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Jeanne Hardebeck

Jeanne Hardebeck

Research Geophysicist

By David Zierler, Director of the Caltech Heritage Project

August 3, 2022

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It's Wednesday, August 3rd, 2022. I'm very happy to be here with Dr. Jeanne Hardebeck. Jeanne, it's very nice to be with you. Thank you so much for joining me.

JEANNE HARDEBECK: Sure, it's my pleasure, thanks.

ZIERLER: Jeanne, to start, would you please tell me your title and institutional affiliation?

HARDEBECK: I'm a Research Geophysicist at the US Geological Survey, located in Moffett Field, California.

ZIERLER: Now, the designation "geophysics" or a "geophysicist," are there seismologists with that title at the Survey, or that's sort of the umbrella term under which seismologists work?

HARDEBECK: Yeah, that's the umbrella term under which seismologists work. I don't think there's anybody who's officially a research seismologist. I think we're all called research geophysicists, along with people who do other sorts of geophysical work.

ZIERLER: Now, as your academic specialty, would "seismologist" be the best way to describe what you work on?

HARDEBECK: Yeah, seismology.

ZIERLER: Just as a snapshot in time, what are you currently working on?

HARDEBECK: I'm currently working on aftershock forecasting. The USGS has a fairly new product that we put out after magnitude 5 and greater earthquakes in the US that we put out a forecast of how many aftershocks we're expecting. What's the probability of a large aftershock that might be felt or might be damaging? I'm working on some applied science in terms of getting that done, and also some more basic research in trying to understand the triggering of aftershocks by main shocks.

ZIERLER: Jeanne, for you personally and institutionally at the Survey, what are the feelings about the prospects of earthquake prediction?

HARDEBECK: [laugh] We mostly don't even say that word. I think the focus is really more on probabilistic forecasting. Rather than sort of a deterministic an earthquake of this size will happen here at this time, more trying to say this is a probability of an earthquake in a certain size range, in a certain area over a certain timeframe. That's everything from the aftershock forecast that my group is putting out are framed like that. It's just the probability of aftershocks of various sizes. For the very short-term aftershock forecasts through to the USGS puts out these national seismic hazard maps, which are basically the probability of shaking at various levels over a 30- or 50-year period. That's really what we're focused on operationally, and it's also I think how the scientists feel that it's not really our goal at the moment to try to be predicting earthquakes. We're taking a longer more circuitous route towards [laugh] something like that by trying to understand better the physics of what's happening to try to get a better handle on if we can say things about the probabilities of earthquakes, and to understand better when an earthquake happens what the probability at various levels of ground motion that then we can communicate with engineers who are worried about building buildings.

ZIERLER: Jeanne, as I've come to appreciate, there's two ways of looking at the problem. As you say, determinism is so far off at this point in terms of being able to accurately predict. To what extent is that about we're simply not there yet in terms of the technology, the tools that we would need, and to what extent is it about it's just not possible because earthquakes are fundamentally unpredictable?

HARDEBECK: My personal feeling on this is that whether or not an earthquake happens in a specific location at a specific time is going to be highly controlled by the state of the Earth at that location that will have been at the fault. How much stress is on it? Are there fluids there? What pressure are those fluids at? Have there been earthquakes nearby in the past that have loaded this up? Is there a little crack there because 100,000 years ago, this was part of something? I think you would have to have that level of information about every location in the Earth at these depths that we mostly can't get to at all. There's a few very deep boreholes for study, but we would have to have that level of information everywhere, I think, to be able to really deterministically say, "OK, now this part of this fault is ready to fail, and it's likely to trigger further failure on this fault, and produce an earthquake of that size." My feeling is that probably just the detail of information you'd need to do something deterministic is probably outside of what we realistically are going to be able to do.

ZIERLER: Do ever, or do, like, in the foreseeable future? Are those not meaningful distinctions as far as you're concerned?

HARDEBECK: I think in the foreseeable future. Like, I can't foresee that we would really have the technology to scan the Earth with the level of detail that we would need, and know the history of it to the level of detail that we need. But, that said, we are being able to image this stuff in better and better detail as the data improves, as data processing improves, as computational speeds improve. I think understanding this stuff a lot better, and I think that can help us narrow down this probabilistic statements that we make. But it certainly doesn't seem in the foreseeable future to me that we're going to be able to do any sort of real deterministic prediction.

ZIERLER: Jeanne, some overall questions on your focus on aftershocks. First, a little bit of a history of the subfield. How far back does this particular line of inquiry go?

HARDEBECK: Oh, gosh, it goes more than 100 years into the past. There's this concept of Omori decay of aftershocks. I can't remember the years of this, but Omori was a Japanese scientist working on an earthquake sequence in Japan that's, I think, in like the 1890s or something [1891 Nobi earthquake], and was starting to be able to see what—at first, you have a lot of aftershocks, and then the rate of aftershocks decreases with time. He started to be able to see that. You can go back now and look at that place in Japan, and see that aftershocks are still going on, and the aftershock sequence is still going on, and those rate of aftershocks still decaying. People have certainly been thinking about aftershocks, and trying to understand aftershocks for over 100 years, which is a long time in seismology. If you think about it, Richter's working like in the '30s and stuff. This really goes back to the beginnings of seismology. Aftershocks are kind of your most predictable earthquakes. If you're looking for predictability, you know you have a main shock. You know what's going to happen is you're going to have aftershocks. It's certainly something that people have been interested in for a long time. There's theories about what triggers aftershocks, and they're mostly around changes in stress from the main shock. But those theories look like they're probably a good first order explanation as to what's happening, but they're obviously not fully developed, and they're not able to take into account yet a lot of this information about, sure, you have a stress change from the main shock, but that's superimposed on what? Are these faults ready to fail? Then maybe you'll figure in a lot of aftershocks that these faults aren't ready to fail, maybe you don't, and kind of that understanding of how all those things interact, I think, is something that we're still working on, and still needs a lot of work.

ZIERLER: Jeanne, for a field of inquiry that's a century old, what are some of the modern technological advances that make this a vibrant field today, that allow you to do new science that wasn't possible before?

