WEBVTT - Can We Predict Earthquakes? 0:00:00.960 --> 0:00:04.680 Hey, welcome to sign Stuff, a production of iHeartRadio. I'm 0:00:04.720 --> 0:00:08.200 hoor Chimp. And today we are answering the question can 0:00:08.240 --> 0:00:12.520 we predict earthquakes? What are ways humans have tried to 0:00:12.560 --> 0:00:15.520 get a heads up on when the ground is gonna shake? 0:00:16.120 --> 0:00:19.200 Do animals have a sixth sense about it? Or can 0:00:19.239 --> 0:00:23.599 AI see things in the data that we cannot. We're 0:00:23.600 --> 0:00:26.640 gonna sit down with two earthquake scientists who are going 0:00:26.680 --> 0:00:31.319 to explain that we can actually predict earthquakes, just not 0:00:31.480 --> 0:00:34.800 in the way you expect. So hold on to something 0:00:35.040 --> 0:00:38.760 because we're taking a dive into the earth shaking science 0:00:39.120 --> 0:00:47.040 of earthquakes. Enjoy. Hey everyone, all right, Here are the 0:00:47.159 --> 0:00:52.000 top three most destructive earthquakes in recorded history, according to 0:00:52.080 --> 0:00:56.080 the US Geological Survey. In two thousand and three, a 0:00:56.200 --> 0:01:01.320 magnitude six point five earthquake happened in bomb Iran, which 0:01:01.400 --> 0:01:05.319 killed more than forty thousand people and collapsed eighty percent 0:01:05.520 --> 0:01:09.280 of all buildings. In nineteen seventy six, a seven point 0:01:09.319 --> 0:01:13.440 eight magnitude earthquake struck Tangshan, China, and it's said to 0:01:13.480 --> 0:01:17.120 have killed between two hundred and fifty and eight hundred 0:01:17.160 --> 0:01:21.800 thousand people, mostly from the collapse of unreinforced brig or 0:01:21.840 --> 0:01:26.000 concrete homes. The deadliest earthquake ever is thought to have 0:01:26.040 --> 0:01:30.000 happened in fifteen fifty six in Shangxi, China, which killed 0:01:30.080 --> 0:01:33.960 about eight hundred and thirty thousand people. It had an 0:01:34.080 --> 0:01:39.600 estimated magnitude of eight and reportedly leveled mountains, redirected rivers, 0:01:39.800 --> 0:01:44.680 and caused flooding and fires. The strongest earthquake ever recorded 0:01:45.040 --> 0:01:48.280 happened off the coast of southern Chile in nineteen sixty 0:01:48.720 --> 0:01:52.680 and had a magnitude of nine point five. About sixteen 0:01:52.800 --> 0:01:56.680 hundred people were killed, mostly from the giant tsunami to 0:01:56.800 --> 0:02:01.120 earthquake cost which had waves reportedly as high as eighty 0:02:01.200 --> 0:02:06.160 feet or twenty four meters. Clearly, earthquakes can be major 0:02:06.400 --> 0:02:10.200 natural disasters, and it would be great if we could 0:02:10.360 --> 0:02:13.720 predict them. So to learn more about the science of 0:02:13.800 --> 0:02:16.840 earthquake prediction, I decided to take a field trip to 0:02:16.919 --> 0:02:20.600 a major city that is fairly close to a huge 0:02:20.880 --> 0:02:25.880 fracture in Earth's crust that has caused several major earthquakes 0:02:26.080 --> 0:02:29.480 in the last century. Now, luckily I didn't have to 0:02:29.520 --> 0:02:33.840 travel very far because that city is Los Angeles, and 0:02:33.880 --> 0:02:37.519 that's where I live, which maybe is not so lucky 0:02:38.040 --> 0:02:41.040 here in La. The threat of a big earthquake happening 0:02:41.320 --> 0:02:43.799 is something you just kind of learned to live with. 0:02:44.480 --> 0:02:46.520 The good news is this is a good place to 0:02:46.560 --> 0:02:50.720 live if you're an earthquake scientist. So to learn more 0:02:50.760 --> 0:02:54.160 about today's topic, I drove over to the headquarters of 0:02:54.240 --> 0:02:58.240 the Southern California seis PIC Network, which is a joint 0:02:58.280 --> 0:03:04.600 project between Caltech and the US Geological Survey or USGS. Now, 0:03:04.680 --> 0:03:08.920 the first thing I asked him was this, how likely 0:03:09.080 --> 0:03:11.800 is it that an earthquake will happen during this interview? 