A finite element model for tides and currents with field applications
Roy A. Walters
1988, Communications in Applied Numerical Methods (4) 401-411
A finite element model, based upon the shallow water equations, is used to calculate tidal amplitudes and currents for two field-scale test problems. Because tides are characterized by line spectra, the governing equations are subjected to harmonic decomposition. Thus the solution variables are the real and imaginary parts of the...
Tectonic evolution of Gorda Ridge inferred from sidescan sonar images
D.G. Masson, D.A. Cacchione, D.E. Drake
1988, Marine Geophysical Research (10) 191-204
Gorda Ridge is the southern segment of the Juan de Fuca Ridge complex, in the north-east Pacific. Along-strike spreading-rate variation on Gorda Ridge and deformation of Gorda Plate are evidence for compression between the Pacific and Gorda Plates. GLORIA sidescan sonographs allow the spreading fabric associated with Gorda Ridge to...
Bacterial ethane formation from reduced, ethylated sulfur compounds in anoxic sediments
R.S. Oremland, Michael J. Whiticar, F.E. Strohmaier, R.P. Kiene
1988, Geochimica et Cosmochimica Acta (52) 1895-1904
Trace levels of ethane were produced biologically in anoxic sediment slurries from five chemically different aquatic environments. Gases from these locations displayed biogenic characteristics, having 12C-enriched values of δ13CH4 (−62 to −86%.), δ13C2H6 (−35 to −55%.) and high ratios (720 to 140,000) of CH4[C2H6+ C3H8]">CH4[C2H6+ C3H8]. Endogenous...
Paleoseismicity and neotectonics of the Cordillera Blanca fault zone, northern Peruvian Andes
David P. Schwartz
1988, Journal of Geophysical Research Solid Earth (93) 4712-4730
The Cordillera Bianca fault zone is a major west dipping normal fault that bounds the west side of a 120- to 170-km-wide zone of active extension along the crest of the northern Peruvian Andes. The fault is approximately 210 km long and exhibits continuous geomorphic evidence of repeated late Pleistocene...
Further comments on sensitivities, parameter estimation, and sampling design in one-dimensional analysis of solute transport in porous media
Debra S. Knopman, Clifford I. Voss
1988, Water Resources Research (24) 225-238
Sensitivities of solute concentration to parameters associated with first-order chemical decay, boundary conditions, initial conditions, and multilayer transport are examined in one-dimensional analytical models of transient solute transport in porous media. A sensitivity is a change in solute concentration resulting from a change in a model parameter. Sensitivity analysis is...
On-line estimation of nonlinear physical systems
G. Christakos
1988, Mathematical Geology (20) 111-133
Recursive algorithms for estimating states of nonlinear physical systems are presented. Orthogonality properties are rediscovered and the associated polynomials are used to linearize state and observation models of the underlying random processes. This requires some key hypotheses regarding the structure of these processes, which may then take account of a...
Taolin Zn-Pb-fluorite deposit, People's Republic of China: An example of some problems in fluid inclusion research on mineral deposits
E. Roedder, K.W. Howard
1988, Journal of the Geological Society (145) 163-174
The large Taolin zinc–lead–fluorite deposit in the People’s Republic of China was discovered 28 years ago, but whether its genetic affiliation is Mississippi Valley-type, epithermal, or mesothermal has remained uncertain. Both the ore and gangue (cherty to coarse quartz, plus barite, chlorite and calcite) occur as open space filling in...
Oxygen isotope variations in granulite-grade iron formations: constraints on oxygen diffusion and retrograde isotopic exchange
Z.D. Sharp, J. R. O’Neil, E.J. Essene
1988, Contributions to Mineralogy and Petrology (98) 490-501
The oxygen isotope ratios of various minerals were measured in a granulite-grade iron formation in the Wind River Range, Wyoming. Estimates of temperature and pressure for the terrane using well calibrated geothermometers and geobarometers are 730??50?? C and 5.5??0.5 kbar. The mineral constraints on fluid compositions in the iron formation...
