Working Group I.2 of IAGA - Electromagnetic Induction in the Earth ================================================================== Electronic Newsletter #18: July 1997 ------------------------------------ Previous newsletters: enews.Oct92 - 1st enews.Jan93 - 2nd enews.Feb93 - 3rd enews.Oct93 - 4th enews.Feb94 - 5th enews.Mar94 - 6th enews.Jun94 - 7th enews.Aug94 - 8th enews.Sep94 - 9th enews.Jun95 - 10th enews.Oct95 - 11th enews.Dec95 - 12th enews.Jun96 - 13th enews2.Jun96 - 14th enews.Dec96 - 15th enews.Feb97 - 16th enews.May97 - 17th enews.Jul97 - 18th (this one) This is the eighteenth electronic newsletter for our group. A newsletter will be sent around when there is enough material, or a special event about to come up, to warrant distribution. Not all of us in the working group have access to an email address; if you are aware of colleagues who are not likely to receive this newsletter, please give them a paper copy (but chastise them for using trees instead of electrons). Also, please forward this to colleagues who may not yet be on my email list and ask them to forward their address to me. Copies of previous electronic newsletters can be obtained from either the MTNet WWW site or by anonymous ftp login to www.cg.nrcan.gc.ca in directory pub/mtnet/docs. Please submit any comments/articles/news-items/gossip/corrections to jones@cg.nrcan.gc.ca. I am particularly looking for meeting and conference reports, papers (EM and non-EM) in the news, high impact EM studies, etc. Contents: >>>18.1 IAGA Meeting News >>>18.2 Position Available >>>18.3 Gough-Reitzel variometers >>>18.4 Marelec97 meeting >>>18.5 New versions of Randy Mackie's codes >>>18.6 Lower crustal conductivity >>>18.7 Request for new ILP proposals >>>18.8 Address Update request >>>18.9 Information about our African colleagues >>>18.10 MTNet news >>>18.11 Junk email >>>Appendix: Email list IMPORTANT DEADLINES:.. -------------------------------------------------------------------------------- >>>18.1 IAGA Meeting News ========================= The 1997 IAGA Scientific Assembly will take place in Uppsala, Sweden, between August 4 - 15, 1997. You can get full information from their Web page:- http://www.irfu.se/iaga_97.html including sessions, logistics, abstracts, etc. -------------------------------------------------------------------------------- >>>18.2 Position Available ========================== [submitted by Hisashi Utada] Postdoctral Positions/Solid Earth Geophysics Two postdoctoral positions (JSPS Postdoctoral Fellowship for foreign researchers) in Solid Earth Geophysics are available at selected universities in Japan, including the Earthquake Research Institute, Ocean Research Institute and Faculty of Science at University of Tokyo. We seek for candidates who are interested in (either direct or indirect) collaboration with our ongoing project to develop a geophysical network (Ocean Hemisphere Network) of seismology, geoelectromagnetism and geodesy in the western Pacific region in an attempt of unified understanding of the solid Earth activity. Each candidate must hold a doctorate degree when this fellowship goes into effect, which must have been received within six years prior to April 1, 1998. Fellowships are awarded for a period of 24 months. If you should not require a full 24 months for your research in Japan, you may propose a shorter fellowship tenure of at least 12 months. Each Fellowship must begin within the 1998 Japanese fiscal year (between April 1, 1998 and March 31, 1999). Eaxh Fellow is provided with the following support. 1)A round-trip air ticket for the Fellow only 2)A monthly stipend of \270,000 (about $2,400) 3)A setting-in allowance of \200,000 4)A monthly housing allowance not to exceed \100,000 5)A monthly family allowance of \50,000 if accompanied by dependents 6)Accident and sickness insurance coverage for the Fellow only In addition, application may also be made for the Monbusho's Grand-in -Aid for JSPS Fellows of up to a maximum of \1,500,000 per year to cover cooperative research expenses. Those interested in applying should immediately notefy their fax numbers by e-mail to Yoshio Fukao (fukao@eri.u-tokyo.ac.jp), who will send a copy of the application form by FAX. The deadline is approaching (The fax copy of the filled application form must be received by July 20th, 1997). The detail will be informed at the time of sending the application form by fax. ******************************************* UTADA, Hisashi Ocean Hemisphere Research Center, Earthquake Research Institute, University of Tokyo Yayoi 1-1-1, Bunkyo-ku, Tokyo 113 JAPAN TEL: +81-3-3818-5096 FAX: +81-3-3812-9417 ******************************************* -------------------------------------------------------------------------------- >>>18.3 Gough-Reitzel variometers ================================= [submitted by Dennis Woods] GOUGH-REITZEL MAGNETIC VARIOMETERS TO GIVE AWAY I have a set of 30 Gough-Reitzel magnetic variometers (Gough and Reitzel, 1967) to give away to a good home. These variometers were originally built by Reitzel et al. at the University of Texas at Dallas in the mid-sixties. They were used by Porath et al. in the late sixties and early seventies in a number of large magnetic array studies in North America and other locations. I acquired them from UTD in 1983, refurbished them with