HARDEBECK: Digital recordings, I think, are one of the key things. Starting at least in California in the '80s, we have really good digital records. We have a lot more information about aftershocks. Then sort of maybe around in the '90s or 2000s, people started keeping continuous data. Up to that point, all the data's coming in, and they just snip out, "Oh, here's an earthquake. We'll snip it out, and we'll save this, and we'll just throw away all this junk in between." But then starting in sort of the '90s and 2000s, people are like, "OK, we have enough. Computer technology has improved to the point where we can just save all of this stuff." Now there are techniques where you can run through all of this data. By matching, like, if you have some earthquake signals, then you can run through, just to correlate with everything. You can find these small earthquakes hidden in the noise because you can match them with the template of these other earthquakes. You can pull out tons more aftershocks than you used to be able to. Even when I was at Caltech in the '90s, we had just those aftershocks that some analyst had picked out for us to look at. But now people run these codes, and you can find 10 times as many aftershocks when you run these codes as you do just with the initial network analysts looking for aftershocks. Now we have an order of magnitude or more aftershocks to look at now than we did in the past. We just have really tons more information now.

ZIERLER: Jeanne, you mentioned theory. What have been some advances in the theoretical world that provide guidance to the data?

HARDEBECK: I think sort of the biggest steps in theory have really been looking at how stress changes might work. Particularly, there's two kinds of stress changes. What we call static stress change, which is the earthquake happens, it stresses everything, there's a change in stress, and that's baked in. There's also dynamic stresses as the seismic waves come through, and they shake everything. Those sort of short-term stresses as everything is getting shook can also trigger earthquakes. There's been a lot of developments in understanding how both of those, well, theoretical developments in understanding how both of those should work, particularly the static stress triggering. There's also been a really important thing that actually came out of USGS is this idea of rate and state friction on faults, and that if you have a fault, the friction is the force holding it together. It depends on how fast things are moving, and it also depends on the history of that fault. This is something from lab work that's been developed, how that friction works. That's been combined then with theoretically how the static stress changes and dynamic stress changes work to get a theory of when a stress is applied to a fault system, how many earthquakes are you expecting? What's the timing of those earthquakes you're expecting? That's turning out to be a pretty powerful combination of those two bits of work, kind of this theory and this lab work that's actually one of the best models and one of the most sophisticated models we have currently of when and where aftershocks are going to occur after a main shock.

ZIERLER: Jeanne, an overall question, a counterfactual question in light of your decision to pursue a career at the USGS as a federal employee. If we can imagine a scale where on one end is a professor with more or less total intellectual freedom to pursue the kind of research that they want to do, and on the other a federal employee, a bureaucratic functionary, if you will—

HARDEBECK: [laugh]

ZIERLER: —whose entire work is defined by the agency, by the taxpayer dollar, where are you on that scale in terms of the kind of research you want to do, the kind of research you're able to do?

HARDEBECK: I feel like I probably have as much academic freedom as a professor does because a professor, to do their work, writes a proposal; sends it to NSF or whatever. They get a yes or no; they fund it or not. I basically go through the same process internally at USGS. Every year, I write a proposal to say, "This is what I want to do this year. This is how it's going to help us understand earthquakes. This is going to help us try to work towards reducing earthquake risk in the US." I get told yes or no, I can do that. My parameters I'm working in is I need to justify to the higher-ups in the USGS, who of course then have to eventually justify that to taxpayers, why the work I'm doing is actually going to be helpful to mitigating earthquake hazards someday. It doesn't have to be immediate. It's not like this year. But this is part of this research that we need to do to get to the point where we can do something to mitigate earthquake hazard. As long as I work in that framework, if one day I decide I'm suddenly really interested in the inner core, and I have no way of relating that to earthquake hazards, then they're probably going to say no. But as long as I'm working within this framework of earthquake hazard, they've never told me, "No, don't work on that."

ZIERLER: Essentially, in an alternate life, had you pursued an academic path, it's totally conceivable that you'd be doing more or less exactly what you're doing right now?

HARDEBECK: Yeah, I think it's possible. Part of how I ended up at USGS, of course, is because studying seismology, I've always been very interested in not just the science of why this is happening but the real-world implications of it. I don't think as a professor I would've one day decided to work on the inner core, but I guess that's possible, and I could have. I know that my friends who are faculty members, sometimes it seems like their interests are driven sometimes by the students as well. I don't know what students I would've interacted with, and what they would've been interested in. It's possible I could've gone in another direction. But I feel like at the Survey, I'm working on the stuff I want to work on, and it's both interesting and, hopefully, someday [laugh], actually contributes to making us safer from earthquake.

ZIERLER: Now, in terms of the funding structure and process, to the extent that there's always some element of drama for professors—will they get funded, will they not get funded?—do you have that uncertainty as well?

HARDEBECK: I think not as much. The professors always have their salary, or at least they always have their nine months of salary. What they're concerned about is are they going to be able to fund students, postdocs? Are they going to have money for a lab if they need a lab or whatever? We have those same kind of questions here. We don't have students, but we do have postdocs, and we do have to go through a process to get funding for those postdocs. If we have big operational expenses, we do have a process to go through to get funded. I think it feels maybe a little bit more stable than the situation of a faculty member of having all your hopes hanging on whether some proposal gets funded this year. I think things are maybe a little bit more stable; that there's a little more understanding of the importance of having some number of postdocs at any one time, and the importance of sustained funding for various projects. We have some of the same problems but I think less of maybe the drama; the ups and downs.

ZIERLER: Jeanne, what about teaching and mentorship? If you wanted to, do you have opportunity to teach undergraduates, take on graduate students, things like that?

HARDEBECK: Yeah, people here do do that. It's usually done by becoming an adjunct faculty at a university. That's if you want students. There's a lot of mentorship opportunities for postdocs, and that's what I've mainly done is mentor postdocs at USGS.

ZIERLER: Jeanne, you mentioned or you indicate that there's sort of future hopes in aftershocks and earthquake hazard. What are the timescales that you're working with? What's that goal end date where we'll have this, and what exactly does that look like?

HARDEBECK: I don't think there's one big goal with a big end date. I think it's more of a process. We have what we currently do in terms of telling people what to expect in terms of aftershocks. I think it's more of how can we improve what people are telling us? Currently, a lot of what we're telling people is just based on the statistics of prior aftershock sequences. The range of behavior of prior aftershock sequences is pretty broad, so we're telling people, "You could get 10 aftershocks or you could get 1,000 aftershocks." We want to be able to narrow that down a bit, and get people more precise but still accurate information. I think that's what it's going to be. It's going to be this winnowing down through time. I'm hoping that on a kind of 10-ish year timescale that maybe we'll get that from a couple orders of magnitude to just one order of magnitude, and feel good about that. [laugh] Then maybe in another 10 years, we can get something smaller than that. I don't know. But it's not like a single big goal that we're trying to get to.

