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# Kerry Sieh

### Founding Director Emeritus, Earth Observatory of Singapore at Nanyang Technological University Singapore, Former Robert B. Sharp Professor of Geology, Caltech

By David Zierler, Director of the Caltech Heritage Project

July 26, 2022

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Tuesday, July 26th, 2022. I am very happy to be here with Dr. Kerry Sieh. Kerry, it's great to be with you. Thank you for joining me today.

KERRY SIEH: Thank you for the opportunity.

ZIERLER: To start, would you please tell me your current title and institutional affiliation?

SIEH: In 2020 I left my last full-time affiliations, which were with the Earth Observatory of Singapore (EOS) at Nanyang Technological University and the Asian School of the Environment there. I am now the Emeritus Founding Director of EOS and an Emeritus Professor at the School. I have active positions as Distinguished Chair Professor at National Taiwan University and as a Distinguished Visiting Scholar with the Academia Sinica's Institute of Earth Sciences in Taipei. I'd say about 20% of my time is spent in Taiwan, and the rest of my time here in Bellingham doing all sort of other things I've always wanted to do but never had time.

ZIERLER: What are the kinds of things you're doing now that you never had opportunity to do before?

SIEH: I'm spending a lot more time with family and doing things like skiing and hiking and gardening. A major non-scientific project that I started during the pandemic has been looking into my ancestry. I had no idea that my American maternal lineages go back to the days of the Pilgrims, Puritans and early American Mennonites. Perhaps I have genes for religious extremism. Judging from the excitement I've felt doing that ancestry work, I wonder, if circumstances had been different, whether I might have become an historian like yourself.

ZIERLER: That's great. Kerry, to set the stage for some context, tell me what was happening in 2008 that compelled you to leave your position at Caltech.

So I started looking elsewhere in the world, because coincidentally, Gerry Wasserburg and his student Larry Edwards had just developed a new technique that was far more precise than radiocarbon, with dating errors of just a few years – on coral. Their technical success convinced me that I should look for a place in the tropics where I could use corals to do what I had been trying to do on the San Andreas Fault. To make a long answer even longer, those constraints led me to pretty much the only place in the world where it was plausible – above the subduction zone offshore Sumatra. A decade after I'd started working there, a structural engineer in Singapore named TC Pan, who was following my work because he was interested in how big earthquakes in Sumatra might affect the buildings in Singapore, got a hold of me and asked me to give a talk sometime when I was on my way to Sumatra, and tell them what I'd been learning. I went there in about 2000 and then returned every couple of years to give an update.

Just as we were making good progress on the Sumatran work, the megathrust unleashed the giant 2004 earthquake and devastating tsunami. I don't think I'd ever devoted as much time to professional work as I did in the two-year aftermath of those two events. By the end of 2006 I was exhausted and had far too many irons in the fire. So I asked the chairman of the Division, Ken Farley, if I could do a sabbatical to devote my full attention to finishing up our work on the Sumatran reefs. He wasn't keen on it, because I had had my first sabbatical in 1995 and a 3-month-long one in 2003, but he reluctantly okayed it. I had a choice of either going to Oxford, where they would be willing to pay for half of my housing, or I could go to Singapore, which would pay for all of my housing plus pay me funds to cover other living expenses. I thought, "Well, I'll go to the geological backwoods of Singapore." I went there for a 9-month stint, beginning in early 2007. During my first week there, the president of the university, Su Guaning, who I think had done an advanced degree in EE at Caltech, called me up into his office and brought in the provost and his American advisor, Haresh Shah, a Stanford earthquake engineer, who happened to have been one of my professors in grad school. Unbeknownst to me, Haresh had pitched to them that they should try to steal me away from Caltech to start a new research center.

They enticed me with mention of a new billion-dollar national program. The government's intention was to fund five big new research institutes to do something that would bolster their national security and accelerate their economic development. I had in years past been teasing TC and Haresh about how little money they were putting to understanding geohazards in Southeast Asia, so they suggested that I propose a $150 million project. So while I was on sabbatical in Singapore, I wrote this little seven-page proposal. To my astonishment, it was shortlisted just four months later. In November, I came back to Caltech, wondering what I would do if it were actually funded. During the first three months of 2008, I was flying back and forth to Singapore every few weeks to make presentations to, among others, their Ministry of Education, National Research Foundation and finally the prime-minister's Research Innovation and Enterprise Council. By January 2008, it was pretty clear this was going to happen, and I decided it would be a great new lease on my professional life and chance to explore living in a part of the world so very different from the US. The question was, "How do I break the news at Caltech, and can I get a one- or two-year leave of absence, so that in case this adventure goes south, I can come back?" Caltech wouldn't give me longer than one year leave of absence, so I had to basically either fish or cut bait. So, I cut bait. I went to Singapore in the middle of 2008, and then with about S$250 million (about US$200 million) I built the Earth Observatory with a faculty about half the size of Caltech's Division of GPS. As part of that, I hired one of Jason Saleeby's former grad students, Charlie Rubin, to head up the Asian School of the Environment. I was impressed by how successful he and his wife had been in creating a strong geology program at Central Washington University. We'd pretty much finished the job by 2020, so I quit a year before my contract ended. I also left early because, although I had begun with substantial autonomy, as the decade went by the bureaucracy at the university had become so controlling and stifling that I had lost most of the momentum needed to continue to grow the Observatory and the School. My experience there slowly made me realize that Caltech's laissez faire approach toward faculty was pretty good [laughs]— ZIERLER: [laughs] SIEH: —in terms of leaving us alone to do our jobs. David Baltimore summed it up pretty well in a single sentence at a luncheon meeting in the library with a delegation of Singaporeans, headed by Tony Tan, the deputy prime minister of Singapore at the time. In anticipation of creating a big biotech entity – it became their Biopolis – they were visiting the U.S. to learn about biotech. He and his coterie came to Caltech because of its reputation of bringing on board so many biologists who had done such wonderful scientific and economic things. I had asked to be invited to the luncheon, because I had been working on the Sumatran reef for a decade and wanted to bring to the attention of the Singaporeans that much of the Sumatran reef had died in 1999. At one point, the DPM looks over at Baltimore, and asks him something like this: "I've visited Harvard and MIT and now Caltech, and I'm so impressed by the group of people you've put together and what they've been able to accomplish. But I'm curious, how do you organize these people?" Baltimore just chuckled and says [laughs], "You don't organize these sorts of people! You just find them, bring them to your organization, give them the resources they need and then you stand back and watch the magic happen." The DPM looked a bit perplexed, for reasons I only later understood. Singapore and its universities are very top-down. Faculty, staff and students and micromanaged. It's pretty much the antithesis of the modus operandi at Caltech. I realize now that's one of the most important things about Caltech – for example, never in my entire 31 years there did I ever have to talk to an auditor or was I asked to raise more research money or to do a better job teaching. All that was expected of me was to do research and teach as best I could. I had never heard of a citation index until I went to NTU, where they are used to determine pay raises and, can you believe it, to distribute annual bonuses. I'd never heard of counting how many people looked at my papers. Culture shock! In contrast, all I was told at Caltech was, "Just do your thing. Just follow your passion." That turns out to be a rarer thing than I had thought. ZIERLER: When you got to Singapore, did you recognize that in building up the Observatory, this would pull you away from the research, that you would become much more involved in administrative matters? SIEH: Yeah, I did, but I felt that I had had a pretty good run already and that the impact I could have in Southeast Asia over the coming decade would be far greater than the impact I could have at Caltech. I'd had about 35 unencumbered years to more or less follow research leads as I wished. I'd had the opportunity to mentor many PhD students and with them create a corpus of work that I was very proud of—furthering paleoseismology and neotectonics, work on the San Andreas Fault, work in Sumatra and so on. I also recognized that if I left Caltech I'd have an opportunity to create a big platform for many scientists a generation or two younger than myself. At Caltech my financial resources had been orders of magnitude smaller than what was waiting for me in Singapore. And, just as importantly, I had never had much opportunity to envision and then build a large research institution and its associated school. As we built the EOS, I often thought of how long the GPS Division and the Seismo Lab had been around. In Singapore and around the region, I often expressed my vision that the EOS would become a "centennial" institution, one that would be influential throughout Southeast Asia throughout the 21st century and beyond. ZIERLER: An overall technical question: I wonder if you can reflect on some of the foundations, scientifically, from which you built this new field of paleoseismology. In other words, you're credited for creating this field of research, but on whose shoulders do you stand in order to make these innovations? SIEH: In March 1971, there was a meeting of the Cordilleran (western) Section of the Geological Society of America, hosted at UC Riverside by its Geology Department, my undergrad school. I was a 20-year-old junior then and was asked to man the registration table as the participants walked up—"Here's your badge" and so on. I'm sitting there at the table and up walks this disheveled fellow who said his name was Charles Richter. Like most people, I knew almost nothing about him except that he had invented the Richter scale. I'm like "Buh buh buh buh buh buh" [laughs], but I manage to sign him in. Later on I had some time to go listen to a few talks. This was the first time I had ever been to a professional meeting. I went in to listen to a talk by a couple of consultants from an organization called Woodward-Clyde, headquartered in the Bay Area. They had been approached by the city of Fremont, which wanted to build a new civic-center complex. They knew that the Hayward Fault ran through the property and they didn't want their new buildings to be built across it, so they asked their consultants how to avoid that? The consultants' novel approach was to dig a long excavation across where they thought the fault was and thereby to expose it in the broken sediments. I was impressed by their use of geology to solve a seismological problem. Coincidentally that Spring, I was taking two key geological classes. In Structural Geology I was learning about different types of faults – strike-slip, thrust and normal – and how to analyze them and their associated deformations, mostly for mining and for petroleum exploration, which is where most of us went in those days after we graduated with our PhDs or master's. In Stratigraphy and Sedimentation, I was learning basically how to interpret geological layers. How do you tell whether they're marine or terrestrial, or windblown, riverine, landslide, or glacial, or whatever. Because that classwork was on my mind, it occurred to me that a geologist could do a lot more than just locate an active fault by digging a trench across it. Why not use the successively deposited layers of swamp mud and peat, or river sands or a lake clays, to tell when in the sequence of deposition the fault ruptured and broke the surface. Successive ruptures would be successively buried, radiocarbon dates could tell when each one happened, and thus you'd get a history of earthquakes extending hundreds and thousands of years into the past, substantially lengthening the time covered since the invention of the seismograph. That was basically the day that paleoseismology, the idea of using landforms and layers and structural geology to interpret seismic history, was conceived. It was a five years later before it was actually born, and an additional 10 years before my USGS mentor Robert Wallace named the baby "paleoseismology." Later in 1971, my most influential undergrad professor, Wilfred Elders, showed me a little red and white pamphlet from the National Science Foundation, advertising that they had$3 million to distribute during the summer of 1972—the year I was graduating—for student-originated, environmentally oriented studies. The NSF SOS program, it was called. Elders suggested, "Why don't you write a proposal to do something environmental?" Over the next week or so, I developed the idea of figuring out the prehistoric history of the San Jacinto Fault, which runs through Colton and San Bernardino, practically in UCR's backyard. It seemed to me that it would qualify as an environmental project. So I put together a team of undergrad geologists, geophysicists, economists and social scientists and we were awarded a whopping $25,000, which paid me a salary of$1,000 for the whole summer. I'd also been offered a job working for ARCO in Alaska and flying around in a helicopter and stuff. But I decided to stay in awful smoggy Riverside, much to the horror of my lungs. I figured it would be more fun to be my own boss than to work for an oil company. Moreover it would be environmentally related. So we dug trenches across the San Jacinto Fault, mapped the walls of the excavations and brought the 14C samples back to UC Riverside's nascent radiocarbon lab. Unfortunately, the analyses were poorly done and yielded no reliable dates, so that first attempt at creating a paleoseismologic record was a flop.

