Oral History Transcript — Dr. Lynn Sykes
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Interview with Dr. Lynn Sykes
Lynn Sykes; May 24, 1997
ABSTRACT: Family background and early education; how he became interested in science; his fatherís career as meteorologist, then air traffic controller; living with his motherís parents, meeting his fatherís parents and their influence on him; influential school teachers and extracurricular activities; hobbies; religion; reasons for choosing Massachusetts Institute of Technology (1956Ė1960); joining a fraternity at MIT and choosing earth science as his major.
Doel:Let me begin by saying that this is Ron Doel and this is a continuing interview with Lynn Sykes. Weíre recording this in Palisades, New York. Lucky, the cat, is also with us for this interview session.
Sykes:Roger the cat, really Oscar the cat. [Laughter] Transcribe that if you will. [Laughter]
Doel:Certain syllables are. I should say today is the twenty-fourth of May, 1997. We had discussed a moment ago off tape that, what probably makes sense for us to continue discussing in the moment, is the work that you do in the 1960s that leads to the new global tectonics paper, the work in long period seismic work. How quickly did you begin transitioning from the kinds of seismic work that you had been doing in the early 1960s — you were doing some of the Arctic work, the ice sheet work? When did the transition to the deep focus earthquake work come about?
Sykes:Well, remember that I said last time that my thesis was on surface waves crossing oceanic areas, and I needed to have accurate locations of earthquakes in oceans. That in fact led me to do my 1963 paper on the South Pacific in which what I found was that there was a major zig in the pattern of earthquakes at a new fracture zone that I found. Fracture zones at that time were enigmatic features that [William P.] Menard had discovered in the 1950s, long linear zones of topography that intersect the mid-ocean ridge system.
Doel:This was the Owen ridge that you had?
Sykes:No, no. That was in the South Pacific — and what was the name of that fracture zone? Anyway, Iíll think of it.
Sykes:I then went on in a paper in 1964 of finding a big offset of a similar type along the Owen Fracture Zone just east of the horn or Africa. And about the same time, I did a paper on the Arctic in which I found a major zig or offset of the pattern near Jan Mayen Island north of Iceland. So I clearly made the transition from my thesis, which had to do with surface waves and which had occupied much of the efforts of Lamont in seismology for probably ten, twelve years, to working on these accurate locations of earthquakes.
Doel:Iím sorry, go ahead.
Sykes:So the next major project that I decided to do along that same line was to start working on, what were then called the island arcs — which with the emergence of plate tectonics were called subduction zones.
Doel:Right. But clearly by the time you first started working on them, that conception wasnít yet —
Sykes:Thatís right. So they were called island arcs, and one place that had a very high amount of [seismic] activity was the Tonga/Fiji/Kermadec region of the southwest Pacific. So I started the project of relocating a lot of the earthquakes there, and in conjunction with that, I did a lot in the northwest Pacific, in the Kuril and Kamchatka region.
Doel:Now, clearly to be able to recalculate precisely where these earthquakes were occurring was both an instrumental problem — developing the quality of the instruments — as well as the location.
Sykes:Well it turned out in this case that there were lots of published readings of the arrival times of P-waves. And so the main project then was to develop a program for relocation by computer in which I adapted a program that [Bruce] Bolt had written around 1960. But made it a lot faster [by computer] to look up stations so that it was possible to process in one run through the computer, twenty-five or fifty earthquakes. At that time, the standard input was punched cards. What was put in was a three letter code for each station, whose location was looked up in this library — computer library — and then the arrival time of the P-waves and then surface reflective waves that you use to deduct the depth of the earthquake. So I was not working with seismograms at that time. But the standard world agencies at that time, many of them had not gotten into computer locations. The U.S. Geological Survey did in the early 1960s, but I was looking for a longer sample of data like ten or fifteen years, and those were not available by computer. So most of these older earthquakes — the readings existed to make a more accurate location — but it was simply too difficult to try and do it by hand. Most of the standard agencies — like the International Seismological Summary — did not locate most earthquakes very accurately. Particularly the aftershocks. And in oceanic areas, particularly remote ones, the locations could be an error by several hundred kilometers. And the depths could be considerably in error. That was true also in the Tonga/Fiji region.
Doel:Yes. Now when you had mentioned that you were able to develop the, adopt Bruce Boltís program, so you were able to run twenty-five to fifty earthquakes through in a single sitting. Had this simply been virtually impossible to do by hand? How were — Iím trying to gauge simply how, how effective the computer became for you once you began using it.
Sykes:Oh, it was tremendously effective, because before time people who would try a kind of a quick and dirty method of location would need to take a few readings, have a big globe, and mark off the approximate distances, and like triangulation, come up with a little triangle or some intersecting, nearly intersecting circles. And that could easily be off by a hundred kilometers. The International Seismological Summary did a more formal procedure of — you might have a hundred and fifty readings and you want to know four unknown parameters, the latitude, longitude, origin time and the depth of each of them. But those are some big matrixes to work with and multiply, and it could take a person all day merely to do one iteration that could be done — even by 1960 generation computers — in a couple of seconds.
Doel:That puts it into perspective.
Doel:Were there reasons that focused your attention particularly on this arm of work compared to other — you mentioned that you were also working in the Aleutians and other very active regions? But Iím wondering what.
Sykes:Well, [cross talk] I was a graduate student, Jack [E.] Oliver decided to run a seismology seminar for credit on deep earthquakes. He thought that the subject had really not been explored much in about twenty years. At that time, we were able to read twenty or twenty-five papers that were the totality of papers written on deep earthquakes. It did become evident that the Tonga/Fiji region had more deep earthquakes that occurred per year than any other region. South America had some of the largest ones, but it didnít have as many moderate size earthquakes.
Doel:So you went, the distribution of energies, in other words to Ė-
Sykes:Well, we merely wanted more events to try and define what this surface that the Japanese called the down going seismic zone.
Doel:When did the Japanese start calling it that?
Sykes:Probably after [K.] Wadati discovered it in the 1920s. [Hugo] Benioff from Cal Tech wrote two well known papers in the Bulletin of the Geological Society of America in the 1950s in which he attempted to map out these zones on a global basis, as did [Beno] Gutenberg and [Charles] Richter from Cal Tech. At about the time plate tectonics broke, a number of Americans starting calling these zones Benioff zones. I have always felt that that did an injustice to Wadati who had called them down going seismic zones Japanese have used that more generic name.
Doel:Thatís interesting. How well known was Wadatiís work in the west?
Sykes:I think among seismologists that it was well known. It was not well known among other geophysicists and a lot of geologists. Benioffís paper was clearly better known in a larger earth sciences community in North America. But one of the things that the Japanese started doing quite early on — and certainly by the 1920s — was to write most of their important papers in English with a Japanese abstract (or less important papers, write in Japanese but with an English abstract). So they — the earth sciences community there — clearly decided that the important foreign language to communicate in was English. Which was fortunate for us.
Doel:Indeed. Indeed. Was he alive during the time that you were already in the profession? Had you ever Ė-
Sykes:Oh yes. In fact, he died just a few years ago.
Doel:Is that right?
Sykes:Yes. And in his nineties. I think perhaps in his late nineties.
Doel:What sort of person was he? You met him [Wadati], I presume?
Sykes:I met him probably about twenty, twenty-five years ago when I was in Japan. He was head of the Japan Meteorological Agency at that time. I donít remember how, you know, more than just kind of a friendly hello and an introduction to him.
Doel:How large relatively was the Japanese seismological community? In addition to Wadati, who else?
Sykes:Well, certainly in the 1960s, it was quite large. Prior to the buildup of the U.S. community say as financed by the VELA program of the Department of Defense. So there were very large numbers of seismologists working at the Earthquake Research Institute in Tokyo, at Kyotoís Disaster Prevention Research Institute, Hokaito University, and at Tohoku, the University in northeastern Japan.
Doel:I would imagine, particularly because the Japanese homelands are so seismologically active.
Sykes:Right. So I mean everyone has felt a number of earthquakes, and, you know, by the time they decide to go to college they have certainly felt a quite damaging earthquake. Thus, there was a very active community in Japan. They tended to focus at that time — probably up until about fifteen years ago — almost exclusively on Japan. Whereas the U.S. community by in the 1960s had a much more global view.
Doel:Was that primarily because of U.S. participation in IGY or did you find that were other factors to help explain the differences?
Sykes:There are probably other factors in that the earthquake problem is more severe in Japan. And there is probably a certain long insularity in Japan that leads to a focus on earthquake problems there. But I have long felt — and the same thing happens in California — people working on California earthquakes become quite familiar with those of either northern or southern California — rarely both, however.
Doel:Well there used to be a famous line across the state.
Sykes:Thatís right. And, so in fact, in a given region, there are going to be some things that will be quite clear and obvious, but there are other things that for various reasons arenít. And so if you have a more global view — and I think that was a very important aspect of Lamont — that you might see something in Alaska that is really clear and sharp. Once you see it, you can see it in the data that are more fuzzy for California. I think an outstanding example of that is the magic profile of [Walter C.] Pitman and [James] Heirtzler across the East Pacific Rise, in which they could see this very clear symmetry for plus or minus five hundred kilometers on either side of the ridge. The idea had originally been proposed of the magnetic imprinting by [Fred J.] Vine and [Drummond] Matthews in their 1963 Nature paper. They applied it to an area in the Indian Ocean, and itís pretty clear when you look at their data that the symmetry and the identification of the magnetic anomalies, is pretty fuzzy and difficult to see. So.
Doel:Whereas in contrast Pitman and Heirtzler with the Eltanin data was quite sharp?
Sykes:Right. The fracture zone that I was thinking of before was the Eltanin Fracture Zone.