ZIERLER: Whatever the timeline looks like, I wonder if you can walk me through the all-important goal of minimizing damage to property, mitigating loss of life? What does it look like when these systems, when this science is mature? What will that mean when an earthquake happens?

HARDEBECK: I think for the aftershock forecasts, what that means is that the information is accurate and precise enough that people can make decisions about, "Should I be in this building or not? If I shouldn't be in this building, when can I come back?" There's going to be decisions about, "Should we close this bridge? When should we reopen it?" We know that aftershocks are more likely in a particular location than others, so there's going to be decisions about, "Where are we going to position fire trucks? Where are we going to position ambulances? Where are we going to put the Red Cross shelter?" That sort of decision is, I think, the sort of decision that we can support with an aftershock forecast that can impact response and recovery and resilience of a community that's just experienced this big earthquake.

ZIERLER: Thinking about buildings and bridges, to what extent does this work get you involved in the whole world of earthquake engineering?

HARDEBECK: I don't interact with that world very much. I think this is actually a problem for seismology in general that there is this, I think, a big culture gap actually between the seismologists and the civil engineers. I think people have been working on bridging that gap. Certainly, USGS has some engineers and some kind of engineering seismology people who bridge that gap. Southern California Earthquake Center has been doing a pretty good job too in trying to bridge that gap. But I think that's a really important gap that we need to keep working to really bridge. I don't personally interact with a lot of engineers.

ZIERLER: Jeanne, besides the Survey itself, what are the scientific societies that are most important for your research, from the AGU, the Seismological Society? What's most important to you beyond the Survey?

HARDEBECK: I think certainly AGU and SSA and the Southern California Earthquake Center, all of those have been really important. Then there's some more international meetings. There's an International Statistical Seismology meeting that happens every two years. That's another really important meeting.

ZIERLER: Internationally, are there seismological or geophysical government agencies that you interface with? In other words, is there the USGS of Mexico or France or what have you?

HARDEBECK: Yeah, most countries have a similar agency. With forecasting, it's usually considered bad form to forecast earthquakes in other people's countries.

ZIERLER: [laugh]

HARDEBECK: [laugh] We don't do much of that unless we're requested by a country. If it's part of an international response to a big earthquake, sometimes we'll do that. But it's more that we interact with our counterparts in different countries who are also working to implement the same sort of forecast in their country that we're working on in the US. There's certainly a community there of scientists, particularly people in—New Zealand and Italy are two countries that are both, I would say, with us or ahead of us in terms of the aftershock forecasting. We have some really important interactions with colleagues in those countries.

ZIERLER: Jeanne, if you'll indulge me, in two years, major awards for you: the Richter Award in 2006; the Macelwane Award in 2007. What were you doing that was resonating so strongly that was recognized as—

HARDEBECK: [laugh]

ZIERLER: —so important in the field at that time?

HARDEBECK: I've been working on aftershock triggering for a while, and I think I had a paper in grad school that is one of those papers that's still cited a lot about aftershock forecasting. I'd also been working on trying to understand the level of stress in the crust, which is a really hard thing to measure. To measure it directly, you have to drill one of these multimillion dollar boreholes. I've been developing some methods to try to pull out information about stress from the earthquake information that we already have. That was also work I started at Caltech, and I think that work's been kind of controversial. If you have a sample of rock in a lab, and you measure how strong it is, it has a certain strength. When I've gone and done studies of what I think the strength of real rock in the real Earth's crust is, it comes up about an order of magnitude lower than that. That was pretty controversial at first, I think. But I think it really got people talking about this, talking about how do we really measure this in the real Earth? Can we just extrapolate these lab measurements? We don't understand a lot of other conditions in the real Earth that affect this like pressure. I think that work really got people thinking and talking, even if a lot of them got there from being very skeptical of my results. I think, in the end, a lot of people have repeated what I've done for different earthquakes, different data sets, stuff like that, and gotten fairly similar results of sort of low stress in the crust that I did. I think that made a bit of a splash in the field, and I think got me noticed as an early career scientist.

ZIERLER: Jeanne, generally, if you can talk about locality versus extrapolation, where your research is really focused on a particular time and place, and when it can be generalized to understand what happens at a planetary level.

HARDEBECK: I'm trying to do work that's general. But we have the earthquakes we have. You can't design an experiment. [laugh]

ZIERLER: [laugh]

HARDEBECK: You have the earthquakes that you have. I try and hope that the stuff I'm doing is relevant outside of the locations where I work. I use a lot of data from California because we have great data here, especially including all that data from the Southern California Network that USGS and Caltech run together. California's a great place to work because we have earthquakes. We have a lot of data. There's also really fantastic data in Japan. Fortunately, seismology is a field where people are very open about data sharing. There's tons of data just out there on the web that you can download from Japan and other countries. There's just fantastic amounts of data to work with in various places. I think myself and a lot of other people do tend to work a lot in those locations. But, certainly, the hope is that what we learn working in those locations is relevant elsewhere; that if we look in the subduction zone in Japan in detail, that that's also relevant to the process in subduction zones in other places in the world.

ZIERLER: Well, Jeanne, let's now go back prior to your time at Caltech. When you were at Cornell as an undergrad, was seismology and geophysics, was that on your radar at all? Was that what you wanted to pursue afterwards?

HARDEBECK: [laugh] No. I'm going to take my history back actually a little bit before Cornell to explain how I ended up—

ZIERLER: Please.

HARDEBECK: —[laugh] at Caltech in seismology. I grew up in Bishop, California. Do you know? Are you familiar with Bishop?


HARDEBECK: Do you know where the Caltech Owens Valley Radio Observatory—

ZIERLER: Sure, yeah.

HARDEBECK: —yeah, so, up on the eastern side of the Sierras. My dad worked there as a member of professional staff.

ZIERLER: Oh, wow.

HARDEBECK: He was a Caltech employee.

ZIERLER: What years was he there?

HARDEBECK: He was there from probably about 1970…so he worked on campus I think maybe from '70 to '72, and then he worked up at the Owens Valley Radio Observatory. I think he retired probably around 2000, something like that.

ZIERLER: What was his area? What did he work on?