I went to grad school at Stanford that Autumn, but nobody there, or anywhere else for that matter, was doing this sort of thing. Everybody was working on older stuff. In fact, in those days, because most geologists were trained to find petroleum and minerals, universities trained them to interpret old rocks – old igneous rocks for copper and gold and zinc and so on, or old sedimentary rocks for oil and gas. Those rocks were the important rocks. When you had young layers on top of them, they were called the "overburden," because they were basically a nuisance. But perhaps you know, as an historian of science, about the time I entered grad school people were starting to be concerned about what we were doing to the environment. The concern wasn't about climate change then, it was mostly about pollution. I went to Stanford, even though nobody was working on the "overburden," because it's just a few miles from the San Andreas Fault.

It was tough to realize though over the course of my first grad-student year or two, that there was no interest in what I wanted to do. I was told by one professor to "either sell your ass to me and do something along the lines of what I suggest or find another advisor." [laughs] That was a shocker, but it certainly got me to focus on finding a solution. I'd been pretty unhappy during my late teens and early twenties, for reasons we can talk about later if you wish, and that academic brick wall just drew me deeper into my melancholy pit. But, fortunately for me, seismologists, in concert with the USGS, had just laid out an escape route, although I didn't know it at the time. It was called the National Earthquake Hazards Reduction Program (NEHRP), motivated by the destruction caused by the eye-opening 1971 San Fernando earthquake. That led to about a $50 million allocation by Congress to the USGS to study earthquakes and to make the country safer with respect to earthquakes. The Survey set aside about$5 million for university researchers. NEHRP came into being in 1975 or 1976, right when I had to figure out how I would avoid "selling my ass" to a professor whose work didn't really interest me.

After that encounter, I started thinking that I may have to leave Stanford, or study to become a high school teacher or something else. As I explored my options, I made an appointment to see Clarence Allen, since I was down in Southern California for Christmas with family later that year. I rented a car and drove up from Newport Beach. I pulled under Clarence's bay window – the Lab was still up in the mountains then – and promptly realized that my seatbelt was broken and I couldn't get out. [laughs] What could I do? I'm stuck in my seatbelt. I can't crawl out, and the eminent Professor Allen is probably watching me from his window. So I got my pocket knife out, cut the seat belt off and went up to see Clarence. I asked him if it might be possible to transfer to Caltech for my PhD. I suspect Clarence's assessment was that I was in trouble, so he wasn't so keen to bail me out. But he sent me in the right direction – to Richard Jahns, the Dean of the School of Earth Sciences. He had been a Caltech professor while Clarence was doing his PhD in the 1950's, and I think he might have been the only full professor up til then to have left the the Geology Department for a greener pasture. I was a bit disappointed, but I went back up to Stanford and talk to Jahns, or "Doc" as I came to call him. He suggested that I work on the San Andreas Fault, not the San Jacinto, because it was a bigger and more consequential target. He gave me $300 to go down into the Southern California desert and scope it out. I did a couple of observations of tiny offset streams that looked like they were offset during the last earthquake. I came back up, and Doc opined that it was enough to write a proposal to NEHRP. We did that, and to my amazement, it was funded. He basically saved my hide, and NEHRP made it possible for me to do what I wanted to do. Two and a half years later he told me as I walked out of his office with my thesis under my arm, "Kerry, I have to tell you now that actually when I gave you that$300, I figured I was probably just giving you enough rope to hang yourself."

ZIERLER: [laughs] Wow. Amazing.