Doel:Thank you. You know, youíve said a number of very interesting things about differences between the Japanese and the U.S. programs. Were there also differences in other ways, other styles in which you sensed that Japanese research in seismology differed from that of the United States?
Sykes:Well certainly in the 1960s, Japan was still recovering from World War IL Thus, the amount of money that was going into seismology and the amount of money that went into — particularly salaries of professors and staff— was pretty low. America had more resources in terms of new equipment. Japan had the advantage, however, of having run instruments all over Japan going back to the late 1890s of which we didnít have as rich a record. The Japanese did a lot more work on geodesy — elevations and determinations of horizontal positioning. They were out there resurveying areas of Japan every few years, and after their earthquake program started in 1965, often a couple of times per year. So there was a very important geodetic base that showed changes in either elevation or changes in horizontal position that were very valuable for all kinds of earthquake studies. It was a very unique record from Japan; we donít have nearly as an extensive record in the U.S.
Doel:Thatís very interesting. So that applies also to southern or central California — those sorts of measurements were not being retrieved.
Sykes:Right. The work - geodetic surveying — started in California, for example, in northern California in 1858, with some [lines) repeated in the 1880s. Before the 1906 earthquake, they were not put in for earthquake studies. They were put in for precise determination of boundaries and of locations of property. In fact, the 1906 earthquake — from the point of view of the agency that did those surveys, the U.S. Coast and Geodetic Survey — regarded the 1906 earthquake as a, as a nuisance. And [H. F.] Reid in the few years after 1906 was able to show that there had been systematic movements that he attributed to slip in the 1906 earthquake; the build up of stresses ahead of time became known as the Reed Strain Build Up hypothesis. But then, for example, in California you only have those surveys repeated, oh, every few decades until the 1960s when the state of California got into making geodetic measurements more extensively and more often. That was more or less taken over by the U.S. Geological Survey, probably around 1970.
Doel:That makes sense. I believe — you mentioned a moment ago — another interesting point about the very intensive seminar that Jack Oliver had.
Doel:Do you remember in addition to reading Benioff and Wadati, others who had focused on deep focus earthquakes? Who seemed, who in your recollection, were at the forefront of the research at the time?
Sykes:Well, I think that in one of Jack Oliverís points was that there was a hiatus that happened with World War II, so there was no one that was in the forefront. There was no one that had done any work Ė-
Doel:Interesting point, yes.
Sykes:— on deep focus earthquakes since the 1930s, it pretty much climaxed with Gutenberg and Richterís first edition or version of their book Seismicity of the Earth. Benioff was really one of the few people to come back to the subject in the 1950s. An important previous contribution in Japan had been by Honda, who examined the focal mechanisms of deep earthquakes. Japan had enough stations, and given their deep earthquakes, that you could get coverage enough to map out the first motions. And so Hondaís analyses of the mechanisms of deep earthquakes near Japan stood the test of time.
Doel:Thatís interesting. Had you met him?
Doel:Okay. Iím wondering who else was in that intensive seminar with you? Brian Isacks?
Sykes:Yes. Brian Isacks and I were two of the members. I think it was a fairly small seminar. I canít remember who else was in there. But I think at the end of the seminar, Jack Oliver had decided to try and mount a field program to study deep earthquakes. Brian Isacks and I were finishing up our theses about the same time. Brian was quite interested in doing a field project on deep earthquakes. Jack Oliver felt that picking Tonga/Fiji was a better area, both because moderate size earthquakes was more numerous, it was an area that was reasonably easy of access, and it didnít involve crossing as many international boundaries as in South America. Logistics would be easier. And in South America you didnít have as frequent moderate size deep earthquakes. Fiji and Tonga are malaria free. It was an area in which you didnít have to go prepared to deal with tropical diseases. So the decision [was made] — Jack Oliver then wrote a proposal to the National Science Foundation, and Brian was involved in that — of doing a field study in that area.
Doel:How did you feel about that possible work at the time?
Sykes:Well I was, I was certainly interested in the subject. I had been pursuing earthquakes along fracture zones about that time. But — and Iím not sure when I got into relocating these earthquakes that had already occurred before the field experiment in Tonga/Fiji. But I then relocated a lot of those events before Brian Isacks, before I went to join Brian in Fiji. I think he had already been out there nine or twelve months when I went out and spent three months there. Brian had gone out with his family and had established one station in Fiji, one station in Tonga, and while I was there, we established two more in Fiji. The two of us worked quite a bit on the data from those local stations while I was there.
Doel:What kind of instruments were you installing or had Brian installed or had you installed?
Sykes:These were more standard, short-period instruments of the Benioff type.
Doel:Was there particular difficulties in setting up stations in the South Pacific or was that a fairly routine operation — simply requiring getting down there to?
Sykes:No. I think that it was fairly routine. Isacks had found a high school in Tonga that was run by the Mormon Church, in which there was a person that taught physics who agreed to change the seismic records. Brian hired a Fijian to learn to fix the instruments and change records in Fiji.
Doel:And this is prior to the time when you had electronic recording instruments? These were.
Sykes:No. No. These were electronic.
Doel:These were already electronics.
Sykes:These had a recorder such that, after one record was written — they were analog, they were not digital recordings — the device had a roll of paper in it, and at the end of one record it would automatically cycle to the next piece of photographic paper.
Doel:Interesting. The reason I was thinking about digital was that, as I recall, wasnít it in the early 1960s that — at least a number of people at MIT were working on digital equipment in seismology? I was wondering how soon you recall that coming into?
Sykes:Well, the oil companies were, probably did the first to work in digital recording [in geophysics]. They were able to afford to develop that and utilize it before the universities got involved. I recall it was probably about 1970 before very many university people got involved in digital recording.
Sykes:Now the signals from the seismometers that went to the Moon were sent back digitally to the earth.
Doel:Of course, the work of George Sutton and Frank Press and those who were involved.
Sykes:Right. And I think some of the first ocean bottom seismometers recorded on film — some of the Lamont ones. And later there was a transition to digital recording.
Doel:You mention that when, that it was particularly Brian Isacks and Jack Oliver who had written the grant proposal for this work.
Doel:And it was to NSF [National Science Foundation]?
Doel:How was NSF as a patron for seismology in those days?
Sykes:I think it was pretty good. Roy Hanson, who was the program manager for geophysics, kept up with what people in the universities were doing. He attended meetings. So he was pretty savvy on what was going on. He had committees of like five people — in which I served on one of those for three years in the 1970s — that evaluated proposals in geophysics and then those in geology along with a separate panel in geochemistry.
Doel:Something actually I want to make sure that we get a chance to cover in one of the later interviews the work of that sort that you were doing. Iím simply wondering if, given how rapidly the funds were coming through in VELA [?] uniform, whether there was any problem in getting funds for different kinds of seismological work?
Sykes:Well, I think it was pretty clear that this [the Tonga-Fiji] project was not related to nuclear testing, so no attempt was made to submit it to the Department of Defense for funding. At that time, probably a good half of the proposals that were sent to NSF were both very good and were funded.
Doel:So that was a different era?
Sykes:Yes, it was a very different era. And so, I mean, this was a proposal — not for a huge amount of money — but it did involve foreign travel and foreign logistics and analysis of data. But it was funded by NSF the first time.
Doel:And when was it that you actually traveled to Tonga? Was that in 1965?
Sykes:So in 1965, probably about June or July. I stayed for three months, and I came back to the U.S. in about October. I can remember on the way back I went to the annual meeting of the Geological Society of America in Kansas City.
Doel:Interesting. What were you doing particularly during the three months that you were there?
Going around with Brian [Isacks] to see the stations. We went up to the second largest island and spent about ten days installing one seismic station there, and probably another ten days installing one in western part of the big island of Fiji. Later on, quite a bit of time was spent just analyzing the data, the records from Tonga were sent to us about once a week. We located the various earthquakes, the small ones, using the data from as many stations as we had. So one of the things that we became aware of at that time and was that there were a lot of higher frequencies on the Tonga records than on the Fiji records. Brian and I debated quite extensively when I was there as to what it was that was causing this. I think that it was, it was kind of the second hypothesis — it wasnít the favorite one — that somehow the waves traveling the down going seismic zone had less attenuation, and therefore the high frequencies propagated along it more readily.
That was more or less there as an idea, but it was really something then that Oliver and Isacks wrote their — 1967 paper on that very subject. It certainly was, I think, all of our ideas that this downgoing seismic zone, if anything, would probably attenuate the seismic waves more than the normal regions outside. So that was certainly our standard working model. Hence, it took some time to come to the conclusion then that was finally, firmly stated and supported in the Oliver and Isacks paper that the down going seismic zone was less attenuating. Then they put in the conclusion that it was lithosphere that had been under thrust or subducted that accounted for that. When I was in Fiji, I went over for about a week to Tonga with some portable equipment. And went out to a fairly remote island called Niumate, which was a pretty agonizing trip on a small boat from the main Tongan island, the capitol, Tonga Tapu. Niumate was closest to the Tonga trench of any island that was reasonably accessible. One of the things that I recorded there was a deep earthquake that had an abundance of high frequency seismic waves. I was aware of that, and Brian and I talked about that. But we still did not put two and two together at that point that it had to do with the easy propagation up the seismic zone.
Doel:That would have involved quite a bit of a change of thinking.
Doel:To do that.
Sykes:We were certainly concerned that we needed to rule out some other things, just wave conversion that — if we proposed something quite radical, someone else wouldnít come along and just say, oh, this, this is really caused by something thatís quite simple.
