Difference between revisions of "Gerard Schuster"
m (Yuk160030 moved page Gerard Thomas Schuster to Gerard Schuster: name change to First name/last name)
Revision as of 11:49, 18 October 2016
The Virgil Kauffman Gold Medal is awarded to Jerry Schuster “for pioneering work on seismic interferometry and imaging.” Schuster has long been interested both in exploiting new types of seismic data and in better utilization of the information contained in conventional data. He consequently extended the daylight imaging concept, originally derived by Jon Claerbout, into a mathematical framework for imaging, called interferometric imaging. The method combines cross-correlation with downward extrapolation and imaging (also a cross-correlation process), which makes his method less dependent on the availability of sources. Interferometric imaging offers new imaging opportunities, such as migration of multiples in data, even of transmitted waves, and identifying the location of unknown source locations from daylight data. His imaging of multiples, particularly from VSP data, is now widely accepted and has had a profound effect on expanding the imaging aperture for salt flank delineation. He integrated these results in the book Seismic Interferometry. Schuster’s contributions to seismic interferometry are seminal and the importance of his pioneering work will become even more important as seismic interferometry becomes widely accepted.
Biography Citation for the Virgil Kauffman Gold Medal Award
Contributed by Tamas Nemeth
A complete scientist significantly impacts many areas in his professional life, such as in basic research, the application of this research to real problems, and in teaching others about what he has learned. It is gratifying to see Professor Jerry Schuster honored this year with the Virgil Kauffman Gold Medal for his work on seismic interferometry, an effort that truly encompasses all these areas.
Jerry has long been interested in unconventional seismic data. His Utah Tomography and Modeling/Migration (UTAM) research consortium started in the late 1980s, and for a long time it focused primarily on crosswell seismic and VSP data. This focus yielded a different perspective on seismic data processing, since traditional hyperbolic-moveout-based processing methods did not work well in this acquisition environment. Jerry found that a combination of: (a) extracting information from all available wave modes, (b) compensating for limited illumination, (c) imaging and inverting directly in depth, and (d) calculating the image resolution addressed the needs for crosswell and VSP imaging. His experience in borehole geophysics led to the ingredients he would use later for his work in seismic interferometry.
In the mid-1990s, Jerry worked on an autocorrelation migration algorithm that he later extended to cross-correlation migration. His goal was to exploit the phase difference between the arrivals of different modes, for these phase differences could be indicative of subtle changes in the properties of the medium. Still, some problems persisted with cross-correlation migration, such as the presence of spurious ghost events generated by the cross-correlation of the input data. These issues were not resolved until he studied the daylight imaging concept derived by Jon Claerbout, who showed that the reflection response of a horizontally layered medium can be synthesized from the autocorrelation of its transmission response, and who understood that these events are a contribution to the integral beyond the evaluation surface. Jerry applied the correlation method not only to passive seismic data, but also to exploration data with active sources. He introduced the concept of interferometric imaging, which involves an integration of cross-correlation and migration. He supported his interferometric-imaging method by an elegant theory based on stationary phase analysis.
Why is seismic interferometry important? Compared with other disciplines, such as medical tomography or nondestructive materials testing, exploration geophysicists are very restricted in where they can place their sources and receivers. Seismic interferometry gives us some relief from our acquisition limitations by creating data as if we had sources or receivers in locations not in the original acquisition. As we understand interferometry today, it allows (a) the reconstruction of the Green’s function of the medium between “virtual” source-receiver locations where there is no direct measurement of the wavefield, or (b) obtaining depth images from the response of a single source, many receiver configuration, or (c) the reconstruction of the reflection response from many uncorrelated noise sources. Thus, the promise of seismic interferometry is to utilize more completely the existing data for the reconstruction of Earth properties, and to compensate for suboptimal acquisition geometries.
Jerry possesses a rare insight into the fundamental issues of geophysical problems and connects our problems with solutions found in other, seemingly unrelated fields. With his exceptional research creativity and old-fashioned scientific curiosity, he has been a fountain of ideas, conjectures, and exciting results throughout his career. He is unusual in his instinct for finding things that might work on a problem and his willingness to test them. And he still beats his students to the office every morning.