HARDEBECK: He's both an astronomer and an electrical engineer. He did design and maintenance and upkeep of a lot of their electrical equipment. They have people coming through to observe all the time, but he was a permanent staff member there who was basically designing and implementing their equipment, and helping people who are observing troubleshoot with the equipment, and stuff like that. That's out in the middle of nowhere [laugh], specifically out in the middle of nowhere so there's not much radio interference. That's where I grew up. I grew up up there. I grew up, first of all, with a familiarity with Caltech because my dad worked for Caltech. As a family, we would drive down to Pasadena maybe twice a year to visit people on campus. As a small child, I hung around in the lily ponds looking for turtles and stuff. [laugh] I have a fondness for the Caltech campus, going back a long time. But the Owens Valley is a very seismically and volcanologically active area. I experienced a number of pretty sizeable earthquakes while I lived there. The Mammoth Mountain volcano goes through these, you know, when it's going to erupt? Is it not going to erupt? There's evidence of pretty recent eruptions, I think, in like 300–400 years ago or something in that area. There's really tons of like very geologically and geophysically interesting stuff up there, and so I grew up kind of interested in this stuff but also, at the same time, having no idea that you could like make a career out of it.

ZIERLER: [laugh]

HARDEBECK: I went to college thinking I was going to do a real kind of make a career out of it thing, and I was going to major in computer science because it's clear that the computer industry is going places, and I want to be part of that, and that's going to make a career. That's what I was thinking when I was at Cornell was kind of focused on a career in computer science. That's how I arrived at Cornell. It took me a while at Cornell to even find that a geology department is a thing, and I can go over there, and I can take some classes, and this is actually a lot more interesting than computer science. I didn't realize I was interested in earth science early enough to change majors, so I went through, and I finished a computer science major, and I even sort of tried to work at a tech start-up for a year. Then that just wasn't working for me, and it's not really what I wanted to do, and I wanted to see if I could just change course and do geoscience.

ZIERLER: Did you do any geoscience at Cornell?

HARDEBECK: Yeah, I did. I took some classes. I did take a geophysics class, I don't know, structural geology class, like, some intro maybe mineralogy. I took probably, I don't even know, like maybe five or six—maybe not that—maybe three or four geoscience classes while I was at Cornell. They were great. It was really fascinating stuff, and it just completely sucked me in. Then it had that resonance too with where I had grown up, and being interested in the earthquakes and volcanoes and stuff around where I grew up. It all just sort of was really interesting, and it really resonated, and I wanted to do that. [laugh]

ZIERLER: Now, was Caltech the be all and end all for graduate school? Did you apply more widely? Would you have gone anywhere?

HARDEBECK: Caltech was my top choice, particularly once I'd really decided I wanted to do seismology. The Caltech Seismo Lab is [laugh], in my view, really the top place to do seismology, so that is where I wanted to go. I definitely applied for some other programs. There's definitely some other great seismology programs out there, and I would've gone to any number of other really good seismology programs. But I really wanted to go to Caltech, and I really saw it as the top seismology program, and I was really amazed and excited that I got in.

ZIERLER: What was the game plan for you? How well formed were your ideas about the kind of research you would want to pursue in graduate school?

HARDEBECK: I think it maybe wasn't that well-formed at that point. I think at that point, knowing that I wanted to do seismology was where I was, and I wanted to do studies of earthquakes. Seismology is kind of two fields. One is trying to understand earthquakes, and the other is using those earthquake waves to image the structure of the Earth. I knew I was really interested in the let's understand more about earthquakes. The more I learned that we don't really understand all that much about earthquakes, the more drawn I was to try to understand more about earthquakes. I think that's where I was. I knew I wanted to work on some projects to try to better understand physically what's going on with earthquakes. That wasn't a game plan at all. That was a general field of interest.

ZIERLER: Jeanne, coming in the early mid-1990s, what was your sense once you got comfortable in the Seismo Lab, what were the big debates? What were people working on? What was sort of the frontier of the field at that point?

HARDEBECK: The frontier that I jumped in on was this stress triggering business. That was a fairly new field in the early '90s, a lot of it actually coming out of USGS here. I felt excitement about it, the possibility of using it to forecast. There had just been the 1992 Landers earthquake, which was this big earthquake east of LA. There was a lot of data. There was a lot of triggering from the earthquake, so it was kind of this type earthquake that people are using to develop these theories about triggering, and not everybody believed it at that point. I feel like I started working on this stuff, and I did feel like I had to defend what I was working on. We always have to defend what we're working on, but I really [laugh] had to defend what I was working on. I felt like that was pretty exciting. Let's see. What else was going on? There were definitely some debates about various earthquake prediction methods, but everybody at Caltech just thought they were bologna, so I don't think there was a lot of debate within the people in the Seismo Lab about that. Let's see. What else were people really excited about? I think there was also a lot of excitement, I think, about trying to understand the role of fluids in faulting. You talked to Emily. She probably talked to you a lot about that. Her work was really pretty exciting, but I think there were some other folks who were really excited about that kind of stuff. Let's see. What else were people excited about? I'm blanking a little bit here. I guess some of it will come back to me.

ZIERLER: Jeanne, what was the process of determining who your thesis advisor would be?

HARDEBECK: When I was accepted to Caltech, Egill Hauksson called me on the phone, and asked me if I wanted to work for him, and I said yes. [laugh]

ZIERLER: That's how it happened, as easy as that?

HARDEBECK: It was that easy, yeah. I knew that Egill was in charge of the Southern California Seismic Network at the time, and also doing a lot of research. He and Hiroo Kanamori were really doing the sort of research I was interested in, the most interested in, and trying to understand physically what's going on with earthquakes. Egill called me up, and asked if I wanted to work for him. We would set it up so Hiroo Kanamori was my co-advisor. He was also my advisor. That just sounded perfect, so yes [laugh], and it was decided that easily.

ZIERLER: Coming in with a computer science background, do you think part of you getting snapped up so quickly was that you had computational skills that could be immediately put to good use?

HARDEBECK: I don't know how much difference my degree made because I think some of the other grad students also had—and it's not like everybody had a geophysics degree or a geology degree. I think a lot of the other grad students, even if they didn't have computer science degrees, I think, had a lot of programming skills. I don't know that I particularly stood out as somebody with a particular amount of programming skills. I think I was just sort of a match based on interests. When you apply to grad school, you write an essay about what you're interested in doing, and I think my interests really matched Egill's interest.

ZIERLER: Now, Egill and Hiroo, were they working together, or was this sort of a separate advisee relationship?