Doel:And clearly it sounds as if, in a common way you were going through alternative explanations. You mention that what becomes known as the under thrust was one idea that was basically not in you minds. What were the other ideas that seemed, that you also recall from that time that you were discussing?
Sykes:Well we were discussing merely that this difference between the frequency content of the seismic waves had to do with wove conversion at certain boundaries. But one of the very important things that happened while I was in Fiji was that I received a letter from Jim [Henry James] Dorman ó who was on the Ph.D. staff at Lamont Ė-
Doel:Yes. Sykes — telling me about this paper that had been published by Tuzo [J. Tuzo] Wilson — his famous 1965 transform fault paper. And that Wilson had utilized my locations of the zigzag patterns of earthquakes. So the germ of the idea was there for me, but, hey, maybe I can do something more to try and prove or disprove Wilson. And I think probably at that time my sense was that this sounded like a rather woolly idea, and that.
Doel:Wilsonís idea of transformed faults?
Sykes:Right. And that using the mechanisms of earthquakes, it might be possible to show that he was wrong.
Doel:Interesting. How long had you known Wilson at that point? Had you met him?
Sykes:I had not met him. I had seen some of his papers. He did some important work of compilation, with money from the U.S. Defense Department, of looking at various oceanic islands around the world and showing that their geology was quite young. Particularly those that were close to mid-ocean ridges. But this, his paper on transformed faulting really represented a new direction for him. Really getting involved in continental drift and earth mobility in a big way.
Doel:And indeed it was a — in retrospect — relative to its importance. It was very widely recognized. And Iím wondering just how, how others at Lamont — including yourself, you mentioned your own reaction to it — what other debates do you remember on that paper?
Sykes:Well, remember, I wasnít there.
Doel:You were at Fiji.
Sykes:I was in Fiji. And I got this letter. I took seriously that here was an interesting idea. At the time, I was committed to working on these data in Fiji — the local data — for a while. I came back to Lamont, and this idea was cooking there. But soon after I came back, I mean I had all these relocations that I had done of earthquakes in the 1950s and early 60s, that I had done by computer. So all of those locations had been done before I went to.
Doel:Went to Fiji?
Sykes:Yes. And I was anxious to get that work written up. I was invited to a meeting — one of many — in Newcastle, England. It was on earth mobility. One of the things that I had discovered from this study of accurate relocations of earthquakes in Fiji/Tonga was that the seismic zone was remarkably thin. It was no thicker than about fifty kilometers. And then at its northern end, there was this gigantic hook, right near Samoa, south of Samoa. And there was a hook in the volcanoes, there was a hook in the trench, the shallow earthquakes, and you could see that hook going all the way down to six hundred kilometers.
Doel:Thatís very interesting. One other question I was curious about is how well mapped was the sea floor in that region by this time?
Sykes:Scripps [Institute of Oceanography] had had a major expedition to the Tonga trench. So they had some modern crossings and soundings of the Tonga trench. There was virtually no mapping of what the sea floor was like beneath that except for a few spot refraction measurements that [Russell] Raitt had done, the crustal structure.
Doel:Right. And Raitt of course was one of the major figures during that program.
Sykes:Thatís right. At Scripps.
Doel:And that was simply an area that Lamont had not — at that time — done any.
Sykes:Well, he did his work in the Pacific. Lamont did a huge amount of work during the IGY of refraction work down in the Scotia Arc in the southern Atlantic, as well as in various parts of the oceans. But anyway, I presented this idea of this big hook at this meeting in Newcastle.
Doel:And when was that meeting? Are we, is this still in 1965, or is it into early 1966?
Sykes:It must have been sometime in Ď65. Letís see, I was there in about April, but it was before I saw the ďmagic profile.Ē So I think that must have been just before I went to Fiji. So it was probably the April before of Ď65, March or April. And so I merely remarked that there was this major structure that extended all the way down to six hundred kilometers, and that ideas of earth mobility would have to take that into account. I was certainly of the standard Lamont opinion that [W. Maurice] Ewing held that probably a lot of the current ideas of earth mobility werenít right, like continental drift, but that something else would emerge from that. One of the people at the meeting who said to me, who was Harold [C.] Urey, Nobel Prize winner in chemistry and who had done a lot of work on the Moon and earth evolution, and was there at the meeting. He said to me, young man, you need to take continental drift more seriously.
Doel:Thatís very interesting. [laughter]
Sykes:And that was probably not one of the things that I wanted to hear, but it turned out to be good that I heard it.
Doel:It sounds like it made an impression on you.
Sykes:It certainly made an impression on me. It did not ďconvertĒ me right away. But I think of two other people at Lamont who by the early sixties had an interest in continental drift. Neil Opdyke had come there with his background from Newcastle.
Doel:Right. Being a [W. Keith] Runcorn student.
Sykes:With Runcorn in paleomagnetism, and in having worked in Africa. But I can remember more a lecture that Bill [William] Ludwig gave. So I can remember one of the lectures that impressed me, which was given as a Friday afternoon symposium at Lamont, was by Bill Ludwig, who worked in marine geophysics. He had been the principal person working up this huge amount of refraction data from the Scotia Arc. It was clear that there was some continental material there, in the Falklands and the area to the east. And so Bill had read a lot of the literature, particularly that South Africans, like Lester King and [Alexander Lugie] DuToit before that, comparing the geology of the southern continents, particularly South America and Africa. And so, in order to make sense of their own geology, they — people in the southern hemisphere — were drawn to continental drift. Ludwig took that very seriously, and he found that from his data that this chunk — of this whole Scotia ridge and Scotia Arc — looked like it fit, tucked rather nicely beneath South Africa. And Ė-
Doel:What was the general reaction to that colloquia as you think back? Do you remember the discussions that —?
Sykes:I think it was probably kind of neutral.
Doel:Was Ewing there do you recall?
Sykes:I donít recall. But certainly, Ludwig was going out on a limb compared to kind of the general philosophy of Lamont that had a lot to do with collecting data but somehow given time, that some time in the future, the big hypothesis will arise from this.
Doel:Although in certain cases, clearly there were broad hypotheses being advocated. Iím just thinking of [W. Maurice] Ewing and [William L.] Dorm in the climate change work that they did over the Arctic.
Sykes:Sure. But I think that Ewing had felt that the ocean floor may contain some of the oldest rocks. That turned out to be contrary to what we found. So that was something that I heard before going to Tonga and Fiji.
Doel:Thatís very interesting. Do you remember, had you already read, Wegener at that point or DuToit or Arthur Holmes, any of the people who had written?
Sykes:No. I had not read about them. I had read more derivative things that were in textbooks about continental drift and pole fleeing forces. I can remember that one of the classical things — classical, but things that I was told as a student at MIT as an undergraduate in the 1950s - won that continental drift is impossible. The continents canít plow through the strong rocks of the oceanic crust and that bright and serious young scientists shouldnít work on such a stupid idea. So.
Doel:Of course Harold Jeffries in the earth had made clear that the continents were not moving horizontally either.
Sykes:Well, one of the things that Jeffries showed — and that Wegener considered some of his best evidence for continental drift — the astronomical observations made between Greenland and Europe that indicated a very high rate of [movement].
Sykes:So that of probably a hundred times what we now know it to be. Jeffries showed that there were some systematic errors in those data and that the astronomical evidence was fallacious. But the mistake that was made there by lots of people was that because that piece of data was incorrect, this much larger body of evidence that Wegener brought to bear on continental drift, could somehow be thrown out the window. Or because mechanisms like continents plowing through oceans were not correct, that therefore, the phenomena hadnít happened. That is something that I have never forgotten because weíre going through some similar arguments right now of people saying, well this mechanism or earthquake precursors isnít correct or we donít have one, and therefore the phenomena of being able to predict earthquakes or of being precursors [existing] isnít worth working on.
Doel:Thatís a very interesting observation.
Sykes:Because they probably do not exist.
Doel:Thatís very interesting. I want to make sure we get back to that when we talk later about your working in prediction.
Sykes:So I had worked up this body of locations of earthquakes in Tonga/Fiji. As soon as I got back, in the late fall and winter, I fortunately got that material prepared and sent it to the Journal of Geophysical Research. It came out in 1966 as my paper on deep structure of island arcs.
Doel:This is the Seismicity and Deep Structure of Island Arcs. Indeed, it appeared in the June 15 issue of the JGR.
Sykes:Right. So that was something that was really on my plate, and that I felt was very important. I think it was, and that I wanted to get into publication. So from about the time that I had that manuscript finished and probably had sent it to the Journal — and that would tell you when it was submitted there Iím quite sure that it was February, 1966 that Jim Heirtzler called up Jack Oliver and said, Walter Pitman and I have a really important piece of magnetics data that you should see. And so Jack invited me to go over with him to see this. They showed us this ďmagic profile.Ē They had made a transparency so that you could flip it and see that there was this virtually exactly symmetry.
Doel:How confident had you felt in the paleomagnetics work prior to that time? Clearly the work that on magnetic reversals through the early 1960s was still contentious.
Sykes:Right. I think it was something that I felt was contentious. It was not something that I knew that much about. And clearly in North America there was this impression that there might be self-reversals, even though I now know in retrospect thereís only one example that was ever found of a self-reversal in one rock. So I think I was just of the standard North American predisposition to be skeptical.
Doel:And many people were, and this was the nature of the debate at the time.
Sykes:And I did not know that in the late 1950s that Ted [Edward] Irving had left England, his thesis was turned down, and that he went to Australia to work on paleomagnetism of rocks from Australia. He was able to clearly show that the polar wander path [of Australia] differed extremely from that of the northern continents. He published it in an obscure Italian journal. So I was not aware of it until, probably the late 1960s.
Doel:Thatís very interesting.