Isotopic evidence for organic matter oxidation by manganese reduction in the formation of stratiform manganese carbonate ore
P.M. Okita, J.B. Maynard, E.C. Spiker, E. R. Force
1988, Geochimica et Cosmochimica Acta (52) 2679-2685
Unlike other marine-sedimentary manganese ore deposits, which are largely composed of manganese oxides, the primary ore at Molango (Hidalgo State, Mexico) is exclusively manganese carbonate (rhodochrosite, Mn-calcite, kutnahorite). Stable isotope studies of the carbonates from Molango provide critical new information relevant to the controversy over syngenetic and diagenetic models of...
New trend- trigonometric model for interpolation and prediction of the geomagnetic field utilizing the new DGRF models
L.R. Alldredge
1988, Journal of Geomagnetism & Geoelectricity (40) 749-759
At the IUGG Assembly at Vancouver during August 1987 new definitive geomagnetic reference field (DGRF) models to degree 10 for 1945, 1950, 1955, and 1960 were adopted by IAGA. Before these new DGRF models were accepted, the author developed a trend and trigonometric model (old trig model) based on the...
Effects of kelp forest removal on associated fish assemblages in central California
James L. Bodkin
1988, Journal of Experimental Marine Biology and Ecology (117) 227-238
Visual surveys along subtidal belt transects were used to compare fish assemblages on an experimental and a control site before and after the removal of a canopy-forming kelp forest. The giant kelp Macrocystis pyrifera (L.) C.A. Agardh was removed at the holdfast from ≈ 1 ha of high relief structurally complex rock...
The seismic radiation from composite models of faulting
J. Boatwright
1988, Bulletin of the Seismological Society of America (78) 489-508
The failure of an asperity, i.e., the dynamic rupture of a small fault area with finite stress drop surrounded by a broken or weak fault area which has no stress drop but which slips after the asperity fails, is proposed as a model for the rupture process of a subevent...
Fuelwood production and use in rural Swaziland: a case-study of two communities
J. A. Allen, D.P. Pimentel, J.P. Lasoie
1988, Forest Ecology and Management (25) 239-254
Information of fuelwood consumption and the local production of wood was collected in two small rural communities in Swaziland. Fuelwood consumption was estimated to be 0.77 t persona??1 yeara??1 in one community (Sigombeni), and 0.63 t persona??1 in the other (Bhekinkhosi). Bhekinkhosi was found to be experiencing a significant fuelwood...
Distribution of late Cenozoic volcanic vents in the Cascade Range: Volcanic arc segmentation and regional tectonic considerations
M. Guffanti, C.S. Weaver
1988, Journal of Geophysical Research Solid Earth (93) 6513-6529
Spatial, temporal, and compositional distributions of approximately 4000 volcanic vents formed since 16 Ma in Washington, Oregon, northern California, and northwestern Nevada illustrate the evolution of volcanism related to subduction of the Juan de Fuca plate system and extension of the Basin and Range province. Vent data were obtained from...
Habitat islands and the equilibrium theory of island biogeography: testing some predictions
M. Brown, J.J. Dinsmore
1988, Oecologia (75) 426-429
Species-area data from a study of marsh birds are used to test five predictions generated by the equilibrium theory of island biogeography. Three predictions are supported: we found a significant species-area relationship, a non-zero level of turnover, and a variance-mean ratio of 0.5. One prediction is rejected: the extinction rates...
Making maps with computers
S.C. Guptill, L.E. Starr
1988, American Scientist (76) 136-142
Soon after their introduction in the 1950s, digital computers were used for various phases of the mapping process, especially for trigonometric calculations of survey data and for orientation of aerial photographs on map manuscripts. In addition, computer-controlled plotters were used to draw simple outline maps. The process of collecting data...