0:03:12.440 --> 0:03:15.160 And this is what they said during this interview. 0:03:15.160 --> 0:03:18.560 So this interview is maybe an hour or so, probably 0:03:18.560 --> 0:03:23.639 a pretty high likelihood, and in California even probably quite 0:03:23.639 --> 0:03:24.560 a high likelihood. 0:03:25.400 --> 0:03:27.679 So at the end we're going to find out if 0:03:27.680 --> 0:03:31.920 there was an earthquake during our interview, and spoiler alert, 0:03:32.320 --> 0:03:35.440 there was. Okay, let me take a step back. I 0:03:35.480 --> 0:03:39.000 went over there to talk to my friend doctor Alan Husker, 0:03:39.320 --> 0:03:43.160 the professor at the Seismological Laboratory at Celtech and the 0:03:43.200 --> 0:03:47.680 manager of the Southern California Seismic Network, and he introduced 0:03:47.720 --> 0:03:51.840 me to doctor Elizabeth Cochrane, a researched geophysicist with the 0:03:51.960 --> 0:03:55.360 US Geological Survey. So here's my visit to the hub 0:03:55.440 --> 0:04:01.400 of earthquake research in Los Angeles. Hey, I'm walking through Caltech. 0:04:01.480 --> 0:04:02.560 Now here we go. 0:04:07.040 --> 0:04:10.600 Hello, how are you good to see? Thank you for 0:04:10.680 --> 0:04:14.400 letting me crash your meeting? No problem, fun well, thank 0:04:14.400 --> 0:04:17.719 you doctor Husker, Thank you Doctor Cochran for joining and 0:04:17.800 --> 0:04:19.280 talking with me here today. 0:04:19.440 --> 0:04:20.200 Happy to be here. 0:04:20.279 --> 0:04:21.320 Yeah, thanks for having us. 0:04:21.400 --> 0:04:23.120 Can you please tell us would you do what your 0:04:23.160 --> 0:04:24.039 every day like? 0:04:24.440 --> 0:04:27.640 So, typically most of my days are spent looking at 0:04:27.760 --> 0:04:31.840 seismic wiggles, so trying to understand what happens when an 0:04:31.839 --> 0:04:36.160 earthquake occurs and the effects on people and things around us. 0:04:36.240 --> 0:04:39.560 I spend a lot of time managing so budgets, people, 0:04:40.160 --> 0:04:42.520 making sure equipment gets out to where it's supposed to 0:04:42.560 --> 0:04:43.839 be in the field. And then I'll have a grad 0:04:43.880 --> 0:04:45.240 student who's looking at moonquakes. 0:04:45.520 --> 0:04:49.560 Oh wow, okay. I started by asking them to give 0:04:49.560 --> 0:04:52.720 me a rundown. The way people have tried to predict 0:04:52.800 --> 0:04:55.800 earthquakes starting with animals. 0:04:56.600 --> 0:04:59.320 So people think that animals can predict earthquake. It's a 0:04:59.400 --> 0:05:01.680 very common. Most people do actually this, well, a lot 0:05:01.720 --> 0:05:04.360 does that learn. So some people just think that their 0:05:04.560 --> 0:05:07.240 dog or whatever has extra senses that humans don't have, 0:05:07.720 --> 0:05:09.719 and so they can sense when something's going to happen 0:05:09.839 --> 0:05:13.159 before it happens, because of better vision or hearing or 0:05:13.160 --> 0:05:15.479 maybe a sixth sense, that kind of thing. There was 0:05:15.520 --> 0:05:17.560 a study a while ago where they had people actually 0:05:17.600 --> 0:05:19.640 fell out cards about how their dog was acting and 0:05:19.680 --> 0:05:22.239 to mail it in, and what they found was people 0:05:22.320 --> 0:05:25.599 observe their pets after an