# PubTalk 4/2011 - Predictable Earthquakes

Video Transcript

## Detailed Description

Title: Predictable Earthquakes - updating earthquake prediction - fact vs. fiction

• Although scientists were optimistic about earthquake prediction in the 1970s, reliable short-term prediction has remained an elusive goal
• What have seismologists learned from recent earthquakes in Haiti, Chile, and Japan?
• Great strides have been made in earthquake forecasting, and to a large extent damaging earthquakes are predictable
• Active fault zones have been identified where damaging earthquakes are inevitable — possibly within our lifetimes

## Details

Date Taken:

Length: 01:24:43

Location Taken: Menlo Park, CA, US

## Transcript

[Applause]

- Good evening. And the first question is whether people can hear me in the back and if I’m wired for sound. No? Okay, can – I don’t have a booming  voice, so I’m relying on this guy to make me audible. Okay. Is that better? Can you hear me? Okay. Now I just have to not move. So, yeah, I had a few very brief introductory remarks of my own. The first is that as – if you’re regulars, your probably know there’s a small group of people who work very hard to make these lectures happen. Starting with Leslie herself, but some other people you might not see – Amelia Barrales, Bill Rambo, who might be in the wings somewhere, and a few others. So I’d like to acknowledge their hard work. Thank you. [Applause] The second is that it’s – I’ve done this once before, and it’s a pleasure to be up here and be part of this series. Tonight, I’m especially glad to be giving a public lecture here as opposed to my home base in Pasadena. Some of you may know that the Lakers are playing game six, and in southern California, it is not a winning game to compete against the Lakers. [laughter] Here nobody cares. If you do, the Lakers are up by nearly 20 at the start of the fourth, so … [laughter]

- Boo! [laughter]

- And then I put the – this photograph – that’s me. About five days ago, I had – I was in Nepal for a workshop on seismic resilience. It was a very good professional experience. I had a chance to go visit elephants. I got back on Monday from the other side of the planet and have been a bit of a zombie since then. So this is not the way to really plan things optimally. I’m feeling better now. I had a nap this afternoon, so we'll see how this goes. And then the last introductory comment is that I know earthquake prediction is a fairly controversial subject. It tends to arouse some passions on both sides. Maybe not quite as much as like, evolution versus creationism, but it comes close. So I know there are some diverging views out there in the world. I’m not sure about in the room. You’re going to get what I think is a fairly balanced view from one seismologist. One of the points that I want to make through the talk is I’m talking about science [feedback], as we understand it now, what we know, what we can say, what we can’t say. And there is, without doubt, things that are going on in the Earth that we still don’t understand. And there may be things related to predictability of earthquakes that we don’t understand. So when you say – when I say earthquakes aren’t predictable, I’m talking about right now, as opposed to …

- Louder?

- Louder. Okay. Hm. I disappeared. Maybe with that brrr. Okay, am I better? No. Okay. I mean, I can hold it, or I can use a mic. But, okay, better now?

- [multiple responses] Yes.

- [inaudible]

- Okay. It’s not me. It’s the system. Okay. Whereas, predictions – you know, I think – I think that’s generally [feedback] – should I go to the hand mic and just try to – would that help?

[Silence]

- Plus or minus two weeks.

[Applause]

Yes? Oh, it – do you want people to use a mic?

- Yeah. Let’s see. Is this on? Okay. Is this on? There you go. You can hear me. Yes. I think Sue will be happy to answer questions. And some of you already know the drill. I’d like you to please use a microphone so everyone can hear you. We have two microphones set up on either side of the aisles. And if you don’t mind, that gentleman had his hand up first. You. Yes. And then we’ll just go back and forth with the mics. And go ahead and answer – ask your question.

- What is the driving force for these plates to move? Why – because it takes a tremendous amount of energy. Where is it coming from? Why are they moving?