HARDEBECK: They definitely did work together. I don't think they have a lot of co-authored publications, but they definitely always struck me as sort of friendly people who worked together. They co-advised me on the same project. It wasn't like I was doing one project with Egill, and one project with Hiroo. They were sort of co-advising me on one project. I would usually meet with each of them individually. I would meet with Egill—I don't know—weekly or something, and I would meet with Hiroo less frequently.

ZIERLER: Tell me about Egill's project, and how far along it was developed when you joined?

HARDEBECK: He started working on this business of trying to understand stress in the crust using lots of small earthquakes. The basic idea is you have tons of small earthquakes, and each of those moved in response to stress. Maybe you can't get much information out of one of them, but with this whole big data set, you can say what was the stress that was driving all of these earthquakes. He had done some work on that in LA Basin, some of these earthquake areas like where the Landers earthquake had occurred, and the idea was to really just do a big all of Southern California look at the stress field. That's sort of how developed that was when I started, and I did end up doing that. We got sort of sidetracked in some other things that I think turned out to be more interesting. But that was the big-picture idea, and that sounded interesting to me. Egill also had another grad student working with him, Julie Norris, who got started on the aftershock triggering. That interested me too, so they pulled me in on that project as well. That's how I got interested in the aftershock triggering.

ZIERLER: What were some of the goals of the project? We talked earlier about the long-term hopes of where the science might take us. How early on in the process, how provisional was the research conceptualized at that point?

HARDEBECK: It's pretty basic research. Stress in the crust is what's driving earthquakes. If we don't [laugh] know what that stress is, how do we ever build any more models on top of that? It's meant to be this very basic foundational piece of information that any kind of physical model of earthquake generation should need to know what the stress field is. It's very basic; not very applied at all. But I think pretty good PhD project because all the data's there. The methodology has been developed. Egill had already done some of these smaller-scale areas. He had already studied one of these smaller-scale areas. It was a good project, and it was something that was clearly doable, would have a clear result, and that result would be useful for other people. I think it was a pretty well thought out project.

ZIERLER: Jeanne, did any of this involve fieldwork, or it was all data coming into the lab?

HARDEBECK: I didn't do any fieldwork at all. This was all based on the Southern California Seismic Network data.

ZIERLER: What were some of the technical challenges in making sense of the data?

HARDEBECK: Technical challenges? I feel like the challenges weren't so much technical as conceptual, I think. One of the things that was sort of, I think, most interesting about understanding stress is trying to understand the stress that's projected onto individual faults like the San Andreas Fault. I think, for me, I was like, OK, yeah, I'm going to make a big map of California, of Southern California that's going to have the stress. But I really want to know is what is the stress on the San Andreas. How conceptually do I go from I'm just going to make this big map, to how am I really going to understand what's the stress right there on the San Andreas? I think that that was the best paper that came out of everything we did for my thesis, was turning it around and saying, "We're going to do this as a very fault-based thing. We're going to look at the San Andreas. What's the stress right at the San Andreas? How does the stress change as you go away from the San Andreas?" We actually find that the stress does change. There's sort of a big regional stress field for Southern California. But as you get into the San Andreas Fault, that stress changes. It rotates to put more stress on the San Andreas than you would've thought if you looked at the far field stress. I think that not so much a technological challenge but just like the challenge of what's the right way to think about this data, and deciding that maybe the right way to think about this data is to think about what's important. The San Andreas Fault is important, so let's think about this from the point of view of the San Andreas Fault.

ZIERLER: Now, the work that you were doing with Hiroo, was that related at all or that was separate?

HARDEBECK: He was advising me on the same project. I was getting advice both Egill and Hiroo on that same project.

ZIERLER: Where was there overlap in their advice, and where were there differences, just based on their own areas of expertise?

HARDEBECK: I think they both just had ideas like, "Try this. Try that. Try this." I'd talk to one of them, and I'd come back to my office with a big list of things to try. I'd go talk to the other, and I'd come back with another big list of things to try. I think it was great. It was very, I think, complementary to get twice as many things [laugh] to try.

ZIERLER: What worked ultimately? When did you know you had enough to complete the project?

HARDEBECK: I think when I discovered that there really was a signature of the San Andreas Fault there in the stress data, that felt to me like, yeah, I actually discovered something. We actually got it published in Science, so it did feel like we had really discovered something. That's I think the point that made me feel like this is a good project. We discovered something. Maybe I can actually do science, because I had kind of—obviously with help from Egill and Hiroo—but I had been the one driving this. Let's look at this from a San Andreas perspective. That's I think the point where I felt like I can do this research stuff. Like, I came up with an idea. I figured out how to implement it. I got a result out of it. That result was actually interesting enough that people were interested. Got it published in Science. A lot of people argued with me; got a lot of people's interest. That's I think where I got pulled in feeling like I did something here that people are interested in. I can do this. This was a good thesis project.

ZIERLER: Jeanne, more of a social and cultural question to historicize the atmosphere of the Seismo Lab in the 1990s. Of course, decades earlier, the Seismo Lab was definitely a boys' club. Did that feel like ancient history when you were a graduate student, or were there still vestiges of that?

HARDEBECK: I don't recall any sort of like boys' club feeling. There was only one female professor: Joann Stock. Definitely women were underrepresented, and it was very white also. There were definitely vestiges of the days when it would've been all white men—and Hiroo, I guess. [laugh]

ZIERLER: Now, the underrepresentation, was that true for graduate students as well? Who else was there? There's you, Emily. Any other women graduate students at that point?

HARDEBECK: Yeah, there were quite a few actually. It was maybe about a third women, I think. Within the grad students, it was pretty comfortable. There were quite a few women, and I think that helped with sort of the atmosphere of being a sort of more inclusive atmosphere. But certainly then when we looked at the professors, and we saw only Joann, it was clear that [laugh] there was still a problem. I don't know. There's definitely more female faculty now in the division.

ZIERLER: Absolutely.

HARDEBECK: But I don't know what fraction it's up to at this point.

ZIERLER: Better, it's better. [laugh]

HARDEBECK: Better, yeah [laugh], things are getting better.

ZIERLER: [laugh]

HARDEBECK: Things are definitely getting better. But there were other weird things. Like, the grad students all had our offices on the third floor in South Mudd, so that third floor just had faculty and grad student offices. I guess when they built the building, they didn't think there would be any women up there, so there was no women's room. There was only a men's room. Basically, every time I had to use the women's room, I had to go downstairs to the second floor—there's one there near the admin office where I guess they thought the women would be—and trek back upstairs. But I came back a couple years after I graduated, and they'd actually changed that into a women's room.