earthquake, and then the amount 0:05:25.640 --> 0:05:27.599 of them sending the cards would die off over time. 0:05:27.880 --> 0:05:30.960 So it's kind of like your pet acts odd a lot, 0:05:31.279 --> 0:05:35.479 and then if an earthquake happens after that, you attribute 0:05:35.640 --> 0:05:39.520 the odd behavior that day, do them knowing an earthquake 0:05:39.600 --> 0:05:42.480 is happening, when in fact, you know five days out 0:05:42.520 --> 0:05:46.240 of seven they're doing something odd. So there is a 0:05:46.279 --> 0:05:49.920 really nice video from one earthquake in Seattle in two 0:05:49.920 --> 0:05:52.359 thousand and one that happens to be focused on a 0:05:52.440 --> 0:05:55.120 dog that's sleeping on the floor, and. 0:05:55.000 --> 0:05:57.520 The dog gets up, runs. 0:05:57.160 --> 0:06:00.880 Away, and then you sort of clearly see that building shaking, 0:06:01.520 --> 0:06:05.080 But it turns out that in fact, if you actually 0:06:05.080 --> 0:06:08.159 look very closely, the building does start shaking when the 0:06:08.200 --> 0:06:12.479 dog gets up the dog noticed the first seismic wave 0:06:12.640 --> 0:06:15.160 to arrive, and you know, because they're laying on the floor, 0:06:15.560 --> 0:06:18.600 they felt that vibration, were startled by it and got up, 0:06:19.120 --> 0:06:21.960 and then the stronger wave arrived. Then that's when people 0:06:22.080 --> 0:06:24.400 noticed and started moving around. 0:06:25.640 --> 0:06:30.360 Yeah, according to our experts, there's no convincing evidence dogs 0:06:30.640 --> 0:06:34.560 can predict earthquakes, but it has to stop people from 0:06:34.640 --> 0:06:36.680 trying other animals. 0:06:37.680 --> 0:06:39.760 There was one experiment I heard about that happened in 0:06:39.880 --> 0:06:44.760 China where they put electrodes on goats nipples, Oh, if 0:06:44.760 --> 0:06:46.120 they could predict earthquakes or whatever. 0:06:46.240 --> 0:06:47.520 Barently nothing came out of There was. 0:06:47.520 --> 0:06:50.920 Also a different experiment that was done similar thing, where 0:06:51.000 --> 0:06:54.080 someone kept tanks of these eels. And because one of 0:06:54.080 --> 0:06:57.039 the ideas are some sort of electrical signal as the 0:06:57.200 --> 0:07:00.680 rocks are breaking, and you get some electrical signals that 0:07:01.000 --> 0:07:03.360 animals that are sensitive to that would be able to 0:07:03.440 --> 0:07:05.440 detect it, it didn't work. 0:07:06.440 --> 0:07:10.280 Now, to be fair, scientists have tried more serious ways 0:07:10.360 --> 0:07:13.880 to predict earthquakes. For example, they've looked to see if 0:07:13.920 --> 0:07:18.720 the ground expands or swells right before an earthquake, or 0:07:18.800 --> 0:07:22.120 if there's an extra amount of radon gas that comes 0:07:22.200 --> 0:07:25.840 up from the ground right before an earthquake hits, but 0:07:25.880 --> 0:07:29.160 none of these studies have found anything that can be useful. 0:07:29.600 --> 0:07:32.760 Scientists have even looked to the sky for signs that 0:07:32.840 --> 0:07:39.760 predict earthquakes, specifically a layer of our atmosphere called the ionosphere. 0:07:40.360 --> 0:07:43.200 So people have looked for other things after really really 0:07:43.200 --> 0:07:46.600 big earthquakes, like magnitude eight point five and above. It's 0:07:46.640 --> 0:07:48.560 so big that it can sometimes see in a signal 0:07:48.600 --> 0:07:52.880 in the ionosphere. So there are all sorts of different 0:07:52.960 --> 0:07:56.280 agnotometers and other equipment on satellites around the Earth all 0:07:56.320 --> 0:07:59.320 the time. So they tried to look for changes in 0:07:59.360 --> 0:08:02.640 the iosphere that what happened beforehand, and it hasn't worked either. 