Continuing with some more history of the geophysics program, I wrote this with the help of memories of my graduate students and those on whose committees I served as Co-Chairman with Cahit Çoruh. Cahit told me that, while he is chairing the Department, he would not feel comfortable about authoring anything about his part of our history, so I have tried to provide an overview. I cannot accurately report Cahit's memories or impressions, but if they differ from mine then I am certain he is the one who is wrong (when you deal with impressions or interpretations, you don't have to be right, you just have to be certain). Anyhow, this was a shared effort. I've sprinkled a few anecdotes here and there, some of which seem funny to me only in hindsight, but they are all true. The references below are to our students' theses and dissertations.
Most (47 out of 88) of the graduate students in geophysics during the years 1967-97 did theses and/or dissertations related to reflection seismology or terrestrial heat flow --mostly the former. Why these two areas of research? Why heat flow? In 1967, there were two outstanding questions concerning observations of crustal heat flow: 1) How to explain the remarkable linear relation between heat flow and surface heat production that had just been discovered by Francis Birch and his students at Harvard, and 2) Why isn't there a heat flow anomaly over the San Andreas fault? Millions of dollars were spent, and are still being spent, to try to understand the observed data. Also, heat flow has always seemed to have the potential to help us to understand the genesis of ancient as well as active orogens. In 1967, there were very few heat flow values in the eastern and southeastern U.S., and so, continuing my research started at the University of Utah, I moved the lab for heat flow determinations to Virginia Tech. Marshall Reiter (Ph.D., Virginia Tech, '69) published the first heat flow values in southwestern Virginia. Why reflection seismology? It really needs no justification. This is the principle geophysical method used to find oil, and what better way to examine the subsurface geometry of an orogen? Furthermore, in '67, very little regional reflection seismic data were available to the public. There was an ongoing friendly but spirited debate between our Byron Cooper and Yale's John Rodgers as to whether Appalachian tectonics were thin-skinned or thick-skinned. Although John Rodgers might have had access to confidential petroleum industry data, the rest of us didn't. Clearly, more reflection data were needed. As it turned out, heat flow and reflection seismology found a common focus and a practical application during the energy crises of 1973 and 1979, and we were there, not only to take advantage of the funding opportunities that arose but also to create a few of our own.
As reported by Gil Bollinger in our Fall 1998 Alumni Newsletter, Professor Charles E. (Rosy) Sears in 1962 had already established the on-campus earthquake seismic station as part of the 120-station Worldwide Standard Seismograph Network funded by the Air Force to monitor underground nuclear explosions. Except for earthquake seismology, however, other kinds of geophysics, especially reflection seismology and heat flow, were relatively new to Virginia Tech. In '67, one of the first efforts of Gil, John Costain, and Ed Robinson, the three new geophysicists hired by Department Head Byron Cooper, was to publicize the new M.S. and Ph.D. degree programs in Geophysics. We sent a description of them, along with course syllabi to companies in the petroleum industry. They liked the programs, they came to recruit our students, and they never stopped coming. Indeed, in 1985, 15 companies from the petroleum industry recruited at Tech during a single recruiting season. All were looking to hire geophysicists. Not bad for a university in the eastern U.S. far from the oil patch.
Byron Cooper admitted that he really didn't know what three new geophysicists would require, so in addition to office space he gave us one huge undivided room on the first floor that extended almost the entire length of the middle section of Derring Hall. This room was so large that it was soon walled off into three, and now consists of the Geological Sciences PC Laboratory with 18 computers (Room 1044), the 3-D Subsurface Imaging Laboratory (Room 1042) with many Unix workstations, and a third lab still used for earthquake seismology (Room 1040). Byron correctly surmised that geophysicists would need a hole for well logging as well as for other things, so he had a 450-foot hole drilled and then he erected Derring Hall over the hole. Nice planning, Byron. The hole is still open in Room 1040.
When Costain came to Tech in 1967, he argued successfully with administrators Byron Cooper and Vice President Warren Brandt, that a productive geophysics program would require at least two full-time technical support persons for geophysics because of the heavy reliance on computers (even then) as well as laboratory and field equipment. Special thanks are due John Wonderley and Bob Montgomery, both computer and instrumentation specialists, who were employed by Virginia Tech in the Department of Geological Sciences specifically in support of the geophysics program. Earlier, Perry Parks held one of these positions until he left to work for Mobil. Without their remarkable technical and communication skills the geophysics program in general, and the heat flow/ reflection seismology programs in particular, would not have succeeded.
Costain's contribution to the geophysics curriculum included a course he first called "Modern Reflection Seismology", which later evolved into two courses. Although the subject matter was not designed to train students just for petroleum exploration, the students received a background that was suited to career opportunities in the petroleum industry. Especially emphasized by John was his computer workshop environment that utilized Fortran programming to illustrate and apply the theory discussed in the classroom. He doggedly pursued this approach until his retirement in 1996 when the declining popularity of Fortran, as evidenced by the reluctance to teach the language in the Computer Science Department, suggested that Mathematica or C might become a viable substitute.