Sykes:I was aware of some of Runcornís data showing a difference in polar wander paths for Europe and North America. At the time I wasnít very convinced because most of the opening had been one of longitude and not of latitude which is what paleomagnetism senses. I now know in retrospect, in fact, that his curves went back far enough in time and the position of the poles for those two continents had moved enough and there was enough of a difference in latitude. It was something that I was skeptical about, including when I heard it at Runcornís Newcastle meeting.
Doel:How well did you come to know Runcorn? Was he someone that you interacted with?
Sykes:Yes. I found him to be a kind of a strange mercurial person. A bit bombastic. Later on he traveled to the U.S. and Canada. Many times people would invite him to be a visiting professor, pay his salary, and he would be off giving lectures elsewhere for most of that time. It was not something that I approved of, his way of doing things.
Doel:Iíll get a copy in a moment of the, of that paper, The Seismicity and Deep Structure of Island Arcs. And that had come out just a little bit after another paper that you had published in JGR that you had co-authored with Don [Donald] Tobin on the relationship of hypocenters of earthquake to the geology of Alaska.
Doel:How did that paper come to fit into the sequence?
Sykes:Well that was part of just relocating a lot of earthquakes to try, and particularly define the downgoing seismic zone in the Aleutians, particularly in southern Alaska. A lot of the older earthquakes in Alaska were quite mislocated. Now the important thing that came out of that work was it was my first involvement with what became to be called seismic gaps. We realized that there were several places along the active zone — as yet to be called plate boundaries — that had been quite deficient in earthquake activity. And so by that time the Ď64 Alaskan earthquake had happened and had occurred in one of those areas that had not had activity or much activity for a long time, particularly big earthquakes. So we did propose that there were some areas — and I believe one near Sitlas southeast Alaska, and another one in the Gulf of Alaska in a zone that had last broken in some great earthquakes in 1899.
Doel:Yes. Indeed thatís one of the themes that you do carry through the paper. You also mention that — in the combined acknowledgments that you wrote — that youíd also gotten a grant from the Home Insurance Company of New York for part of this.
Sykes:Right. And Ė-
Doel:I was curious how that had come about.
Sykes:Someone from the Home Insurance Company approached us — probably Jack Oliver who referred them to me — that they were concerned about the amount of potential liability that they were accumulating, more in the Caribbean and Central America. They agreed to support some of my work probably for about ten thousand dollars. So I did do a paper on the seismicity of the Caribbean that I co-authored with Ewing in 1965 of again looking at the downgoing seismic zone in Puerto Rico and the Lesser Antilles. Some of that money supported part of the work in Alaska.
Doel:And you were also able to get computing time from the Goddard Space Flight Center?
Sykes:Yes. So about the time I became a Ph.D. and needed to do relocation of earthquakes — it was slow on the very slow Lamont machine that we had at that time which was punch paper tape. NASA had one of the worldís fastest computers - a 7090 at the time. And so was able to get access, to get time on that machine.
Doel:How easy was it to get access to that computer?
Sykes:I think that it was not too hard. [Robert] Jastrow was head of the center, was an adjunct in our department, and I think that it just took a letter to him asking for some time, in fact, what was a probably two hours per half year or something, at that time, or two hours a year. He just wrote back permission granted.
Doel:That worked rather well then. It was quite straightforward. Let me get the seismicity paper here — single author paper. And actually that, you had clearly worked rather fast on that since the paper was actually, the first manuscript was received December seventeenth of 1965. So that was very soon after you had returned.
Sykes:Yes. So that I obviously worked very hard from the time of coming back from Fiji to put the text together and get it off. In retrospect that turned out to be immensely fortunate. Because when I walked into Heirtzlerís office in February my life was really to change. You may want to come back.
Doel:I want to come back just in a moment to that because one of the very interesting things that you write about in the conclusion of your paper is relating the phenomena that youíre seeing to the idea of convection zones.
Doel:And Iím wondering how widely you remember those ideas being discussed. Clearly they had been major parts of geological discussions from the late 30s, 40s, 50s.
Sykes:Right. But I think from my point of view and of most people from Lamont, that convection currents — as they were called — were a rather nebulous idea. I had taken a course from Francis Birch my last year at MIT on heat flow problems, so I was well aware of different types of heat transport, including convection. But one of the things that was perplexing was this very sharp hook in the deep earthquakes beneath Fiji. And it was hard to imagine a very big convection cell fitting in and accounting for that.
Doel:Right. You also make a passing reference here to [Egon] Orowanís work, if Iím pronouncing that correctly.
Sykes:I forget what the remark is so you remind me.
Doel:It was concerning the instability of creep appears to be the fundamental cause of the concentration of deformation in certain Pacific zone. Iím just wondering if that was a topic that you had discussed with him directly or —?
Sykes:Not with Orowan. I had been aware of Orowanís work my last year at MIT, and through my association with Bill Brace. Bill knew Orowan, who was in the mechanical engineering department.
Doel:Right. Did he come to visit at Lamont. Was there much contact —
Sykes:I donít think so.
Doel:— between his way of —
Sykes:But I think he, I think he was the person who called downgoing seismic zones Benioff zones.
Doel:I think thatís right. Yes. You had mentioned that you had felt uncomfortable with the term. Did others too or did the term become fairly widely used in that period of time?
Sykes:Well in fact the term convection currents dropped out altogether — with the plate tectonic revolution — to talk changed to convection in the mantle. There were a lot of what were frankly kind of hand waving arguments about these great big cells that went all the way from the surface down to the core-mantle boundary and were of very large extent. Debate has gone on now for twenty-five years as to what is the form of convection in the earth, and how much is convection shallower than 670 kilometers isolated or coupled to that deeper.
Doel:Indeed. When you had that interesting exchange with Harold [C.] Urey on accepting tectonics, did Urey give you reasons why he had become convinced that plate tectonics was a theory?
Sykes:Well, continental drift — not plate tectonics.
Doel:Thatís right. Thatís right.
Sykes:No. So he didnít give me any evidence. Several people at that meeting had thoughts on convection currents, paleomagnetic evidence, and of people that had worked on — and Runcorn had done along with some of his students — that convection could occur in a solid material at a temperature below that of melting. I was certainly aware of that.
Doel:Right. And of course a lot of this work too was being supported under the aegis of the Upper Mantle Project, ongoing in the 1960s.
Doel:Were you involved in any of the administrative or planning aspects of the Upper Mantle?
Sykes:No. I was not. But I think that the National Science Foundation — they made a big pitch after IGY with the Upper Mantle project to use it to get additional funding. But when the whole plate tectonic revolution came along, NSF did nothing to capitalize on what had happened. They just doggedly stuck to the Upper Mantle Project is what we said weíre committed to. So I think a major mistake that they made was just of being too conservative and not going after major new amounts of money, as people in astronomy were to do with major discoveries or people discovering new particles in high energy accelerators.
Doel:Thatís really interesting. Do you have a feeling for why that was? Was it particularly in the earth sciences leadership within NSF?
Sykes:That was at least a major factor, that the person who was head of earth sciences, Bill [William] Benson, was quite conservative. He certainly would have come out of the school of more quadrangle mapping and of a non-mobilistic earth. I think he was not very familiar with geophysics or geochemistry. He was a curmudgeon.
Doel:I recall reading sentiments of that sort. In fact a number of people worrying that earth sciences would not advance well at NSF until he either left or was replaced.
Sykes:Right. But I had some long arguments afterwards with Jim [James D.] Hays — the Jim Hays of Harvard, who would head up earth sciences [at NSF] and who just retired a year ago ó in which I too felt that Jim was pretty conservative. Jim, although he never said so directly, I think felt that earthquakes were applied science and things like what the Geophysical Lab in Washington did in high pressure research and what he, Jim, did at Harvard were really basic research.
Doel:Thatís very interesting.
Sykes:So I think that Jim continued the tradition of conservatism. He did attempt to start a number of big projects, but more kind of on the philosophy of the 1960s that if you had some big, sexy projects, you could get big new sources of money from the leadership of NSF, the National Science Board, and that this would represent a step in funding that, you know, would carry out from there to infinity. That step increase.
Doel:That sounds like the thought behind Project Mohole for instance or Ė-
Sykes:Right. Well, Mohole happened before that, but it was more the philosophy also of the lunar program.
Doel:I see. Yes. Thatís a good point.
Sykes:[NSF became interested mainly] in really big projects that would bring tens of millions, not hundreds of millions of dollars into a field. And so NSF started a number of big initiatives. COCORP [?] was one that was already underway, but they put that in a basket of about eight major initiative. Using the GPS [Global Positioning Satellite] receivers was another. Deep drilling in the continents. The IRIS [Incorporated Research Institutions for Seismology] modern seismic network. There was a program called Cal Crust for studying the crust of California. There was an East African rift project. And there was something called EM-Slab, of an electromagnetic study of the downgoing Juan de Fuca plate in Oregon and Washington. These then were things that were started by NSF earth sciences in probably the early 1980s.
Doel:And this under Jim Hays?
Sykes:This was under Jim Hays.
Doel:Did he succeed Benson directly, do you recall?
Sykes:I donít recall, no.
Doel:But clearly itís the 1980s that weíre talking about here.
Sykes:Thatís right. And so what happened was it was a different era. They [NSF] didnít get nearly the money that they needed to fund these big projects. So the first thing that happened was that small science was level funded and continued to be level funded probably through now. And, of course, when corrected for inflation, it represented real decreases. Ultimately there had to be a big shoot out, which happened about six years ago with the fact that they couldnít support as many of these big projects. So at that time it was decided that the most important ones to continue were the IRIS seismic network and GPS. COCORP got downgraded. The DOSECC [?] deep drilling program was supposed to be canceled after the Cajon Pass well was completed. But some of these things have a habit of coming back. So thereís now a proposal by some of those same people who were involved in deep drilling to spend two hundred and fifty million dollars drilling a deep hole with a number of side holes going off it.