0:08:03.240 --> 0:08:04.920 I would say I'm on the skeptical side. 0:08:05.720 --> 0:08:08.800 Okay, the I in the sphered doesn't quite work either. 0:08:09.520 --> 0:08:11.280 How about using AI? 0:08:12.480 --> 0:08:15.000 Yeah, so I think most of the studies that have 0:08:15.240 --> 0:08:19.640 suggested that earthquakes might be predictable using sort of deep 0:08:19.720 --> 0:08:25.040 learning AI techniques are applied to laboratory data, so those 0:08:25.240 --> 0:08:28.680 I think potentially are successful. Boothquakes are quite a bit 0:08:28.680 --> 0:08:30.320 different than earthquakes. 0:08:29.760 --> 0:08:30.240 In the lab. 0:08:30.520 --> 0:08:33.120 The ones in the lab are more predictable. 0:08:32.600 --> 0:08:33.839 Because they're more predictable. 0:08:34.240 --> 0:08:36.360 The other thing that I've seen with some of these 0:08:36.480 --> 0:08:39.000 AI techniques is they'll say that they get ninety percent 0:08:39.040 --> 0:08:41.679 prediction rate, which is great, but ninety percent of the 0:08:41.679 --> 0:08:42.560 earthquakes don't matter. 0:08:43.040 --> 0:08:44.559 The ones that matter are the big ones. 0:08:44.760 --> 0:08:47.440 So there was a kind of a prediction conference in 0:08:47.640 --> 0:08:50.439 China where if they can predict an earthquake using AI. 0:08:50.720 --> 0:08:53.079 So they said that all their predictions were doing really well. 0:08:53.280 --> 0:08:55.360 There was a nineteen six point four that actually occurred 0:08:55.400 --> 0:08:57.120 during the conference that none of them predicted. 0:08:58.360 --> 0:09:03.800 Okay, so apparently dogs can't predict earthquakes, and neither can 0:09:03.840 --> 0:09:08.680 goats or eels, or studying the ground or analyzing the 0:09:08.679 --> 0:09:13.400 gases emitted underground or measuring the Earth's ionosphere, and not 0:09:13.480 --> 0:09:17.400 even AI can predict when the next earthquake is going 0:09:17.480 --> 0:09:22.840 to happen. So does this mean it's impossible. When we 0:09:22.880 --> 0:09:25.520 come back, we're going to ask our experts why it's 0:09:25.559 --> 0:09:29.600 so hard to predict earthquakes and how in some cases 0:09:29.880 --> 0:09:33.320 we totally can predict them. Also, we're gonna find out 0:09:33.360 --> 0:09:36.800 if there was an earthquake during the interview, So keep 0:09:36.840 --> 0:09:39.880 your feet on the ground, stay with us. We'll be 0:09:40.080 --> 0:09:55.600 right back and we're back. Okay, we're asking the question 0:09:55.960 --> 0:09:59.319 can we predict earthquakes? And I already said the answer 0:09:59.400 --> 0:10:03.080 is yes, sort of. But first I wanted to know 0:10:03.360 --> 0:10:07.320 why earthquakes are so hard to predict. I mean, we 0:10:07.360 --> 0:10:12.680 can predict hurricanes, tsunamis, even solar storms. Why is predicting 0:10:12.679 --> 0:10:16.520 the ground right under our feet so tricky? We'll ask 0:10:16.559 --> 0:10:19.600 our experts this question, but before that, here's a quick 0:10:19.679 --> 0:10:23.800 two minute crash course on what earthquakes are. You might 0:10:23.840 --> 0:10:26.960 remember from school science that the Earth is made up 0:10:27.160 --> 0:10:30.800 of layers, that the topmost outer shell of the Earth, 0:10:31.280 --> 0:10:35.880 the crust, is actually made up of pieces called tectonic plates. 0:10:36.600 --> 0:10:39.720 These hard, brittle plates are sort of floating on top 0:10:39.760 --> 0:10:43.880 of softer, harder, flowy rock. It goes up and down, 0:10:44.280 --> 0:10:47.360 sort of like a lava lamp the size of a planet. 