SIEH: [laughs] Actually that was a while after I'd already been hired at Caltech, because I was hired a few months before I'd finished at Stanford. What had happened was that Clarence Allen and Lee Silver had heard of what I had been able to do and had gone to the chairman of the department at Caltech at the time, Barclay Kamb, to suggest hiring me. I was to give my first talk about this work at the December 1976 meeting of the AGU in San Francisco, but I was still finishing writing it up. I still needed about a year or so to finish. I hadn't even started thinking about what I'd do after I finished my PhD, other than supposing I'd have to find a postdoc somewhere. So during the AGU meeting, Barclay takes me out to lunch on Polk Street, to a little vegan place where the choice was either lima bean or pumpkin soup. Lima beans had made me sick when my parents forced me to eat them as a child, so while I had pumpkin soup Barclay offered me a job. I thought he meant a postdoc with Clarence, but no he said he was offering me a job as an assistant professor. I was dumbfounded and told him that I didn't think I'd finish my thesis til the end of the coming year. He said he wanted me to come sooner than that. I asked him if I could wait until I finished my PhD. He then totally bluffed me, saying that it might not be available that far in the future. [laughs] So, I came before I had finished. He set me up in my office and paid me $500 a month less because I was only a lecturer at that point, not a professor yet because I didn't have my PhD. Anyway, I finished up my PhD within a few months. Incidentally, my start-up was an shaggy old yellow rug, a desk and a barely functional old drafting table. Fortunately, I was able to bring my NEHRP grant with me. ZIERLER: You mentioned you were rather unhappy in your teenage years and in your twenties. I wonder if that is connected with the fact that you're gay and that was not such an easy time to deal with that. SIEH: It's totally why. Totally. But let me precede my answer to your question with a little anecdote that connects my being a closeted young gay guy to my becoming a scientist. I have a little PDF that used to be on my website that explains the connection. It's the text of the acceptance speech I gave when I got a little award at the AAAS meeting back in 2006 or 2007, from an organization led by a woman who I think is still at Caltech, or maybe she's retired now – Rochelle Diamond. ZIERLER: Oh yes, I know Rochelle well. She's wonderful. SIEH: Shelley Diamond, yeah. Shelley was the driving force behind an organization called NOGLSTP – The National Organization of Gay and Lesbian Scientists and Technical Professionals. You know it? ZIERLER: Yes. SIEH: I get this call from Shelley one day saying, "Hey, we've elected you Gay Scientist of the Year." I was very flattered, but then I started thinking, "Is there any connection between my being gay and my having become a scientist?" Shelley and NOGLSTP helped me realize, by giving me this award, that I was gay long before I was a scientist, and that the former led to the latter. I become a loner and a seeker because of my unspeakable attractions back then. And my becoming an explorer of the forest and the woods and having a butterfly collection, and being a bookworm, and becoming interested in science had everything to do with my being a solitary, inward person. I'm pretty sure that if I had been straight, I would have headed off in a very different direction – perhaps becoming a lawyer. Yeah, so my being aware of my same-sex attractions drove me to becoming a seeker from a very early age, and a seeker of something that didn't yet exist. ZIERLER: When did you come out? SIEH: Thirty-five. ZIERLER: Where were you professionally at that point? SIEH: At Caltech in the GPS Division. ZIERLER: What was that like? How was that news received? SIEH: Oh my god, do I answer that question? ZIERLER: Not well, I take it? SIEH: Not so well by my family and many others in my fundamentalist community. But, for the most part, my colleagues and students were surprised but okay with it, although there were a few who seemed a bit more distant afterwards. There was certainly no overt antagonism. In fact, it was quite encouraging to me that several students actually made the effort to say things that were quite comforting. ZIERLER: As far as you know, were you the first Caltech professor to come out? SIEH: At the time, as far as I knew, yeah. Later I became aware that there was another professor in Biology. I don't know where he is now. He seemed a lot more well-adjusted. [laughs] I envied his being so stable and so content with himself. But getting there took me years. I went from being what I would call a "golden boy"—blonde-blue, successful, married, parent of three wonderful children, well-employed, somewhat famous in my field and in the media, the L.A. Times, National Geographic, television documentaries and news, and such. But nonetheless, in an instant I went from feeling successful to feeling like a pariah. ZIERLER: What aspects of this decision, because you were eminent in your field already at that point, was simply stepping forward as a role model for other gay people out there? SIEH: None of it. I've never thought of myself as a role model. I've just lived my life as best I could, and whether or not I've been a good example to anyone has been, as they say, in the eyes of the beholder. ZIERLER: It was more about being honest with yourself at that point? SIEH: Yup. I was occasionally suicidal during the couple of years when I was coming out at Caltech. Actually I tried to kill myself once – admittedly in a sort of passive-aggressive way. I was in an excavation—we revisited the same site that I worked at as an undergraduate, that same place along the San Jacinto Fault. Some students and I went back to redo it because the radiocarbon dates we had from my undergrad project had been ruined. I went back to redo it with a postdoc and a grad student. When you do an excavation a meter wide, you put in these aluminum hydraulic braces to keep it from collapsing on you, when you lay a sewer line or an electrical line or whatever. If it's more than five feet deep, OSHA requires you to have bracing so that it doesn't collapse on you. In fact, one of my colleagues at the California Division of Mines and Geology was killed that way. He went into an excavation across the San Andreas Fault the same time I was doing mine at Pallett Creek, and it collapsed on him and it killed him. So I walked into one that was unbraced one time, hoping it would collapse on me. ZIERLER: That's a poetic way to go for someone in your field, that's for sure. SIEH: Yeah, and it's also the way that the Clarence Allen character in the movie—what was it, back in 1974, Earthquake, I think. Was it Charlton Heston who played the Clarence Allen role? I'm not sure. In any case, it was an older professor in the Seismo Lab who goes into a trench and gets killed when the "Big One" hits and collapses it. That was modeled after my work, but I think it was poor Clarence who they were putting in the trench. [laughs] Maybe I misremember. Anyway, I felt I had gone from being golden boy to pariah, basically. It was largely in my head, but it was also a time when it wasn't all that acceptable even in academia. In hindsight, it was a good thing I was in academia at Caltech, though, rather than at the University of Alabama, I suppose. ZIERLER: The timing of this, coming out in the 1980s, to what extent did the AIDS crisis play a role in your decision? SIEH: It didn't play any role in my process of coming out. But the coincidence of the crisis and my coming was very fortunate for me. If I had "come out" when I was in my teens, like most straight people do, it's quite likely that I would have died from AIDs in the late ‘80s or early ‘90s. So my coming out in the mid-80's was critical timing. If it had been a couple years earlier, I don't think I'd be around today. ZIERLER: Meaning you were so ensconced in the research, that kept you safe? It kept you away from dangerous relationships? SIEH: It kept me away from any relationships other than my marriage. [laughs] I was a prude. I was a conservative Christian fundamentalist, gradually working my way toward being a more rational Episcopalian. [laughs] But coming out, I basically let go of Christianity altogether. I told my brother, who was a fundamentalist preacher at the time, that his God was just too small for me, and if I was going to survive, I had to find another community with a greater appreciation for the Creation's great diversity. ZIERLER: Was there anybody in a position of leadership at Caltech—division chairs, provost, president—who was a real source of support, that came out ahead of other people in supporting your decision at that point? SIEH: No. But neither did I ask for it. Perhaps mercifully for them, I didn't feel the need to talk to them. I suspect there are people that if I had gone to talk to them, they would have been supportive, even in the Division I suspect, but I didn't feel comfortable doing that. Actually, now that I think of it, there was one person at Caltech who actually did help me out – the GPS division administrator, Jean Grinols. ZIERLER: Oh yes, Jean! That's wonderful. SIEH: Jean became a good friend. ZIERLER: Oh, that's great. SIEH: She helped me a lot, although she did sometimes look at me askance when I told her about some of the crazy things I was doing in those early years of liberation. [laughs] ZIERLER: When did you know this about yourself, given that you were married? SIEH: I started becoming aware that my attractions and affections were toward other boys when I was about age ten. And before I married, I shared this with my fiancée when we were at Stanford. She was an undergraduate there, two and a half years younger. We talked about on a picnic one Sunday afternoon, after we were already engaged. I told her that I had these feelings, and asked her what she thought. Together we decided that the Holy Spirit would take care of it, and we can work it out. I'm grateful in retrospect that I had shared that with her before we ever got married, so there was no question of my being dishonest. ZIERLER: Did your family know, even from childhood? SIEH: No. No suspicion. I didn't have any of the stereotypical attributes that people commonly associate with being gay, so it was a total shock to everybody. People like me learn to hide our feelings very well. ZIERLER: Tell me about your family. They came from a conservative Christian background? SIEH: No, my father was adopted by first-generation German Americans in Iowa, and my mother was born to a family of third- to eighth-generation European immigrants in Iowa. We were raised, because of my paternal adopted grandmother, as nominal Christian Scientists, but kind of like Jack Mormons; Jack Christian Scientists. My parents dropped us off at Sunday school to please my grandmother, and that was it, but we were basically raised non-religious, even though we lived in the Bible Belt. ZIERLER: Where did you grow up? What was the town? SIEH: Cedar Rapids, a small city of about 100,000 people, until I was 12. My siblings and I spent quite a bit of our summers on my maternal grandparents dairy farm. Those summers we had were pretty important in my creative development, I think. Playing on the farm, you've got to put lots of different things together to make things work, and you've got to invent play. You don't have a swing set or whatever; so you to tie a rope to a tire to a tree, and then swing with it, and if the rope comes off, you break something. You find a corn cob on the ground, go into the crib and see a duck up in the rafters. You throw the corn cob at the duck, and the duck flies over your head and poops on your head. Hmm, didn't expect that! You've got to invent. To the degree that I'm creative, I think a lot of it comes from having spent large amounts of time in the summers of my single-digit years on the farm. Like Claire Patterson, the famous Caltech geochemist, who grew up on an Iowa farm not far from where my father's grandparents lived. ZIERLER: When it was time to go to college, were you already scientifically oriented? SIEH: Yeah, but I didn't realize it. I was taking a science track in high school – biology my sophomore year, chemistry my junior year, physics in my senior year, and math all the way through. I liked math. I liked chemistry. I liked physics to a lesser degree. I loved biology. But I felt I wanted to be involved in politics, so I wondered about becoming a lawyer. My dad said I'd be a great lawyer because I loved to argue. He said I'd be a horrible engineer, because I was too emotional. He was right about the emotional, but not about the other. As a young teenager, I was a Barry Goldwater Republican. My dad was basically an ultraconservative. [laughs] A member of the John Birch Society. He was an extraordinarily reactionary fellow, so, like father like son. Anyway it was my being gay that led me to becoming more open-minded and eventually spared me the fate of following in my father's political footsteps. ZIERLER: Going back to the narrative, was going to California for college an escape hatch for you to some degree? SIEH: More like the Ugly Duckling story, actually. My dad actually was a draftsman at Collins Radio in Cedar Rapids, and they moved us out when I was 12 to Newport Beach, so I was thrown in with a bunch of California surfer boys. But I continued evolving into a total nerd, totally closeted and confused. As they would say today, "Awwwk-ward!" thrown in with a bunch of cool surfer boys and girls at school. I was totally a fish out of water, which of course made me even more nerdy. The fellow who steered that nerdiness toward science was John Johnson, my high-school biology teacher in my sophomore year. He was an avid lepidopterist and an incredibly passionate and capable teacher. Later, after a a couple of quarters at UC Riverside I realized I was more interested in geology than in biology. Actually, I became a geology major the same week I converted to fundamentalist Christianity. I think in both I was after the same big-picture things: Power and immortality. [Laughs] When you become religious, when you're looking for God, you're searching for those two things. Looking back on that week, I think the same two things led me into geology. I took a class at the end of my freshman year and learned that geologists could tell stories going back billions of years. That's practically half of all time, so half of immortality! If I could go back and see—it wasn't known at the time, but—if I could go back and envision an impact crater in the Yucatan and tell that it is what extinguished the dinosaurs, it's like me being alive 65 million years ago. The way David Attenborough's recent film tells the part of this story that took place in North Dakota, based on my earth-science colleagues' work, makes you feel as if you were there watching the waves sweeping up the river and bury the dinosaurs there. Wow! And if you can forecast when or where an earthquake is going to happen or how big it will be, or when a volcano is going to erupt, that's power. I wouldn't have been able to articulate it back then, but by studying to be a geologist, I was climbing into the chair at the right hand of God! [laughs] Right? So I became a geology major and a fundamentalist Christian the same week in 1969, and they were avenues that served the same purpose. ZIERLER: And they both did a pretty good job of suppressing your sexual orientation, too, it seems like. SIEH: Oh, I don't think geology or religion had much of a role in that, but yeah. I was already totally suppressed. My becoming a fundamentalist I think saved my life, because there were two periods of my life where I was bordering on suicidal or actually suicidal. One was that time in my mid-30s, and the other was about when I was in my late teens-early twenties. That was my first time away from home, I was in a new environment, I had no idea who I was, where I was going, who my friends were going to be in life, what I was going to be in life and so on. It was a hard time. Going through that then has given me compassion for all sorts of young adults—male, female, straight, gay, whoever. I think the period from 18 to 24 years is the hardest time in many peoples' lives. You have only a nascent idea of who you are, where you're going to be, who your relationships will be, et cetera. Becoming a Christian late in my freshman year was really critical to keeping me alive because then I had community. I had people to pray with. I had a "blueprint" for survival, as we called the Bible in those days, during the early days of the Jesus movement. I'd say for a few years it basically gave me a foundation. It was built on a totally bogus foundation, but it served suitably for a few precarious years. And studying to become a geologist gave me the beginnings of a professional identity. ZIERLER: Was seismology on your radar at all as an undergraduate? SIEH: Not until my senior year. ZIERLER: What happened then? SIEH: Well, the San Fernando Earthquake shook me out of my bed in Riverside on February 9th, 1971, in the middle of my junior year, but understanding what had happened and what had caused it really didn't interest me at the time. Because of the Apollo mission's return of rocks from the Moon around that time, I was thinking more of becoming an igneous petrologist so I could study Moon rocks. But remember what I told you earlier about that GSA meeting in March 1971, a month later? That's when I first realized a geologist could study earthquakes by looking at the sediments cut by a fault. ZIERLER: Did that inform the kind of graduate programs you wanted to look at? SIEH: I didn't know of any graduate programs that focused on studying active processes, but I applied to Stanford because it was so close to the San Andreas Fault, so I thought it would somehow be the best bet for me. ZIERLER: Were there undergraduate professors who were really encouraging of you, telling you that you could apply to places like Stanford and get in? SIEH: Oh yeah, two of them in particular. Wilfred Elders was a significant influence during my UCR years. I took more classes with him than anybody else. He took me under his wing as his assistant one summer. Shawn Biehler, who has just recently passed away, was a geophysicist, a super enthusiastic, gregarious guy, always excited about his projects and life in general. He'd host parties at his home for us students, and although he was usually sloshed by the end of the evening, he was great to be around. Wilfred Elders was just the opposite, a total curmudgeon [laughs]. Those two guys I think more than anybody helped launch me into earth sciences. Elders through his teaching and leading me to the NSF SOS program and Biehler for being so passionate about the seismological work he was doing. ZIERLER: Did you think about Caltech for graduate school? SIEH: I did – for about ten seconds. I didn't apply because I didn't want to be in the smog any longer. In those days the smog in Pasadena was just as bad as in Riverside, and I had to get out of there. It was just awful. In hindsight, Caltech would have made a lot more sense! ZIERLER: Tell me about the geology program at Stanford. SIEH: There were two people besides the School of Earth Sciences dean, Dick Jahns, who eventually became my advisor. Doc had arrived in 1965 from Penn State and had created the Applied Earth Sciences Department. There was already Geophysics, Geology, and Petroleum Departments. Stanford was big into petroleum and mining. Geophysics was totally separate from geology, like it pretty much has always been at Caltech, except during the period of the Tectonic Observatory. I was in the geology program. In that program, two guys were assigned to co-advise me. Arvid Johnson was a rock mechanician, who used mathematics and physics to figure out how debris flows worked, how glaciers cut U-shaped valleys and how faults and folds formed. Bill Dickinson was using the sedimentary rocks of the Coast Ranges to figure out how California fit into the new plate-tectonics paradigm. Both those guys wanted me to be their grad student, and Johnson is the one who gave me the "Sell your ass" ultimatum. Dickinson suggested I work on a problem in the Santa Cruz Mountains. I just wasn't interested enough in these guys' research to climb on board. As I mentioned earlier, geologists at the time used to talk about overburden as being something that obscured what was really interesting. From my perspective, all that bedrock beneath the interesting young sediments was "dead rock." [laughs] I still use the term to tease my dead-rock geology colleagues. What's interesting about something that has been lying around for the last 40 million years? Well, actually, it turns out there's a lot of interesting stuff in those dead rocks, most of which we've learned in the past half-century or so. ZIERLER: I've often heard it said—probably you have, too—that plate tectonics passed by the Seismo Lab at Caltech. I wonder if that was the same at Stanford, or if looking back that was really an intellectual center for plate tectonics in its early days. SIEH: The formative centers for plate tectonics were mostly on the East Coast and at universities that had oceanographic research facilities – places like Lamont-Doherty Geological Observatory at Columbia University, MIT as well, in part via its Woods Hole Oceanographic Institution, and at Princeton. Those were three of the prominent pillars of early plate tectonics. Caltech missed the first boat out of the dock totally, largely because it didn't do research on boats. Stanford played a small, but key role – paleomagnetist Allan Cox and his colleagues at the nearby USGS figured out how to date the magnetic stripes on the ocean floors by correlating them to datable deposits on the continents. So, yeah, Caltech did miss the first boat. It had people who were interested in the details of igneous petrology and the details of seismograms. But it was right at the forefront of studying the lunar samples. In hindsight, it seems that Bob Sharp's unquestionably brilliant creation of a geochemistry/petrology group in the 1950s – Lee Silver, Harrison Brown, Gerry Wasserburg, Clair Patterson and Sam Epstein – may have been one indirect reason we missed the initial boat out of the plate-tectonic dock. We chose to focus on geochemistry, lunar petrology and later planetary science, rather than on the marine geophysics that played the pivotal role in the plate-tectonic paradigm shift. ZIERLER: Tell me about the field work at the San Andreas Fault. What was it like? What were you there to do? SIEH: As a grad student or as a professor? ZIERLER: As a graduate student at Stanford. SIEH: I used the$300 that Dick Jahns pulled out of a petroleum fund to fund my walking and bicycling along the south-central 350 km of the San Andreas Fault – from San Bernardino all the way to near Paso Robles, halfway between LA and San Francisco. This was the middle of summer of 1975, so it was like 100 degrees out most days. It was never below 85 and sometimes it was like 105, so it was miserable. [laughs] But I'd measure these little offsets of young channels and other landforms, five meters here, ten meters there, thirty meters here, twenty meters there. After every few weeks in that sweltering, dried out desert and steppe, I'd be so worn out, both physically and psychologically, that I'd drive back to Stanford and have my once-a-month meeting with my Doc. Eventually he'd told me my sketches weren't accurate enough and that he'd spend a few days with me to teach me how to make a properly surveyed map of a few of the best offsets. He came down with me for about five days and taught me how to make a map using a plane table and alidade — old tools of the surveying trade. You could survey in [laughs] maybe 200 points a day, and then you'd draw the contours by hand. Now, you can do 50,000 points in a second using today's laser-based instruments or satellite imagery, and the computer draws the contours for you in a few seconds. It's astonishing how much faster we can make observations these days. He and I made two or three maps, and after I'd made a few more the following Winter with the help of my brother and an undergrad frat brother of mine, I started working on a chapter about the offsets produced during the great southern California earthquake of 1857.