In the early days of our reflection seismology program, which started
long before the COCORP program of Cornell, we used explosives as an energy
source. We sent Perry Parks, then a member of our geophysics technical staff,
on a mission to Texas to find a used shothole drill. He soon phoned back with
the comment "Wait till you see what I found", and he drove back with this
enormous (to us at the time) Mayhew 500 shothole drill that was a real work
horse for us for many years. We also had a couple of
one man drills (an
oxymoron). There is a picture at
http://rglsun1.geol.vt.edu/DrillingProgram.html. Don't ask how long it took to
drill a 3-foot hole! There was a camaraderie within the reflection seismology
group brought about by common interests and a willingness to help each another
in the field, as well as in the processing and interpretation of the data.
Reflection seismology at Tech had a laboratory component, too. In the lab, David Worthington (M.S. Geophysics, 1969) completed some novel ultrasonic seismic wave model studies; alas, David, we stopped just short of owning the whole field of what is today called AVO (amplitude versus offset)! In the field, Tom Kolich (M.S, 1974) took our old Amoco-donated instruments to the top of the nearby Price Mountain window and obtained some of the best (still) reflections from the deep (1.2 sec) Early Paleozoic shelf strata that have since been obtained anywhere in the southeast, giving us a good idea of the structural complexity and thickness of the shelf strata beneath our Price Mountain window.
Velocity is important to geophysicists and we began a systematic program (Kolich, '74; Wells, M.S., '75; Brennan, M.S., '85) to determine the rock velocities characteristic of each of the geologic provinces in the southeast. We acknowledge the cooperation of Professor Wally Lowry and later Lynn Glover who took our students and me to the field and showed us where to obtain samples of the thick sequence of Paleozoic shelf strata and the Piedmont and Blue Ridge allochthon. We set up a laboratory for measurements of rock velocities in a pressure cell under hydrostatic pressure to simulate depth of burial. Tom Kolich and others made laboratory determinations of P-wave velocities and densities of the lithostratigraphic units. We were soon able to compute the magnitudes of the reflection coefficients to be expected from these rocks, which helped us to interpret the source of those large-amplitude, deep reflections. We needed this when we later compared synthetic seismograms for the folded strata of the Valley and Ridge province with those west of the structural front (Gresko, Ph.D., 1985). Paul Wells (M.S., '75) added refraction to the mix with his structural modeling near the Blue Ridge overthrust that allowed us to compare field and laboratory determinations of rock velocities. For some of the later laboratory velocity setups, we used a flexible sleeve around the rock cylinder inside the pressure cell in order to prevent the confining fluid from entering the pore space in the core. We tried condoms. Other unusual supplies were also necessary including, of course, explosives. John recalls the time when he phoned the Purchasing Department and ordered 200 pounds of explosives and a gross of condoms. There was a pause at the other end of the phone line, and finally, somewhat tentatively, came the question "Say, just what does geophysics do, anyway?"
The tectonic setting of the overthrust(?) Inner Piedmont was a more controversial subject then than it is now. In 1973, John Costain and Lynn Glover collaborated on an NSF grant to use reflection seismology and geology to investigate what was beneath the rocks of the Inner Piedmont, a terrane bounded on the west by the famous Brevard Fault Zone in North Carolina. This was Butch Clark's thesis (M.S. 1974). Using the Mayhew 500 drill, by this time converted for air drilling, John Wonderley drilled a 150-foot hole in the Henderson Gneiss. Costain said "Let's case it before we put the explosives in so the hole won't cave and then we can use it for a second shot." Shothole casing comes in 10-foot lengths, and you screw the 10-foot lengths together as you lower the casing into the hole. So we had 150 feet of shothole casing screwed together in fifteen 10-foot sections in a hole in the Henderson Gneiss. The students and I earlier had laid out the receiver spread in a desolate area that was being cleared for a future housing development. When we finished laying out the spread it was 3:00 A.M. and we were all exhausted. There was, however, a full moon, no wind or traffic, and enough light and someone suggested that we should just stay and finish the job. So we loaded the cased hole with 25 pounds of explosives and shot it off. Well, that 150-foot string of shothole casing just rose out of that rifle barrel of a hole with a vengeance, straight up it shot, pausing just in front of the full moon where the string began to break apart into its component 10-foot sections. These pieces then rained down from above as the startled crew watched at least two of the sections bury themselves nine feet in the saprolite (one foot sticking out). Costain was heard to mumble "ÆZ!OÑS! There must be a better way to do this.", and the Virginia Tech Vibroseis program was conceived in terror early that very morning and actually started up with a full-time seismic crew in April, 1979. (The vibroseis source is a non-destructive, low-energy surface source. You don't have to drill holes.)
Butch's explosive thesis (Clark, M.S., 1974) described the reflections that were interpreted to originate from autochthonous shelf strata beneath the Inner Piedmont, the thesis was published, and has since been widely referenced, even in the Scientific American (Yes, it's nice to get something published in Nature or Science, but when someone else refers to your research in the Scientific American, then you know you've arrived). Butch's research provided the first geophysical evidence that the Inner Piedmont might be allochthonous. There were sceptics because it was such a short spread and such a shoestring operation, but the disbelievers eventually came around and to their credit even said so in print. For forgotten reasons, Lynn and I did not follow up on this discovery and ask the NSF for more money to expand the research. It must have been because of the program in geothermal energy, which began the next year. As a result, the COCORP group at Cornell got lots of publicity when they later shot lines in the same area and confirmed Butch's earlier results.