0:10:48.040 --> 0:10:50.959 But because these tectonic plates, which is what we're all 0:10:51.000 --> 0:10:55.679 standing on, are floating, they tend to move. You can 0:10:55.760 --> 0:10:59.120 think of them like giant sheets of ice floating on 0:10:59.200 --> 0:11:03.640 a crowded pool. The tectonic plates are all crowded together 0:11:04.080 --> 0:11:06.480 and they push on each other as some of them 0:11:06.600 --> 0:11:09.720 grow or get sucked back into the Earth due to 0:11:09.760 --> 0:11:13.720 the motion of the flowy rock below them. Now, imagine 0:11:13.760 --> 0:11:18.080 two big rocky tectonic plates nice to each other, and 0:11:18.120 --> 0:11:21.120 they might be pressing against each other, or they might 0:11:21.120 --> 0:11:24.040 be going in different directions, in which case it might 0:11:24.080 --> 0:11:27.920 be pressing and rubbing against each other. Or one of 0:11:27.960 --> 0:11:30.440 them might be trying to slide under the other one, 0:11:30.840 --> 0:11:34.600 in which case they might be pressing, rubbing, and lifting 0:11:34.920 --> 0:11:38.160 or sinking each other. The point is that you have 0:11:38.280 --> 0:11:42.160 two giant bodies of rock and they're pressing against each other, 0:11:42.760 --> 0:11:46.680 and all that pressure creates a lot of stress, and 0:11:46.720 --> 0:11:51.760 at some point something gives the two rocks can slip 0:11:51.800 --> 0:11:55.480 past each other suddenly, either sideways or one under the other, 0:11:55.960 --> 0:12:00.640 and that sudden slip is what an earthquake is. 0:12:02.360 --> 0:12:06.160 So an earthquake is a rapids breaking. 0:12:05.880 --> 0:12:09.960 Or slip along a fracture on the Earth. So basically, 0:12:10.000 --> 0:12:13.920 stresses build up in the earth and they're released really 0:12:14.040 --> 0:12:15.719 rapidly during an earthquake. 0:12:16.960 --> 0:12:20.120 Now, according to our experts, there are two things that 0:12:20.200 --> 0:12:24.000 make earthquakes so hard to predict. The first is that 0:12:24.040 --> 0:12:27.360 it all happens miles under the ground. 0:12:28.320 --> 0:12:31.280 So most of the earthquakes happen sort of five to 0:12:31.320 --> 0:12:32.280 ten miles deep. 0:12:32.840 --> 0:12:34.440 Oh, in subduction zones. 0:12:34.480 --> 0:12:37.360 It's much deeper because it's between where the two plates 0:12:37.360 --> 0:12:40.000 are rubbing against each other, deep underneath the earth, so 0:12:40.040 --> 0:12:42.080 it might be like fifty miles. 0:12:43.280 --> 0:12:47.720 Here's an interesting fact. Earthquakes happen at very specific depth 0:12:48.160 --> 0:12:51.240 depending on how the rocks are rubbing against each other. 0:12:51.800 --> 0:12:55.720 Earthquakes don't happen deeper because the rock gets hot, which 0:12:55.760 --> 0:12:59.160 makes it flow instead of crack, and they don't happen 0:12:59.160 --> 0:13:02.440 above about a mile or so down because the rock 0:13:02.480 --> 0:13:06.240 there is too loose or crumply. But the ones that 0:13:06.320 --> 0:13:10.600 do happen still happen about ten to fifteen miles under 0:13:10.600 --> 0:13:14.160 the ground, which makes them hard to study. 0:13:15.120 --> 0:13:15.280 Well. 0:13:15.360 --> 0:13:19.079 It's difficult to predict earthquakes is we can't see, like there's. 0:13:19.000 --> 0:13:21.840 Rock in the way, so a nice analogy. 0:13:21.920 --> 0:13:25.040 It's quite difficult even to predict what the weather's going 0:13:25.120 --> 0:13:28.559 to be like tomorrow, and in that case, there's all 0:13:28.679 --> 0:13:32.520 kinds of information about the pressures in the atmosphere, the 0:13:32.559 --> 0:13:37.680 temperatures across a whole three D volume, and even then 0:13:37.880 --> 0:13:40.440 our weather forecasts are not exact. 