Subsurface mooring data from St. Paul Island, Bering Sea: Station St. Paul Island 4. Data were collected from 1994 through 2004. Sampled months varied through the years but were usually during September. Salinity, temperature, and UV vector data were collected at various depths throughout the years using instruments such as RCM-7. 24m was the maximum bottom depth.

A numerical procedure has been developed to determine the tsunami response of an island system and the surrounding underwater topography. The main algorithm is based on the Eulerian equations of motion and continuity which correspond to the classical, linear, long-wave equation in the absence of friction and rotation. It performs an integration of these equations in terms of an explicit scheme based on centered differences. The computations are carried out on a Cartesian grid network and employ a condition of no normal flow at the island shoreline representation as well as an approximate radiation condition for the scattered portion of the wave field at the outer boundaries. The responses at the island shorelines are determined by introducing a time sequence input with a stipulated spectrum covering the tsunami range (4-90 min). Computations are continued for a duration sufficient to establish a statistical equilibrium within the system. The shoreline time series of water elevations are then Fourier-analyzed to obtain the spectrum for each point. Each spectrum is normalized by the spectrum of a time series taken of the forcing function, propagating on a grid of constant, deep water depth at a central position in the model. The normalized spectra or energy ratios are averaged for each island and for the entire set of shoreline points to produce the responses. The results are presented as graphs of averaged normalized spectra and as contours of (energy ratio)ﾽ on period vs island perimeter plots. An application of the technique is given for the Hawaiian Islands with a northern (Alaskan) wave approach angle. The results indicate energetic response is possible at ten periods from 12.5 to 73.1 min.

None available at this time.

The major components of the marine boundary layer biogeochemical sulfur cycle were measured simultaneously onshore and off the coast of Washington State, U.S.A. during May 1987. Seawater dimethylsulfide (DMS) concentrations on the continental shelf were strongly influenced by coastal upwelling. Concentrations further offshore were typical of summer values (2.2 nmol/L) at this latitude. Although seawater DMS concentrations were high on the biologically productive continental shelf (2-12 nmol/L), this region had no measurable effect on atmospheric DMS concentrations. Atmospheric DMS concentrations (0.1-12 nmol/m), however, were extremely dependent upon wind speed and boundary layer height. Although there appeared to be an appreciable input of non-sea-salt sulfate to the marine boundary layer from the free troposphere, the local flux of DMS from the ocean to the atmosphere was sufficient to balance the remainder of the sulfur budget.

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This study shows that many aspects of existing U.S. technology have potential applications to the problem of providing early tsunami warning information in developing nations of the Pacific which do not have their own regional warning network. A simple conceptual model is developed which shows how these technologies could be integrated into an early warning "system." The basic elements are described for a demonstration program which would confirm the practicality of such a technologically feasible system. Such a demonstration--to which the acronym THRUST (Tsunami Hazard Reduction Utilizing System Technology) is applied--would be a significant step toward achieving the goal of hazard mitigation in the developing areas of the Pacific community. It is recommended that an active program of tsunami hazard reduction in developing nations be established within the Office of U.S. Foreign Disaster Assistance of the Agency for International Development.

Fifteen dives along the Galapagos Ridge in the region between 85°49'W and 85°55'W were made to examine the detailed relationships among tectonics, hydrothermal activity and lava compositions. Extensive tectonic activity and physical weathering have exposed the inner parts of large Cu-Zn sulfide mounds and the uppermost part of the underlying stockwork zone. The mineralization occurs at the top and southern base of a horst block, 40 to 80 m high, that separates the present Neovolcanic Zone to the north from an older rift valley to the south. The lavas in the Neovolcanic Zone are homogeneous MORB pillows; those on the horst block and within the southern valley are evolved MORB to andesite pillow and sheet flows. The alteration zone exposed beneath the sulfide mounds comprises a network of fracture-controlled pipe and sheet-like bodies of highly altered material which changes outward into relatively fresh but similarly closely fractured rocks. The hydrothermal upflow zone is extensively brecciated on a centimeter scale and encloses a stockwork of veinlets now filled largely by silica, clays and sulfides. The most highly altered rocks are strongly depleted in Ca, Na, K and Mn, and are enriched in S, Fe, Cu and Zn relative to their fresh analogs. Si and Mg are variable, the latter showing local depletions and enrichments according to the proportion and distribution of chlorite. Depletions in O with increasing Sr/Sr suggest extensive seawater-rock interaction (W/R up to 100:1) at T up to 350°C. Deep-two and ALVIN-based magnetic profiles have a relative magnetization low centered over the southern valley and the horst block that could reflect more extensive hydrothermal alteration zones associated with the older seafloor. The Gal pagos stockwork is most analogous to the alteration zones associated with massive sulfide deposits in the ophiolites of Cyprus and Oman.

Beginning at 0700 GMT on 28 February 1996, intense seismicity was detected in the northeast Pacific Ocean using the T-phase Monitoring System developed by NOAA/PMEL to access the U.S. Navyﾒs SOund SUrveillance System (SOSUS) in the North Pacific. The event was preliminarily located on the northernmost segment of the Gorda Ridge near 42.67°N and 126.8°W, in the vicinity of the ridge segment high ("narrowgate"). The nature of the seismicity was similar to that observed in June 1993 at the CoAxial segment of the Juan de Fuca Ridge, which was later documented to be a lateral magma injection with subsequent eruption. Due to several gaps in the data, the detection information was not as comprehensive as during the CoAxial event, but an initial migration of epicenters from the narrowgate area down-rift is inferred based on arrival bearings from a single array; there is evidence for an additional diking event on the second and third day of activity. There is also indication of a concentration of epicenters located near 42.6°N, as occurred during the CoAxial episode at what was later determined to be an eruption site. Examination of T-wave rise times generally supports this interpretation. Based on the nature and duration of the activity, a response effort was initiated, which later confirmed hot-water plumes and fresh lava flows at the site. Based on both hydroacoustic information and field observations, it is proposed that the episode began with a lateral dike injection, possibly with eruptive activity in the summit region, followed by multiple magma pulses and eventual focusing of the seismic activity and extrusion near 42.6°N.

Rapid-onset natural hazards have claimed more than 2.8 million lives worldwide in the past 20 years. This category includes such events as earthquakes, landslides, hurricanes, tornadoes, floods, volcanic eruptions, wildfires, and tsunamis. Effective hazard mitigation is particularly difficult in such cases, since the time available to issue warnings can be very short or even nonexistent. A general approach to mitigate the effects of these disasters was demonstrated in 1988 that included preevent emergency planning, real-time hazard assessment, and rapid warning via satellite communication links. In this article, we report on improvements in this satellite-based emergency alerting communication system that have reduced the response time from 87 to 17 s and expanded the broadcast coverage from 40% to 62% of the earth's surface.

High precision measurements of the solubility of carbon tetrachloride (CCl) in pure water and seawater were made over the temperature range of ~0-40°C. For comparison with previously reported results, the solubilities of CFC-11 and CFC-12 were also measured during these experiments. The experimental data were fit to equations in temperature and salinity, in the form used in previous gas solubility studies. The CFC-11 and CFC-12 results were generally in good agreement with earlier work, although some differences were noted. For CCl, the standard error of the measurements from the fitted curves was ﾱ2.5%. The concentrations of dissolved CCl measured in near-surface waters on a recent long meridional section in the South Pacific Ocean (where the temperature ranged from -1 to 29°C) are compared to calculated saturation levels based on these solubility data and atmospheric levels of CCl measured along the section.