Doel:Youíre talking horizontally.
Sykes:Right. From the San Andreas Fault in California. If we had an earthquake program that was funded at ten times the level of the present one, that could be worth considering. But it is several times the amount of money spent on the entire U.S. earthquake program, including engineering, mitigation, earthquake insurance, mapping of faults, earthquake prediction, etc.
Doel:That drives the point home. When do you date the time that the funding for the smaller science projects began to be eroded? Was it already in the 1960s or did that come later?
Sykes:That came later. So it probably happened in the late 1970s.
Doel:Did you feel it happened particularly within the earth sciences, given the leadership at NSF at the time? Or do you feel this was part of an already growing trend among all the sciences?
Sykes:Well I think there probably was a growing trend. It was that sense in, say with Jim Hays, that other fields like astronomy had been able to put together proposals for really big projects. Astronomy clearly had done better than the earth sciences. So they, he thought that the only way of getting more money into the earth sciences was with some of these really big projects. Of course, big projects had long been a part of high energy physics research and astronomy.
Doel:Sure. No, all thatís very, very interesting. Iím glad we had a chance to talk about that. I donít want to get too far away from the thread that you were continuing though. Of what seems to have been a kind of a pivotal moment for you.
Sykes:Right. So let me go on to that. Because Heirtzler invited Oliver, and Oliver took me over to Heirtzlerís office. Walter Pitman was there. We were presented with this ďmagic profile,Ē and Heirtzler said something to the effect of, gee, I donít know what this means about continental drift, but I think weíre going to have to revise our ideas.
Doel:Heirtzler had not supported drift up until that point had he?
Sykes:No, And, in fact, prior to that time, Xavier Le Pichon —who had been at Lamont and was doing a lot of work in marine geophysics — he had strongly criticized the Vine-Matthews idea, using some of the data that were collected in the Reykjanes ridge, south of Iceland, which in retrospect turned out to be some of the most symmetric data in terms of magnetic imprinting.
Doel:Was his interpretation you mean that hadnít allowed him to see the symmetry that was actually?
Sykes:I think so. But in any case, he [Le Pichon} gave a seminar in which my main memory was a strong criticism of the Vine-Matthews hypothesis.
Doel:What sort of person is he? Le Pichon.
Sykes:I would say that he is stereotypically French intellectual; that he was quite convinced that he was smarter than other people. He was certainly a very clever guy in a lot of ways. But I think that his haughtiness got in the way of him interacting, particularly when he went out to sea with the captain and other people on the ship.
Doel:Interesting. But was this on Vema?
Sykes:Yes. But anyway, let me come back to this meeting. That was a moment of epiphany for me. I had heard about Tuzo Wilsonís paper on transform faulting. In the back of my mind, cooking had been using focal mechanisms to test Wilsonís idea. Thatís probably one of the few times in my life in which I made the decision overnight that I need to start working on that tomorrow morning. Probably my mind was cogitating on it at night as well. So I dropped everything else that I was doing. Fortunately the paper on island arcs was finished.
Doel:What were the other projects that you would have been working on had that not occurred?
Sykes:Iím not quite sure. Well, some of the things on Alaska. But in any case, I made the decision that this was so important and things that I had been thinking about really clicked, Here was all of this data that we were getting from the World Wide Standard Seismic Network that were right there at Lamont, and which you could go down and read the film chips of the seismograms and determine the first motions. You could get them better from the long period instruments for the moderate to large earthquakes. This was the first time, in fact, that this network presented the opportunity of looking at original seismograms, a whole bunch of them, in a relatively short amount of time. Before that, people might have taken years to collect the records, just from one earthquake and then to study it. [John H.] Hodgson in Canada had a project from the 1950s, in which he would just send out questionnaires to seismic observatories, [asking] please tell me for the following earthquake whether the P-wave motion is up or down. He always had something like twenty percent inconsistencies, which turned out to be pretty fatal for focal mechanism studies. He didnít realize that.
Doel:Where was the problem coming from?
Sykes:Well the problem comes that particularly in an island arc with thrust earthquakes as in Tonga that there is one of the nodal planes where you get the transition from upward to downward motion that is quite well defined. The other plane is nearly horizontal, and with stations at a distance, you usually donít have good control on it. So if you have a whole lot of stations at a distance that are largely sampling a cone oriented straight downward [at the source], plus or minus thirty degrees, you got one nodal plane through them. If you have twenty percent inconsistencies, you will try and draw another plane through there which also will be a steep plane. Hence, you will come out with a strike slip mechanism, even though in reality, itís a thrust earthquake.
Doel:So he was misled in those instances.
Sykes:So he was misled. I realized this pretty soon with my work. So I sat down with some earthquakes from the mid-ocean ridges, particularly from the mid-Atlantic ridge, and right away started going through the records for a couple of them. I thought about how to portray the data. One of the things that came back to me from taking structural geology from Bill [William] Brace at MIT was a standard method, was an equal-area projection. Use of it does not bias data that leave in various directions from a small sphere surrounding an earthquake. [Perry] Byerly, at Berkeley, had used a method that he called extended distance that was almost the inverse, and it badly biased data sampled on a sphere. Most Americans had used it.
Doel:Had followed his.
Sykes:Right. One of his students, [William] Stauder — from St. Louis — had started using S waves for focal mechanisms and had a project to do that. Just after I started using the equal-area projection, I had realized that Stauder had also started using that projection as well.
Doel:Was that something that you were discussing with any others? Or was it one that given your experience with Brace you had worked out more or less on your own?
Sykes:Well, in making this decision to start working on focal mechanisms earthquakes to mid-ocean ridges of the use of stereographic projection was my idea. I certainly also was having talks with Brian Isacks. I forget exactly when Brian came back from Fiji, but it was probably early in that time interval. I had already started working on the mechanisms of mid-ocean ridges. But I was certainly talking to him when he returned from Fiji, pretty early on. So he was the main person I talked to. Jack Oliver was generally encouraging. And so, letís see what else happened there. The other thing was that I also wrote a computer program for plotting out all hundred and twenty-five of the world wide plus Canadian stations. I could into the computer enter the coordinates and depth of the earthquake, and the program then would plot out all the stations on an equal-area projection.
Sykes:In doing that I realized that there was a formula for the equal-area projection. In my early work I found it within a couple days. And it was easy to program that in Ė-
Doel:And then were able to apply this to these large data sets?
Sykes:I didnít have to hand plot all this stuff. The stations were on there. I could go through and make the readings as to whether the motion was up or down. And then just put that on the little symbol that was already on the computer plot that was done using a big plotter.
Doel:Youíre holding your hands out about three feet apart, or two feet.
Sykes:No, itís probably about fifteen inches.
Doel:But thatís still a large scale for the time.
Sykes:Right. With the data on the computer lots I could then by hand draw in the nodal planes.
Doel:How long did it take you to begin compiling? You began with the North Atlantic data that you had available.
Sykes:I found that in a matter of two or three days I could do an earthquake. At the same time, I pretty quickly wrote this computer program. So probably within about three months, I had done about a dozen earthquakes — several from the Atlantic, some from East Africa. They are most of the earthquakes that are in my 1967 paper, Mechanism of Earthquakes and the Nature of Faulting on the Mid-Oceanic Ridges. So, certainly within a month or less, I knew that I really had something. When I plotted up the first couple of strike slip earthquakes, they clearly agreed with the direction of motion that Wilson had proposed for transformed vaulting. They were exactly opposite the direction as if the seafloor across the fracture zone had originally been together and later offset.
Doel:The lateral offset.
Sykes:Lateral offset, which was a common idea at that time. But thatís what accounted for the zigzagged pattern. Wilson pointed out that if things were later offset, you should expect to see some earthquakes that went off beyond the ridges, which you didnít see. At the same time I was doing the focal mechanisms, I also relocated lots of earthquakes from the mid- ocean ridge system.
Doel:Thatís when you were increasing the resolution so that you could pinpoint Ė-
Doel:— within. What was the accuracy that you were able to achieve roughly?
Sykes:Well, certainly the precision of, was something like five or ten kilometers. Which is not quite as good as the accuracy, and maybe that all of the earthquakes in one area in fact had systematically occurred a little bit to one side. But for seeing the pattern, that didnít matter. Precision was sufficient.
Sykes:So very quickly I knew that I had something really big, and that I was not going to prove Wilson wrong. I was going to prove him right. [Laughter] I turned out to be, in fact, a good person for doing this. I was skeptical about his proposal, but I did a test that showed that he was right.
Doel:Did you talk to Wilson about that after that?
Sykes:Well, it was probably the next fall that Wilson came down and gave a lecture, I think at Queens College. By then the information [news] had gotten out. Some of my colleagues at Lamont started to hear about it in the summer of Ď66 — Pitman and Opdyke, and a lot of the other people in marine geophysics. I was then invited by Paul Gast, who was a geochemist, who heard about it and asked me to give a talk at an upcoming invitational meeting that was to be held at the Goddard Space Flight Center in New York. And we can get the title of that. Important to get that. I just donít have it off the top of my head.
Doel:Okay. If itís in your CV, we may only have to give it a quick look. You gave the invited talk.