0:13:40.679 --> 0:13:40.959 Right. 0:13:41.640 --> 0:13:43.480 In this case, we're trying to do the same thing, 0:13:43.600 --> 0:13:47.920 except buried under miles of rock, where we don't have 0:13:48.040 --> 0:13:51.839 any or many measurements of exactly what the temperatures are, 0:13:51.880 --> 0:13:53.960 exactly what the pressures are. 0:13:54.559 --> 0:14:00.319 We're kind of blind. Yeah, So the first reason earths 0:14:00.360 --> 0:14:03.120 are hard to predict is that they happen ten to 0:14:03.200 --> 0:14:07.800 fifteen miles and sometimes fifty miles under ten to fifteen 0:14:07.840 --> 0:14:11.560 miles or fifty miles of rock. We don't have a 0:14:11.640 --> 0:14:15.040 direct view or even a way to directly measure what's 0:14:15.080 --> 0:14:19.520 happening down there. Scientists have to infer what's happening from 0:14:19.640 --> 0:14:22.320 what we can see and hear on the surface from 0:14:22.400 --> 0:14:26.520 up here and from satellites and kind of guess what's 0:14:26.640 --> 0:14:30.960 going on. Now, we can drill holes to see what's happening, 0:14:31.320 --> 0:14:36.360 but apparently that's expensive, so we. 0:14:36.440 --> 0:14:37.960 Have drilled into faults. 0:14:38.120 --> 0:14:40.840 For example, there was a hole that was drilled across 0:14:40.840 --> 0:14:45.200 the San Andreas fault perpendicularly through the fault, and if 0:14:45.240 --> 0:14:48.920 not that deep, so it's down I think it was 0:14:49.040 --> 0:14:52.960 two kilometers three kilometers, and from that one hole, we 0:14:53.160 --> 0:14:57.120 have so much more information about exactly what those materials 0:14:57.160 --> 0:15:01.560 look like, what the stresses are in that one hole, right, 0:15:01.640 --> 0:15:04.360 So it's just sampling that one point. But we haven't 0:15:04.400 --> 0:15:06.600 trailed a bunch of holes because each one of those 0:15:06.800 --> 0:15:09.440 holes cost millions of dollars and we don't have that 0:15:09.560 --> 0:15:12.560 much money. 0:15:11.320 --> 0:15:11.800 All right. 0:15:11.920 --> 0:15:14.640 The second reason earthquakes are hard to predict is that 0:15:14.720 --> 0:15:20.080 earthquakes happen basically without warning. Remember I said that earthquakes 0:15:20.080 --> 0:15:23.200 happen because two rock plates are pressing on each other, 0:15:23.760 --> 0:15:26.840 and they're pressing really hard, and at some point something 0:15:27.000 --> 0:15:30.520 gives and the plates slip past each other or one 0:15:30.640 --> 0:15:34.000 goes under the other. Well, that give is really hard 0:15:34.040 --> 0:15:36.800 to know when it's going to happen. It's kind of 0:15:36.840 --> 0:15:39.760 like when you're standing on ice and you're pressing down 0:15:39.800 --> 0:15:42.960 on the ice. It's really hard to tell when exactly 0:15:43.280 --> 0:15:47.240 you're going to slip. Or one analogy or experts like 0:15:47.400 --> 0:15:51.560 us is bending a stick until it breaks. 0:15:54.480 --> 0:15:57.600 An even simpler example is it take a stick and 0:15:57.640 --> 0:16:00.960 you start to bend it. Can you even exactly when 0:16:01.000 --> 0:16:03.520 that stick is going to break before it snaps in half? 0:16:03.560 --> 0:16:05.680 And so this is kind of the same thing except 0:16:05.680 --> 0:16:06.240 in the earth. 