Start with this . +quot;Geophysical Applications of VeryLongBaseLine Interferometry+quot;

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Start with this ... "Geophysical Applications of Very-Long-Base-Line Interferometry" by Douglas S. Robertson Reviews of Modern Physics, Vol 63 #4, October 1991, Pp 899-918. The NASA Crustal Dynamics Program has been using portable VLBI receivers in the field since 1980, so this review paper has plenty of data to review. As this is a review paper, there are plenty of references to the original research publications. Here are some other papers/journals worth looking at ... "Utilization of Mobile VLBI for Geodetic Measurements" by J.M. Davidson & D.W. Trask IEEE Transactions on Geoscience and Remote Sensing, Vol GE-23, #4, July 1985; Pp 426-437. Some early results presented here. "The First Geodetic VLBI Experiment with the Bologna Radio Telescope" by Tomasi P. Mantovani et al. Nuovo Cimento, series C, Vol 11, #2, 1988, Pp 205-208 "Geodetic VLBI Data-Analysis using VLBI3 Software" by Verrone G. Picca et al. Nuovo Cimento, series C, Vol 13, #5, 1990, Pp 817-822 Astrophysics and Space Science, Vol 177 #1-2, 1991 Special Issue: "The George Teleki Memorial Colloquium on Fundamentals of Astrometry", 8-11 Sep, 1987, Beograd. Papers: "Realization of a Celestial System Based on VLBI Geodynamics Programs" by E.F. Arias et al., Pp 187-192 "Geodynamic Implications of Astrometry" by E. Groten & H. Lenhardt, Pp 409-426 Not just VLBI. GPS was very useful during General Schwarzkopf's recent middle east military training seminar. It is also useful for geodesy. "Few Millimeter Precision for Base-Lines in the California Permanent GPS Geodetic Array" by U.J. Lindqwister et al. Geophysics Research Letters, Vol 18 #6, June 1991, Pp 1135-1138. "Measurements of Strain at Plate Boundaries using Space-Based Geodetic Techniques" by S. Robado & C.G.A. Harrison. Geophysics Research Letters, Vol 20 #17, 3-Sep-1993, Pp 1811-1814. The latter paper uses both VLBI and GPS. Clearly, if GPS isn't already measuring the break-neck speed of continental drift, it soon will. More recently ... "Tectonic Plate Motion and Deformation Inferred from Very Long Base-Line Interferometry" by K. Sato Tectonophysics, Vol 220, #1-4, 1993, Pp 69-87. Unfortunately, I could not find Tectonophysics in our library, to review the paper myself. Astrometric techniques have been used to diagnose the peculiar nature of the Earth ever since the late 19th century, when astronomers first discovered the Chandler Wobble, as an unexplained systematic variation in observatory latitude, derived from precision astrometry and meridian transit timing. Now precision VLBI, and GPS data, can be used to measure the Earth's variable rotation and polar wander, both with high accuracy, as well as the direct observation of continental drift. These observations, in turn, strongly constrain detailed models of the Earth's internal physics, including the nature of the core-mantle boundary. Certainly the use of astronomy to study the structure of the core- mantle boundary, must be an excellent example of the unexpected use of a scientific tool, to study something it was never intended to study. ------------------------------------------------------------ Timothy J. Thompson, Earth and Space Sciences Division, JPL. Assistant Administrator, Division Science Computing Network. Secretary, Los Angeles Astronomical Society. Member, BOD, Mount Wilson Observatory Association. INTERnet/BITnet: tjt@scn1.jpl.nasa.gov NSI/DECnet: jplsc8::tim SCREAMnet: YO!! TIM!! GPSnet: 118:10:22.85 W by 34:11:58.27 N

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