More about the Vibroseis program later, but first a few words about another research area in the department --terrestrial heat flow. John started the heat flow program in '67 with an $80K NSF grant that was transferred to Virginia Tech from the University of Utah. Research in heat flow requires drilling holes and therefore, like reflection seismology, requires a lot of outside funding. John recalls being introduced to a new Dean of the College of Arts and Sciences at Charles Gilbert's (a former Chairman) house. "John is a geophysicist", Charles said. "Oh, yes, that's expensive, isn't it", was the Dean's chilling response. I tried to explain that yes, geophysics is expensive, but if you want to extend the details of mapped surface geology into the third dimension of depth, then reflection seismology is the way you do it. The geophysics faculty, with one of them as first principal investigator, brought in more than $10,000,000 in outside funds between 1967-1999 for research that was directly related to heat flow and reflection seismology. Additional collaborations with Lynn Glover that included geophysics and Gil Bollinger's earthquake studies increased this total to perhaps as much a $15M. That's also a lot of overhead. Furthermore, in the 1988 Gourman Report (7th Edition, p. 94), which publishes a national ranking of academic programs, the Virginia Tech undergraduate Geophysics B.S. degree program was listed as the highest-ranked program in the College of Arts and Sciences, one of the top three in the entire university, and 14th in the nation. The new Dean was completely satisfied and geophysics continued to receive fine support from the administration, including all of our elected departmental Chairmen, without exception.
In the years before Çoruh, all of our seismic data processing was done on the university's IBM mainframe using software written entirely in Fortran by John, who called his programs "Program ONE", "Program TWO", ... "Program TEN", etc. When Cahit came on board he looked around, shook his head, mumbled something in Turkish, and politely said "John, maybe we should try to get funding to buy some commercial software for processing the seismic data." "What for?", I asked. "We have all the software we need. With my fast IBM mainframe Fortran programs, we can demux the field tapes, filter, deconvolve, stack, ray-trace, plot...", I continued modestly. "Yes", interrupted Cahit, "But there will be so much more data coming in when we get the new instruments. We will need something more user-friendly". Cahit volunteered to go to "Hooston", look at available commercial software, and come back with a recommendation. Soon thereafter we became the first university in the United States to install the then state-of-the-art DISCO (Digicon Interactive Seismic COmputer) processing software. This important turning point toward "icon-based" commercial reflection seismic data processing software has today evolved into the sophisticated FOCUS 3D processing software, AIMS modeling, and Landmark interpretational software, and much more, available to students and our new geophysics faculty on powerful workstations in the 3D Subsurface Imaging Laboratory. In the classroom, however, I continued to use the mainframe and Fortran so that our geophysics majors would be "computer literate", and not just "icon literate". Almost from the beginning, one of my goals was to put a computer terminal with access to the university's mainframe in the cubicle (and in our branch library in Derring Hall, too) of each of our geophysics graduate students. Today this simple office adornment is taken for granted, but during the early years this objective was met with scepticism or indifference by just about everyone.
The oil embargo imposed by the Arabs in October 1973 stimulated a search for alternative sources of energy. For example, why do we have hot springs in Virginia? Are they a geothermal resource? In 1975, John received a 1-year research contract from ERDA (Energy Research and Development Administration) to examine the origin and geothermal potential of the hot springs in northwestern Virginia. This was Lawrence Perry's M.S. thesis (1975) and marked the start of the more applied geothermal studies. In addition to obtaining normal regional heat flow values near Warm Springs, VA, numerical modeling studies by Lawrence demonstrated that the source of the hot water could not be attributed to Eocene intrusives such as those exposed nearby in Highland County, but instead were simply the result of deep circulation of meteoric groundwater. Comprehensive numerical modeling of temperature and heat flow in the crust by Ming (M.S., '69), Perry (M.S., 1975), Dunbar (M.S., 1979), and Pyrak-Nolte, M.S., '83) resulted in the development of general mathematical models to predict temperature and the expected heat flux from buried, heat-producing intrusives, and see the effect of thermal conductivity contrasts on terrestrial heat flow determinations. Funding for the hot springs contract was increased by ERDA the following year and in 1977 was considerably expanded under the newly formed Department of Energy (DOE) as a program entitled "Evaluation and Targeting of Geothermal Energy Resources in the Southeastern United States". From 1976-82, research was supported by contracts to Principal Investigators John Costain and Lynn Glover. Krishna Sinha was a Principal Investigator from 1977-1979. The geothermal program was the largest funded program ever in the Department of Geological Sciences, increasing to a total of over $5M over the next 5 years. Over 100 people were employed on this project from 1976 to 1982. This large a program required better than average communication with our sponsor, the Department of Energy in Washington, D.C. Meetings were often rather spontaneous with very little warning. Lynn Glover and I had many prolonged, productive, creative, and pleasant dinners at a certain Italian restaurant near the Washington airport where, after reviewing the often (for me) tense budget meetings with DOE project managers, we suddenly realized that we needed to call our wives and say that "It looks like we are going to miss the plane again back to Blacksburg. See you tomorrow." Hey, we took our job seriously. It's not easy to raise funds to support over 100 people year after year.