- Okay. Yeah, and I should – I know it’s 8:00. So if people need to leave, that’s fine. Yeah. What’s happening – if you go sort of deep in the Earth, the Earth’s core is radioactive, so it’s generating heat. And then you have – most of the Earth is what we call the mantle. And it’s more plastic, and it’s hot. And so it’s convecting or sort of – it’s like a big soup pot, except it moves slowly. So things are moving, you know, a few inches a year. And the crust is just, you know, like, a brittle layer on top of it. So the mantle is trying to move, and it’s pushing the plates around. And the plates are moving, as I said. They just get stuck at the boundaries. So, yeah.

- So if you had any – if you could have, like, a magic wish, and you could have any measurement that you wanted – unlimited budget, whatever – what measurements do you think you could do that would help you predict earthquakes?

- You know, what I would really love to see is, like, an earthquake catalog from the Earth that’s a million years long. I mean, I would really like to see the patterns that have been played out. Are there any patterns? But things you could measure – I guess one question is …

- I mean, like, drilling down into, like …

- Yeah. No, if – one question is, you know, what’s happening on faults? And is there a build-up of stress or strain? There are – measuring at the surface, you’re really limited. You know, suppose some fault is starting to move slowly. The amount that that’s going to move the surface is so tiny that, with the best instruments, we’re pretty limited. So if you could measure stress or strain very precisely at depth, that would tell you a whole lot. And I use – I’m using stress and strain. I probably should have explained them. Stress is – you know, is – is the – well, not quite a force, but it’s essentially the pressure that’s driving a fault. And strain is the warping that happens in response to stress. But, yeah, that’s one of the big unknowns.

- Let’s see. I think I’m supposed to the …

- Okay. What is the prediction f or the New Madrid Fault? [laughter]

- Oh, boy. You’re going to get me into trouble.

- Yeah.

- No, it’s – and that’s one of my research interests, and I actually just had a paper that came out with revising – with revised estimates for the magnitudes of the earthquakes that happened 1811 and 1812. And I actually estimate them to have been closer to magnitude 7 than magnitude 8. So there’s a big question about how big the earthquakes were. But we had a sequence in 1811, 1812. There was a sequence in around 1450 A.D. and a sequence in 900 A.D. And we know about those from geology. So, over the last couple thousand years, there have been big earthquake sequences. They're about every 400 years or so. But in terms of what’s going to happen next, it’s really not clear in that case. Because it’s not like the San Andreas. There’s no plates that are moving. And we really don’t understand why you have earthquakes at all in the middle of the North American Plate. So there could be more earthquakes – you know, there could be another sequence a hundred years from now. It could be over. We could have seen the last of this little cluster of earthquakes. But that’s – compared to California, it’s just much, much more uncertain.

- And what information have you gotten from Parkfield?

- What …

- Over – like, over the last 20 years. What has it actually told you?

- Yeah. There was the – you may have heard about the Parkfield prediction experiment made, you know, from scientists here in – [chuckles] that was the next question? In the early 1980s, people identified Parkfield and realized that there had been a fairly regular sequence of magnitude 6-ish earthquakes in ’34, in ’66, and they made a prediction of the next earthquake in 1988 plus or minus four years. And 1992 came and went. No earthquake. But then the earthquake did happen. And it’s – I always forget if – 2005, I think. Or 2004. ’05, I think. So the earthquake did happen, and it was on the part of the fault that been identified. It was a magnitude 6. And I think that was a qualified success scientifically that it was identified – you know, and that's sort of the irregular clockwork. If you plot Parkfield earthquakes, you know, it fits the pattern. But it just – it’s the disconnect between clockwork in a geologic sense and clockwork in a human sense. You know, in a human sense, if you say ’84 to ’92, and the earthquakes is in 2005, that’s a pretty big deal. And that’s what happened. But that is a part of the fault that these moderate quakes do happen relatively regularly.

- That was such a refreshing presentation that you gave. It makes one proud to have been associated with the Geological Survey. My question has to do with the North American Plate. It’s really a huge plate.

- Yeah.

- From your pictures and the pictures that are in the papers now. I don’t think many people realize that it just doesn’t include the North American continent. It includes all the way over to Japan and all the way across the top. Is there any chance that, within that plate system, there are smaller plates which have not been identified yet? Like you – like the Caribbean system that you showed?

