The Bishop Tuff: New insights from eruptive stratigraphy
C. J. N. Wilson, W. Hildreth
1997, Journal of Geology (105) 407-439
The 0.76 Ma Bishop Tuff, from Long Valley caldera in eastern California, consists of a widespread fall deposit and voluminous partly welded ignimbrite. The fall deposit (F), exposed over an easterly sector below and adjacent to the ignimbrite, is divided into nine units (F1‐F9), with no significant time breaks, except...
Determination of site amplification in the Los Angeles urban area from inversion of strong-motion records
S. C. Harmsen
1997, Bulletin of the Seismological Society of America (87) 866-887
The amplification of strong ground motion at sites in the greater Los Angeles, California, region is determined using the generalized-inverse method of Andrews (1986). Site-amplification estimates are determined at 281 strong-motion sites that provided horizontal-component accelerograms from the 1971 San Fernando, 1987 Whittier Narrows, 1991 Sierra Madre, or 1994 Northridge...
Estimating the diminution of shear-wave amplitude with distance: Application to the Los Angeles, California, urban area
S. C. Harmsen
1997, Bulletin of the Seismological Society of America (87) 888-903
The rate of decay with distance of shear-wave amplitude, computed from 20-sec S-wave spectra, is determined from TERRAscope records of small earthquakes in the greater Los Angeles area. Piecewise log-linear interpolation functions and traditional diminution functions are used to fit spectral decay to a...
Anthropogenic molecular markers: Tools to identify the sources and transport pathways of pollutants
H. Takada, F. Satoh, Michael H. Bothner, B.W. Tripp, C.G. Johnson, J.W. Farrington
1997, ACS Symposium Series (671) 178-195
The activities of modern civilization have released to the oceans a wide variety of both mobilized natural compounds and synthetic compounds not found prior to modern times. Many of these compounds provide a means of identifying sources of inputs and pathways of movement of chemicals through oceanic ecosystems and serve...
222Rn transport in a fractured crystalline rock aquifer: Results from numerical simulations
P. F. Folger, E. Poeter, R. B. Wanty, W. Day, D. Frishman
1997, Journal of Hydrology (195) 45-77
Dissolved 222Rn concentrations in ground water from a small wellfield underlain by fractured Middle Proterozoic Pikes Peak Granite southwest of Denver, Colorado range from 124 to 840 kBq m-3 (3360-22700 pCi L-1). Numerical simulations of flow and transport between two wells show that differences in equivalent hydraulic aperture of transmissive...
Using δ87Sr values to identify sources of salinity to a freshwater aquifer, Greater Aneth Oil Field, Utah, USA
D. L. Naftz, Z. E. Peterman, L.E. Spangler
1997, Chemical Geology (141) 195-209
Salinity increases in water from the freshwater Navajo aquifer in the Aneth area have been documented in recent years. Previous studies during the 1980s in the Aneth area suggested that brines associated with oil production and their subsequent re-injection were the probable source of salinity in the Navajo aquifer. Differences...
Evidence for radionuclide transport by sea ice
D.A. Meese, E. Reimnitz, W. B. Tucker III, A. J. Gow, J. Bischof, D. Darby
1997, Conference Paper, Science of the Total Environment
Ice and ice-borne sediments were collected across the Arctic Basin during the Arctic Ocean Section, 1994 (AOS-94), a recent US/Canada trans- Arctic expedition. Sediments were analysed for 137Cs, clay mineralogy and carbon. Concentrations of 137Cs ranged from 5 to 73 Bq kg-1 in the ice- borne sediments. Concentrations of ice...
Foreland crustal structure of the New York recess, northeastern United States
G.C. Herman, D.H. Monteverde, R.W. Schlische, D.M. Pitcher
1997, Geological Society of America Bulletin (109) 955-977
A new structural model for the northeast part of the Central Appalachian foreland and fold-and-thrust belt is based on detailed field mapping, geophysical data, and balanced cross-section analysis. The model demonstrates that the region contains a multiply deformed, parautochthonous fold-and-thrust system of Paleozoic age. Our interpretations differ from previous ones...
