摘要:

Progress in long‐period seismology has been considerable in the past few years, owing to the availability of digital data from well‐calibrated worldwide instruments. The very long period International Deployment of Accelerometers (IDA) network [Agnew et al., 1976] has provided many new measurements concerning both earth structure and seismic source studies and demonstrated the usefulness of sparse global digital networks. The broadband Global Digital Seismographic Network (GDSN) network has given access to a large quantity of data whose exploitation can be readily automatized.Both networks have their shortcomings, however, now expressed in the desire of many U.S. scientists to develop a new global digital network better adapted to present requirements of geophysical research. In the very long period domain (periods from about 100s to 1 hour), the IDA network only records the vertical component of ground motion, making information from horizontally excited modes of the earth unavailable. It also saturates the first Rayleigh wave trains from the largest earthquakes, causing a loss of data on direct source station paths, regrettable both for source and structure studies. The GDSN network suffers from some nonlinearity problems and, above all, the inadequacy of instrument responses for present needs of seismologists: The Seismic Research Observatories (SRO) network [Peterson and Orsini, 1976], which is the main constituent of GDSN, was designed mainly for discrimination between earthquakes and nuclear explosi

ISSN:0002-8606    

DOI:10.1029/EO065i042p00753-01

年代:1984

数据来源: WILEY

摘要:

For the first time, scientists have documented the direct melting of diamond, the hardest known substance. The evidence may help confirm theories that carbon is in a liquid state at the high pressures and temperatures of the earth's mantle. Evidence of melting had been discovered previously only when graphite was used as the starting material.Four geologists at Cornell University were conducting mineralogy experiments in which temperature and pressure conditions of the earth's interior are simulated using a yttrium‐aluminum‐garnet (YAG) laser as a heat source and a diamond anvil cell, capable of generating pressures greater than 450,000 times atmospheric pressure at sea level, containing a mixture of potassium bromide and graphite. During the course of the research last February, the laser was inadvertently run at a higher power density than planned and caused damage to the face of the diamond an

ISSN:0002-8606    

DOI:10.1029/EO065i042p00754

年代:1984

数据来源: WILEY

摘要:

The U.S. Geological Survey invites proposals for research contracts and grants under the continuing Earthquake Hazard Reduction Program. The proposed research must be directed toward the goal of identifying, evaluating, and characterizing the immediate and long‐term seismic hazard. Program objectives and tasks required to achieve those objectives are described in Proposal Information Package RFP‐1586Written inquiries concerning this program and requests for Proposal Information Package RFP‐1586 should be addressed to Contracting Officer, U.S. Geological Survey, MS 285, 345 Middlefield Rd., Menlo Park, CA 94025. Proposals will be due in early February 1985. It is anticipated that funding of selected programs will start on or after October 1,

ISSN:0002-8606    

DOI:10.1029/EO065i042p00755-01

年代:1984

数据来源: WILEY

摘要:

The stated purpose of this volume is the development and evaluation of operating policies for the Aswan High Dam and their relation to the development of water resources policy in Egypt. That objective is admirably fulfilled through discussions of water use in Egypt and the operation objectives of the High Dam, the behavior of the physical system and simulation of the reservoir, a realtime management model of the dam, management of water shortages and trade‐offs between major uses, and coordinated operation of the dam with new upstream as well as downstream developments.The High Dam has been a source of controversy, particularly with regard to its environmental impacts. Its adverse effects include changes in the water table and attendant salt buildup in irrigated areas, excessive growth of aquatic plants below the dam, shoreline erosion, and increases in water‐borne diseases such as schistosomiasis (bilharzia). The dam was intended to offset rapid population growth by increasing food supplies through the transformation of irrigated land in southern Egypt from seasonal to perennial cultivation and by providing water for the reclamation of desert land. Unfortunately, such benefits have been outstripped by the rapidly growing population, and water shortages will be experienced by the end of the cent

ISSN:0002-8606    

DOI:10.1029/EO065i042p00756-03

年代:1984

数据来源: WILEY

摘要:

It has been nearly a year since Ronald Cummings took over as policy sciences editor ofWater Resources Research(WRR), and in that time he has worked to make the journal live up to its role as “an interdisciplinary journal integrating research in the social and natural sciences of water.” Cummings takes the “interdisciplinary” part seriously. “I'd like to see a much broader range of policy issues presented to readers,” he says. “I would hope it would then stimulate interchange between our colleagues concerning evolving issues of the '80s and '90s.”Cummings brings a solid background as a resource economist to his 4‐year term as editor, which began last January and runs until December 1987. Cummings succeeds Jared Cohon as policy sciences editor. Stephen J. Burges is the WRR editor for hydrological, physical, chemical, and biological sciences. Now a Professor of Economics and Director of the Program in Natural Resources Economics at the University of New Mexico, Cummings is a past president of the Association of Environmental and Resource Economists. He has been a consultant in matters of water resources management, forestry management, and energy policy for more than a decade, working on projects in both the United States and Latin America. Since joining the faculty at New Mexico in 1975, he has, among other things, worked with engineers at the Los Alamos National Laboratory in developing operation'management models for hot, dry rock g

ISSN:0002-8606    

DOI:10.1029/EO065i042p00759

年代:1984

数据来源: WILEY

摘要:

Strict adherence to the following time‐tested guidelines will ensure that both you and your work remain obscure and will guarantee an audience of minimum size at your next talk. Continuity of effort may result in being awarded the coveted 5:00 P.M. Friday speaking time at the next national meetin

ISSN:0002-8606    

DOI:10.1029/EO065i042p00762-01

年代:1984

数据来源: WILEY