Sykes:So I was invited to give a talk. Pitman or Heirtzler gave a talk on their work. Fred [J.] Vine was a post-doc under Harry Hess at Princeton at that time. And so Fred had come up to Lamont in February, he had also been shown the ďmagic profile.Ē Fred told Walter Pitman that until he saw it that he had felt that he wasnít sure that the Vine-Matthews hypothesis was going to go anywhere. When he saw that data, he about jumped out of his skin, knowing that it was something really big. Fred started work doing more world wide compilation of sea floor spreading. Thereís a little bit of a controversy that happened Pitman and Heirtzler submitted their paper on the ďmagic profileĒ to Science. Fred submitted a much longer article that would have been a lead article for Science at about the same time. They were all working very fast, knowing that this material was really important to get it out. I think that Pitman and Heirtzler complained to Science, that Science was about to upstage them by either printing Vine first or printing it in the same issue. Science decided to wait a week or two and print the Pitman and Heirtzler ďmagic profileĒ paper first. But anyway, Fred was really into this. He presented his work at the Goddard meeting.
Doel:Interesting. Just to be sure, the Pitman/Heirtzler feature did appear first in Science, then followed by the Vine piece.
Sykes:Thatís right. So the exact date as to whether it was August or September, October, Iím not quite sure when the Goddard meeting took place. It was in Ď66. And it was not planned to be the definitive meeting establishing earth mobility, but it turned out to be the critical meeting.
Doel:It sounds like it in just in number of people just how significant these data from different fields. How many people were there at that meeting?
Sykes:Letís see. Probably of invited speakers, like myself, about twenty. Probably fifty to seventy-five people were in attendance. There was a whole community who had an interest, a lot of them from the ocean sciences. Teddy, [Edward C.], Sir Edward Bullard came over from England and gave a major paper. He along with two of his students had done a computer fit of Africa and South America that he talked about. He brought along a very young, bright student, Dan McKenzie to that meeting, who was, was one of those who was convinced that things were taking off. [William P.] Menard was there. Frank Press was there. Frank told me later on that he regarded my paper as being the first one that really convinced him of the reality of continental drift.
Doel:Thatís interesting. Very interesting.
Sykes:There were a couple papers that were more anti or thinking that they had data that did not support sea floor spreading. The two Ewings [W. Maurice and John] had some data, either then or shortly thereafter, of the distribution of sediments in the Atlantic, that they thought was not in accord with the idea of simple uniform spreading. There was another point — it probably didnít come up at that meeting but shortly thereafter — of some rocks that had been dredged from the mid-Atlantic ridge that appeared to be quite old. And I think later the consensus was that those were probably not rocks that were freshly broken off [by the dregging process] and that many of them were glacial erratis.
Doel:That had been dragged in.
Sykes:Drafted in by icebergs and dropped in the North Atlantic. Some of those rocks that probably were fresher and broken had been collected many years before. They were lying in a box up in the core lab at Lamont. It wasnít quite clear exactly where they had come from, given the navigation at that time in the 50s with respect to the Atlantis fracture zone, from which they were collected. Also, there was some doubt cast by both Le Pichon, Langseth, and Ewing about the heat flow across the mid-Atlantic ridge in that it didnít seem to fit the expected pattern.
Doel:Steep rise at the center of the ridge and sloping decline.
Sykes:Right. But that they did have data from the East Pacific rise that seemed to show that that were in agreement with the hypothesis.
Doel:Do you remember discussions with Marc Langseth about drift and his views toward drift?
Sykes:No. Le Pichon was certainly one of those who by the time of that meeting, and he was there, quickly converted and he started working on seafloor spreading. Well, the next sequence after that meeting was that Heirtzler, Pitman, and a couple of students from Lamont, really started working up this huge database of magnetics data that Lamont had. They published a series of papers — probably in Ď68 — that showed the [magnetic] anomalies and the rates of spreading in various oceans. But that was to come a little bit later. And letís see. The next thing that happened for me was that I wanted to get my data published quickly. One of the most fortunate decisions I ever made in my life was to get that paper on the focal mechanisms written up as fast as possible and submit it to Journal of Geophysical Research. Fortunately it went through the review process quickly and got published quickly. Several people were anxious to have a volume of papers to come out of the Goddard meeting. Bob [Robert] Phinney from Princeton agreed to get Princeton University Press to quickly publish a group of those papers, and that they wouldnít have to be reviewed. I decided to do a kind of second generation paper for that volume. It turned out that it was, in fact, almost two years before it came out. By then, the entire plate tectonic revolution had happened.
Doel:Having made the decision to publish JGR [Journal of Geophysical Research] was quite fortuitous.
Sykes:Right. Otherwise, certainly somebody else would have beat me to it if I had stuck with the Princeton volume. The Princeton volume had some pretty pictures in it, but all of the excitement was all over by the time it came out. Our paper on global tectonics, seismology and global tectonics was coming out as well.
Doel:Right. Thatís 1968.
Doel:I wanted to hear also about how, how the planning for that paper came about.
Sykes:Yes. Well, let me just go back.
Doel:Go ahead in sequence in what you want.
Sykes:Right. To follow up a couple of other things. That was after the Goddard meeting, or about the time of it, when I knew I knew that I really had something. I wanted to present it at a national meeting. At that time, there was not a big AGU meeting in San Francisco. The big AGU [American Geophysical Union] meeting was in the spring in Washington. So I attempted to get on the program for GSA [Geological Society of America] during the fall of Ď66. GSA, as they still are today, is very rigid about deadlines in July for abstracts. Then the meeting doesnít happen until five months later. But I had talked to Allen Cox who I think was at the Goddard meeting. I believe he may have been president of GSA at that time. So he said call up so and so, the program committee, tell them to put you on the program. I called up this person, who was a paleontologist from I think Berkeley, who said, youíve missed the deadline, blah, blah, blah. Well, if Allen Cox thinks that itís important. I guess weíll put you on the program. So I got on the program. By then Fred Vineís paper in Science either had just come out or was just about to. He had been invited to give a major GSA talk. He was aware then of my work as a result of hearing it at the Goddard meeting. He plugged that there was going to be this additional GSA session in which I would speak in his longer talk. I gave my talk — I believe it was on the last day of the meeting and it may have been a Saturday morning — in the bar at the Hilton in San Francisco. A lot of people showed up. The room was this fairly small bar, just converted into a room to show slides and present papers. It was pretty much full. A lot of people heard about it and came to hear what I had to say.
Doel:How broadly did you cover issues in that presentation?
Sykes:Well by then I was more bold in realizing that this really did prove Wilson, it really did prove continental drift. I stuck more to the data in my Goddard talk. I really had to do that to show that the focal mechanisms data were really good — there were practically no, uncertain points. I did say it this was in accord with Wilsonís idea [at the Goddard meeting]. By the time of my GSA talk I did go on to say that this demonstrates continental drift, sea floor spreading and transform faulting. I was prepared to say to that.
Doel:What was the reaction at that meeting?
Sykes:There were two reactions. The first person who asked me a question was from an oil company, named [Mason] Hill, who had written some papers on strike slip faulting. He got into just a question of nomenclature as to whether these should be called transform fault or strike-slip faults or transfer faults, etc. Afterwards, Dave [David T.] Griggs came up to me and with a great big smile slapped me on the back and said, ďThatís great!Ē That certainly made my day.
Doel:Iím sure, particularly coming from David Griggs too. I was curious too, what reaction did you get from the JGR paper, the one in which you were developing the focal point mechanism.
Sykes:Well, letís see, it came out, what June Ď67?
Sykes:So by then, things were breaking so fast that all of the people who went to the Goddard meeting, had spread the word among their friends. There was a special union session at the April AGU meeting, in which I was one of the organizers. The Oliver and Isacks work was presented there. I updated work on focal mechanisms. I think [Harry H.] Hess and [Robert S.] Dietz each talked. And Vine talked. So I think most people in the profession regard it as kind of the defining session. But really the Goddard one was, for those people who were more insiders.
Doel:This is very interesting that decision. You say you played a role in organizing the AGU fall all union session as well.
Doel:What role were you playing?
Sykes:I think I was one of, I think, maybe two co-organizers of, that put together the session.
Doel:Do you remember who the other coordinator?
Sykes:No I donít.
Doel:I was curious if you remember too which people particularly you were trying to recruit to talk in this session?
Sykes:Well, certainly we wanted to get the all things in magnetics. The things on reversals in cores that [Neil] Opdyke had done with [John) Foster and some of his students. That may have been also at the Goddard meeting. But I was certainly then aware of the Oliver and Isacks and the Vine work. And I forget. And by then, well, with the heat flow data. And so that session probably had at least a thousand people in attendance. It was in a big just everyone in solid earth had heard about this and came to hear the session. One of the papers that was given there was by [W.] Jason Morgan.
Doel:He was at Princeton at the time.
Sykes:He was at Princeton. Jasonís paper had to do with relative motions of rigid spherical shells that relative transform faults should define small circles about a center of rotation. He took that from some of Bullardís work, which showed that Africa and South America — you can rotate things about an Euler pole, for finite rotations. Jason followed up on that by putting together both rates of spreading and — directions of transform faults to look at motions of plates on a sphere. Jason had before that sent me an early draft — very poorly written — but containing the basic ideas of plate motion on a sphere. Jason was also a poor speaker. So I donít think a lot of people at the meeting appreciated what he had to say. He had really taken the work to plate tectonics. One small controversies was that McKenzie and Parker had done a study of the motion of the Pacific and North American plates on a sphere, using focal mechanisms. They submitted that to Nature and got it published very quickly. McKenzie was at the AGU meeting, but claims that he did not hear or hear about the Morgan paper. I donít know whether thatís true or not. But, so thereís, yes, some question about priority of ideas. Jasonís paper was more inclusive on a global scale of plate tectonics. McKenzie and Parker also were looking at a similar thing the just motion between two plates. But still important.