- Yeah, actually – I mean, that’s – it’s a good point. Because it includes half the Atlantic too. You have the Atlantic coast, and it goes from the continental crust to the oceanic crust. That’s a pretty big transition, but there’s not an active plate boundary there. So that’s why you don’t have as many earthquakes along the East Coast as you do in California. But it is a massive plate. No, people have GPS measurements now, and GPS – you can literally watch the plates moving. And so, if part of North America was moving significantly relative to another part, I think we would – we would have seen it by now with GPS. And, in fact, someone asked about New Madrid. People have looked with GPS trying to find some strain that’s going on. And they can’t find any. The better the measurements get, the closer the strain gets to zero, which really raises the question of why you’re having earthquakes there. But at least right now, the plate seems to be pretty stable, pretty rigid, and there’s no major earthquakes zones. Well, I’ll take that back. Okay. Not – some earthquakes are happening as a result of other forces than plate tectonics. And the one notable example that I know about, at least, involves post-glacial rebound. So much of North America was covered by these massive ice sheets. You took that ice away. The crust rebounds, just like putting your hand on a cushion, and it rebounds up, right? But that goes on over thousands of years. So, up in Canada where it was closer to where the ice sheets are at, the crust is bouncing back. And you can actually see that with GPS. And that’s driving earthquakes that happen along the St. Lawrence in particular. So there is – within the North American Plate, there are stresses that are associated with other things, but it’s not really breaking up the plate.

- Thank you.

- I haven’t read your book, but I did read the flier for your book. And it – and it mentioned – you were discussing in that, earthquake lights. And do you feel that there’s any possibility for the electromagnetic effects that might be generating earthquake lights can become a precursor?

- Okay. I’m smiling because I wrote a book about earthquake prediction, and I did that on my own time. And then I’m giving this talk in my capacity as a USGS scientist. And the ethics rules say that I can’t benefit from – use my official position for personal gain. So I’m allowed to talk about earthquake prediction, but I was very careful not to mention the book because I can’t. But I’m allowed to answer a question. [laughter]

- It’s a fine line.

- No. It is this – you know, this is the position I am in, and it’s – you know, okay, so yeah, there’s a lot more to the story. I did write this book. And I didn’t talk about electromagnetic precursors very much, but that’s a whole realm of earthquake prediction. And one of the interesting observations is, as you mentioned, there are these anecdotal accounts that go way back hundreds of years about earthquake lights that are seen in the sky before earthquakes. And that sort of, you know, maybe suggests there's some sort of electromagnetic precursor that’s going on. And so, yeah, there could be electromagnetic precursors that are going on before earthquakes. And you’re getting earthquake lights. You know, you may be getting other phenomenon – earthquake fog. You know, so those things are possible, and it’s worth – it’s worthy of investigation. As far as people have seen, if you get really good data, there hasn’t been any documented electromagnetic precursor that’s really been shown to be significant. But, yeah, it’s possible that it’s happening.

- Not even Tony Frazier-Smith’s work?

- Okay. That was – so that was the case of the ultra-low-frequency anomaly that was supposedly observed before Loma Prieta. And some of you may have heard about this. There was an article in Science because, by chance, there was a magnetometer in Corralitos. And scientists have looked at that record very carefully, and there’s pretty good evidence that it was some sort of instrumentation glitch that caused the signal. And this was back in ’89. You know, computers are not what they – what they are now. The way the data were – scientific instruments – the instrument wasn’t even able to store the raw data because it didn’t – there wasn’t enough computer memory. So there was sort of processing that was done, and the data were stored. So it’s pretty limited data, and there’s some really strong indications that something went a little haywire with the instrument a few weeks before the earthquake. But it’s never – people have been looking. That sort of launched a cottage industry to look for similar signals. And they haven’t been documented, seen, before other earthquakes.

- Thank you.

