Calculation of earthquake rupture histories using a hybrid global search algorithm: Application to the 1992 Landers, California, earthquake
S. Hartzell, P. Liu
1996, Physics of the Earth and Planetary Interiors (95) 79-99
A method is presented for the simultaneous calculation of slip amplitudes and rupture times for a finite fault using a hybrid global search algorithm. The method we use combines simulated annealing with the downhill simplex method to produce a more efficient search algorithm then either of the two constituent parts....
Seismic velocities for hydrate-bearing sediments using weighted equation
Myung W. Lee, D. R. Hutchinson, T. S. Collett, William P. Dillon
1996, Journal of Geophysical Research B: Solid Earth (101) 20347-20358
A weighted equation based on the three-phase time-average and Wood equations is applied to derive a relationship between the compressional wave (P wave) velocity and the amount of hydrates filling the pore space. The proposed theory predicts accurate P wave velocities of marine sediments in the porosity range of 40-80%...
Contaminant trends in lake trout and walleye from the Laurentian Great Lakes
David S. DeVault, Robert J. Hesselberg, Paul W. Rodgers, Timothy J. Feist
1996, Journal of Great Lakes Research (22) 884-895
Trends in PCBs, DDT, and other contaminants have been monitored in Great Lakes lake trout and walleye since the 1970s using composite samples of whole fish. Dramatic declines have been observed in concentrations of PCB, ΣDDT, dieldrin, and oxychlordane, with declines initially following first order loss kinetics. Mean PCB concentrations...
Episodic acidification of a coastal plain stream in Virginia
A. K. O’Brien, K.N. Eshleman
1996, Water, Air, & Soil Pollution (89) 291-316
This study investigates the episodic acidification of Reedy Creek, a wetland-influenced coastal plain stream near Richmond, Virginia. Primary objectives of the study were to quantify the episodic variability of acid- base chemistry in Reedy Creek, to examine the seasonal variability in episodic response and to explain the hydrological and geochemical...
Paleomagnetism of Jurassic radiolarian chert above the Coast Range ophiolite at Stanley Mountain, California, and implications for its paleogeographic origins
J.T. Hagstrum, B.L. Murchey
1996, Geological Society of America Bulletin (108) 643-652
Upper Jurassic red tuffaceous chert above the Coast Range ophiolite at Stanley Mountain, California (lat 35°N, long 240°E), contains three components of remanent magnetization. The first component (A; removed by ≈100–≈200°C) has a direction near the present-day field for southern California and is...
Distribution of nitrate and orthophosphate in selected streams in Central Nebraska
R.A. Boyd
1996, Water Resources Bulletin (32) 1247-1257
The Central Nebraska Basins is one of 60 study units in the National Water-Quality Assessment Program of the U.S. Geological Survey. The study unit includes the Platte River and two major tributaries, the Loup and Elkhorn Rivers. Agriculture is the predominant land use in the study unit, with only eight...
Characteristics of the 1 km AVHRR data set for North America
Z.-L. Zhu, L. Yang
1996, International Journal of Remote Sensing (17) 1915-1924
The North America portion of a new global 1 km AVHRR time-series dataset was produced recently by the U.S. Geological Survey, EROS Data Center. Characteristics of the dataset were evaluated for scan-angle distribution, image area distortion as the result of map projection, distribution of high solar zenith angle, and cloud...
How many seabirds were killed by the Exxon Valdez Oil Spill?
John F. Piatt, R. Glenn Ford
S.D. Rice, R.B. Spies, D.A. Wolfe, B.A. Wright, editor(s)
1996, Conference Paper, American Fisheries Society Symposium 18: Proceedings of the "Exxon Valdez Oil Spill Symposium"
After the Exxon Valdez oil spill of 24 March 1989, 36,115 dead seabirds were recovered from beaches and processed at morgues. Most or all of 1,888 live oiled seabirds brought to rehabilitation centers also died and about 3,260 oiled carcasses were never delivered to morgues. Of these 41,263 carcasses accounted...
