental mode (Xia et al., 1999) and h
Authors
J. Xia, R. D. Miller, J. Ivanov
Simulation of submarine groundwater discharge salinity and temperature variations: Implications for remote detection
A hydrological analysis using a numerical simulation was done to identify the transient response of the salinity and temperature of submarine groundwater discharge (SGD) and utilize the results to guide data collection. Results indicate that the amount of SGD fluctuates depending on the ocean stage and geology, with the greatest amount of SGD delivered at low tide when the aquifer is in direct hyd
Authors
A.M. Dausman, C.D. Langevin, M.C. Sukop
Size-based trends and management implications of microhabitat utilization by Brown Treesnakes, with an emphasis on juvenile snakes
The brown treesnake (Boiga irregularis, or BTS), a costly invasive species, has been the subject of intensive research on Guam over the past two decades. The behavior and habitat use of hatchling and juvenile snakes, however, remain largely unknown. We used a long-term dataset of BTS captures (N = 2,415) and a dataset resulting from intensive sampling within and immediately around a 5-ha fenced po
Authors
Gordon H. Rodda, Robert N. Reed
Spatial and temporal structure of macroinvertebrate assemblages, San Francisco Bay salt ponds
No abstract available.
Authors
A.K. Miles, S.E. Spring, M.A. Ricca, J.T. Takekawa, N.D. Athearn, D. H. Schoellhamer