new electronic controls and camera mechanisms (Geiger, 1989), and used them in two array studies, including the multi-collaborative EMSLAB experiment in the northwest US in 1986 (Gough, et al., 1989). Since then, they have been in secure and environmentally stable storage (i.e. my garage). The instruments are in perfect working condition. For the past decade they have been stored air-tight with enclosed desiccate bags changed periodically. The instruments come complete with a full set of spare parts: e.g. extra electronic control boards, polished sensor magnets and auxiliary magnets of known moment, miscellaneous camera parts, and the world's supply of special torsion wire. There is also a complete set of special tools as well as a detailed log book and manual to facilitate maintenance and use of the instruments. The only thing you'll need to get up and running with your own array studies is a set of batteries (100+ amp-hour lead-acid industrial batteries are recommended), rolls of 35 mm monochrome film, and some miscellaneous field equipment for installation: total cost est. US$ 10,000. (I have 30+ rolls of film, pieced together from left-overs from my array studies and kept in a freezer for the past decade, which might be useful for testing purposes). I am offering these instruments to anyone who thinks they might use them - or even anyone who will take them off my hands. We are moving house in a few months and I don't particularly want to drag them along. I'm prepared to crate them up and take them down to the Vancouver shipping terminal. Shipping costs anywhere in the world would be less than US$ 1,500 (port-to-port). If I can't find any takers, I regret to say that I'll simply scrap them. I can be contacted at: Dennis V. Woods email: woods@mindlink.bc.ca 2539 140th Street telephone: 604-538-1445 Surrey, B.C. facsimile: 604-538-7354 Canada V4P 2C5 References: Geiger, H.D., 1989. A Study of the Accuracy of Data from a Set of Gough-Reitzel Magnetic Variometers, unpubl. M.Sc. thesis, Queen's University, Kingston, Canada. Gough, D.I. and Reitzel, J.S., 1967. A portable three-component magnetic variometer, J. Geomagn. Geoelectr., 19, 203-215. Gough, D.I., McKirdy, D.M., Woods, D.V. and Geiger, H.D., 1989. Conductive structures and tectonics beneath the EMSLAB land array, J. Geophys. Res., 94, 14099-14110. -------------------------------------------------------------------------------- >>>18.4 Marelec97 meeting ========================= John Weaver attended the recent Marelec97 (Marine Electromagnetics) meeting held in England. Here is his meeting report... [submitted by John Weaver] I recently attended a conference on Marine Electromagnetics organised by Imperial College, Dept Elec & Electronic Engineering. It was surprising to meet so many people there who were working on problems that overlap with Working Group I-2 of IAGA, and yet seemed unaware of some of the recent developments that have taken place in our field. Likewise, some of our working group would possibly profit by keeping in touch with some of the work in marine electromagnetics undertaken by engineering departments and defence laboratories around the world. Those from our our working group who were present were Nigel Edwards, Ted Lilley, Adam Schultz, I. Fujii, and one or two Russians whose co-authors were Michael Zhdanov, and Leonid Vanyan, and one or two other less regular attendees. The organiser, Prof. Ernie Freeman of Imperial was most anxious to keep the communication doors open so I said I would send him the www page for MTNet so that he could put it on the conference web page for delegates to see. Likewise I thought you might like to mention in the next Electronic Newsletter, or in News on MTNet, that the home page for "Marelec97" is http://www.ee.ic.ac.uk/conferences/marelec/ and that it will be kept open at least for a year or two for the exchange of information. -------------------------------------------------------------------------------- >>>18.5 New versions of Randy Mackie's codes ============================================ [submitted by Randy Mackie] Randy Mackie has released updated versions of his 2D MT inverse and 3D MT forward modeling programs. Updates to the 2D MT inverse codes include: 1) A new and very fast true 2D inversion algorithm titled d2inv_nlcg2_fast. This algorithm is almost as fast as RRI, and computes true 2D sensitivities. It has been tested on a wide variety of real and synthetic data. It does not require a large amount of computer memory. 2) Data can be specified at arbitrary frequencies for both TM and TE modes. 3) Automatic adjustment of air layer thicknesses to be compatible with the earth model (TE mode only). 4) Other minor bug fixes and updates. 5) A manual explaining the theory and operation of the codes. Updates to the 3D code include: 1) Automatic adjustment of air layer thicknesses to be compatible with the earth model. 2) Improved and more accurate boundary value program. 3) Improved error reduction stopping value. 4) Automatically searches down through the model to output field values at the first earth layer - useful if wanting to output values on the bottom of the ocean floor, or if topography is built into the model. 