A watershed approach to ecosystem monitoring in Denali National Park and preserve, Alaska
L.K. Thorsteinson, D.L. Taylor
1997, Journal of the American Water Resources Association (33) 795-810
The National Park Service and the National Biological Service initiated research in Denali National Park and Preserve, a 2.4 million-hectare park in southcentral Alaska, to develop ecological monitoring protocols for national parks in the Arctic/Subarctic biogeographic area. We are focusing pilot studies on design questions, on scaling issues and regionalization,...
Seismic source study of the Racha-Dzhava (Georgia) earthquake from aftershocks and broad-band teleseismic body-wave records: An example of active nappe tectonics
H. Fuenzalida, L. Rivera, H. Haessler, D. Legrand, H. Philip, L. Dorbath, D. McCormack, S. Arefiev, C. Langer, A. Cisternas
1997, Geophysical Journal International (130) 29-46
The Racha-Dzhava earthquake (Ms=7.0) that occurred on 1991 April 29 at 09:12:48.1 GMT in the southern border of the Great Caucasus is the biggest event ever recorded in the region, stronger than the Spitak earthquake (Ms=6.9) of 1988. A field expedition to the epicentral area was organised and a...
Coseismic deformation during the 1989 Loma Prieta earthquake and range-front thrusting along the southwestern margin of the Santa Clara Valley, California
V.E. Langenheim, K. M. Schmidt, R.C. Jachens
1997, Geology (25) 1091-1094
Damage patterns caused by the 1989 Loma Prieta earthquake along the southwestern margin of the Santa Clara Valley, California, form three zones that coincide with mapped and inferred traces of range-front thrust faults northeast of the San Andreas fault. Damage in these zones was largely contractional, consistent with past displacement...
Shallow seismic reflection profiles and geological structure in the Benton Hills, southeast Missouri
J. R. Palmer, D. Hoffman, W. J. Stephenson, J. K. Odum, R. A. Williams
1997, Engineering Geology (46) 217-233
During late May and early June of 1993, we conducted two shallow, high-resolution seismic reflection surveys (Mini-Sosie method) across the southern escarpment of the Benton Hills segment of Crowleys Ridge. The reflection profiles imaged numerous post-late Cretaceous faults and folds. We believe these faults may represent a significant earthquake source...
Upper Mississippi embayment shallow seismic velocities measured in situ
Huaibao P. Liu, Y. Hu, J. Dorman, T.-S. Chang, J.-M. Chiu
1997, Engineering Geology (46) 313-330
Vertical seismic compressional- and shear-wave (P- and S-wave) profiles were collected from three shallow boreholes in sediment of the upper Mississippi embayment. The site of the 60-m hole at Shelby Forest, Tennessee, is on bluffs forming the eastern edge of the Mississippi alluvial plain. The bluffs are composed of Pleistocene...
Geology and preliminary dating of the hominid-bearing sedimentary fill of the Sima de los Huesos Chamber, Cueva Mayor of the Sierra de Atapuerca, Burgos, Spain
J. L. Bischoff, J.A. Fitzpatrick, L. Leon, J.L. Arsuaga, Christophe Falgueres, J.-J. Bahain, T. Bullen
1997, Journal of Human Evolution (33) 129-154
Sediments of the Sima de los Huesos vary greatly over distances of a few meters. This is typical of interior cave facies, and caused by cycles of cut and fill. Mud breccias containing human bones, grading upwards to mud containing bear bones, fill an irregular surface cut into basal marls...
Characterisation of physical environmental factors on an intertidal sandflat, Manukau Harbour, New Zealand
R.G. Bell, T.M. Hume, T.J. Dolphin, M.O. Green, R. A. Walters
1997, Conference Paper, Journal of Experimental Marine Biology and Ecology
Physical environmental factors, including sediment characteristics, inundation time, tidal currents and wind waves, likely to influence the structure of the benthic community at meso-scales (1-100 m) were characterised for a sandflat off Wiroa Island (Manukau Harbour, New Zealand). In a 500 x 250 m study site, sediment characteristics and bed...
Moss and soil contributions to the annual net carbon flux of a maturing boreal forest
J.W. Harden, K. P. O’Neill, S.E. Trumbore, H. Veldhuis, B.J. Stocks
1997, Journal of Geophysical Research D: Atmospheres (102) 28805-28816
We used input and decomposition data from 14C studies of soils to determine rates of vertical accumulation of moss combined with carbon storage inventories on a sequence of burns to model how carbon accumulates in soils and moss after a stand-killing fire. We used soil drainage—moss associations and soil drainage maps...