Elk response to the La Mesa fire and current status in the Jemez Mountains
Craig D. Allen
Craig D. Allen, editor(s)
1996, General Technical Report RM-GTR-286
Faunal remains in local archeological sites and historic information suggest that elk populations in the Jemez Mountains were low from ca. 1200 A.D. through ca. 1900 A.D., when they were extirpated from this region. Elk were reintroduced to the Jemez country in 1948 and 1964- 1965, and their population apparently...
'Little Ice Age' aridity in the North American Great Plains - a high-resolution reconstruction of salinity fluctuations from Devils Lake, North Dakota, USA: a comment on Fritz, Engstrom and Haskell
Gregg J. Wiche, Robert M. Lent, W. F. Rannie
1996, The Holocene (6) 489-490
On the basis of three sediment-based chronologies, Fritz et al. ( 1994) concluded that during the ’Little Ice Age’ (about AD 1500 to 1850), the Devils Lake Basin generally had less effective moisture (precipitation minus evaporation) and warmer temperatures than at present. In this comment, we argue that historic...
Integrated borehole logging methods for wellhead protection applications
Frederick L. Paillet, W.H. Pedler
1996, Engineering Geology (42) 155-165
Modeling of ground water infiltration and movement in the wellhead area is a critical part of an effective wellhead protection program. Such models depend on an accurate description of the aquifer in the wellhead area so that reliable estimates of contaminant travel times can be used in defining a protection...
Analytical solutions to non-Fickian subsurface dispersion in uniform groundwater flow
S. Zou, J. Xia, Antonis D. Koussis
1996, Journal of Hydrology (179) 237-258
Analytical solutions are obtained by the Fourier transform technique for the one-, two-, and three-dimensional transport of a conservative solute injected instantaneously in a uniform groundwater flow. These solutions account for dispersive non-linearity caused by the heterogeneity of the hydraulic properties...
Isotopic evidence for shifts in atmospheric circulation patterns during the late Quaternary in mid-North America
Ronald Amundson, O. Chadwick, C. Kendall, Y. Wang, M. DeNiro
1996, Geology (24) 23-26
Wyoming is now at the eastern margin of westerlies originating in the Pacific, but in the Pleistocene appears to have received moisture from elsewhere, possibly the Gulf of Mexico. Oxygen isotope ratios of pedogenic carbonate in postglacial terraces correspond to ratios in equilibrium...
An introduction to the Woodworth Study Area
Douglas H. Johnson, Kenneth F. Higgins, Robert O. Woodward
1996, Conference Paper, Proceedings of the North Dakota Academy of Science
The Woodworth Study Area (WSA) was purchased by the U.S. Fish and Wildlife Service (FWS) during the early 1960's as a waterfowl production area. Unlike most such areas, its primary purpose was not to provide waterfowl breeding habitat directly, but instead it was dedicated for use as a research area...
Site response for urban Los Angeles using aftershocks of the Northridge earthquake
S. Hartzell, A. Leeds, A. Frankel, J. Michael
1996, Bulletin of the Seismological Society of America (86) S168-S192
Ground-motion records from aftershocks of the 1994 Northridge earthquake are used to estimate site response in the urban Los Angeles area. Over 1300 shear-wave records from 61 sources and 90 sites are used in a linear inversion for source and site-response spectra. The...
Crustal velocity field near the big bend of California's San Andreas fault
R.A. Snay, M.W. Cline, C.R. Philipp, D.D. Jackson, Y. Feng, Z.-K. Shen, M. Lisowski
1996, Journal of Geophysical Research B: Solid Earth (101) 3173-3185
We use geodetic data spanning the 1920–1992 interval to estimate the horizontal velocity field near the big bend segment of California's San Andreas fault (SAF). More specifically, we estimate a horizontal velocity vector for each node of a two-dimensional grid that has a 15-min-by-15-min mesh and that extends between latitudes...
Hydrologic evaluation methodology for estimating water movement through the unsaturated zone at commercial low-level radioactive waste disposal site
P.D. Meyer, M.L. Rockhold, W.E. Nichols, G.W. Gee
1996, Report
This report identifies key technical issues related to hydrologic assessment of water flow in the unsaturated zone at low-level radioactive waste (LLW) disposal facilities. In addition, a methodology for incorporating these issues in the performance assessment of proposed LLW disposal facilities is identified and evaluated. The issues discussed fall into...