5) Other minor bug fixes. Randall Mackie GSY-USA, Inc. 2261 Market St., Suite 643 San Francisco, CA 94114-1600 (415) 643-3191 randy@geosystem.net -------------------------------------------------------------------------------- >>>18.6 Lower crustal conductivity ================================== In their latest paper, Yardley and Valley (1997) state their petrological arguments against the notion of free fluid in the lower crust of the continents as an explanation for our observed lower crustal high conductivity. Before those of you who subscribe to the carbon thin-film theory rejoice, the paper also discredits thin films, as they have so seldom been seen on rocks from the lower crust. Also, they wonder about the applicability of many of the laboratory studies on rocks from the lower crust. Clearly, the debate on the cause of the observed enhanced conductivity of the continental lower crust is not advancing. The parties involved on both sides of the issue ("wet" or "dry") are restating their positions and casting aspersions on their opponents theories. Scientific breakthroughs will come from a coordinated effort between geologists, geochemists and geophysicists involving specially-designed field programs (e.g., for MT: is the conductive zone thin or thick?), laboratory studies, theoretical advances (wetting angle?), etc. Combining our information obtained from EM studies with other observations leads to rejection of hypotheses that may be tenable if only one of them is applied. Equally, inferences supported by all have stronger conviction. Perhaps most useful is when apparent incompatibilities must be reconciled by re­examination of the various datasets. Please read through the paper by Yardley and Valley, and email me your views. I will start a discussion forum on MTNet so each of us can read the emails of the others, and can respond. I would hope that from this discussion forum we may decide how best to proceed forward. See web page http://www.cg.NRCan.gc.ca/mtnet/fora/clc/clc.html Yardley, B.W.D. and Valley, J.W., 1997. The petrologic case for a dry lower crust. J. Geophys.Res., 102, 12,172­12,185 Abstract: Fluid pressure in the crust may be controlled by different mechanisms according to depth, temperature, and the mineralogy of the host rocks. Where rocks are fluid-saturated, fluid pressure may approach lithostatic or hydrostatic pressure depending on the ductility of the wall rocks and the connectivity of pores and fractures. However, if the host rocks contain minerals formed at temperatures higher than those currently prevailing, they will react with fluids to produce hydrated (or carbonated) retrograde minerals, and the fluid pressure will be limited by thermodynamic equilibrium between high-grade reactant minerals and retrograde products. The thermodynamically constrained parameter, water fugacity, may have a value of tens to hundreds of bars in the lower crust. In practice, this means that for typical igneous or high-grade metamorphic rocks now occurring in stable lower crust, notional fluid pressures are substantially (1 to 3 orders of magnitude) lower than lithostatic. No free, connected fluid phase can be present in deep stable crust, and alternative explanations must be sought for the relatively high electrical conductivity of such rocks. The proposal that high lower crustal conductivity is due to thin grain boundary films of graphite is also unlikely to be generally true because films of sufficient thickness would be readily visible on broken surfaces of hand specimens. An alternative explanation of the discrepancy between laboratory and field measurements of the conductivity of high-grade rocks is that laboratory measurements are not normally made under appropriate conditions of rock-buffered fluid pressure. -------------------------------------------------------------------------------- >>>18.7 Request for new ILP proposals ===================================== [submitted by ILP] ANNOUNCEMENT The Inter-Union Commission on the Lithosphere (ICL) invites proposals for new projects to be conducted under the auspices of the International Lithosphere Program (ILP). Established in 1980 by the International Council of Scientific Unions (ICSU) at the request of the International Union of Geodesy and Geophysics (IUGG) and the International Union of Geological Sciences (IUGS), the ILP seeks to elucidate the nature, dynamics, origin and evolution of the lithosphere through international, multidisciplinary research projects and coordinating committees. Since 1990, ILP projects have been operating under the umbrella of four program themes: 1. Geoscience of Global Change; 2. Continental Dynamics and Deep Processes; 3. Continental Lithosphere; 4. Oceanic Lithosphere. ILP provides each Project Leader with a small amount of money (about $5000/year) for administration and travel. Further financial support for scientific investigations, conferences and workshops must be sought from national and international funding agencies; experience suggests that ILP's "stamp of approval" offers considerable credibility to grant applications. Information on current ILP projects can be obtained from the 1995 ILP Annual Report, which is available from ILP Secretary General Joerg Erzinger or through ILP's home page at http://www.gfz-potsdam.de/pb4/ilp/. All ILP projects must have an international character and should address issues of interest to both parent unions (IUGG and IUGS). Some projects have