ZIERLER: Now that's progress.

HARDEBECK: It is, yeah.

ZIERLER: [laugh]

HARDEBECK: [laugh]

ZIERLER: Jeanne, it's going to sound like a long time ago also, but tell me about computers and the internet when you were in graduate school. What seemed really primitive in retrospect? What seemed cutting edge at the time?

HARDEBECK: My first maybe three years or something, I didn't have my own computer. That seems really primitive now. I have four computers in this office right now, so there is that. [laugh]

ZIERLER: [laugh]

HARDEBECK: We had a student computer lab, and it was kind of first-come, first-served. There were not quite enough computers. Those first couple of years, I ended up working, like, sometimes I would work like all night because that's when computers would be available. It was really fantastic when maybe my fourth year or something like that, we put in a proposal. One of Egill's proposal included a computer for me, and we got it, and I had my own computer on my desk. That was a fantastic day. It was pretty primitive. [laugh]

ZIERLER: What about the databases, the way that you would access the data? Was anything analog still at that point?

HARDEBECK: The data I was using was all digital from the network. I think the network was probably pretty cutting edge for its time. They had a lot of data, and it was pretty easy to access. They wrote their own little codes that you could use to access their data that worked pretty well. That was pretty good. There was still a lot. Everything before the '80s, I think, was analog. I didn't use that data but other people did, and I know that some of the grad students had to go through this thing of, like, hand-scanning these old paper records and stuff. [laugh] That didn't seem appealing. The internet was I think pretty difficult at that time too. There were certainly search engines, but I don't think there were any very good search engines for scholarly articles. There wasn't anything like Google Scholar that we have now where you can just find articles. We would have to go to the library, and I think the library computer had a system where you could search for articles on various topics, and it was like really, really slow. I remember spending long times just sitting in front of this terminal at the library, trying to find papers on some subject. I think that was slow. I think also one of the really fantastic things that's happened with the internet is when you're trying to research a subject, you find a paper that you're interested in, and they have a reference list. That gives you a clue where to go. You find the references. You find those papers. You look at their references. You find those papers. You can go backwards in time really well when you've found a paper that's interesting, but you can't go forwards in time from that paper. Now, we have, with Google Scholar and stuff, now you can go forwards in time. You say, oh, this is a great paper. Who cited this paper? Then you can find all those papers, and you can go forward in time as well. I think that sort of stuff I think has been really fantastic for research because I think that was one of the hardest things during grad school was finding all of the literature that you needed to find. The data was easier than the literature search, I guess.

ZIERLER: Jeanne, you've probably heard the same stories as me. In the days of Frank Press and Benioff that the Seismo Lab was this intellectual magnet where senior people would come and spend time and give talks and things like that. Do you recall that still being the case? That it was a place that people at other institutions wanted to visit or even needed to visit because of what was happening there?

HARDEBECK: Yeah, certainly a lot of visitors came through. At the time, I think I thought that was normal that you have this constant stream of visitors. Nowhere else I've been since has had quite that constant stream of visitors. I think it was still seen as an important place. Another thing I think to mention when you talk about the high-powered people coming through to talk, I think one of the great things about the Seismo Lab was the extent to which the grad students really got incorporated in all the conversations. People will probably talk to you about coffee hour where, twice a day, everybody goes into the coffee room, and sits around and talks about science. You have all of these really big-name people there. You have Hiroo Kanamori, you have Don Anderson, and all of these big-name people sitting around talking. The grad students are just sitting around in a circle with them, fully participating in the conversations. Grad students bring their work to show off. Sometimes, somebody will ask you, a grad student, a question because you're the expert on something. When there would be visitors, the visitors would participate in these coffees hours and so you, as a grad student, got to interact. You'd fully interact with these visitors at coffee hour and stuff. I think that was really a great aspect of the Seismo Lab is that coffee hour, and the amount of interaction and how non-hierarchical it was.

ZIERLER: Just freely like free ideas flowing from one person to the next?


ZIERLER: Jeanne, you mentioned the conceptual challenges of the project. With that in mind, when did you know you were ready to present this, defend it as a complete project?

HARDEBECK: I guess I had to defend it a bunch of times. [laugh]

ZIERLER: [laugh]

HARDEBECK: The way a lot of stuff would work there is that you'd be working on something. You'd show it to your advisor. Then you'd take it to coffee hour, and you'd show it to everybody at coffee hour. They would be very challenging. The atmosphere at Caltech is certainly that if you're going to say something, you need to be ready to defend it. The professors and other grad students would challenge you there at coffee hour, and you'd start to understand maybe what are the things you haven't fully thought through. What are the things you need to do to better defend what you're trying to say? What are things that you tell somebody, and they just don't even understand, so you need to figure out how to go back and explain that better? I think I had a lot of opportunities to explain what I was doing at various stages; get a lot of feedback; get familiar with what the arguments against it were going to be. Then you take it out, and you present it at a scientific meeting, or you get invited to give a seminar at another institution. Then you have another round of maybe skepticism and questions and challenges, and you figure out how to respond to all of that. I think once I'd shown my work and defended it to various audiences, and understood what are all the possible challenges here, what are all of the weaknesses, and how do I fix those weaknesses, and once I felt that I'd heard all that, and I'd fixed everything, and I still had something that worked, and I still had a good result, and it stood up to all of the challenges that people had thought of, then I'm like, yeah, OK, this is solid. This is done.

ZIERLER: You mentioned before that this research was really fundamental. You were not thinking yet about—

HARDEBECK: [laugh]

ZIERLER: —societal applications, mitigating risk, and things like that. How, looking back, would you translate that fundamental work to getting closer to something that actually helps people in an earthquake situation?