Doel:How well did you come to know Jason Morgan?
Sykes:I would say moderately well. Jason either just after he received his Ph.D. — or as part of his Ph.D. at Princeton, in physics — did a study of the Puerto Rico trench. He had modeled some blobs of high density material that he described as sinkers that were pulling down the trenches and producing gravity anomalies. There were a whole bunch of people from Lamont, about five or six of them, who got together and wrote a rather scathing letter to the editor.
Doel:I seem to recall that. I think Manik Talwani was one of the co-authors.
Sykes:Right. And I think [W. Maurice] Ewing certainly was. Iím not sure, Le Pichon may well have been. And I had felt at the time that was rather overkill, addressed to a poor graduate student. And I think some other people felt that. But I think that Jason probably never quite forgave people from Lamont, which is understandable.
Doel:This is true. He had not finished his own Ph.D. work at that point.
Doel:I do recall that was a rather strident criticism of Jason.
Doel:Had that been discussed? Do you remember discussions at Lamont over Morganís ideas?
Sykes:I guess it must have happened in the group in marine geophysics. But it was before the sea floor spreading hypothesis. Probably late fifties or 1960 or something like that I would guess. But I donít remember being called. I would say that — at the time I was doing my work in seismicity — that the people that I interacted more with than the marine geophysicists was Bruce [C.] Heezen. He was very interested in the location of the earthquakes. An interesting, I had one little bit of controversy with Bruce. After I wrote and probably had published my paper on the nature of transform faulting, the nature of, or mechanisms of earthquakes, etc., in which Bruce said something to the effect of, oh yes, we had done that. The we being he and Marie Tharp. Their first map of the Atlantic didnít have any fracture zones on it. But when Menard discovered them, Heezen and Tharp did one of the South Atlantic that had lots of fracture zones, and then they re-did the North Atlantic and put them in. They had little arrows showing the direction of motion. I said to Bruce, that your sense of motion is exactly opposite that of transform faulting. ďAh, we just put it in that way. We didnít really mean it.Ē [Laughter] And that I did not believe.
Doel:I think you mentioned earlier that you spoke with him much more than you did with Marie Tharp on the mapping.
Sykes:Yes. And I talked some to Chuck [Charles L.] Drake who was quite interested in what I was doing. And, of course, Jack Oliver, and Brian Isacks. But at about the time that I obtained the focal mechanisms — probably just before the Goddard conference — I went to see Ewing to show him them, which was rather customary for everybody to do. He said, this is really interesting and some really good data. He said, but I would suggest that you get two or three times as many solutions. I donít think that he said before publishing, but it was rather clear that he was skeptical and yet encouraging. Fortunately, I decided to go [publish] — and I think Jack Oliver encouraged me — with what I had.
Doel:And that didnít include other speculations or hypothesis at that point?
Sykes:Right. Except to say that it supported — Iím pretty sure that it says there — that it supports Wilsonís hypothesis on transform faulting.
Doel:Was there anyone else that you would routinely show your work to outside of the immediate group like Jack Oliver with work of this sort?
Sykes:I think not right away.
Doel:Later there was?
Sykes:Well letís see, later one person who came as a graduate student, Peter Molnar. He and I then went on to do what was the first paper on a plate tectonic interpretation of the Caribbean which came out in Ď69. So, by the time of the new global tectonics paper, Peter was around. And I talked with him. And Muawia Barazangi, who with Dorman a very nice map outlining plates, using I think seven years of earthquake data from whatís now the U.S. Geological Survey that was then part of NOAA [National Oceanic and Atmospheric Agency].
Doel:Do you remember how early it was that you and Brian Isacks and Jack Oliver began writing the new global tectonics paper?
Sykes:Well I think that probably about the time — of that [spring) AGU [American Geophysical Union] meeting in Ď67. Isacks and Oliver had shown that you had a high-velocity, low-attenuation zone that coincided with the downgoing seismic zone. They made the crucial suggestion that that was lithosphere that was underthrust. So, and probably then also as a result of the AGU meeting in April, Le Pichon started working on a major compilation of spreading data to calculate what the plate motions would be, along the other boundaries that were not spreading boundaries. That paper came out in JGR, probably in Ď68.
Doel:JGR clearly remained the journal of preference for these longer papers?
Sykes:Right. And to really reach a wide audience in the earth sciences, both in the U.S. and abroad. So we became aware of Le Pichonís results early on.
Doel:Was he still at Lamont at the time?
Sykes:He was still at Lamont at the time. So, yes, it was soon after the AGU meeting — probably it was something like halfway through Ď67 — that we made the decision in talking about that the work — to address a whole bunch of other ideas. What types of earthquakes generate tsunamis in a plate tectonics setting? The setting of volcanoes. And to write a paper that would pull together all the data from seismology, including my data from the mid- ocean ridges second generation of my work there and the locations of earthquakes. Where do deep-focus earthquakes occur? We then both collected and analyzed ourselves a lot of data on focal mechanisms of shallow earthquakes at subduction zones. And we were able to get the slip factor indicating the relative motion. We very quickly found that they agreed very nicely with Le Pichonís calculated motions. He had about six or seven major plates. He didnít have some of the moderate size ones, but it was good enough. And so in fact, I think that was one of the major conclusions of our paper. They [the focal mechanism data] really cemented that subduction was one of the major processes in addition to sea floor spreading and transform faulting. So that put the nail in the coffin that was started by Oliver and Isacks with their data from Tonga.
Doel:Was there any other points in that paper that you felt werenít appreciated at the time by the broader community or were you generally pleased by the reception?
Sykes:Generally pleased. Richter wrote a letter that was, well moderately critical.
Doel:A letter to the editor?
Sykes:A letter to the editor that we responded to.
Doel:What were the points he was raising?
Sykes:I forget now. I donít think that they were a big deal. But I think that our  paper in the main was very widely read and quoted. So I think it was overwhelmingly accepted as was the plate tectonic revolution by about 98% of the people in the field. Yes, the number of people that were hold outs was quite small.
Doel:How did you actually go about doing the writing of the paper? Did you each take different sections to write it?
Sykes:Yes. I think that I put together many of the focal mechanisms from subduction zones and compared them with Le Pichonís. I did a section on the generation of tsunamis. Brian worked with me, but he took the lead in working up a lot of the focal mechanisms from Tonga that we also wrote a separate paper on. He and Oliver mapped more the places that where either high-frequency [seismic] waves are propagated or theyíre not, following up more on the Isacks and Oliver paper. Oliver probably did more on the overall organization, like writing the introduction. We decided in the beginning that it was pretty clear that this was a joint effort of all [three] of us, and that we would, probably decide the order of authorship — unless it was very clear that there was one person above the others — by flipping a coin.
Doel:Is that in fact what happened?
Sykes:Yes. So if you look at the paper, down at the bottom is a footnote on the first page that references the authors, it says ďorder of authors determined by lot.Ē
Doel:Thatís right. I do recall that now.
Sykes:So, I lost the toss. I was number three.
Doel:Thatís very interesting. Very interesting. How long did it take you to get the paper written once you started?
Sykes:I would say roughly six months. So, letís say if sometime in the summer of Ď67 we started working on it, that it was probably ready sometime early in Ď68. So whatís the date on it?
Doel:I donít have that, a copy available with me here. But I believe thatís right. I do think it was early in 1968. One other person I was curious about when you had mentioned Jason Morgan at Princeton, Walter Elsasser had of course been at Princeton in the early 1960s. Did you have any interactions with him during that time?
Sykes:I can remember him coming to Lamont. I think I talked to him personally, and I think that he gave a lecture, and I think, about the nature of plates. The propagation of disturbances in them. I think he undoubtedly influenced Oliver and Isacks in their work.
Doel:Thatís an interesting point.
Sykes:Elsasser by then was a fairly old man. But he was still, you know, very sharp. He had moved around a lot in different universities in the U.S. — for what reason I donít know.
Doel:He was also working between biology and the earth sciences at different points.
Sykes:Right. I think I probably mainly new him from, he wrote a major review article — I think in Physical Review — on the geodynamo. Late Ď40s, early Ď50s.
Doel:Which of course has remained one of his principal contributions to the earth sciences.
Sykes:So I just want to make one other comment and that there was one other person who I and we interacted with quite a big Dan McKenzie. Dan McKenzie spent quite a bit of time in the U.S. at Lamont, where he looked at a lot of film chips, and at Scripps several times. We showed him a version of our new global tectonics paper. One of the things that he rightly criticized was our interpretation of the lengths of downgoing seismic zones. The places that had the highest rates of underthrusting had the longest ones and generally those that go down the deepest. We explained that in the first version of our paper, i.e. a draft as the pattern of plate motion having changed about ten million years before that, and so that underthrusting had started in those places at that time. I think that idea came from Ewing and Ewingís statement that they thought in the North Atlantic that there had been a big change [in spreading] as indicated by the thickness of sediments, about ten million years ago. McKenzie pointed out that there was another viable hypothesis and that was that ten million years or twenty million years was about the time for a slab to warm up and that could turn off the earthquakes. So we added that as a second hypothesis in the paper. I think that that is surely the correct explanation, and not of there having been a world-wide beginning of underthrusting that was new, some ten million years ago. That was really a very catastrophic [hypothesis].
Doel:Philosophically itís a more difficult issue to reconcile. Thatís a very interesting point. I know our time is getting very tight right at the moment. Iím just curious for your reflections on how this work to which you were principally contributing here to the global tectonics paper, all that work, how that affected the future development of Lamont in the late Ď60s, 1970s.