People already knew a lot about the 1906 earthquake, because it happened after the creation of geology departments at Berkeley and Stanford and the USGS and after a few seismographs and geodetic monuments had been installed in the State. We knew basically seismologically and geodetically what happened, that there had been a rupture of about 400 km of the San Andreas Fault, from down near San Juan Bautista up through Point Arena, and that it was accompanied by the "elastic rebound" of the adjacent crustal blocks. But all we knew about the 1857 earthquake were the historical records published in 1955 by the Seismo Lab's first director, Harry Wood. To compare the slippages in 1906 and 1857, I went back to the famous big thick volume on the 1906 earthquake, and I constructed a graph of slip along the fault from the ten or so places where measurements of offset fences and roads had been taken. And then I did the same with the 150 or measurements I'd made along the 1857 rupture farther south.

You might ask, why bother? Well, it was the just a few years after the plate tectonic revolution of the late ‘60s and early ‘70s, and so I wondered if these measurements, combined with the rate of plate motion, could be used to estimate how often these great fault ruptures might incrementally, seismically shift the plates past each other. If the recently determined rate of horizontal slip between the Pacific and North American Plates, about 60 mm/yr, and if the San Andreas Fault forms the plate boundary between them, then the recurrence of these great earthquakes would be their slip in 1857 and 1906 divided by 60 millimeters a year. Well the largest slips in 1857 and 1906 were about 10 meters and 5 meters, respectively, so these earthquake ruptures should happen about every 160 years in Southern California and every 80 years in Northern California. Whoa! It had already been 120 years since 1857 and 70 years since 1906, so were we due for the next great earthquakes? But looking at the details, the slips varied markedly along each rupture. How do you use the irregularities in slip within the plate-tectonic paradigm? Do later earthquakes fill in slip where they were low in the historical earthquakes. Or are these irregular slip functions characteristic, and the San Andreas not carry all of the plate motion?

