Bathymetry and Canyons of the western Solomon Sea

The floor of the western Solomon Sea (for new bathymetric map see inside back cover of this issue) is dominated by the arched and ridged basement of the Solomon Sea Basin, the partly-sediment-filled New Britain Trench, and a more completely filled trench, the Trobriand Trough. There is a deep basin where the trenches join (149° Embayment), and a silled basin west of the New Britain Trench (Finsch Deep). Submarine canyons descend from the west and south to the 149° Embayment. Abyssal fans and plains are structurally defined and locally disturbed by young faults. Probable submerged pinnacle reefs stand in water depths as great as 1,200 m.     

Crustal Stress in the northern North Sea as inferred from borehole breakouts and earthquake focal mechanisms

The regional stress field in the northern North Sea (offshore western Norway) has been studied through the acquisition and analysis of directions of maximum horizontal compression (_H) as extracted from borehole breakouts and from earthquake focal mechanism solutions.
The results indicate that the regional stress field is dominated by NW-SE compression, with good consistency between shallow borehole breakouts (2–5 km depth) and deeper earthquakes (10–25 km depth). The broad spatial consistency in stress direction indicates that the main stress field is related to factors of primarily plate tectonic origin, and the results are in good agreement with the western Europe trend found in earlier investigations.
The Tampen Spur region in the northern North Sea has been subjected to particularly complex deformation, with two dominating fault directions trending NW-SE and NE-SW. From Tampen Spur in the west to the Sogn graben in the east an anomalous stress field is indicated, with NE-SW oriented maximum horizontal compressions. This anomaly is clearly seen both in the borehole breakout data and in the earthquake data. Possible sources for this anomaly are discussed, and include postglacial uplift and/or lateral variations in the physical properties of the crust.     

Accuracy of kinematic wave and diffusion wave approximations for space-independent flows on infiltrating surfaces with lateral inflow neglected in the momentum equation

Error equations for the kinematic wave and diffusion wave approximations with lateral inflow neglected in the momentum equation are derived under simplified conditions for space-independent flows. These equations specify error as a function of time in the flow hydrograph. The kinematic wave, diffusion wave and dynamic wave solutions are parameterized through a dimensionless parameter γ which is dependent on the initial conditions. This parameter reflects the effect of initial flow depth, channel-bed slope, lateral inflow, infiltration and channel roughness when the initial condition is non-vanishing; it reflects the effect of bed slope, channel roughness and acceleration due to gravity when the initial condition is vanishing. The error equations are found to be the Riccati equation. The structure of the error equations in the case when the momentum equation neglects lateral inflow is different from that when the lateral inflow is included.     

Simulation and evaluation of satellite scanner stereo images

During 1986–1996, several satellite missions on Stereoscopy are planned. This paper sumarises an attempt in evaluating these stereoscopic images for cartographic purposes. For the purpose, we have taken into account a proposed Indian experiment on satellite stereoscopy, which will be based on push-broom type scanning and a ground resolution of 70m×70m. *** DIRECT SUPPORT *** A04KF003 00004     

Fluid venting from a mud volcano in the Mediterranean Ridge Diapiric Belt

Direct observation of active emission of fluids and mud from a submarine mud volcano were made for the first time in an extensive field of mud diapirs and mud volcanoes on the Mediterranean Ridge using a video camera towed 2 m above the seafloor in 1800 m of water. This recent research using both long range and deep-towed sidescan sonar systems indicates also that diapirism and eruption of mud along the crest of the ridge is more common than previously thought. The southwards increase in age of rock fragments carried within the erupted mud supports the hypothesis that the fluid mud becomes overpressured within a southward-dipping backthrust from the Inner Deformation Front of this accretionary prism.     

Stable isotopic ratios of lead in surface waters of the Central Pacific

The geographic variation in the isotopic composition of lead in surface waters of the central Pacific provides new evidence of the global anthropogenic perturbation of the element's cycle. Ratios of ²⁰⁶Pb/²⁰⁷Pb decrease from 1.196 in the northern hemisphere (19°N, 158°W) to 1.176 in the southern hemisphere (15°S, 150°W). This decrease parallels the geographic variation in surface concentrations of soluble lead which decrease from 13 ng kg^?1 at the northern station to 4 ng kg^?1 at the southern station. Both the ²⁰⁶Pb/²⁰⁷Pb and the ²⁰⁶Pb/²⁰⁸Pb ratios of those waters fit between the isotopic ratios of Australian (Broken Hill) and North American (Mississippi Valley) leads which are the predominant sources of leads in anthropogenic emissions to the Pacific Ocean basin.     

On pressure-work,viscous dissipation and the energy balance relation for geothermal reservoirs

This article examines the conditions under which the pressure-work and viscous dissipation terms should be retained in the energy balance relation for single (liquid water or vapor) and two-phase (liquid water and vapor) fluid flow through porous media. It is shown that if one wishes to retain the pressure-work term, then one must also keep the viscous dissipation term in the energy balance. Consideration of steady non-isothermal radial flow demonstrates that both pressure-work and viscous dissipation are liable to have negligibly small effects in single phase liquid water and in two-phase liquid-vapor systems. This conclusion is, however, not generally valid for pure vapor systems; in this case, pressure-work and viscous dissipation can produce significant variations in the computed reservoir response.