Regression equations for disinfection by-products for the Mississippi, Ohio and Missouri rivers
R. E. Rathbun
1996, Science of the Total Environment (191) 235-244
Trihalomethane and nonpurgeable total organic-halide formation potentials were determined for the chlorination of water samples from the Mississippi, Ohio and Missouri Rivers. Samples were collected during the summer and fall of 1991 and the spring of 1992 at twelve locations on the Mississippi from New Orleans to Minneapolis, and on...
Using remote sensing and GIS techniques to estimate discharge and recharge. fluxes for the Death Valley regional groundwater flow system, USA
F. A. D’Agnese, C.C. Faunt, Turner A. Keith
1996, IAHS-AISH Publication 503-511
The recharge and discharge components of the Death Valley regional groundwater flow system were defined by remote sensing and GIS techniques that integrated disparate data types to develop a spatially complex representation of near-surface hydrological processes. Image classification methods were applied to multispectral satellite data to produce a vegetation map....
Criteria for reducing predation by northern squawfish near juvenile salmonid bypass outfalls at Columbia River dams
Rip S. Shively, Thomas P. Poe, Mindi B. Sheer, Peters
1996, Regulated Rivers: Research & Management (12) 493-500
Predation by northern squawfish (Ptychocheilus oregonensis) has been documented to be significant on emigrating juvenile salmonids near juvenile bypass outfalls at hydroelectric dams on the Columbia River. Criteria for siting juvenile fish bypass outfalls to reduce predation were developed using locational data from radio-tagged northern squawfish...
Bacteriological quality of ground water used for household supply, Lower Susquehanna River basin, Pennsylvania and Maryland
Tammy M. Bickford, Bruce D. Lindsey, M.R. Beaver
1996, Water-Resources Investigations Report 96-4212
This report describes the bacteriological results of a ground-water study conducted from 1993 to 1995 as part of the U.S. Geological Survey's National Water-Quality Assessment Program in the Lower Susquehanna River Basin study unit. Water samples collected from 146 household supply wells were analyzed for fecal-indicator organisms including total coliform,...
Effects of cavity-entrance restrictors on red-cockaded woodpeckers
B.E. Raulston, D.A. James, J.E. Johnson
1996, Wildlife Society Bulletin (24) 694-698
The U.S. Forest Service has installed restrictors on cavity entrances of red-cockaded woodpeckers to limit access by larger cavity-dwelling competitors. This study tested the hypothesis that restrictors have no adverse effects on red-cockaded woodpeckers. Entrance restrictors were placed on openings to 20 cavities used by roosting red-cockaded woodpeckers, and 20...
Relation of landscape position and irrigation to concentrations of alachlor, atrazine, and selected degradates in regolith in northeastern Nebraska
Ingrid M. Verstraeten, D. T. Lewis, D. L. McCallister, A. Parkhurst, E.M. Thurman
1996, ACS Symposium Series (630) 178-197
Concentrations of alachlor, its ethanesulfonic acid degradate, atrazine and its degradates, deethylatrazine and deisopropylatrazine, in the upper regolith and associated shallow aquifers were determined in relation to landscape position (floodplains, terraces, and uplands) and irrigation (nonirrigated and irrigated corn cropland) in 1992. Irrigated and nonirrigated sites were located on each...
The 1993 Mississippi river flood: A one hundred or a one thousand year event?
B.D. Malamud, D.L. Turcotte, C.C. Barton
1996, Environmental & Engineering Geoscience (2) 479-486
Power-law (fractal) extreme-value statistics are applicable to many natural phenomena under a wide variety of circumstances. Data from a hydrologic station in Keokuk, Iowa, shows the great flood of the Mississippi River in 1993 has a recurrence interval on the order of 100 years using power-law statistics applied to partial-duration...
Channel response to sediment wave propagation and movement, Redwood Creek, California, USA
Mary Ann Madej, Vicki Ozaki
1996, Earth Surface Processes and Landforms (21) 911-927
Redwood Creek, north coastal California, USA, has experienced dramatic changes in channel configuration since the 1950s. A series of large floods (in 1955, 1964, 1972 and 1975) combined with the advent of widespread commercial timber harvest and road building resulted in extensive erosion in the basin and contributed high sediment...