Geology, thermal maturation, and source rock geochemistry in a volcanic covered basin: San Juan sag, south-central Colorado
R. R. Gries, J.L. Clayton, C. Leonard
1997, American Association of Petroleum Geologists Bulletin (81) 1133-1160
The San Juan sag, concealed by the vast San Juan volcanic field of south-central Colorado, has only recently benefited from oil and gas wildcat drilling and evaluations. Sound geochemical analyses and maturation modeling are essential elements for successful exploration and development. Oil has been produced in minor quantities from an...
Effects of carbon dioxide variations in the unsaturated zone on water chemistry in a glacial-outwash aquifer
R. W. Lee
1997, Applied Geochemistry (12) 347-366
The research site at Otis Air Base, Cape Cod, Massachusetts, has been developed for hydrogeological and geochemical studies of sewage-effluent contaminated groundwater since 1982. Research of hydrologic properties, transport, and chemical and biological processes is ongoing, but the origin of background water chemistry has not been determined. The principal geochemical...
The wind-forced response on a buoyant coastal current: Observations of the western Gulf of Maine plume
D.A. Fong, W.R. Geyer, R. P. Signell
1997, Journal of Marine Systems (12) 69-81
The Freshwater plume in the western Gulf of Maine is being studied as part of an interdisciplinary investigation of the physical transport of a toxic alga. A field program was conducted in the springs of 1993 and 1994 to map the spatial and temporal patterns of salinity, currents and algal...
Seasonal Sea-Level Variations in San Francisco Bay in Response to Atmospheric Forcing, 1980
Jingyuan Wang, R. T. Cheng, P.C. Smith
1997, Estuarine, Coastal and Shelf Science (45) 39-52
The seasonal response of sea level in San Francisco Bay (SFB) to atmospheric forcing during 1980 is investigated. The relations between sea-level data from the Northern Reach, Central Bay and South Bay, and forcing by local wind stresses, sea level pressure (SLP), runoff and the large scale sea level pressure...
Scale-up of ecological experiments: Density variation in the mobile bivalve Macomona liliana
Davod C. Schneider, R. Walters, S. Thrush, P. Dayton
1997, Conference Paper, Journal of Experimental Marine Biology and Ecology
At present the problem of scaling up from controlled experiments (necessarily at a small spatial scale) to questions of regional or global importance is perhaps the most pressing issue in ecology. Most of the proposed techniques recommend iterative cycling between theory and experiment. We present a graphical technique that facilitates...
Geochemical mole-balance modeling with uncertain data
David L. Parkhurst
1997, Water Resources Research (33) 1957-1970
Geochemical mole-balance models are sets of chemical reactions that quantitatively account for changes in the chemical and isotopic composition of water along a flow path. A revised mole-balance formulation that includes an uncertainty term for each chemical and isotopic datum is derived. The revised formulation is comprised of mole-balance equations...
Evaluation of conditions along the grounding line of temperate marine glaciers: An example from Muir Inlet, Glacier Bay, Alaska
K.C. Seramur, R.D. Powell, P.R. Carlson
1997, Marine Geology (140) 307-327
In the marine environment, stability of the glacier terminus and the location of subglacial streams are the dominant controls on the distribution of grounding-line deposits within morainal banks. A morainal bank complex in Muir Inlet, Glacier Bay, SE Alaska, is used to develop a model of terminus stability and location...
Applications of the U.S. Geological Survey's global land cover product
B. Reed
1997, Acta Astronautica (41) 671-680
The U.S. Geological Survey (USGS), in partnership with several international agencies and universities, has produced a global land cover characteristics database. The land cover data were created using multitemporal analysis of advanced very high resolution radiometer satellite images in conjunction with other existing geographic data. A translation table permits the...
Watershed responses to climate change at Glacier National Park
D.B. Fagre, P.L. Comanor, J.D. White, F. Richard Hauer, S. W. Running
1997, Journal of the American Water Resources Association (33) 755-765
We have developed an approach which examines ecosystem function and the potential effects of climatic shifts. The Lake McDonald watershed of Glacier National Park was the focus for two linked research activities: acquisition of baseline data on hydrologic, chemical and aquatic organism attributes that characterize this pristine northern rocky mountain...