The focus of the geothermal program was primarily on what we called the "Radiogenic Model". The warm springs in Virginia and elsewhere are certainly a geothermal resource, but they are few in number and quite localized. A more widely distributed resource is the fluids within the highly porous and permeable sedimentary wedge of Atlantic Coastal Plain sediments that overlie crystalline basement rocks. In some locations these sediments overlie heat-producing granitoids that were intruded into the crystalline basement and occur like plums in a crystalline pudding. The heat comes from the radioactive decay of U, K, and Th (mostly U and Th). The optimum locations would therefore be where the sedimentary wedge "insulator" overlies these heat-producing Late Alleghanian, post- and syn-metamorphic, relatively unmetamorphosed granite bodies. There are many of these granitoids exposed in the Piedmont, but of particular interest from a geothermal standpoint are those that are hidden beneath the sediments of the Atlantic Coastal Plain. The sediments have a low thermal conductivity and therefore support a relatively high geothermal gradient for any given heat flow. Like a sweater. Reflection seismology was ideal for determining the thickness of the Coastal Plain sedimentary insulator and also for providing detailed information about the continuity of the highly porous and relatively permeable deltaic and marine sediments that cradled the aquifers. So find out where these granites are located (they produce well-defined negative gravity anomalies), drill a hole in the sediments over them, and you will have the highest temperatures at the shallowest depths (e.g., Pratt, M.S., 1982). Funding in 1977 from DOE and generous matching funds from Virginia Tech allowed us to purchase new multichannel equipment for reflection seismic data acquisition as well as computer facilities. We replaced our older equipment with state-of-the-art instruments (MDS-10) and a VAX 11/780 computer for processing. For the radiogenic model we needed to know the thickness of the overlying Atlantic Coastal Plain sediments, the quatity of heat-producing radioactive isotopes in the crystalline basement beneath the sediments, and the heat flow. The model, with its predicted higher temperatures over heat-producing granite, was confirmed by drilling holes at Portsmouth, VA, and at a nearby location not over the radioactive granite, at Isle of Wight, VA. Considerably higher temperatures were obtained at the Portsmouth location because of the extra heat generated by the underlying granite. More details at http://rglsun1.geol.vt.edu/confirm2.html. But would the overlying Coastal Plain sediments be thick enough and permeable enough to be a practical source of geothermal fluids? Laczniak (M.S., 1980), in an elegant numerical modeling study of fluid withdrawal/reinjection and heat transport in Coastal Plain sediments, showed that it was indeed a feasible model. Indeed, the potential of geothermal energy is being realized even here in Blacksburg, where details of our first geothermally-heated residence can be viewed at http://rglsun1.geol.vt.edu/blacksburg.html.
The year 1979 was a great one for geophysics as well as for the Department of Geological Sciences. That was the year Cahit Çoruh joined the geophysics program as a Visiting Associate Professor of Geophysics. Costain recalls the day when, with the help of Professor Ertugrul Topuz of the Mining and Materials Engineering Department, who helped him communicate with the telephone operators in Turkey, he phoned Cahit in Istanbul to discuss with him the job application that he had submitted in response to the advertisement placed in EOS for a full-time professor to collaborate in research and teaching during the busy geothermal days. Cahit said yes, he was interested and would like to hear more. How about the salary? How many courses would he be able to teach? After much bargaining, the likes of which Costain says he has not seen since, and from which he has yet to recover, Cahit accepted the job of Visiting Associate Professor of Geophysics, a position paid entirely from our DOE funds. John wasn't in the country to greet Cahit when he arrived, but the large and congenial geothermal group, hosted by Lynn Glover, took him to lunch and left him with a fine lasting impression (so I'm told). Cahit's wife and daughter, Dilek and Basak, arrived a few months later. Cahit actually already had a job as Professor of Geophysics in the Department of Geophysics (he was head of the Department there from 1984-85), Faculty of Engineering, University of Istanbul, Vezneciler, Istanbul, Turkey, and so the family had to go back to Istanbul, but Cahit returned again by himself on and off averaging about five months per year during 1982-1984, this time as Visiting Professor of Geophysics, for what was probably one of the most complicated commutes in the history of Virginia Tech. In 1985 he stopped commuting between Istanbul and Blacksburg and was appointed a tenured, full-time Professor of Geophysics in the Virginia Tech Department of Geological Sciences. Less than ten years later he was elected Chairman of the Department of Geological Sciences, a position that he holds today. Time passes so quickly. Indeed, Cahit and Dilek's daughter, Basak, just graduated from the University of Virginia in June, 1999, with a B.S. degree in Chemistry. But I digress.