HARDEBECK: I think where I hope that that sort of information about stress gets used is in physical models of earthquake interaction, and physical models of earthquake rupture. Those are both developing fields as well. I think it's been a challenge to get people working in those fields to use the stress information that we have from observations. Modeling of the dynamics of an earthquake rupture seems to have a lot of difficulties, a lot of choices that have to be made, a lot of assumptions, and it seems to be difficult to just have somebody hand you a data set, and you just swap out what you were using, and swap something back in, and expect it to still all work. [laugh] I think there's been a little bit of hesitation on the part of the people who do that dynamic rupture modeling to really use the information that we have about stress. I'm close colleagues with some people who do that kind of work, and we talk about it, and they want to incorporate this information, but maybe their modeling isn't quite to the point where they can. Their modeling needs them to have a constant stress date. When I tell them, "No, the stress state varies a lot. Maybe that doesn't work anymore," they need to have a particular stress state even to propagate the rupture, and maybe the stress state I'm telling them, "No, this is the real stress in the Earth, as far as we can tell," that a rupture doesn't even propagate. There's still all these mysteries and stuff. It's not as straightforward as I think I had hoped; that we could just hand off the stress information to people who are doing physical models, and that would improve the model. I think there's a long way to go in both fields, both determining the stress and taking that stress and using it in physical models. I think we maybe need to be talking to each other more to make sure that we're actually giving them something they can actually use.

ZIERLER: Jeanne, besides your two advisors, who else was on your thesis committee?

HARDEBECK: Tom Heaton. He's very, very interested in stress. He has a lot of ideas. We'd had some disagreements, but he's a good guy. He was a lot of fun to have on the committee. Joann Stock was on my committee, and there must've been one other person. Mike Gurnis was also on my committee.

ZIERLER: Anything memorable from the oral defense? Any discussions or questions?

HARDEBECK: [laugh] Knowing that group of people, I went in with the feeling that if I could get them talking amongst themselves, I could just stand there, and let that happen—and that definitely did happen a few times. They asked me questions, and then they felt like they needed to respond to each other's questions, and I could just stand there and listen to this discussion for a while. That was fun and interesting. Everybody was very engaged. It went well. They didn't leave me out in the hall too long afterwards. [laugh]

ZIERLER: What would you say in that moment, when you really have to summarize your thesis, what your principal conclusions or contributions were at that point?

HARDEBECK: I think my principal contribution was saying that it looked to me like the level of stress in Southern California was much lower than people had thought, based on lab experiments, and that the San Andreas was not as unusual of a fault as people seemed to think at the time. I think those were the big takeaways of the time.

ZIERLER: Now, even before you defended, just a question on the timing. Was your postdoc at Scripps already in place at that point?

HARDEBECK: Yeah, I think I went pretty quickly between the defense and moving to San Diego. I defended in 2000, but I think it was in the summer. I guess I had just missed the graduation, so I graduated the next year. Like, I marched in 2001, even though I had finished at Caltech in 2000, and defended in 2000, and moved to Scripps.

ZIERLER: Tell me about Scripps. Why was that attractive to you for your postdoc?

HARDEBECK: Two things: one was to work with Peter Shearer, who is just an all-round really smart guy. The other is I was in an office with a view of the beach. [laugh]

ZIERLER: That's pretty good.

HARDEBECK: Yeah. I really liked San Diego. I thought it would be a great place to live for a while. I learned a lot working with Peter. He does both earthquake seismology and global or structure seismology. While I was there, his other postdocs and students were mostly working on these global seismology projects. I didn't work on a global seismology project, but I was there in enough meetings with them, and talking to them about their projects and stuff that I learned a lot more about global seismology than I had known before that.

ZIERLER: Institutionally, what were some of the things that were really different that were happening at Scripps, compared to just coming from Caltech?

HARDEBECK: Scripps, I think, it's physically separate from most of UC San Diego, and it felt more like an independent research institution. Caltech, the Seismo Lab always felt like part of a bigger campus, and it seemed like there would be more interaction with people from physics and engineering departments and stuff. Whereas at Scripps, there were no undergrad students, I mean, not like there's tons of undergrad students at Caltech but there were like no undergrad students there. I didn't feel like we had a lot of interaction with the rest of campus. It felt like its own little isolated research institution. I think, maybe culturally, it had a little bit more of the top-down, here's a professor and all the people who work for them. Whereas I always felt like Seismo Lab had a very flat feel to it. Like, all of the grad students would be working with different professors, but we would still all get together a lot. We would get together for everybody to practice their thesis defense, so you got to help somebody prep for their thesis defense that worked for different professors and stuff. Whereas I feel like at Scripps, it did get more like I'm in Peter Shearer's group, and here are the other people in Peter Shearer's group. I think I knew less about what was going on with some of the other professors, and the postdocs that worked for them.

ZIERLER: What was Peter's main research at that point?

HARDEBECK: He'd done a lot of global seismology, and he was just getting into regional seismology of Southern California. He was working a lot on improving ways to locate earthquakes. This is something that happened with having more digital data, and having more computer power and stuff. He was coming up with these ways to take all of Southern California, and every earthquake that happened in Southern California in the last 40 years, and relocating each of those earthquakes, and observing those structures and stuff. He was doing a lot of that. He and I were working on focal mechanisms, which is the orientation of slip of the earthquakes. He wanted to do that in that big data kind of way too, that he wanted to take all of Southern California, and process all of it to get focal mechanisms. In the end of that project, we had locations and focal mechanisms for I don't know how many tens of thousands of earthquakes in Southern California.

ZIERLER: What aspects of your research at Scripps, would you say, is an extrapolation or an extension of what you were doing at Caltech, and what was brand new?

HARDEBECK: I think a lot of it was new. A lot of it was a step backwards because when I was doing my research at Caltech, a lot of it was using the focal mechanisms, and the focal mechanisms were determined using a method that had been around for a while. While I was doing my thesis work, sometimes, I would look at some of these mechanisms, and question their quality. With Peter, what we wanted to do is we wanted to go back and say these mechanisms are really important basic data that a lot of stuff is built on; not just the stress stuff, but a lot of trying to understand seismo tectonics is built on these focal mechanisms. How reliable are they, and can we do a better job at it? That's basically what we were doing while I was at Scripps, and coming up with a new method for estimating the focal mechanisms that did a lot better quality control than prior methods, and then chugging through all of the data of Southern California, and using that method. Our methods, a lot of people are using now, it's the default that Southern California Seismic Network puts out mechanisms, and they're using our new method for that. I think that postdoc, we ended up having a lot bigger impact on the basic data that goes into a lot of stuff.

ZIERLER: Jeanne, when it was time to enter the job market, was the Survey really where you wanted to be? Were there other opportunities you were considering? What did that look like at the time?

HARDEBECK: I did really want to work at the Survey. When I was doing my work at Caltech, and particularly on stress triggering, a lot of the really important work in that field was going on at USGS, so that really put USGS on my radar as a good place to do research.

ZIERLER: Would you go across the street? Did you have interface with USGS while you were at the Seismo Lab?

