Search Results

No abstract available....

We analyzed spectra of local microearthquakes recorded by the Anza, California, seismic network to isolate the effects of site response and to investigate the scaling of source parameters for small earthquakes. Spectra of microearthquakes (M < 2; Mo < 1019 dyne-cm) at Anza have shapes characteristic of the receiver sites...

Drilling of a 12,000-foot-deep scientific well has been completed at Cajon Pass in southern California to measure crustal properties, to determine crustal structure, and to better understanding the generation of earthquakes along the San Andreas fault. A joint effort of the National Science Foundation (NFS) and the U.S Geological Survey...

The teleseismic long-period waveforms recorded by the Global Digital Seismograph Network from the two largest Superstition Hills earthquakes are inverted using an algorithm based on optimal filter theory. These solutions differ slightly from those published in the Preliminary Determination of Epicenters Monthly Listing because a somewhat different, improved data set...

There were no major earthquakes (7.0-7.9) during this reporting period. Earthquake-related deaths were reported from Czechoslovakia and injuries were reported from Algeria and Greece. In the United States a sharp earthquake occurred in eastern Kentucky, causing some minro damage. ...

The first great earthquake (8.0 or above) to occur since 1986 struck in this period in the Macquarie Island region, a very sparsely populated area. In the United States a strong earthquake hit Hawaii on June 26 injuring five people and causing considerable damage....

Chemical hydrogeology, including organic and inorganic aspects, has contributed to an increased understanding of groundwater flow systems, geologic processes, and stressed environments. Most of the basic principles of inorganic-chemical hydrogeology were first established by investigations of organic-free, regional-scale systems for which simplifying assumptions could be made. The problems of groundwater...

The first major earthquake (7.0-7.9) of the year hit Mexico on April 25, killing three people and causing some damage. Earthquake-related deaths were also reported from Malawi, China, and New Britain.  In the United States minor damage was reported from both central and southern California and from Puerto Rico. ...

Gas phase axial dispersion was characterized within an enclosed packed column receiving oxygen and water under counter-current flow conditions. Steady-state gas phase profiles (longitudinal) were measured during a series of 90 column runs in which, at each of three bed depths (0·362, 0·699, and 1·041 m), all combinations of the...

Organic geochemical properties of the oil produced from the Lower Cretaceous O sandstone on the eastern flank of the Denver basin indicate that this oil has been derived from a different source rock than other Cretaceous oils in the basin. O sandstone oil is characterized by low pristane/phytane ratio, high...

The nesting biology of Pacific Loons, Gavia pacifica, was studied from 1973 to 1975 on the Yukon-Kuskokwim Delta, Alaska. Loons maintained territories on ponds throughout the pre-nesting period. Both adults incubated eggs and raised the young. Males incubated more than females during early incubation, and females more than males during...

Controlled experiments and quantitative field studies with both captive and wild waterfowl (Family Anatidae) have demonstrated that extra-pair copulations (EPCs, both forced and unforced) may be a viable alternative reproductive strategy for males (Mineau and Cooke 1979; Burns et al. 1980; Cheng et al. 1982, 1983; Afron 1985; Evarts and...

It had been a long, productive trip. Launched in 1977, the two Voyager spacecraft had visited three giant planets, a dozen major Moons, three ring systems with thousands of rings composed of a myriad of tiny Moonlets. The spacecraft had returned 5 trillion bits of data and over 100,000 photographs....

Volumetric strain meters (Sacks-Evertson design) are installed at 15 sites along the San Andreas fault system, to monitor long-term strain changes for earthquake prediction. Deployment of portable broadband, high-resolution digital recorders (GEOS) at several of the sites extends the detection band for volumetric strain to periods shorter than 5 ×...

Dipolar dephasing 13C NMR studies of three highly aromatic humic acids, one from a modern soil and two from paleosols, have permitted the determination of the degree of aromatic substitution. From these data and the normal solid-state 13C NMR data we have been able to develop a model for the average chemical...

The principal finding of this paper is that the far-field slope has a first-order effect on model age determinations of scarplike landforms in weakly consolidated terrains. Observationally, this can be demonstrated in two ways using the Lake Bonneville and Lahontan shoreline scarps as separate and combined data sets. Use of...

Several young lava fields were imaged by GLORIA sidescan sonar along the Hawaiian Arch south of Hawaii. The largest, 35 by 50 km across, includes a central area characterized by high sonar backscatter and composed of several flow lobes radiating from a vent area. Reflection profiling and sea-floor photography indicate...

A soil column study was conducted to assess the movement of Zn in sewage-sludge-amended soils. Varables investigated were soil properties, irrigation water quality, and soil moisture level. Bulk samples of the surface layer of six soil series were packed into columns, 10.2 cm in diameter and 110 cm in length....

Geochemical mixing theory suggests that the mixing of seawater and calcite-saturated fresh ground water can result in a solution that is undersaturated with respect to calcite. Previous studies of the mixing of such waters in carbonate rocks along certain coastlines have indicated that...

Glaciation together with tectonism have been dominant factors affecting sedimentation in the Gulf of Alaska area from at least the late Miocene throughout the Quaternary. The effects of tectonism are apparent in high mountains that border the gulf, raised terraces of...

Short-term variability of a conservative quantity (salinity) and two nonconservative quantities (chlorophyll a, suspended particulate matter) was measured across a sampling grid in the South San Francisco Bay estuary. Surface measurements were made every 2 h at each of 29 (or 38) sites,...

The set of hypotheses calling for bar formation at the break point was tested with field data. During two different experiments, waves were measured across the surf zone coincident with the development of a nearshore bar. We use a criterion, based on the wave height to depth ratio, to determine...

On days that are quiet with respect to solar-terrestrial activity phenomena, the geomagnetic field has variations, tens of gamma in size, with major spectral components at about 24, 12, 8, and 6 hr in period. These quiet daily field variations are primarily due to the dynamo currents flowing in the...

Inaccuracies in parameter values, parameterization, stresses, and boundary conditions of analytical solutions and numerical models of groundwater flow produce errors in simulated hydraulic heads. These errors can be quantified in terms of approximate, simultaneous, nonlinear confidence intervals presented in the literature. Approximate confidence intervals can be applied in both error...

The hydrologic response to development of three of the most heavily pumped sedimentary aquifer systems in the United States is similar in some aspects and different in others. In the semiarid West, an unconfined sand aquifer and a confined sand and clay aquifer system have...