The permanent technical support staff in reflection seismology/heat flow was not entirely on hard money. Mildred Memitt came to work in the Department in July 1979 as a bookkeeper for the DOE-sponsored Geothermal Program. In September, 1979, she took over as Lead Computer Operator for the VAX 11/780 computer that was installed for the processing of reflection seismic data being acquired by the Virginia Tech Vibroseis Crew for the geothermal program. From 1979 to 1998, when she retired, Mildred was on soft money. She was the software applications person. Her support was invaluable, and has been documented by geophysics graduate students in reflection seismology who are invited to recall fondly what they wrote in the acknowledgments of their Theses and Dissertations (http://rglsun1.geol.vt.edu/Mildred.html).
Operating a seismic crew does not conveniently fit in with the schedules of students, so although we started with some student help, we eventually evolved into a full-time non-student seismic crew. The patience, dedication, and competent efforts of Wayne Compton (Vibrator Mechanic), Bill Davis (Foreman), and Frank Greenlee (Instrument Operator), the entire crew, and the departmental and project support staff are gratefully acknowledged. We worked in a research mode and rarely did things the same way twice ("If we knew what it was we were doing, it would not be called research, would it?" --Albert Einstein), often under difficult and rapidly changing circumstances. For a seismic energy source we only had one single large Model Y-1100A vibrator manufactured by a well-known company named Failing, Inc. If that vibrator malfunctioned, then the entire field operation shut down, but we still had to pay the salaries of the crew. John recalls the day when he walked into the office of our beloved then-Chairman, Dave Wones, and said "Dave, I need to talk with you about the Failing vibrator." "What?!", shouted Dave, leaping up from his chair. "John, you didn't tell me there was anything wrong with the vibrator!" "Wait Dave", replied John while quickly backing out of strike range. "The vibrator is fine. It's not a-failing. It's a Failing. There's nothing wrong with it. I just need you to sign a purchase order for some more supplies." Dave breathed a prolonged sigh of relief, sank back in his chair, and we both got through another day.
Concurrent with seismic data acquisition, we had a major in-house drilling program with our own drills and drillers and obtained a cumulative total of tens of thousands of feet of crystalline basement core from the exposed Piedmont as well as from beneath the Coastal Plain sediments. We started with a Longyear Model 38 core drilling system and later upgraded to a Model 44. If you are not familiar with drills, one like that is designed to recover core from depths of thousands of feet; it is not for the faint of heart. The core we recovered from crystalline basement is still stored on campus, available to interested investigators, and, in fact, was sampled as recently as April, 2000 by a scientist from Woods Hole. John distributed daily drilling progress reports that were circulated to the other principal investigators, graduate students, research associates, and technical personnel on the geothermal project. These reports were prepared after telephone calls from Bill Coulson, our congenial and dedicated head driller, who faithfully telephoned me at home every evening from the field. One night the call came late, the phone rang, Rose answered, shook me out of a deep sleep and said "It's Bill Coulson." She handed the phone to me and Bill started filling me in on the drilling progress. While he was talking, every once in a while I groggily injected something appropriate like "That's great", "OK', "Hmmm", finally degenerating to something unintelligible (--sounds like zzzzz)--and then I fell asleep, while still holding the phone, and with Bill still talking. Rose tells me she explained the situation to Bill and hung up. It was the first time I ever fell asleep while talking to someone on the telephone. The next time I saw Bill Coulson, he was still laughing.
In late 1980 I received a phone call from our DOE program director in Washington who wanted to know if the objectives of our geothermal program had been reached. We had confirmed the radiogenic model, a deep test well had been completed at Crisfield, Md., and Laczniack (M.S., 1980) had used an "integrated finite difference" numerical model to simulate an injection/pumping dipole, demonstrating that the (now) known permeability values in the Coastal Plain sediments were high enough to sustain a geothermal system. (The economics of a viable geothermal system in the eastern United States was in the capable hands of the Applied Physics Laboratory at The Johns Hopkins University; we were only concerned with the scientific aspects.) I reluctantly said "Yes, we had reached our objectives", and the program wound down to end in June of 1982.