Nearest L.A. and Palmdale, the 1857 offsets were about four meters, but up in the Carrizo Plain, they were more like ten meters. I wondered if earthquakes happened twice as often near L.A. than farther north. Well one way to figure that one out is to measure the slip rate at both locations. Another is by doing excavations to reveal sediments that would allow me to date ancient earthquakes.

So, for the slip rate story, I started looking for a place where I could determine the slip rate. I found this place halfway between L.A. and San Francisco, halfway between Caltech and Stanford, that had no name. I ended up naming it Wallace Creek, for the fellow who was one of my mentors at the USGS. It had a little 130-meter offset on it, a beautiful dogleg, first recognized way back in 1909 but not studied then. I started work on the landforms and stratigraphy of Wallace Creek during my PhD, but I didn't finish until several years after I'd arrived at Caltech. That involved interpreting the offset landforms and then hand- and machine-digging exposures of the key sediments. It turned out that the 130-m offset had accrued in about 3700 years, so the slip rate there is about 35 millimeters a year, surprisingly only about 70% of the plate rate. That was a strong clue that other faults also played a role in the slippage of the North American past the Pacific plate.

I also looked for a place to do the slip rate farther south, to see if the slip rate was slower. I came across a place called Pallett Creek, which also had a little 130-m dogleg in it. I guessed at the time that it would be about twice as old as the offset at Wallace Creek. I raced down there in my little Toyota, and found that the wall of the little canyon consisted of interbedded peats and gravels and sands. That made it a no-brainer to do radiocarbon dating. I grabbed a sample from the bottom of the canyon wall and another from right near the top, thinking that the radiocarbon lab would return a date of 10,000 years at the top, and 20,000 at the bottom.

Six months later, in early 1976 I got back dates of just 2000 years at the bottom and 200 at the top. That threw me for a loop for a few minutes. How can 130 meters accrue in just 200 years?" Well, it turns out it's not an offset. It turns out that as the stream flowed down toward the Mohave Desert, it hit a little bulge along the fault, which diverted the stream by 130 meters. I was looking for a slip rate site, but I instead ended up with a paleoseismic site. Accidentally. I got pretty excited realizing that if I could find the fault cutting through that 2000 years of peats and sands and silts, I could recover a history of ancient earthquakes. I couldn't see the fault because of all the slough off of the sandy banks, so I took a shovel and starting following one layer of peat along the canyon wall—ch ch ch ch ch ch ch—and toward the end of the day, I suddenly hit this break in the peat layer – the fault. Later, during the summer, I came down with my brother and my wife—he helped with the manual labor, she did the cooking—and we started making excavations. Still later, in the Autumn an undergraduate friend of mine came down with me to help survey new machine-dug trenches and string up grids to guide the mapping of the trench walls. That was the beginning – we ended up with an average interval between big earthquakes of about 160 years. It took another decade to refine it down to 130 years, with a very large coefficient of variation of 105 – one of the intervals was only 44 years long, and another was about 300. By the late ‘80s, then, the important question had become, why are the intervals so irregular?

ZIERLER: Before the term "paleoseismology" came into being, and it wasn't even you, did you recognize immediately that you had founded a new subfield?

SIEH: Yeah. I think it's important to call it that. It was a new way of looking at earthquakes. I had demonstrated that earthquake geologists, as we have come to be called, could extend the record of earthquakes back 1,000 years, 10,000 years or even further. But that subdiscipline didn't have a name, so I didn't know what to call myself.

Aren't I a seismologist if I study earthquakes, even if I don't use the records written by a seismograph, like Richter did or like Hiroo Kanamori and Don Helmberger were doing? But I was a geologist because I was using basic geological techniques. It was right about the time that GPS geodesy also started becoming a major tool for studying earthquakes, too. So weren't geodesists who studied the strain accumulating before and relieved during earthquakes also seismologists.

So I wondered if "seismologist" should be the overarching label for all of us. And since what Don and Hiroo were doing was look at the writings, the seismograms, perhaps they should be called seismographers, folks doing what I had started could be called earthquake geologists. After I shared this idea with some of my colleagues, one of them came back to tell me that Hiroo was pretty angry with me for suggesting that.

ZIERLER: Wow! What was the problem?

SIEH: I guess that the problem was that he felt it was insulting to call him a seismographer. I guess it sort of sounded like a stenographer, maybe. [laughs] Or a lithographer. It was totally benign on my part, but I said to myself, "Oh! Okay, that's not going to work." [laughs] Then Bob Wallace in a paper sometime in the mid 1980s solved the problem by suggesting that geologists studying earthquakes were paleoseismologists, so that's what we call ourselves now. Paleoseismologists are people who look at the record of ancient earthquakes going back tens or hundreds or thousands of years. Then some of we geologists also study the results of this incremental building of mountains, and we call ourselves neotectonicists – tectonicists who aren't interested in the dead rock tectonics; but rather are interested in slip rates on faults, how mountain ranges are currently being built, and so on. So, I became a neotectonicist and a paleoseismologist.

ZIERLER: After you defended, what opportunities were available to you?

SIEH: Actually, I failed my first PhD exam, because my committee didn't think what I was proposing was possible. At the time there was no place in the geological world for people who wanted to do what I wanted to do. It was a terrible experience at the time, but I'm kind of proud of it now, actually! I struggled because even at Stanford, I'd taken a class in fault mechanics from Amos Nur and I just didn't get it. I wasn't a very good mathematics student. I loved it, but I wasn't very good at it. It was the same with physics and chemistry. But I realized I was really good at synthesizing layers and landforms and structures and so on, and synthesizing these things is what a good geologist really has to be able to do. You have to have that ability to be a good observer and interpreter of complicated processes and events.

ZIERLER: What happened after you finally did successfully defend at Stanford?

SIEH: Actually, in the months before I defended, word got out to the media that I'd determined whether or not the "Big One" would soon hit L.A. I think it was George Alexander, the science writer at the L.A. Times, who first called me up and asked about it. In my first few years at Caltech, the story ended up being in TIME and Newsweek and National Geographic and on Nova and such. If I recall correctly, one of the writers for one of the local LA weeklies wrote that the first impression I gave him when I gave him a tour of Pallett Creek, shirtless in the summer heat, was that I looked like a Southern California"pool man." All of that was kind of fun.

ZIERLER: When did Caltech reach out to you?

SIEH: I arrived on July 5th, 1977. The AGU pumpkin-soup lunch with Barclay Kamb would have been in December of 1976.

ZIERLER: You were not on the market at all? They grabbed you before anyone else could?