recently been completed (e.g. World Stress Map; Paleoseismicity of the Late Holocene), whereas the final products of several others will be published in 1998 (e.g. Global Seismic Hazard Assessment Program; Global Geoscience Transects). A few projects will continue to the end of the century (e.g. Origin of Sedimentary Basins; EUROPROBE). The ILP is now accepting suggestions for four to five new projects to begin in 1998. A non-exclusive list of potential research topics is included in the covering letter. Project proposals based on these and other topics would be most welcome. Each proposal should be no longer than four pages and contain information on the project's objectives, duration (maximum 5 years) and expected participants, together with short comments explaining how the project will address ILP's principal goals and program themes. The proposed leader and co-leaders of the project should also submit one-page Curriculum Vitae. Further information on ILP activities and guidelines may be obtained from ILP Secretary General Joerg Erzinger (ILP Secretariat, GeoForschungsZentrum Potsdam, Telegrafenberg A540, 14473, Potsdam, Germany; Phone: +49 (0) 331 288 1421; Fax: +49 (0)331 288 1474; e-mail: ilp@gfz-potsdam.de) or ILP President Alan Green (Institute of Geophysics, ETH-Hoenggerberg, CH-8093, Zurich, Switzerland; +41 (0) 1 633 2657; Fax: +41 (0) 1 633 1065; e-mail: alan@augias.geo.phys.ethz.ch). Proposals should arrive at the ILP Secretariat in Potsdam by July 31, 1997 for initiation of projects January, 1998 and by December 31, 1997 for initiation of projects July, 1998. -------------------------------------------------------------------------------- >>>18.8 Address Update request ============================== The working group address list is badly out-of-date. Please check your address on URL http://www.cg.NRCan.gc.ca/mtnet/addresses/addresses.html If there is a correction required, send it to Gwen Mason at mason@cg.nrcan.gc.ca You can do this from the Web page. Please also send notification of any deletions. -------------------------------------------------------------------------------- >>>18.9 Information about our African colleagues ================================================ I am concerned about the lack of attendance, and even research activities, by many of our African colleagues, especially from Nigeria and Kenya. We appear to have ``lost'' many of our African colleagues who were more regular attendees at our meetings and workshops. Indeed, at Brest in 1994 there was not a single representative from central Africa, and only one from north Africa. In Onuma in 1996, of the 58 requests for financial support, only one was from an African colleague. As the current Chairman of the Working Group, I would like to try to bring African colleagues back into our working group's activities. In terms of apparent lack of news, part of the problem may lie in the fact that a lot of communication is now done through electronic means, using electronic mail and MTNet on the World Wide Web. I do not know if any of our African colleagues has access to the Internet. If they do, then please let me know their email address so I can send them material on a regular basis. If not, then perhaps in future when I have a mailing of the electronic newsletter that I distribute, I will send them a copy by post and ask you to ensure that it gets widely distributed amongst their African colleagues. There may be ways to try to aid our colleagues, but I do not know what the best and most appropriate form of aid is. For example, as in the past I am sure that students could get support from aid agencies to study in Europe and North America. But to my knowledge there are not many (any?) African EM students at our universities at present. The offer by Dennis Woods to give away his magnetometers may be useful. If you are in contact with any of our African colleagues, please let them know about the group's activities. Especially that there has been in the past, and hopefully will be in the future, opportunities for financial support to help with attending our EM workshops. I would appreciate any news you may have, especially updated mailing addresses. -------------------------------------------------------------------------------- >>>18.10 MTNet news ================== The Discussion Fora area is open on MTNet. To initiate a topic, send a provocative email to Alan Jones. To contribute to a topic, read all the previous submissions, and send your submission to Alan Jones. See the Web page... http://www.cg.NRCan.gc.ca/mtnet/fora/fora.html -------------------------------------------------------------------------------- >>>18.11 Junk email ================== Are you receiving junk email? If so, it is possible to put your email address on a global removal list for all members of the Internet EMail Marketing Council (IEMMC). Go to web page http://www.iemmc.org/remove.htm -------------------------------------------------------------------------------- Alan G Jones Ottawa, 14 July, 1997 -------------------------------------------------------------------------------- >>>Appendix: Email list ======================= The list updated to 9 July 1997 is available on MTNet at http://www.cg.NRCan.gc.ca/mtnet/email/email.html If you cannot access the WWW and need your own copy, please send me an email.