Sykes:Well, there were a bunch of us who worked on kind of follow-up studies. Brian Isacks and I did more work on the Tonga/Fiji region. Molnar and Oliver did a more extensive study of the propagation of the high frequency waves on a global scale. Molnar and I did a major paper on the Caribbean. Then it also led me into the question of what we called seismic gaps — places along plate boundaries that had not experience big earthquakes for a long time. One graduate student who I got involved in and who also worked with Jack Oliver was John Kelleher. He did a paper on places that had had big earthquakes giant earthquakes off the coast of South America and along the Aleutians, southern Alaska. And that those that hadnít. So it followed on from some of the ideas from the Tobin and Sykes paper which were then touched upon, the global tectonics paper. What the emerged became known as the seismic gap hypothesis. Two workers from other countries, S. A. Fedotov from the Soviet Union and [K.] Mogi from Japan had some similar ideas that they published [in 1968] that did not have a plate tectonic basis. They hypothesized some of the very active zones of either on Kamchatka, the Kurils, or Japan that had not had big earthquakes for a long were the most likely places for the next ones. I then put that in a plate tectonic framework and did a major paper that came out in JGR in 1971. It attempted to forecast what were the likely sites in southern Alaska and the Aleutians for large [future) earthquakes. Within a year, one of those, the smallest zone, near Sitka [Alaska] ruptured in a magnitude seven and a half earthquake.
Doel:Was this one of the earliest — in one sense — prediction papers that you became involved in?
Doel:We need to cover that in detail when we get into other subjects.
Sykes:Yes. Because that kind of also steps back. So, well, and that kind of brings us up to about the time that Oliver was invited to become department chairman at Cornell. He and Brian [Isacks] went there.
Doel:And he had been chair of the department prior to the time that he left as I recall? Of the geology department at Columbia.
Sykes:I think so.
Doel:Had he discussed his thinking about leaving Columbia and Lamont with you?
Sykes:I donít think so. It came as a surprise to me. One thing that he said that I didnít like, and that was that he would invite any of the graduate students who wanted to go to Cornell to go there. I felt that was stealing our graduate students.
Sykes:And, so in fact, no one left. I then ended up with about nine graduate students.
Doel:How many had you had before then?
Sykes:Well, I had worked for the Federal Government, but at Lamont, for about a year and a half at about the time of the 1968 paper. And, or just before that. That had in fact helped us. One of the things it included as kind of a bonus was getting all of these film chips from the Federal Government, which we then continued to get thereafter. But, Jack Oliver felt that we needed to have another professor in seismology. So I think he approached the president of the university to —
Doel:Would that have been McGill already at this point?
Sykes:No. It was before the ďbig disturbanceĒ at Columbia.
Doel:So itís still Grayson Kirk.
Sykes:So itís still Grayson Kirk. Thus, I was offered an assistant professorship. It was pretty clear that it was a tenure track line. I accepted it in mid-Ď68. I then started working with some students like Molnar and Kelleher, who I worked with quite a bit, but they formally had started with Jack Oliver and did finish with Jack Oliver. Barazangi as well. We had a very large group. I think, we made offers in seismology alone to something like nine students, and eight accepted in one year. So all at once I went from very few to a very large number of graduate students. But fortunately it was still at the peak of federal funding, from different sources. One of the things that did happen in the late sixties was that the U.S. government decided to test two large [nuclear] explosions at Amchitka Island, in the western Aleutians, that would be bigger than what could be tested, or at least the last one, would be bigger than what could be tested safely at the Nevada Test Site. And Howard Hughes was also making a lot of noise. His windows were being rattled in Las Vegas at the time. The Department of Energy was interested in hiring us — Lamont — to do a study, but more for them and for their consumption on earthquakes in Alaska and the Aleutians. Jack Oliver was partly involved in that, but I was the lead person. We decided that we could accept, and would be willing to accept, a grant. Not to do monitoring out there, but to do a general study of earthquakes in the Aleutians. So that was done through more of the normal basic research, grant writing part of the Department of Energy.
Doel:Were these data kept classified for you at this point?
Doel:It was open.
Sykes:So that study was entirely open. The group that did monitoring at Amchitka was Engdahl and others in the old U.S. Coast and Geodetic Survey.
Doel:We will need to pick up on some of these things as we get into the, particularly the nuclear testing.
Sykes:But I think that that did get me more involved in Alaska and the Aleutians, the plate tectonic aspects, the earthquake prediction aspects.
Doel:I was interested to hear a moment ago that Jack Oliverís departure then did come as a surprise to you.
Doel:How did that affect Lamont and your own position and work?
Sykes:Well, Jack had started to think about the ideas that got formalized in his later work on seismic reflection surveys. I think that he did mention that when he said that he was planning to leave, that was one of the main things that he wanted to work on. He had started doing some work in earthquake prediction, but I moved more in that direction. I moved more into studies of eastern North American earthquakes, of stresses with the lithospheric plates, neither of which Jack [Oliver] was working on. I wasnít particularly interested in the reflection work things or of trying to compete, unsuccessfully, with what Jack was doing there. I stepped up my interest in nuclear test verification whereas Jack, when he moved to Cornell, got completely out of that area. Probably by about Ď68, or before that, Jack had dropped out of any involvement in test verification as well. So that had happened before he went to Cornell.
Doel:Did you feel you had enough resources from Lamont to re-build seismology after?
Sykes:I was very worried of being the lone professor. I started working immediately to get a second professor. The first person we approached had been a graduate of Lamont, a few years before me, Jim [James Brune], who had gone to Cal Tech and then to U.C. San Diego. Jim came to visit, and I think that, he met with Ewing, and Ewing didnít give him a very warm reception. I donít know why. And so the person that we approached next — it really was kind of up to me to do the search —
Doel:But Ewing had in some sense was able to undo it.
Sykes:Right. With Brune, but I mean, unlike what we would do now, we did not have a formal search committee. I had heard about Paul Richards and so we made him an offer. I was able to get that through the Department [of Geology] and through Lamont. So Paul has been here ever since. So that, that I felt, gave me some relief, to know that I had another colleague who had a tenured position, or tenured-track position.
Sykes:But there were a lot of people then who were on the research staff One person that Jack Oliver had gotten to come to Lamont just as a post-doc was in Ď68 was Klaus Jacob, and Klaus has continued as a senior research associate. I had been instrumental — probably about the time that Jack left — in getting David Simpson, who was a new graduate from Australia National University, to come as a post-doc, and he then became a senior research associate, and is now head of the IRIS [Incorporated Research Institutions for Seismology], the university consortium for seismology, and was at Lamont for twenty some years. I also attracted Chris [Christopher] Scholz, I guess around 1968, when he finished his Ph.D. with Bill Brace. He came as a post-doc, and then became a research associate, and then he got a tenure-track position. So that helped to round out things. Iíve done a lot of work with Chris ever since. That really helped to have someone who had one foot in seismology, but one foot, or more than one foot in rock mechanics. And more of the mechanics of faulting and earthquakes.
Doel:A good point. Iím just thinking back to those ten, the eight graduate students that you so quickly inherited back then. What sort of positions did they find once they were done back in those days?
Sykes:Well, letís see. One person, Paul Einarson was one of the brightest ones, is now a professor at the Icelandic Science Institute. He is more or less in charge I think of both volcanology and earthquakes in Iceland. Fred Klein went to work for the U.S. Geological Survey, and has been there ever since. One person who worked with Lee Alsop, who was an adjunct professor at the time and worked for IBM — from Denmark, I think I was on his committee, and had a lot to do with overseeing his work since I was a regular tenured faculty person by then and Alsop was an adjunct — [Soren] Gregerson is his name. Letís see, one other person who did quite a bit of work with me on instrumentation for better detection of surface waves from earthquakes and explosions, Andy [Andrew] Murphy went to work for the U.S. Nuclear Regulatory Commission. Marc Sbar worked with me on stresses in eastern North America as did Joe [Joseph] Fletcher. A little bit later Fletcher went to work and is still at the U.S. Geological Survey. Sbar went to the University of Arizona and then went to work for, I think, SOHIO [Standard Oil Company, Ohio], which was later absorbed by British Petroleum. He is a fairly high level person in British Petroleum in the U.S. now. I have to stop and think about who else.
Doel:This is a good list though. It gives a good indication of the kinds of opportunities that people were finding at that time.
Sykes:Well, letís see I had one other student, Bob [Robert] Tathum who had in fact worked for Texaco and he had a scholarship to get a Ph.D. So he worked with me, and then went back to Texaco. Bill [William] McCann did a lot of work with me in the late Ď70s on seismic gaps and on the Caribbean. He now works in Puerto Rico, I think as a separate consultant.
Doel:All that is helpful and weíre moving I think to areas that I think weíre going to be covering in subsequent sessions. Let me just ask as a final question for today. Thinking back to these heady times with the moment of seeing the Eltanin data that Heirtzler and Pitman had developed, were there any subsequent moments in your scientific career where you felt things occurring with quite the same intensity as you did in the 1960s in developing your work on the, on then the island arcs and then into the new global tectonics.
Sykes:Probably not as big and all encompassing as that. I had work that I did on seismic gaps I felt was quite important. But it was something more of interest to seismologists and of long- term earthquake prediction. So that, that certainly excited me. Work that I followed up on in earthquake prediction with [Yash P.] Scholz and Agarwal, I certainly felt excited about that. But thatís not something that has stood the test of time.
Doel:Like the other things. Yes. Is there anything else that we havenít covered that you particularly wanted to with regard to development of plate tectonics and confirmation of drift?
Sykes:I donít think so. I think that that pretty much touches all the bases.
Doel:Well, let me thank you again very much for this long session that weíve had today. And you will be getting the transcripts from Columbia.