Meanwhile, the Soviet Union was undertaking a successful program of drilling to depths of up to 15 km in crystalline rocks. Everyone has heard of the Kola Penninsula hole (12 km deep) and the Soviets were persuing an ambitious and successful program of deep drilling for purely scientific purposes in a number of other locations. Why weren't we doing the same thing in the U.S.? We needed to catch up. In 1983, we were invited by Professor Bob Hatcher of the University of Tennessee to contribute our expertise and participate in a multi-university NSF-sponsored study to site the first ultradeep scientific hole to be drilled in the United States, in northwestern South Carolina. The proposed ultradeep hole was slated to reach a depth of 10-12 km, cored all the way. The objectives were to sample Grenville basement and on the way down to core through the allochthonous Inner Piedmont, continue down through the famous Brevard Fault Zone --a structural lineament that extends from Georgia to Virginia and can be seen from orbit and about which some twenty hypotheses had already been proposed regarding its origin and tectonic significance, --on down through autochthonous Paleozoic shelf strata into an Eocambrian(?) basin that had been imaged on our regional seismic data, and wind up below that in crystalline basement. The project acronym was ADCOH (Appalachian ultraDeep COre Hole). Bob Hatcher tried to promote the name "AppleCore" but some thought that was too frivolous for a multi-million dollar program. Virginia Tech was to determine heat flow values, design and supervise the field acquisition by GSI of the regional seismic reflection data, process the seismic data, and collaborate with several other universities in the interpretation of all of the data. We were not ADCOH's first choice, though; Cornell's COCORP was, because they had already shot several lines in the southeast. Their calendar was full, however, and additional regional seismic lines were clearly justified. But what resulted from our involvement was a series of regional lines that was heralded as being "the best crustal reflection data obtained to date anywhere in the world". Interpretations of earlier COCORP data were revised. The ADCOH seismic data (Scott, 1987; Laughlin, 1988; Hubbard, M.S., 1990) were so good that I actually heard (tongue-in-cheek, I'm certain) that funds to drill an ultradeep hole in that South Carolina location would now be unnecessary! I was also told that some suspected I was witholding information about why our data were so good compared with that obtained earlier by COCORP --in the same area. Here's the secret, revealed here for the first time! The recording aperture was designed so that the expected normal moveout at the depth of the target reflector (top of Grenvillian basement) at the farthest receiver offset would be in the range of 80-100 ms. Furthermore, to avoid any 60 Hz noise I chose an integer two-octave bandwidth with an upper frequency limit as close as possible to, but less than, 60 Hz. Hence, a 12 sec, (1-sec taper on each end) pilot upsweep of 14-56 Hz. Some secret. Sadly, the ADCOH project was not continued after the preliminary site selection investigation was completed, even though the heat flow data predicted benign temperatures at 10 km, even though the core and the seismic data would have provided a remarkable pencil of information for subsequent extrapolation and correlation with the geologic framework in all directions, and even though the fluid pressures at 10-12 km were expected to be simply hydrostatic. Politics soon reared its ugly head about where the best site for an ultradeep scientific hole really should be located. Concerned letters were written by Hatcher and one by me to the NSF about the apparent political nature of the decision to abandon the ADCOH site, which, even if the site didn't satisfy everyone, might have launched this country into a multi-hole, ultradeep (15 km) scientific drilling program that might now be a line item in the federal budget.
Anticipating the end of sustained funding from DOE, we had been looking elsewhere for financial support. DOE said from the beginning that they were not interested in supporting a full-time seismic crew indefinitely. During and after the geothermal program, Lynn Glover, Cahit Çoruh and I received funding from such diverse sources as the Nuclear Regulatory Commission, the U.S. Geological Survey, the Virginia Division of Mineral Resources, Maine Geological Survey, Sohio, Chevron, Southeastern Exploration and Production Corporation (SEPCO), and many others. We wrote dozens of research proposals. In 1981-83, Sohio was delighted to take advantage of any available crew time. Ditto for SEPCO and Chevron. Each project gave us a little more insight into the local or regional geology, and we were given permission to publish the results. In 1984 we three received a grant of $232K from the NSF to upgrade the reflection seismology instruments. From 1982-84 we created the Virginia Tech Vibroseis Consortium (VTVC) and thought up projects that would be of interest to us as well as to industry and governmental subscribers, who contributed $20,000/year. Cahit and I also had a non-vibroseis "Thin-Bed Consortium" that focused on the theoretical aspects of thin bed detection (Marangakis, M.S., 1983; Bryan, M.S., '85) and the seismic response expected from sequences of thin beds (Brennan, M.S., '85) as well as the potential of high resolution seismic data to examine (and reinterpret) the depositional environment of coal (Weisenberger, M.S., '85). These were exhilarating times for me --especially the learning part and exploring new ideas that were triggered by data arriving almost daily. Although we gave and published many papers, at times it was an exhausting effort and it became obvious that without a sustaining sponsor like DOE or the NSF, we could not maintain a full-time seismic crew. At one point we did have a brief discussion with the NSF, and it appeared that there might have been an "opportunity", perhaps, to submit a proposal and become some kind of a central NSF-supported reflection seismology facility in collaboration with other universities; however, that would mean we would have to become involved with projects that might be of little interest to us. The days of full-time seismic data acquisition were over, and in May of 1988, we sent our inventory of vibroseis and drilling equipment to Virginia State Surplus Property to be put up for sale.
A major contribution that resulted from the collaboration of geologist Lynn Glover and his students and geophysicists Cahit Çoruh and John Costain and their students was an understanding of the tectonic framework along Lynn's "James River Corridor" in Virginia. The geologic cross section and interpretation that eventually resulted from this collaboration is the most complete and best documented of any geologic/geophysical traverse on the passive margin of the eastern United States. The union of surface geology and the subsurface images obtained by the Virginia Tech seismic crew, as well as our reprocessing of available seismic data from other sources, particularly USGS seismic line I-64 and the regional Petty-Ray lines, led to a clear understanding of where the elusive Taconic suture was not located in central Virginia. Collaborations with other institutions and agencies made possible extended geographic excursions of the seismic crew, and these, combined with a computer-intensive effort, provided background for geologic interpretation in the Corridor. We were able to recognize similar seismic signatures from the crystalline terranes beneath the Culpeper Basin north of I-64 all the way to Georgia (Brennan, M.S., '85; Pratt, Ph.D., 1986; Lampshire, 1992; Pappano, M.S., 1992; and unpublished data). We were among the first to integrate the regional seismic data with major potential field anomalies that can be traced from Virginia to Georgia (Pratt, Ph.D., 1986; Pappano, M.S., 1992; Peavy, Ph.D., 1997).