HARDEBECK: Yeah. A lot of the USGS people would come across to go to coffee hour and seminars and stuff. Most of the stress triggering work was happening in the Menlo Park office up here in the Bay Area. That was one of my places that I really wanted to go was USGS in Menlo Park, which is where I went. Now, we're in Moffett Field, but we're still at the Menlo Park office. That was somewhere I was really excited about going. I considered some faculty jobs, and I did apply for some faculty jobs. I think I was afraid of spreading myself too thin in faculty job of having to do a good job at research and a good job at teaching. I felt like pursuing a job where I could just focus on the research really felt good to me at the time. If it hadn't worked out at USGS, I think a university job would've been fine, and I think I probably would've been fine. But that was my fear at the time was the fear of just getting spread too thin, and not being able to do a good job at the research and the teaching.

ZIERLER: Jeanne, to round out our conversation, to bring up a point from earlier, talking about academic freedom, even as a junior scholar when you joined the Survey, was it true even then that you could essentially set your own agenda, do what you wanted to?

HARDEBECK: The first two years I was here, I was a postdoc. This was through the Mendenhall Postdoc Program, and I basically wrote a proposal for this is the work I would do for those two years. At that point, I did what I proposed, but I'm the one who proposed that work. Then when I was hired, I feel like I've ever since then had a lot of freedom to pursue what I feel is interesting and useful. I certainly talk to my supervisor and others about directions. I do spend a certain amount of my time working on applied stuff for this aftershock forecast product. I feel like I have had a lot of freedom here to pursue what I want.

ZIERLER: Jeanne, have you kept up with the Seismo Lab over the past two decades? Are you following what's going on?

HARDEBECK: I haven't really. I've not really followed a lot. I went back, I think, a few years. Maybe a few years after I came to the Survey, I went back and gave a talk. But I haven't been back there since—I don't know—probably 2006, something like that.

ZIERLER: Well, maybe there's a centennial observance that could change that, finally.

HARDEBECK: Yeah, that would be great.

ZIERLER: [laugh]

HARDEBECK: It would be great to go back, yeah.

ZIERLER: Jeanne, a few last questions to round out our conversation. What has stayed with you ever since that you learned at the Seismo Lab: collaboration; analysis of the data; being able to identify the most important problems to work on; those kinds of things?

HARDEBECK: I think it's been how to identify problems to work on, and so I think there's two things. One is this feeling that if you can be the first person to have an idea, and do it, and measure it, you don't have to be perfect, but if you can be first, you're making a big impact. If there's something new to measure, and you figure out a way to measure it, and you say it's 10, and then other people come by later, and they're like, "Actually, maybe it's 9.73, whatever, whatever," that initial thing of like, "Here's a thing. It's worth measuring. I measured it. This is what I got," is a really important impactful thing to do, and it's more maybe big-picture important than chiseling around edges of that, deciding if it's really 9.9 instead of 10 or whatever. I think that's a thing I learned at Caltech because I think that's what a lot of the professors did, and a lot of what they encouraged grad students to do was jump after those new things, and maybe it doesn't have to be perfect, but it's really important to just jump after that new thing. Then the other thing that I really took to heart about choosing projects is one time in coffee, Don Anderson told us that Richard Feynman [laugh] had told him [laugh] that the way to figure out the value of a project was the importance of the thing multiplied by how much you can actually do about it.

ZIERLER: [laugh]

HARDEBECK: If it's super important but you can't do anything about it, don't bother with it. If you can do a ton about it but maybe it's not so important, don't bother with that either. Find something that's important and you really actually have a thing you can do about it. I think that's been something that really has stuck in my mind.

ZIERLER: Jeanne, on that point, if you look at your contributions so far, where are they more on the fundamental research side, and where are they more about translating them to societal benefit?

HARDEBECK: I think my impacts, my societal impacts have not been actually particularly great research. That's not quite the way to say it. The places where I've had societal impacts are not things where I'm particularly proud that I think this was really groundbreaking research. We're implementing this aftershock forecasting. It's based on models from the '80s. I'll be honest about that. It's based on models from the '80s. The other big societal impact that I had is I found a fault next to a nuclear power plant.

ZIERLER: Wow. [laugh] That's pretty good.

HARDEBECK: [laugh] That obviously has huge societal impact, but the work itself was kind of turn the crank. It was, "Here's an area. Let's get a better idea of where all the earthquakes are." Turning the crank is just sort of making that initial data set of earthquakes. Then you notice that some of the earthquakes line up, and it's a fault, and it's next to a nuclear power plant. [laugh] I feel like I've had some of those impacts, the societal impacts, but weren't really real scientific breakthroughs. That fault would've been of no interest to anybody if there hadn't been some critical infrastructure next to it. But I think where I've made impacts with research has really been with pushing people's ideas about what's the stress in the crust; pushing people's ideas that maybe the crust is a lot weaker than we thought; pushing people's ideas about what's the stress on the San Andreas fault. I think that's where I've had the most impact. I think, again, those are things where it's been new things, leap for it, and I don't think there's really a consensus yet of whether—obviously, I think I was right, but there's not necessarily a consensus that I was necessarily right about that. But I think I really pushed through a new boundary of research, and a lot of people followed, and there was new research and new thinking. I think that's the stuff I'm most proud of from a research perspective.

ZIERLER: Finally, Jeanne, looking to the future, both in terms of what you want to study and where you want to do it, do you think you're a lifer both in terms of continuing on with aftershocks—

HARDEBECK: [laugh]

ZIERLER: —and doing it at the Survey?

HARDEBECK: I don't have any particular desire to leave the Survey. I would be happy to be a Survey lifer. I don't know. I feel like the aftershocks are important, and I'm going to keep at it for a while, but I'm probably not a lifer on that.

ZIERLER: Is that because you think that the research will achieve some level of finality at some point, or just you'll want to move onto other things that interest you at that point?

HARDEBECK: Yeah, I think it's good to find different interests and try different things after a while. I also suspect this "how important is it versus what can you do about it" problem, at some point, I'm probably going to hit the end of what can I do about the aftershock problem, and then it's going to be time to find something else.

ZIERLER: When will you know when you find it? What will you be looking for?

HARDEBECK: [laugh] I don't know. I'll probably go to talk at a meeting, and go, "Oh, my gosh, what about this?" [laugh] It'll be hard to know until it hits me.

ZIERLER: That's great. Jeanne, this has been a great conversation. I want to thank you so much for spending this time with me.