bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sediment sound velocities from Sonobuoys: Sunda Trench and forearc basins, Nicobar and Central Bengal Fans, and Andaman Sea Basins
Authors: Bachman Richard T. , Hamilton Edwin L. , Curray Joseph R. 
Published: February 2008

Supplement is available with entire article on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, DC 20009. Document B83‐007; $2.50. Payment must accompany order.Measurements of mean sound velocities in the first, largely unlithified layers in the seafloor were made using the sonobuoy technique in several areas in the northern Indian Ocean. Older measurements were added to new measurements, and regressions for mean and instantaneous velocity versus one‐way travel time of sound are presented for the central Bengal Fan, the central Andaman Sea Basin, the Nicobar Fan, and the Sunda Trench. New data and regression equations are presented for the Mergui‐north Sumatra Basin and for four forearc basins between Sumatra and Java and the Sunda Trench. Minimum velocity gradients were found in those areas where sedimentation rates were high, and sediments have accumulated in thick sections which have not had time to fully consolidate (porosity in the top of the sediment section has not been fully reduced under overburden pressure). These minimum velocity gradients (just under the seafloor) were found in the four forearc basins where they ranged from 0.34 s−1 to 0.84 s−1 with an average of 0.58 s−1. The near‐surface velocity gradient in the Sunda Trench was 1.33 s−1, but was higher in the adjacent, fossil Nicobar Fan (1.62 s−1). In the surface of the Bengal Fan the velocity gradient was low in the upper fan (0.86 s−1), high in the central fan (1.94 s−1), and again lower in the southern fan (1.18 s−1), which may support sedimentation models calling for bypassing of the central fan and higher rates of accumulation on the southern fan.
Introduction to Seamount Special Section
Authors: Watts A. B. 
Published: February 2008

This special section is the outcome of a symposium held at the Lamont‐Doherty Geological Observatory November 17–19, 1982, on the origin and evolution of seamounts. The topic for the symposium arose from the realization that although there is now a wealth of new ideas on the geology, geophysics, and geochemistry of the ocean floor, the study of seamounts has been relatively neglected despite their great importance to plate tectonics.One of the most interesting features of the ocean floor is the large number of small volcanoes or seamounts. Usually, these features are circular in plan view and have a sharp summit. There has been extensive debate in the literature about the significance of the different morphological types of seamounts. A traditional view has been that flattopped seamounts (e.g., guyots) formed as a result of subaerial erosion when the volcanoes were above sea level. Seamounts covered by fringing reefs or sediments (e.g., atolls), on the other hand, are believed to have formed when the original volcanic foundation subsided below sea level.
Introduction to Special Section on How Volcanoes Work: Part 2
Authors: Tilling Robert I. 
Published: February 2008

The special section on “How Volcanoes Work” is a collection of some of the nearly 300 papers presented at the Hawaii Symposium on How Volcanoes Work, held in Hilo in January 1987 [Tilling, 1987a]. The response of the symposium participants to the invitation to submit their papers for consideration in the special section exceeded expectations. In all, more than 70 manuscripts were received, reviewed, and handled following regular JGR editorial procedures.Part 1 of the special section, composed of the papers that were processed and accepted in time to meet the production schedule, was published in the December 1987 issue of the Journal of Geophysical Research‐Solid Earth and Planets [Tilling, 1987a]. Even though part 1 contained only eight papers, it nonetheless provided a representative sampling of the multidisciplinary nature of the investigations undertaken to improve our understanding of volcanic systems. The papers published in part 1 included ground deformation studies on caldera systems [Dzurisin and Yamashita, 1987; Mortensen and Hopkins, 1987], geochemical and observational studies of the lava fountains and of volcanic fume during the 1983–1984 activity of Pu'u 'O'o in Kilauea's east rift zone [Crowe et al., 1987; Head and Wilson, 1987], magmatic crystal stratigraphy and theoretical petrology [Pearce et al., 1987; Russell, 1987], dynamics of active lava lakes [Tilling, 1987b], and seismic evidence for a subcrustal intrusive complex beneath the Island of Oahu, Hawaii [ten Brink and Brocher, 1987].
An important scientific controversy: Oceanic CO2 fluxes
Authors: O'Brien James J. 
Published: February 2008