Failure of self-similarity for large (Mw > 81/4) earthquakes
S.H. Hartzell, T. H. Heaton
1988, Bulletin of the Seismological Society of America (78) 478-488
Compares teleseismic P-wave records for earthquakes in the magnitude range from 6.0-9.5 with synthetics for a self-similar, omega 2 source model and conclude that the energy radiated by very large earthquakes (Mw > 81/4) is not self-similar to that radiated from smaller earthquakes (Mw < 81/4). Furthermore, in the period...
Goose counts from aerial photographs using an optical digitizer
D.S. Gilmer, J.A. Brass, L.L. Strong, D.H. Card
1988, Wildlife Society Bulletin (16) 204-206
Abstract has not been submitted...
Lateral fluid flow in a compacting sand-shale sequence: South Caspian basin
John D. Bredehoeft, R. D. Djevanshir, Kenneth Belitz
1988, American Association of Petroleum Geologists Bulletin (72) 416-424
The South Caspian basin contains both sands and shales that have pore-fluid pressures substantially in excess of hydrostatic fluid pressure. Pore-pressure data from the South Caspian basin demonstrate that large differences in excess hydraulic head exist between sand and shale. The data indicate that sands are acting as drains for...
[Book reviews] The Science of Allelopathy, edited by A. R. Putnam and C. Tang; Allelopathy, by E .L. Rice
Jon E. Keeley
1988, Ecology (69) 292-293
Review of: Putnam, Alan R., and Chung-Shih Tang (eds.). 1986. The science of allelopathy. Wiley-Interscience Publications, John Wiley and Sons, New York. xi + 317 p. $52.50. Rice, Elroy L. 1984. Allelopathy. Second Edition. Academic Press, New York. xi + 422 p. $71.00....
Absence of strain accumulation in the Shumagin seismic gap, Alaska, 1980-1987
M. Lisowski, J.C. Savage, W.H. Prescott, W.K. Gross
1988, Journal of Geophysical Research Solid Earth (93) 7909-7922
Measurements of the deformation of a trilateration network in the Shumagin seismic gap in the interval 1980–1987 failed to detect any significant strain accumulation (observed extension rate in the direction of plate convergence 0.00±0.03 μstrain/yr). Dislocation models of the subduction process and measurements at a comparable network at a known...
Deformation in the Yakataga seismic gap, Southern Alaska, 1980-1986
J.C. Savage, M. Lisowski
1988, Journal of Geophysical Research Solid Earth (93) 4731-4744
A 60-by-40-km trilateration network in the Yakataga seismic gap was surveyed in 1980, 1982, 1984, and 1986 with precise electro-optical distance-measuring equipment to measure strain accumulation. The overall deformation is roughly approximated by a 0.24±0.03 µstrain/yr N32°W±2.4° uniaxial contraction that is uniform in time. However, the spatial distribution of deformation...
Resonance of a fluid-driven crack: Radiation properties and implications for the source of long-period events and harmonic tremor
B. Chouet
1988, Journal of Geophysical Research Solid Earth (93) 4375-4400
A dynamic source model is presented, in which a three-dimensional crack containing a viscous compressible fluid is excited into resonance by an impulsive pressure transient applied over a small area ΔS of the crack surface. The crack excitation depends critically on two dimensionless parameters called the crack stiffness, C = (b/μ)(L/d), and...
A statistical method for estimating rates of soil development and ages of geologic deposits: A design for soil-chronosequence studies
P. Switzer, J.W. Harden, R. K. Mark
1988, Mathematical Geology (20) 49-61
A statistical method for estimating rates of soil development in a given region based on calibration from a series of dated soils is used to estimate ages of soils in the same region that are not dated directly. The method is designed specifically to account for sampling procedures and uncertainties...
Parkfield, California, liquefaction prediction (USA)
T.L. Holzer, M.J. Bennett, T. L. Youd, A.T.F. Chen
1988, Bulletin of the Seismological Society of America (78) 385-389
The primary purpose of this short note is to formally record the liquefaction prediction (Holzer et al., 1986) made in connection with this predicted earthquake. In addition, this note serves to alert the seismic engineering community to special instrumentation being installed at the prediction site. The instrumentation will consist of...