- It seems everybody wants earthquake prediction for lots of reasons, and we’re working hard on it, but what happens when we do get earthquake prediction? What’s – would you care to comment on the economic impact?

- Well, it’s – you know, people ask that question. Because it’s a good point. And especially – you know, if I could say – if science could say there’s going to be an earthquake tomorrow, 100% probability, you could sort of imagine dealing with that. Although, you know, you quickly get into these nightmares. You know, how do you evacuate San Francisco? But what happens if you can say that an earthquake is very, very likely to happen in the next six months? You know, what do you really do about that? I think if scientists could predict earthquakes, they’re going to predict earthquakes. And then, you know, just the consequences will play out as they – as they may. But, yeah, I mean, it raises some interesting questions. We think we want prediction. You know, we want a heads-up that an earthquake is going to happen. But, you know, if we get to that point, it’s going to be a challenge to deal with.

- Okay, thank you. I’m surprised you didn’t mention Billy Meier’s prediction about a large earthquake in the land of cherry blossoms, about 35 years ago.

- Okay. That’s …

- Anyways, it’s another one of these …

- That’s one I don’t know about.

- Okay. You should, you know, Google that.

- This is for D.C.? Or Japan?

- The land of the cherry blossoms. So it’s pretty wide. [laughter]

- So, but anyway, my real question is, I do understand, in Japan, they have some sort of earthquake sensors or detectors that maybe sense some P mode oscillations that give you at least a 60-second – perhaps you can talk about the geology of the P modes versus the S modes.

- Yeah, there’s …

- And the time difference to – I guess depending on how deep it is.

- Yeah, Leslie and I were talking about this. There may be, in the future, a public lecture would be on earthquake early warning, what we call it. Early warning is different from prediction. And it sounds like you’re familiar with this, and maybe a lot of you are. If an earthquake happens, the P wave – well, okay. An earthquake happens. It generates waves. So there’s the P wave. The S wave travels more slowly. But the thing is, if an earthquake happens, and I had a seismometer sitting here, and I could tell that there was a magnitude 8 earthquake, I could send a signal at the speed of light to you and say, an earthquake just happened here, before either the P wave or the S wave get here. So it’s the same delay between thunder and lightning. And you can get – so if you have to observe an earthquake, figure out that it’s going to be big, get the warning sent out, and you can get yourself, you know, seconds, tens of seconds, of warning, potentially. Japan does have a system. They stop the bullet trains. Mexico had a rudimentary system. I heard that it actually managed to kill somebody with a false alarm, and somebody jumped out of a window. [laughter] But it’s – people are working on it – people at Berkeley, at Caltech, USGS. It’s – the science is sound, but it’s a huge technological challenge. A big earthquake is going to last for two minutes, maybe. The 1906 earthquake – the fault was actually in motion for two minutes. Well, you can’t wait two minutes to determine the magnitude because you’re – the warning would be over. So you have to look at the very first few seconds of a seismogram and know it’s going to be a big earthquake, and that’s tricky. Because the beginning of a 7 may not look that different from the beginning of an 8 or a 5. So that’s one challenge. And, you know, pulling the data together quickly to look at data from different seismometers – it’s a big – it’s a challenge, but people are working on some fairly clever approaches. And, you know, it may be – it may come to pass in California in the next 10 years or so. But you’re never going to be able to count on a lot of warning because it really works – you need to have distance between the fault and where people are. So it works pretty well in Japan. The big faults of offshore. The people are some distance away. Here, you have people and faults and faults and people. And, you know, the San Andreas just isn’t that far from here. The Hayward isn’t that far. So if you’re too close to where the earthquake happens, you’re not going to – there’s not going to be time for warning.

- Thank you.

- Didn’t the Japanese earthquake recently last more than two minutes? I think it’s – at least some reports seemed that it lasted an immensely long time, considering.