SIEH: They grabbed me before anyone else realized the significance of what I'd done. I've realized over the years that the ability to quickly recognize talent is one of the great strengths of Caltech. I contrast that with what I saw in Singapore. I'm convinced that the only reason that I got that S$250 million from the Singaporean government to set up the EOS and ASE, was that I was a Caltech professor, publicly well-known, and a member of the National Academy. They didn't have to make their assessment of my accomplishments or promise from scratch, shall we say. What I mean to say is that when you're at a university where the professors and administration don't know how to judge quality directly, they rely on other peoples' opinions, as manifested in membership in academies, publication-citation numbers, dollars in grants brought in, and such. At Caltech, most faculty are right in the vanguard of their fields, and they know quality and potential when they see it. I'm being a bit hyperbolic here, of course. After all, Caltech did miss the plate-tectonics revolution. But a place like where I was in Singapore had difficulty recognizing talent directly. The way they did it is they looked and saw, "Oh, you're a member of the National Academy." "Oh, you're from Caltech." "Oh, you're from Harvard." "Oh, you're from Stanford." "Oh, you've written a lot of popular papers." Caltech doesn't rely on that. So in my case, it was the first and only university to recognize what I had done as being important. No other offers, except from the US Geological Survey, which had been closely following my work and realized I could fill a key role in their NEHRP mission. But I opted for Caltech, mostly because I'd be able to mentor future generations directly. ZIERLER: Wow. You came to Caltech as a married man? SIEH: Yeah, I got married the year before. My wife actually helped support us during my last year of grad school. ZIERLER: The beginning of your golden boy faculty appointment. SIEH: Yes, right. [laughs] ZIERLER: What was the game plan for your research when you got to Caltech, being at the Seismo Lab, being connected to all of the things that were happening? SIEH: Actually I wasn't in the Seismo Lab during my first 15 or so years at Caltech; I was a member of the Geology Option. I was only in the Seismo Lab from about 1992 until 2002. Most of my time I was in North Mudd, with geochemists and other geologists. But to get to your question: I initially spent most of my time wrapping up the things I'd started. I finished writing up five papers from my thesis work. Then I began expanding my paleoseismological and neotectonics work – like finishing the slip-rate study in the Carrizo Plain, improving the dating at Pallett Creek, looking for other sites where I could determine slip rates, finding a paleoseismic site down around Palm Springs, where Clarence had opined the fault might not even be active. I typically had anywhere from$200,000 to $500,000 a year to work with. With that, I supported a student or two and eventually a postdoc and so on. My first postdoc wasn't for ten years, and the first PhD I graduated was nine years later. By the way, Dave Jackson is the guy who suggested you talk to me, right? ZIERLER: That's right. SIEH: Dave has a reputation as a contrarian. I think he was a Caltech Seismo Lab PhD, and then he went to UCLA for the rest of his career. But right about 1975, while I was doing my thesis, the Palmdale bulge happened. A USGS geologist had discovered a large, 50-cm high geodetic bulge centered on the San Andreas Fault, a sort of kidney-shaped bulge. Dave later called into question whether the bulge was real or not. It was still a hot topic when I first arrived at Caltech, because some thought it might presage the next great seismic rupture of the San Andreas Fault. That was one of the reasons why people were so excited about my Pallett Creek result – it was right in the middle of the Palmdale bulge: "Oh, the recurrence interval is 160 years or so; wow, we're already 75% of the way to the next one." ZIERLER: When you joined Caltech, was it fully moved out of the old mansion? Was it already on campus? SIEH: When I went to see Clarence as a desperate Stanford graduate student, the Seismo Lab was still in the old mansion, practically autonomous from the rest of the GPS Division. That would have been in late 1974. By the time I got there in mid-1977, it was in the new building and struggling to stay as separate as possible from the rest of the Division. [Laughs] ZIERLER: Did you ever visit? Did you have a sense of what it was like there at all? SIEH: As I mentioned earlier, I went there to ask Clarence if he would take me as a grad student when I was failing at Stanford. That's the only time I ever saw it. ZIERLER: What were the big ideas at the Seismo Lab at that point when you joined the faculty? What were faculty excited about? SIEH: It seemed to me that each Seismo Lab faculty member was doing their own thing, and for the most part superbly. Each of them had "big ideas" that they were pursuing more-or-less independently, even though many of them interacted faithfully twice daily at morning and afternoon coffee. Clarence was the only geologist there, and he, concurrently with our French colleague, Paul Tapponnier, had been demonstrating that one could use the new Landsat satellite imagery to map active faults. That was the topic of his GSA Presidential address in 1975. Hiroo was doing really innovative work on earthquake sources, like inventing the moment-magnitude scale for large earthquakes and interpreting the seismic landslide that precipitated the eruption of Mt St Helens. Bernard Minster had just finished his work with former Caltech student Tom Jordan to refine the relative motions of the tectonic plates. Tom Ahrens was continuing his high-velocity impact experiments on the nature of meteorite impact cratering. USGS geophysicist and later Caltech professor, Tom Heaton, and Seismo Lab student Dave Wald had started to explore mapping the slip distribution of fault ruptures from seismograms. But the folks around me in North Mudd were mostly geochemists. Patterson was early in initiating pollution studies, using lead isotopes, the same element that he had used years earlier to determine the age of the Earth. Epstein was continuing his pioneering work on climate change via his use of hydrogen and carbon isotopes. And so on. ZIERLER: Interesting. SIEH: It seemed to me that most of the Division faculty were working, should I say, atomistically, bouncing off each other, but working more or less independently on important problems. The Lab was a tightly knit group of geophysicists who didn't encourage expansion of their realm into non-geophysical earthquake-relevant fields. Nonetheless, it was encouraging a few years after I arrived at Caltech that the Division hired Brad Hager, a geophysicist who expanded the Lab's earthquake studies into GPS geodesy. In any case, there was a great spirit among the geophysicists in terms of— ZIERLER: Community. SIEH: Community, yeah, right, but not in a scientifically integrated sense. There's a reason why the Southern California Earthquake Center ended up being headquartered at USC and not at Caltech. The Earthquake Center, initially under the leadership of seismologist Kei Aki, and later Dave Jackson and Tom Jordan, recognized that earthquake science, seismology sensu lato, if you will, was a lot bigger than the seismology being done in the Lab, and it was a lot bigger than geophysics. Seismo Lab leadership in the ‘70s, ‘80s, 90s and ‘00s was for the most part not receptive to that. The Seismo Lab wasn't really a seismological laboratory; it was a geophysical institute. They were basically a very talented and interactive group of geophysicists, seismological and otherwise. Actually, when it was running and then improving and expanding the network of Southern California seismograph stations, you could have said that part of it was a seismological observatory as well. ZIERLER: When you got tenure, was that a factor in the timing of when you decided to come out? SIEH: No. Let's see, when did I get tenure? I think I got tenure in—was it five years later that I became an associate professor?—yes, I think that happened in 1982. ZIERLER: Yeah. You were definitely tenured by the time you came out. SIEH: I came out in the years between 1984 and 1987, So no, there was no calculus there. I wasn't waiting for job security. I simply fell apart. [laughs] ZIERLER: Do you think you would have still had a job if you came out before you were tenured? SIEH: Yeah, I suspect so. ZIERLER: That's good to hear. SIEH: I don't think there was a pervasive anti-LGBT attitude at Caltech then. I say LGBT, because back then the Q, I and + had not yet been added [Laughs] ZIERLER: It was so rare. It was probably more people just didn't know how to respond. SIEH: I think people probably heard that I was gay and were just going, "Blrrrrr. What?" [laughs] ZIERLER: Did the process of coming out change your research at all? Did it make you feel liberated and more whole that opened up new research vistas? SIEH: Made me want to quit. Made me want to stop being a geologist, so I could focus on exploring this new world that I'd had no idea existed before. [Laughs] As an illustration of how clueless I was – one of my PhD students at the time was asked by another grad student "Do you think Kerry's gay." She replied "Well, if he is, he'll never know it!" Fortunately I had a couple of friends who advised me against quitting my day job, but I wanted to stop. I felt like I had discovered myself, actually, to borrow a Christian fundamentalist concept, I'd been "born again." I felt like I had realized something fundamentally much more important to me than being a geologist. Suddenly, what I was doing scientifically seemed dreadfully unimportant. I was thinking, "What will I do? Well, maybe I'll become a novelist." Duh duh duh duh duh. All these crazy imaginings, while I was making this major life transition. Very fortunately, early in the process I was put in touch with a wise fellow All Saints parishioner, the Rev Mel White, who subsequently became one of my best friends. He himself had just come out a few years earlier, after about 20 years in a heterosexual marriage. In addition to helping me stay alive, he suggested I give it ten years and not make a rash decision while I was finding my new footing. I spent an awful lot of time not doing much science in those first couple of years, just reading voraciously whatever I could get my hands on, figuring out how to be involved in the gay community, figuring out how to survive a divorce and that sort of thing. ZIERLER: What ultimately did you get back into, once you did re-embrace the research? You stayed in the field. SIEH: Good question. In 1989 I published one of the last papers I had on Pallett Creek in which we re-dated the sediments using new radiocarbon techniques. That finally got that story out of the way. Soon after I had come out, I started thinking about what else I should take aim at. In 1987 or 1988, I started thinking, "What else can I do? California is getting kind of boring." Tapponnier was teasing me that I had had blinders on all these years, focusing just on coastal California. I think I've described earlier how and why I got involved with paleoseismic work in Sumatra. I went to Sumatra first in 1990, then Taiwan at the turn of the millennium and then Myanmar a few years later. So, I got caught up in the neotectonic and paleoseismological wonders of Southeast and East Asia – and made lots of gay friends there in the process [laughs]. ZIERLER: Did the research in Sumatra plant a seed, do you think, for being more involved in Asian science later on? SIEH: For sure, but it was the second seed. My interest in Asian neotectonics and paleoseismology was kindled by Clarence, when he took me to southern China in 1981. We went on a six-week trip. My oldest daughter was two then, and my middle daughter was a couple months old. I went for six weeks to China and lived in the countryside and explored with Clarence and one of his grad students who was about my age, Alan Gillespie. We ended up publishing a paper in 1984 or 1985 with him as lead author on the Red River Fault, a big San Andreas-like strike slip fault that runs from eastern Tibet all the way down to Hanoi. That was my introduction to Asian neotectonics. I went back there in 1983 with my family, which at the time consisted of my two older kids and my pregnant wife, and we spent three months there, doing more work on the Red River Fault and living in communes and having a pretty eye-opening and enriching experience. My two little, blonde-haired kids were called "jin wa-wa," golden dolls, by some of the folks who saw us in the countryside. It was the first time they had seen any children that looked like them since before the revolution in the late ‘40s, so quite a new experience for them and for us. In fact it once led to a bit of a dangerous situation. A bit of a telephone-game gossip chain got going while we working in a little mountain valley and living in a commune there. Some of the minority-nationality people who populated the valley thought we and our Han Chinese colleagues were actually excavating ancient treasure at our paleoseismic site, and someone must have said they'd actually seen us with two "jin wa-wa." One night some villagers actually confronted our translator and threatened to harm us if we and our colleagues took their golden figurines out of the valley and back to Beijing! Fortunately our translator succeeded in convincing them that we were not digging up golden figurines. It was about that time that I realized I couldn't get what I wanted from the San Andreas Fault. I mentioned the irregularity in timing that I found at Pallett Creek, 44-year to 300-year recurrence intervals. The question then was, well, why is the pattern so irregular? Is it because there's something fundamentally stochastic about the nucleation of great earthquakes? Or is it because the Garlock Fault moves during a big earthquake and changes the stress regime on the San Andreas and therefore it triggers an advance or a delay in the next one? I was coming to realize that there was no way I could answer this in my own lifetime or even in my students' lifetimes, and so I started looking elsewhere. Wasserburg and Larry Richards' invention of precise Uranium-Thorium disequilibrium dating of corals steered me to the tropics, which led to Sumatra. I might just as well have picked the west coast of South America if it had had islands offshore right above its subduction zone. ZIERLER: What was the big research objective in Sumatra? What were you looking at? SIEH: What I proposed for myself in 1989 was to find a fault in the tropics that is almost perfectly planar, like a rectangle, and that dominates the regional tectonics, so that its behavior was unlikely to be affected by a bunch of other nearby faults. It seemed to me that paleoseismic work on such a fault would avoid the three problems inherent to the San Andreas Fault – imprecise dates, a long time to collect relevant stratigraphic data, and the complex, shattered-glass neotectonic plate boundary it runs through. Radiocarbon dates on San Andreas paleoseismic sites are so imprecise that dates for the 1906 rupture near San Francisco for the 1857 rupture near LA would overlap, for example, suggesting a 1000-km long mega-rupture up and down almost the entirety of California. U-Th dating of corals would solve that problem, so I looked for a place where the fault was very simple and a place where there were islands above the fault, so when it ruptured, the islands rose a meter or so and the corals rose above the water and died. One big plus I didn't bargain for was that the corals' annual growth bands would also give me what I came to call "paleogeodetic" stories, showing us the strain that accumulates between earthquakes. Between earthquakes, the islands sink at a centimeter or so per year and the corals keep growing upward to find the new sea surface. So, I went to Sumatra because it seemed like the best place in the world to answer the question of, "Why are earthquakes along the San Andreas Fault, or any fault for that matter, irregular, and why don't they happen like clockwork?" So, a rather simple idea. Not surprisingly, because the idea was a bit wild, I couldn't get NSF funding for it until after I'd first done a scouting mission, funded by$20,000 graciously given to me by a group of Caltech Associates, who'd I'd lectured to on a cruise around the Mediterranean.