The following three papers [Broecker et al., this issue; Smith and Jones, this issue; Wesely, this issue] are a detailed discussion between the oceanographic geochemical community and the physical oceanographic air‐sea interaction community. It is my opinion that these papers provide for the general scientific community an in‐depth review of the methods to estimate CO2 fluxes across the sea surface.The differences between the two scientific groups were brought to my attention when we received the original manuscript submitted by and finally published by Smith and Jones [1985]. During the review process, all geochemists criticized the manuscript and all physicists applauded it. W. Broecker was invited to provide a response to Smith and Jones [1985] and they and Wesely et al. [1982] were invited to provide replies to Broecker et al. [this issue].
Diachrony of Late Neogene microfossils in the southwest Pacific Ocean: Application of the graphic correlation method
Authors: Dowsett Harry J. 
Published: February 2008

The assumption of synchrony of first and last occurrences of fossil taxa can be tested using graphic correlation procedures which, by allowing measured stratigraphic sections to be compared on a common depth scale, make it possible to develop a correlation model which integrates information from a number of cores. The strategy of the test presented here is to use a graphic correlation model that is based on data from the Atlantic (Deep Sea Drilling Project (DSDP) sites 502, 516A) and north Pacific (DSDP site 577A) as a basis for determining to what extent fossil datums in the southwest Pacific are synchronous.First and last occurrences of Pliocene calcareous nannofossils and planktonic foraminifers have been compared in five DSDP cores from the southwest Pacific ocean (sites 586, 587, 588, 590A, and 592). All cores were recovered using hydraulic piston coring technology, which assures the best recovery and minimal disturbance. Most of these cores contain abundant, well‐preserved foraminifers and nannofossils, as well as a partial record of many of the expected magnetic polarity reversals in this part of the section. To assure taxonomic consistency, all taxonomic identifications were made by the author.Graphic correlation of this data set suggests that several important biostratigraphic markers are highly diachronous. For example, this study confirms thatGloborotalia truncatulinoidesfirst occurs at approximately 2.4 Ma between 20° and 35° south latitude in the southwest Pacific, approximately 0.5 m.y. earlier than it is found elsewhere in the Atlantic and Pacific. Other datums, such as the last occurrence ofDiscoaster brouweri, are essentially synchronous. These findings suggest that biostratigraphic models based on the assumption of synchrony of first and last occurrences of fossil taxa may be incorrect. Biostratigraphic models created with the Graphic Correlation method offer an opportunity to examine the biogeographic dimensions of origination, migration, and extinction of planktonic taxa.
Brief history of the Martian ‘violet haze’ problem
Authors: Thompson Don T. 
Published: February 2008

A brief but thorough survey of the literature on the Martian ‘Violet haze’ problem is presented. It is evident that both the normal lack of contrast of the surface features in violet light and their occasional appearance are phenomena intrinsic to Mars. Models involving simple uniform layers of scattering or absorbing materials are inadequate to account for the observations.We suggest that the role of haze has historically been misinterpreted. The blank disk of Mars in violet light occurs when the atmosphere is relatively free of haze. The formation of optically thin white hazes over the bright areas increases the contrast and produces ‘blue clearing.’
Petrology and plate tectonics
Authors: Miyashiro Akiho 
Published: February 2008

Petrology played an important role in the formulation of plate tectonics and early plate tectonic interpretations of the geologic past. In the last few years widespread interest in plate tectonics and progress in plate tectonic interpretations have begun to give petrology various feedback effects.In the period 1971–1974 there were two symposiums intended particularly to connect petrology with plate tectonics [Wyllie, 1973; Yoder, 1971]. Some other symposiums in plate tectonics involved the reading of a paper or papers dealing with petrologic problems.
Meteorite research
Authors: Wasson John T. 
Published: February 2008

Although lunar samples were competing for the attention of meteorite researchers during the 4 years since the reports of Bogard [1971], Burnett [1971], Dodd [1971a], and Wasson [1971a], a number of exciting developments can be reported. Since this paper is the only survey of progress in meteoritics to appear in this quadrennial report, the bibliography is relatively long. The references regarding meteorite research in the United States are essentially complete for the period from July 1970 to June 1974. A number of important studies carried out outside the United States are also cited.References have been assigned to the eight broad subject categories discussed in the text. In some cases any such assignment is arbitrary, and the reader is advised to search through other categories if complete references are needed.
Paleomagnetism, continental drift, and plate tectonics
Authors: Van der Voo Rob 
Published: February 2008