- There are – there’s two different things. One question is, how long was the fault actually moving? And when a big earthquake happens, it’s not like the whole fault just lurches at once, right? It’s like, if you had to pull a long carpet, and you put a ripple into it, and the ripple travels down, and you can move the carpet on the floor. So that’s how big earthquakes happen – like a ripple. And the ripple goes down the fault about 3 kilometers per second. So if an earthquake is – how long the earthquake is sort of gives you a pretty good idea of how long it takes in time. Sorry. That was a little garbled. But the Japan quake was about 300 kilometers long, so the fault was probably moving for about two minutes. The earthquake in Chile in 1960, it may have been closer to five minutes. That’s the duration the fault is moving. But then, what you feel is much longer because, as the earthquake moves, it sends out waves. The whole time the earthquake is going on, you get the P wave, the S wave, other waves. They bounce around. So you can easily feel five minutes of strong shaking from an earthquake that lasted two minutes. And that – you think about it – you know, if you felt Loma Prieta, and it felt like it lasted forever, that was a 6.9. And, you know, a magnitude 8 would last many, many times longer than that.

- Before I get to the question that I wanted to, what you just said made me think of something. When you think about the origin of the – what was actually starting – what actually started that earthquake that lasted, let’s say, one minute, was – that one minute, is that all the reverberations that you heard? And the actual earthquake was only five seconds? Or is it really moving, you know, in one direction for a whole one minute?

- Yeah, so you’re talking about Loma Prieta?

- Or just an arbitrary earthquake.

- Yeah, so Loma Prieta was pretty small. That earthquake was probably over within 10 seconds – the motion on the fault. But, I mean, how many people here felt it? And … [laughter] Wow. I was in New York. Do you remember the study that – about the Nimitz Freeway and that it collapsed where it was built over mud? Okay. That was my study. I was a postdoc at Columbia. And I came out to study the earthquake, but I didn’t feel it because I was a long way away. But, no, I felt the Northridge earthquake in southern California – similar magnitude, similar duration. And, yeah, I mean, so how long was the duration that [audio cutting out] of shaking that people felt, for example. [inaudible]? [very quiet audio] I mean, it’s going to vary depending on where you were, so …

- I was on the second floor of a building in South San Jose, and I – after it was going a long time, I figured, I got to time this. I timed it for about 15 seconds after that, so it was probably 30 seconds total.

- Yeah. So it’s going to vary. And depending on the geology – if you’re in the middle of a basement, it’s going to slosh more or [inaudible]. So, yeah, it’s – what you feel is going to be a lot longer than the actual earthquake on the fault.

- The question I really wanted to ask was, do you see any great scientific value to the amateur seismographs that are increasingly being deployed and connected?

- Yeah. I think, you know, making observations is great. And, you know, I talked about how the gulf between the amateur community – you know, you can call it fringe – and the mainstream community, that gulf – and I concluded this working on the book – isn’t as wide as we like to think. There’s some interesting work being done in the amateur community on any number of [normal volume] aspects of seismology. Collecting data is almost always a good thing. There’s a new project that’s being led by a woman who’s going to be joining the Pasadena office to develop very low-cost seismometers. I think this is really exciting. Okay. If you – if you have an iPhone, do people know about – or a Mac laptop – do you know about SeisMac? Or let me just make sure I have the name. For an iPhone, you can look for iSeismo. So there are – there’s an accelerometer – there’s basically a seismometer in this phone. And there’s – there are little, tiny seismometers that have been developed for commercial applications, for airbags, for video games, for iPhone. The way the phone knows what direction it is is by measuring the acceleration. So there’s actually an app. I can turn my iPhone into a seismometer. It’ll measure – if you can see – so just look for iSeismo. Download it. It’s free. It’s really cool. [laughter] So if you’re a geek, this is, like, the best thing ever. [laughter] So there’s – there’s – okay, for a Mac laptop, there’s an app called SeisMac – M-A-C. If you have an iPhone, it’s, like, iSeismo. And they’re both free. And I actually – I was riding an elephant, and I was holding my seismometer to see how the – and then you can actually do some basic analysis of this. So – okay, people realized that, well, I could put this down on the ground, and poof, I have a seismometer. You know, so you could have a seismic network that’s made up of everybody’s iPhone. Well, that doesn’t work so well because most of the time, my iPhone is in my pocket. You know, but then people had the – the next idea was to take these itty-bitty instruments and build them into a scientific – a better housing to use for monitoring earthquakes. They’re dirt cheap. You can get a little instrument for 50, 80 bucks. And they’ve designed the housing. You plug it into a computer through a USB cable. You install some free software. You have a seismometer in your house for 80 bucks. They’ve developed the software that’ll gather the data kind of in the background. If an earthquake happens, it gets beamed to home base, so …

- This is iSeismo. If anybody can see the screen here. It’s jumping up and down.