ZIERLER: Going to Sumatra made you think more deeply about the San Andreas Fault?

SIEH: Oh, yeah, in the sense that the data I collected from the corals assisted we earthquake scientists in figuring out why faults behave with varying degrees of regularly and irregularly. For one, we now realize that you inherently can't know precisely where and when a fault is going to nucleate and start a great earthquake. But we can discover decadal to centennial patterns that tell us important things for reliable, useful long-term forecasting of big earthquakes.

In Sumatra we found that each few-hundred-km-long section of the megathrust has its own distinctive behavior. The Mentawai section south of the Equator, which several of my PhD students focused on, experiences what we call "supercycles," that is centuries of quiescence, followed by a flurry of great seismic ruptures over a few decades to a century. Just a bit farther north, straddling the Equator, is a short section that clearly slips during smaller earthquakes but also in large part aseismically. Still farther north is a long section that the corals tell us ruptures in nearly identical earthquakes several centuries apart. Still farther north, offshore Aceh Province, along the section that produced the giant earthquake and tsunami of 2004, we found corals that recorded two great ruptures about 50 years apart, during the early Ming Dynasty. Following that lead, we then discovered abundant geo-archeological evidence for coastal communities being wiped out by the tsunamis they generated, as happened along the same coast in 2004.

Our paleoseismic, paleogeodetic and geodetic data from Sumatra are much more robust than the data we have for the San Andreas fault. That's partly because we could complete the investigation of one site in a matter of a couple months to a year or so, whereas on the San Andreas Fault. one site would take a decade or longer. We didn't have to dig big holes in the desert and spend years studying it archeological-style. Instead, we snorkeled around a reef and found several generations of coral, we made a map of them, then cut slabs from them with a chainsaw, x-rayed the slabs, counted and traced the annual rings revealed by the x-ray, and interpreted what sea level has done over the lives of the corals. Most commonly, we saw a coral sinking during the decades to centuries between earthquakes and then popping up suddenly during a large earthquake. This was a lot more fun than sweltering in the desert, and it's about two orders of magnitude faster. Since the data are so much more abundant and precise, my sense is that our Sumatran work has been more influential in the advancement of earthquake theory and hazard assessment than our work on the San Andreas Fault.

ZIERLER: Going back to this idea that you never sought to be a role model, when you were elected to the National Academy in 1999, even though it wasn't something that you sought, was it something that was foisted upon you to some degree?

SIEH: [Laughs] I don't think many of us would feel burdened by being elected to the Academy. Like a lot of people who get something done in life, I had quite an inferiority complex, so my election was helpful my lifting that burden [laughs]. After all, at Caltech, it's not hard to feel inferior! There're a lot of very smart people around you. When I was elected, it was totally out of the blue, totally a surprise, and I was very happy about it. But actually, the most important professional consequence of my being elected the NAS is that it helped Singapore decide to gamble on hiring me to create the Observatory and the School.

ZIERLER: To bring it back to what we were talking about earlier in our conversation, the sense of—futility is not the right word, but recognition that the research that you were after was not something that you would accomplish, your students, or your grand-students—if you could just explain, why the magnitude? Why the time scale of this problem, that it could not be resolved in the short term?

SIEH: If you watch a documentary program about the development of an archeological site, they will commonly interview a lead archeologist who has been working on a particular site for a decade or two decades, right? It's commonly their life's work or at least a large part of it. To develop a site like Pallett Creek, it took me from 1975 when I discovered it, until 1989, when I finally wrapped it up. Part of that is because of technological advances not occurring until the 1980s, but part of it was just that archeological-style excavations take a lot of time to do right. It took basically three full summers to just dig it all up, and then years more to get all the samples properly dated and manuscripts written up and published. It was a matter of logistics. And that was just for one of the sites that would need to be studied along the fault and on neighboring faults. On this score, I have to say that I've always been a bit envious of seismologists and geodesists, because their field area is usually manned by instruments and their data streamed onto their computer screen. Once their community builds a seismic network and hands it off for technicians to maintain and improve, they can just sit back and call in the data they want. Sometimes I assuage my feelings of inferiority by telling myself that we field-oriented scientists just have to spend a lot more time getting our basic data. Oh well!

ZIERLER: Even though you had this sense, you were not looking to leave Caltech? You were recruited out of the blue, essentially?

SIEH: At the time, no, I wasn't looking for a change of professional venue. But – I don't think I've never told anybody this except my wife—in my first I would say ten years at Caltech, I was actively looking for another place to go to. I wanted to leave. I wanted to be part of a community of earthquake geeks that was less siloed, a place that was more interested in an integrated approach to studying earthquakes, and with a critical mass of people who were competent in stratigraphy and geomorphology. But of course that was a bit of a fool's errand in the ‘70s and ‘80s, because there really wasn't such a place. When the opportunity came along to create a broad community of earthquake scientists, first with the Southern California Earthquake Center in the early ‘90s and then with the Tectonic Observatory in the early ‘00s, I climbed on board and felt better being at Caltech. Finally, when the opportunity to create a geohazards community from scratch came along in 2008, I thought, "Well, this is good." [laughs] By that time, seismologists, geodesists, geologists and engineers were commonly working together under the broad umbrella of earthquake science.

But there was another reason why building a multi-disciplinary geohazards hub in Southeast Asia was a thrill – there's so much to investigate and so few people doing it. Here's an illustration of that: Take the magnitude 6 Napa Earthquake in 2014. It happened in October of that year, as I recall. By the time of the AGU meeting in mid-December, there were already 57 abstracts for talks about that earthquake, so there were already 57 people or groups working on that little magnitude 6. In Sumatra, there has been one magnitude 9-plus, four magnitude 8-pluses, about 30 magnitude 7-pluses, about 150 magnitude 6-pluses, and the great majority of those earthquakes have had nobody publish an abstract or or paper about them. You could have a magnitude six, like the one a few days ago—and I'll bet you dollars to donuts that nobody will publish a paper on it.

There's a lot going on in Southeast Asia, and the fields of earthquake science, volcanology, flood hazards, and climate change are just wide open—it's like my ancestors coming over with the Puritans and the Pilgrims to what became Massachusetts or my Mennonite ancestors arriving in Pennsylvania and thinking, "Wow, there's a whole empty continent for us here. [laughs] There's a million places we can cut down the forests and make our farms, whereas in England or in Southern Germany it's awfully crowded." In their case, of course, they more than decimated the indigenous communities there after they landed there. Not so with our landing in Southeast Asia. Rather, the EOS and ASE have become a hub to help them build on their own geohazards education and research – witness former Helmberger post-doc, now EOS/ASE professor, Shengji Wei, who has helped his Indonesian and Myanmar colleagues install seismic arrays and conduct research on their own turf. Anyway, California, the US and Europe have a crowdedness to them in Earth sciences that makes it harder to find a scientific problem of first-order importance. Southeast Asia is just an open field. There are primary questions that nobody is even thinking about addressing, whereas here in the West, it's mostly the tertiary Earth Science problems that people are working on.

ZIERLER: What was your sense of what it would be like to be gay living in Singapore? Did you have a good sense one way or the other?

SIEH: You're asking questions I never anticipated you would ask. Yeah, it was a big deal. They offered this grant, and I still had to decide whether to accept it. I decided during one of my later trips over there, after it had been announced that EOS was going to be funded. They of course assumed I'd come, but I had this partner who I had been with since 2003, and Singapore was not exactly renowned for being very gay-friendly. So during a conversation with the university provost, who was a Swede and had just moved to Singapore, I said, "I can't do this unless my partner and I feel welcome." He says something like, "Oh my god, you're gay? Oh, that's fantastic! When I was president of the Karolinska Institute in Sweden, I had a Black lesbian woman; I solved three problems all in the same person!" [laughs]

ZIERLER: [laughs] My goodness.