In 1990, Cahit and I turned our attention exclusively to computer-intensive research, including the reprocessing and interpretation of reflection data of interest to us but acquired by others. For the most part, we had been working with vibroseis data, which are different. Such data are conventionally displayed after a "full correlation" with a "pilot sweep"; however, a "partial correlation" is also possible, which allows you to look considerably deeper into the crust to depths never before seen on a particular data set. Pratt (M.S., 1982; Ph.D, 1986) used this technique with remarkable success in central Virginia. Furthermore, Çoruh and Costain published on a procedure that results in a considerable increase in seismic resolution. We called this "vibroseis whitening". Çoruh took this idea much further and showed that the increase in resolution could be recovered from any seismic source, whether offshore, onshore, vibroseis, or explosives! In addition, Çoruh introduced what he called the "automatic line drawing" (ALD), which minimized the subjective drawing of lines on a seismic record section to emphasize the location and quality of a reflector. Now we let the computer generate a quantitative measure of reflection quality on the basis of coherency and continuity between traces, and plot out a trace whose amplitude was a measure of this coherency. These novel computer algorithms, and so many others, provided financial support for our program for many years. It wasn't just "vibroseis whitening" and all the rest, but also Cahit's novel approaches to imaging and interpreting deep as well as shallow subsurface structures, and combining the two using composite refraction-reflection stack sections, that kept our research creative and stimulating over the years (Laughlin, M.S., '88; Sen, M.S., '91; Moore, M.S., '97). We have several years of results that await publication.
One of our more publicized examples of reprocessing with partial correlation, vibroseis whitening, and the ALD was the U.S. Geological Survey I-64 vibroseis line across central Virginia (Pratt, Ph.D., 1986), a line that was acquired by GSI. This image remains the best regional look at the reflective upper crust and Moho in the eastern United States, and provided support that eastward crustal thinning was a Mesozoic feature. In South Carolina, the unprecedented clear deep crustal images of Domoracki (Ph.D, 1994) from reprocessed Conoco data obtained by using only two vibrators gave us new insight into the geometry and root zone of the Blue Ridge Master Decollement and associated major thrusts, and should remain a reference standard for the southern Appalachians for years to come. Minnich (M.S., '96) revisited an industry reflection seismic data set and enhanced its temporal and spatial resolution. We even reprocessed some of our own data (Belcher, M.S., 1984) and were pleasantly surprised to discover that the version of Belcher's thesis published in the SEG journal Geophysics was later selected by an editor for inclusion in a special volume on vibroseis data acquisition and processing.
Processing can introduce many pitfalls. We didn't wait until the processing was over before making a geologic interpretation. Cahit emphasized "interpretive proccessing", which means that we should think about the geology during the processing. Nothing about processing is routine. His emhasis on interpretive reprocessing led us to think about the introduction of the regional geology at the earliest possible stage --starting with the survey data, in what we called "tectonic strike binning". Crooked-line (land) data should be processed, or reprocessed from scratch, by projecting the data in the direction of the regional tectonic strike. Results by Bill Domoracki, Cahit, and me using synthetically-generated 3-dimensional multifold data convinced us that this was the way to go. But there were some problems with some real data. The fold (number of reflection paths from the same "point" in the subsurface) turned out to be highly variable. Sam Peavy cleverly solved the problem by projecting pre-processed CDP gathers -- filtered, deconvolved, and corrected for statics -- onto the new, straight, dip-directed CDP line and using small gathering bins -- 1/5, say, the size of ordinary CDP gathers, thus allowing the collecting of lower fold CDPs into CDPs with more uniform fold. This equalized the fold along directions of regional tectonic strike (Peavy, Ph.D., 1997).
We went far and wide trying to understand how the orogen was assembled, --from Maine where we contributed (in Geology) a striking crustal image that included the crust-penetrating, steeply-dipping Norumbega Fault Zone, southwest to Georgia, and west to the New York-Alabama Magnetic Lineament where Deb Hopkins (Ph.D., 1995) showed everyone for the first time (in this location) the Grenville Front Tectonic Zone as well as the deep crustal setting that cradles the Eastern Tennessee Seismic Zone, and east to the easternmost Atlantic Coastal Plain. I received a request as late as 1999 for a reprint of the published version of King's (1980) M.S. thesis, with his Atlantic Coastal Plain correlations between onshore and offshore well logs and seismic data. Our group became experts at imaging and interpreting faults in the sediments of the Atlantic Coastal Plain, an area of critical impact for groundwater use. The results of Yantis (M.S., 1978), Bielanski (M.S., 1981), Dysart (M.S., 1981) clearly demonstrated the potential for the future widespread use of high resolution reflection seismology to define lateral and vertical changes in aquifer geometry in the ancient near-marine and marine sediments of the Atlantic Coastal Plain. Miller (M.S., '85) applied complex trace attributes to reflection seismic data near Charleston, South Carolina. We reported on numerous exposed and concealed Mesozoic basins and discovered growth faults associated with the continuing(?) deformation of the overlying younger Coastal Plain sediments (D'Angelo, M.S., 1985; Schorr, M.S., 1986; Luongo, M.S., 1987; Pappano, M.S., 1992; Domoracki, Ph.D, 1995; Moore, M.S., 1997). The numerical modeling of Pyrak (M.S., '83) gave us a clear understanding of how isotherms are warped by the presence of thermal conductivity contrasts associated with these Mesozoic basins, and how this could affect our heat flow values.