- Yeah.

- [inaudible] you can see the lines moving. You can see the lines. [inaudible] seismographs out there.

- Yeah, so …

- [inaudible] you can steady it on the chair and then stamp your foot on the floor, you can see it. [laughter]

- Yeah. Oh, no, there are – you can measure the vibrations of an elephant. I mean, it’s just the coolest thing ever. But I think there’s some really exciting possibilities. And I just put together a proposal. You could deploy 100 instruments in Kathmandu for, you know, a relatively cheap amount of money and monitor the earthquake shaking. You could have thousands of instruments in the Bay Area. So I think, as this technology is exploited, there’s going to be some really exciting opportunities for scientific studies, I think.

- One of my friends in Los Altos Hills has a seismometer in his basement that’s bolted to the floor. He says it’s hooked up on the net to a master system.

- Okay.

- Do you know many of those are – are there around here?

- Yeah, a conventional seismometer may cost on the order of $5,000 to$10,000. So there are – there are instruments – there’s probably, in total, a thousand of them in California. There was an instrument developed recently called the NetQuakes. It’s a little bit cheaper. It’s more like 4,000, and there was a program to deploy those in people’s houses. I think the number of those is a few hundred. But it still – I think the – you know, using this kind of technology is going to be a game-changer. Because that’s what’s going to make this affordable to really, you know, get into monitoring on a much bigger scale.

- My next question, though, is, my biggest fear, really, is shutting off natural gas. And does PG&E have automatic shut-off in a major quake?

- Yeah. Well, I don’t – I’m sure they have systems for their main lines. But if you – I have a little box on my gas line at home. I bought it through the gas company, and they were – they billed it in a few payments spread out over my gas bill.

- It’s hooked up to the valve? Is that it?

- Yeah. And it’s basically a little strong motion seismometer. And if a big earthquake happens, it’s designed to shut the gas valve off. Because that is a concern. If your house is well-built in its wood frame, bolted, it should be in pretty good shape. But if you’re – if the gas line ruptures, fires are a big concern, so …

- Of course, my insurance friends say, if you have a major quake damage to your house, you really want it to burn down because the fire insurance will cover it. [laughter]

- Yeah, but do you really want your house to burn down? So I would urge you, if you have natural gas, look for these little devices. They’re not that expensive, and it’s a really good investment.

- Quick question. What is the method for figuring out the dates of pre-historic earthquakes? Is there an easy answer for that one?

- Ah. It mostly – if you find geologic evidence – so you look along a fault, and you can see breaks that happened in the past. So, like, along a creek bed, if a fault cuts a creek, and sediments are coming down, an earthquake happens, it moves the sediments, then more sediments come down. And if you date – you can find the cracks, and you date with carbon-14 the sediment layers, you can sort of pinpoint the earthquake. That’s basically how the game is played. Sometimes there’s, you know, historic accounts if it’s within the historic record. That gives you the precise date.

- I want to thank all of you for your great questions and for coming tonight. [Applause] And, of course, I want to thank Sue Hough. It was a wonderful talk. I think everybody enjoyed it. It’s 8:30, and you’re still all here. That’s a good sign. So thank you very much. Thank you, Sue. And a lot of people asked about things like the NetQuakes system and about early warning, and I’m pretty sure, within the next year or so, or sometime next year, we’ve got some lectures scheduled on those subjects. So stay tuned, and I’ll see you next month.

[inaudible background conversations]

- Thank you, Leslie.