ZIERLER: That's true for a variety of reasons all over the world.

SIEH: Yes. Incidentally, the only flak we got in Singapore was before we arrived, from a few gay activists, who complained, and understandably so, that it was easy for us to be openly gay and for my partner to find work here, but that wasn't, and still isn't true for most expats. And yes, I think Singapore became a little bit more closed and more homophobic in the 10 or 12 years we were there. [Actually the government took their anti-gay law off the books just after this interview, but in deference to the more conservative citizenry, stated that they would change their constitution to make it clear that marriage as only for straight citizens]

ZIERLER: What do you see as your key achievements directing the Observatory?

SIEH: Creating it and its academic partner, the Asian School of the Environment. My vision was to establish a research organization and a school that, for the first time in Singapore and in Southeast focuses on geohazards. I'm happy that I left it in good enough shape that it will continue on, hopefully as I said before, as a centennial institution.

ZIERLER: Did you keep up with the Seismo Lab at all while you were in Singapore, or were you sort of happy to leave that behind?

SIEH: Actually, I had already moved out of the Seismo Lab and back into North Mudd, about when the Tectonics Observatory was funded in 2002. I never really felt like I was a welcome part of the Seismo Lab. Don Anderson was pretty antagonistic to expanding the Seismo Lab beyond geophysics, so it had taken more than a decade after my arrival at Caltech to be allowed to have an office there.

Then, at about the turn of the millennium, GPS Chairman Ed Stolper had the idea that five of us could put together a multi-disciplinary proposal to secure some of the $600 million grant that the Gordon and Betty Moore Foundation had just given Caltech. We wrote a proposal for$60 million—Mike Gurnis, Mark Simons, Brian Wernicke, Joann Stock, and myself. Mike's a renowned whole-earth geodynamicist, Mark specializes in GPS geodesy, Brian is primarily a "deadrock" geologist, but had been starting to use GPS to understand active deformation in Nevada. And Joann is in both the geological and geophysical realm, working on plate-tectonic and tectonic problems. Turns out we weren't a very compatible group. [laughs] I think we drove Ed nuts, but the proposal ended up being written and then funded at a level of about \$28 million. But then we had a hard time deciding what one or two big, interdisciplinary projects to work on together. I proposed using a small part of it to begin to create a small Sumatran GPS array (SuGAr) in above the Sumatran megathrust, to answer some key questions that the neotectonic and paleo work had raised. Brian wanted to strengthen his GPS array across Nevada and establish a GPS array and neotectonics work in Iran. But the geophysicists were keen on working in Mexico and Chile. In the end, Ed appointed Ken Farley as Director of the TO, and that helped to start breaking the logjam. I hated his doing it at the time, but he said to me quite a while later that he hoped we were still friends. [laughs] We are. In hindsight, I think he made the only practical choice he could have made. Even so, none of us were able to herd each other to our favored focus areas, so we had quite a dilemma on our hands. [laughs] Ken solved it administratively, by parceling the funds out in support of a variety of worthwhile, stand-alone projects, rather than a single integrated one. We prima donnas just didn't want to work under anyone else. But at least it was a move in the right direction – toward an institution that had geodetic, seismological, and earthquake geological projects under one roof. When Ken became Division Chairman, Jean-Philippe Avouac became TO Director. He's a very broadly based earth scientist and was able to steer us into a somewhat more integrated direction. In fact the most productive collaborative work I've done has been with Jean-Philippe during the time of the TO. We really made hay by combining our geological, geodetic and mechanical data and talents in Sumatra, in the aftermath of the great earthquake sequence of 2004-2009. I was sorry to hear from him a few years ago that there wasn't enough support within the TO to search successfully for continued funding after the ten-year grant ended.

ZIERLER: When you retired, what were the options in terms of where to return to? Did you think about becoming an expat and staying in Singapore?

SIEH: I wanted to apply for Singapore citizenship until about 2012, when I started realizing the stifling top-down nature of the place and that its gay-friendliness was declining. I started realizing that we'd be better off having American passports than Singaporean ones. Better to stay an American. There's not as much money here, but there's much more room for diversity among its citizenry, and for creative endeavors and such. Even so, it never appealed to me to return to Caltech.

ZIERLER: You wanted to be retired at that point, to be unbound from all of the responsibilities?

SIEH: No it wasn't that, really. I just wanted to have time to explore some new directions. I resigned as Director of EOS a little over year before my contract was up because the University had made it nearly impossible to move EOS farther in the directions I had been aiming at. Doesn't this commonly happen in all sorts of new, creative enterprises? You start something bold and new, and it starts to become apparent that, hey, this is turning out pretty well. So the powers-that-be decide they'd better tighten their control over it. [laughs] Late in my tenure as director, I had a meeting with the provost – the post was held by a Singaporean by then – and had planned to give him a sense of what I had been feeling of late, by telling him the famous phrase "Death by a thousand cuts." I started by saying "Freddy, in English we have a phrase that explains what I've been experiencing …" But before I could get the phrase out of my mouth, he grinned and said "Death by a thousand cuts." He knew that that was, indeed, pretty much what he'd been doing to me over the previous few years.

I'm proud to say that at the university and within the government, EOS was considered the most successful of the five new research centers. And so it was a good time to leave, because I no longer had the kind of influence I needed to continue moving in the direction I wanted the EOS to go. Hiring new faculty and high-level staff had became very difficult. Paperwork had become much more burdensome and so on.

Also, Kemp had gone back to the US in 2017, and we were finding that our long-distance relationship was fraying a bit. So I returned to the US a year early, in early 2020, right before the Covid pandemic struck, luckily.

ZIERLER: Now that we've worked right up to the present, we've circled back from the beginning of our talk, I think I'd like to ask two overall questions to wrap things up, one technical and one social. On the technical side, what do you see as the long-range legacy of the development of paleoseismology? How has it influenced the larger field and where is it headed from here?

SIEH: Paleoseismology has become an integral part of earthquake science and of earthquake hazard mitigation. But it's always going to be a fairly small subdiscipline, I think. Young people are still being trained in the fundamentals of stratigraphy and geomorphology, but with a view more toward environmental work. Smartly, many young earth scientists are going into climate science these days. This sort of evolution of fields is a constant in science, right? We and earthquake geodesy were the sharp, new observational end of the wedge to create earthquake science as the multi-disciplinary field of earthquake science – together, paleoseismology, paleogeodesy, earthquake geodesy, neotectonics, fault mechanics, and seismology, sensu stricto. I think that's our legacy.

There will always be people trying to figure out what the history of their particular active fault is. For that matter, the same thing with volcanology. Volcanologists need to know the history of their volcano so they can diagnose the disease. You need to know whether a fault in the Mojave Desert moves every 10,000 years or whether it moves every 200. It will continue to be logistically harder to do that than it is to look at a squiggle or a deformation time series that comes in on your computer screen from the international array of instruments. But I think we earthquake geologists will continue to extend the length of the story for active faults.

I think those of us who work as neotectonicists, we will continue to play the role of putting seismographically determined focal mechanisms into their tectonic context. For example, the reason the M7.6 earthquake struck central Taiwan in 1999 is that the island is squeezing tectonically and its principal mountain range is thrusting over its western plain at a rate of so many mm/yr. We'll continue to figure out on which active tectonic zones future earthquakes occur because we see ancient fault scarps at the base of the mountain range and so on. So, we'll keep providing the geological context for the earthquake geodesists, source seismologists, fault mechanics, and earthquake engineers. That's probably the best sentence to sum it up with.

ZIERLER: Listening to your life story, I know that being a role model is not something that you've ever sought, but just hearing the challenges that you've had to overcome and you superimpose that on the science you were able to accomplish in addition to the administrative success in Singapore, what do you think are some of the life lessons for younger people in the field who will ultimately read this transcript? What do you want to convey about overcoming challenges in order to succeed about the things you're passionate about?

SIEH: In the midst of the turmoil of coming out in the mid-80's, I was fortunate to hear Bill Moyers' interviews of Joseph Campbell, who at the time was in his mid-80s. When Moyers posed a similar question to him he replied, "Follow your bliss." That has turned out to have been the route to happiness, fulfillment, and significance in both my personal and my professional life. So figure out what your passions are, and then try your damnedest to explore where they lead. Hopefully along the way you'll come across people, living or not, who inspire you to continue. Am I dodging your question?

ZIERLER: I don't think so. It's a scientific answer to the question. I do appreciate that.

SIEH: I guess if I have any regret about the paths I chose to become myself, it's that at times I was too scared or insecure to explore. I guess another obvious thing to offer is to look at my decision to leave Caltech and start something new in Southeast Asia via Singapore—look for opportunities. [laughs] I couldn't have made that opportunity; I was simply the right fellow at the right place at the right time and when the opportunity arose, and I went for it. But I don't know; I guess I consider myself to be an explorer, both socially and intellectually and scientifically, and explorers always figure out a way to do something, with the means they have at hand, or they die trying.

ZIERLER: On that note, this has been a wonderful conversation. Thank you so much for sharing with me, for being so honest. It's a terrific historical record. Thank you so much.

[END]