The title of this chapter might induce the reader to expect rather more than what actually is being offered; this review restricts itself to those aspects of paleomagnetism that are related to continental drift, polar wandering, and plate tectonics, and vice versa. A sensu lato interpretation would not only lead to a lengthy recitation; it would also in fact be an impossible task to list all U.S. contributions for the period 1970–1974, so pervasive have the mobilistic concepts been in gaining acceptance in all subdisciplines of the earth sciences.Below, the accomplishments and highlights of the past 4 years are reviewed. Emerging and remaining questions that still require satisfactory answers are occasionally outlined. The publications in paleomagnetism as it relates to tectonics can be classified in three major categories. The first category comprises the contributions that have provided the details for those theories that gradually gained acceptance during the period of 1960–1970. Then there are the publications that contributed in the last 4 years to the successful formulation of tectonic ideas, which previously were just emerging or not even thought of. Finally, I will mention those contributions that outlined newly emerging areas of research but that await independent confirmations and/or more concise formulations. The following sections roughly follow this trend.
Control surveys
Authors: Meade Buford K. 
Published: February 2008

This report covers the national and international activities of U.S. federal agencies engaged in the establishment of geodetic control in the United States, and in other areas through international cooperation, during the period January 1, 1971, to December 31, 1974. The control established by the various agencies is summarized by agency under horizontal control, vertical control, and geodetic astronomy. These agencies are the National Ocean Survey (NOS); Defense Mapping Agency Topographic Center (DMATC); Defense Mapping Agency Aerospace Center, Geodetic Survey Squadron (DMAAC/GSS); U.S. Geological Survey (USGS); and the U.S. Naval Oceanographic Office (NAVOCEANO).The Department of Commerce is responsible for the basic geodetic networks in the United States and for coordinating the surveying activities of all federal agencies. This primary responsibility, assigned to NOS of the National Oceanic and Atmospheric Administration, includes planning, processing, publication, and distribution of geodetic data to meet the national needs.
Earth tides
Authors: Kuo John T. 
Published: February 2008

Since the last U.S. national report on earth tides to the Fifteenth General Assembly, International Union of Geodesy and Geophysics [Kuo, 1971], research activities in tidal gravity have been moving rapidly from the search for a basic understanding of the predominant influence of ocean tides on tidal gravity toward studies of interaction of the earth and ocean tides. These activities in tidal tilt and tidal strain are as yet centered around the problem of evaluation of ocean tidal and local influences.However, all accumulated knowledge of spatial variations of earth tides points the direction of earth tidal research toward attacking the inverse problem for ocean tides by means of earth tidal measurements on the lands and islands, supplemented by ocean bottom measurements. Attempts at solving the inverse problem by means of tidal gravity measurements have already begun. Once the local influences on tidal tilt and tidal strain are understood and can be corrected, the precise tidal tilt and tidal strain measurements can also be of great value in solving the inverse problem. The prospects for satellite mapping of both earth and ocean tides are very hopeful.
Geodesy by very long base line interferometry
Authors: Counselman C. C. 
Published: February 2008

Important advances were made between 1971 and 1974 in the development of very long base line interferometry (VLBI) techniques for precision geodesy, including repeated determinations of the length of a transcontinental base line within 5 parts in 108, accurate measurements of polar motion and the variation of universal time, and the establishment of a catalog of extragalactic radio sources with positional uncertainties smaller than 0.1 arc sec.An introduction to VLBI and an account of its early development have been given by Cohen [1973]. Counselman [1973] has reviewed applications of VLBI to geodesy and astrometry prior to 1973, and recently, Moran [1975a] has described the geodetic and astrometric results which have been obtained by VLBI through June 1974. Moran's review is particularly timely because he discusses important unpublished data, preliminary results, and work now in progress or being planned by the major VLBI groups in the United States.
Interactions of sea and atmosphere
Authors: Businger J. A. 
Published: February 2008

Since the previous review of this subject by Pond [1971], a lively activity in air‐sea interaction research has been displayed. A number of large‐scale experiments have been and will be carried out since the Barbados Oceanographic and Meteorological Experiment (Bomex, 1968), notably: Joint North Sea Wave Project (Jonswap, 1968,1969,1973, and probably 1975), Atlantic Trade Wind Experiment (Atex, 1969), International Field Year of the Great Lakes (IFYGL, 1972), Joint Air‐Sea Interaction (Jasin, 1972 and probably 1977), Garp Atlantic Tropical Experiment (Gate, 1974) and Air Mass Transformation Experiment (Amtex, 1974, 1975) and others. It will be some time before all the information from these field experiments will have been digested, and so we may look forward to continued active reporting in this area for the coming years.Numerous publications carrying articles in this area have appeared recently. The new Journal of Physical Oceanography has given ample space to air‐sea interaction topics as have the almost equally new journals, Geophysical Fluid Dynamics and Boundary Layer Meteorology. In 1974 this last journal devoted a special double issue to air‐sea interactions in memory of the German scientist Karl Brocks. Furthermore, the first textbook in the English language has appeared [Kraus, 1972].
Solar wind‐magnetosphere coupling
Authors: Crooker Nancy Uss 
Published: February 2008