You have to look at our published results and interpretations to see what this computer intensive effort did for us. Among other things it revealed a remarkable regional continuity of deep crustal seismic signatures in the hinterland as well the foreland of the Appalachian orogen from Virginia to Georgia (Pratt, 1986; Lampshire, 1992; Pappano, M.S., 1992; Domoracki, Ph.D, 1995; Peavy, Ph.D., 1997). We imaged lithotectonic facies and crustal structure in each of Virginia's two seismogenic zones, the Central Virginia Seismic Zone (Brennan, M.S., '85; Pratt, Ph.D, '86) and the Giles County Seismic Zone (Edsall, M.S., '74; Gresko, Ph.D., '85). Our research gave us confidence to publish in 1999 on a single large crustal antiform that extends from I-64 in Virginia all the way to Georgia, and allowed us to describe and justify naming the unique NW-SE trending zone of earthquake activity from Charleston, South Carolina, to eastern Tennessee the "Bollinger Seismic Zone".
Some old tools were used to obtain new data, but we also took available data and used it to generate new ideas, and we solved old theoretical problems. We suggested reasons for what the Central Virginia, Eastern Tennessee, New Madrid, Charlevoix, and Bollinger earthquake seismic zones might have in common in the framework of "Hydroseismicity", our new hypothesis for the origin of intRAplate earthquakes (Needham, M.S., 1987; Setterquist, M.S., 1989; Tsoflias, M.S., 1991). Ecevitoglu (M.S., 1984; Ph.D., 1987) resolved the decades-long historical conflict between the different analytic expressions for the frequency dependence of body wave dispersion (and therefore, Q) and came up with a single exact theoretical solution for the velocity of P-waves versus frequency (called body wave dispersion) that required no arbitrary constants but still agreed beautifully with the approximate results of early workers.
Should an academic institution mount large computer-dependent, field-oriented, equipment-driven programs like those in reflection seismology, earthquake seismology, and heat flow? Or would it be better to concentrate exclusively on developing new theory and algorithms that might be applied to someone else's data from a different area or continent? If there are interesting local problems but a limited amount of data then clearly the more challenging approach is to do both, which is what we did. McCarron (1984, M.S.) looked into the feasibility of using PS converted waves for seismic imaging long before the use of converted waves became commonplace in the oil industry. Converted waves and 4-D reflection seismology will surely be used in the future to quantify and monitor changes in the fluid regime in shallow groundwater reservoirs. Demirbag (Ph.D, 1990) estimated seismic parameters (velocity, density) from reflection data by generalized linear inversion and bootstrapping. His work was later included in a special volume on AVO. Guo (M.S., 1994) moved into the tau-p domain to increase even further the resolution of the seismic method.
How do you measure the value of such large programs? One of the critical measures is clearly the number and quality of the students attracted to the programs, and ours attracted excellent ones, as well as recruiters from industry, and the attention of other universities. We feel that, collectively, we left an overall positive imprint on the scientific literature of the southeastern United States. (The imprint we left in Georgia cost the university a fine of $20,000 because of what looked like regularly-spaced pad indentations made in the road by our Y-1100A vibrator. "Moi?", I asked when confronted with this interpretation.)
In recalling this part of our history, I have emphasized research, but my first love was teaching my undergraduate course in exploration seismology. To those of you who majored in geophysics, I applaud you. It was not an easy route. Most of you are now practicing geophysicists, Chief Geophysicists, CEOs, COOs, Vice Presidents, teachers, owners of your own companies, environmentalists, are working for federal or state agencies, or are otherwise gainfully employed. David Worthington (M.S., 1969), CEO and owner of TGS-Calibre, Inc., and now Chairman of the Board of TGS-NOPEC, was the prime mover who spearheaded the successful 1995 fund drive to establish our new 3-D Subsurface Imaging Laboratory in Room 1042 in Derring Hall. Marshall Reiter (Ph.D., 1969) convincingly explained to me at the 1997 GSA convention in Salt Lake City his as-yet unpublished ideas about why there is no heat flow anomaly across the San Andreas Fault. Each of you as individuals is the measure of our success and pride, not grant money or any external evaluations of our program. Teaching undergraduate and graduate courses and doing research together is a two-way street, and I have learned much from you. Thanks for all the discussions, for your enthusiasm, and for sharing your ideas.