During the past 4 years the interplanetary magnetic field (IMF) has been firmly established as a major influence in interactions between the solar wind and the magnetosphere. Evidence of its control over magnetospheric processes provides the thread of continuity in the following sections of this report: merging, polar cap disturbances and sector polarity, geomagnetic activity and solar wind structure, periodicities in geomagnetic activity, access of solar wind particles to the magnetosphere, the magnetopause, and the bow shock. A brief listing of references on aerodynamics is also included as a final section. The topic of tracing of magnetic field lines by solar particles has not been covered. The reader is referred to recent reviews by Morfill and Scholer [1973] and Paulikas [1974].The references listed in each section are meant to be examples. More exhaustive listings covering the period fromlate 1970 through late 1974 are included in the bibliography.
Elastic and anelastic structure of the Earth
Authors: Dziewonski Adam M. 
Published: February 2008

The objective of this review is to outline the progress made in the last four years in studies of global or large scale properties of the Earth. Work related to strictly regional structure of the crust and the uppermost mantle is described in other reports in this volume.During the previous reporting period 1971–1974 (Anderson, 1975) there was a large increase in the data base relevant to the average structure of the Earth. The number of normal modes for which eigenfrequencies have been measured increased by an order of magnitude; observations of travel times of body waves (differential travel times, in particular) were reported for several phases of key importance in constraining the core radii as well as distribution of the seismic velocities in the core and lower mantle. Quite naturally, the emphasis has been placed on construction of Earth models that would be consistent with this substantially enlarged data set.
Auroral mechanisms and morphology
Authors: Swift Daniel W. 
Published: February 2008

This past quadrennium has witnessed a considerable expansion of our knowledge and understanding of processes responsible for the aurora. Because of the number and diversity of contributions, a complete description is difficult, and many topics are presented here in summary form only. Instead, this review will emphasize the major accomplishments and outline the major problems that should be addressed during the next quadrennium.The scope of this review includes observations, analysis of observations and theoretical work which are likely to be relevant to the understanding of the aurora. Ground‐based observations reviewed include (l) auroral imagery, both by television and all‐sky camera, (2) gross magnetic variations indicative of ionospheric currents, (3) VLF hiss observations, and (4) effects of high‐energy electron impact measured through cosmic radio noise absorption and by observations of bremsStrahlung x‐rays from balloons. Not included in this review are spectroscopic observations, observation of micropulsation activity and auroral radar observations, as these observations seem to provide less direct diagnostic information on the basic auroral mechanism. However, incoherent scatter radar observations are utilized to the extent they provide information on ionospheric currents and electric fields.
Hydrology 1979–1982
Authors: Wood Eric F. 
Published: February 2008

The quadrennium 1979–1982 produced notable advances in surface water and groundwater hydrology, as well as important trends towards a more scientific basis for engineering hydrology. Examples of these developments will be given below, as well as an assessment of current trends.One of the most significant areas to emerge during the last quadrennium is stochastic groundwater analysis. The basis for the conceptualization of groundwater flow and transport as a stochastic process is two‐fold: 1) the realization that hydrologeological environments are extremely heterogeneous, regardless of the scale of modeling or data collection and 2) the use of groundwater flow and transport modeling results within broader water resources or hazardous waste management studies where risk analysis requires and incorporates groundwater uncertainty.
Deep earth structure
Authors: Cormier Vernon F. 
Published: February 2008

Major developments in earth structure in the last four years have been concentrated in the description of the earth's lateral heterogeneity: the regions that are heterogenous and the per cent variation of velocity and density in each region. Most studies find that lateral variation is concentrated in the upper 400 and lower 200 km. of the mantle.A radially symmetric earth model has been defined that represents the best average fit to seismic data in a broad frequency band, sampling many regions. P and S velocity is found to increase in zones of 50 km. or less at 400 and 650 to 700 km. depth. The model is transversely anisotropic in the upper mantle. It possesses a vertical axis of symmetry such that the elastic constants are different for vertical propagation than for horizontal and intermediate angles of propagation. The real earth generally exhibits azimuthal anisotropy as well, but the azimuthal anisotropy cannot be resolved by a global average of data. The nature and magnitude of the anisotropy agrees with that found in ultramafic samples of the upper mantle.In attenuation, models of intrinsic attenuation have included the dispersive properties of intrinsic anelasticity and constructed relaxation models consistent with an observed frequency dependence of Q in the body wave band. There has been progress in mapping the scattering properties of the lithosphere. Attenuation due to scattering in the crust and lithosphere has been shown to have strong effects on the amplitudes of seismic waves at local and teleseismic distances.