0:16:07.040 --> 0:16:09.640 Okay, this is something you can try at home. Rub 0:16:09.680 --> 0:16:13.160 a stick or a wood pencil, or better yet, a 0:16:13.200 --> 0:16:17.480 single stick of uncooked dried spaghetti and start bending it 0:16:17.920 --> 0:16:20.440 as you put more bend into it. You can feel 0:16:20.480 --> 0:16:23.520 the stresses building up in the stick or pencil, and 0:16:23.560 --> 0:16:28.280 at some point you can't predict it's going to snap. 0:16:28.960 --> 0:16:32.200 The same thing happens with these tectonic plates. They press 0:16:32.200 --> 0:16:35.080 on each other, the stress builds up, and at some 0:16:35.200 --> 0:16:39.720 point they crack and slip, and that's an earthquake. Now, 0:16:39.760 --> 0:16:44.320 it's not always totally unpredictable. Sometimes an earthquake will give 0:16:44.360 --> 0:16:48.320 you some warning. It'll give you four shocks. You might 0:16:48.320 --> 0:16:51.760 have heard of after shocks. Those are smaller earthquakes that 0:16:51.840 --> 0:16:54.760 happen after a big one. A four shock is a 0:16:54.800 --> 0:16:58.760 smaller earthquake that happens before a big one. Now you 0:16:58.840 --> 0:17:02.360 might think, wait, are smaller earthquakes that happened before the 0:17:02.400 --> 0:17:05.560 big ones. Doesn't that mean the big ones are predictable. 0:17:06.760 --> 0:17:09.640 Not quite. Only some of them give you four shocks, 0:17:09.800 --> 0:17:12.520 which means it's still unpredictable. 0:17:15.000 --> 0:17:16.960 About ten percent of the time is a four shock, 0:17:17.040 --> 0:17:18.800 but it's most of the time there isn't. 0:17:19.200 --> 0:17:22.520 Although we've gotten really good at detecting really small earthquakes, 0:17:22.640 --> 0:17:26.160 we still don't necessarily see a lot of four shocks. 0:17:26.400 --> 0:17:30.159 In addition, there's nothing different about a foreshock. It doesn't 0:17:30.200 --> 0:17:34.120 look different. There's nothing that we can when an earthquake happens. 0:17:34.119 --> 0:17:36.000 We can't be like, oh, this is a foreshock. 0:17:36.160 --> 0:17:38.320 You can't take the difference between a four shock to 0:17:38.359 --> 0:17:42.520 a big one and just a regular, smaller earthquake, right, Okay, 0:17:42.920 --> 0:17:46.720 So that's why earthquakes are hard to predict. They happen 0:17:46.840 --> 0:17:51.080 ten to fifteens, sometimes fifty miles under solid rock. It's 0:17:51.119 --> 0:17:55.000 a process that happens, usually without warning, just from the 0:17:55.000 --> 0:17:58.680 physics of it. Now, again, does that mean it's impossible 0:17:58.720 --> 0:18:01.640 to predict an earthquake. Well, it turns out there are 0:18:01.640 --> 0:18:05.840 two ways in which we sort of can predict earthquakes. 0:18:06.200 --> 0:18:08.199 So when we come back, we're going to learn what 0:18:08.240 --> 0:18:11.119 those two ways are and what we can do with 0:18:11.240 --> 0:18:24.919 that information. Stay with us, we'll be right back, Welcome back, Okay. 0:18:25.080 --> 0:18:28.040 At the beginning of this episode, I asked our experts 0:18:28.280 --> 0:18:31.760 what the chances are that an earthquake would hit during 0:18:31.800 --> 0:18:34.159 our interview, and we're going to find out at the 0:18:34.240 --> 0:18:37.640 end here. But first I promise there were two ways 0:18:37.840 --> 0:18:42.159 in which we can predict earthquakes. The first is that 0:18:42.200 --> 0:18:44.480 we can cause earthquakes. 0:18:45.840 --> 0:18:50.399 All right, So a fault basically is stuck for most 0:18:50.480 --> 0:18:53.159 of the time, right, And the reason it's stuck is 0:18:53.200 --> 0:18:57.760 because the forces pushing the fault together are higher than 0:18:57.800 --> 0:19:01.840 the forces trying to move it sideways. And so if 0:19:01.880 --> 0:19:05.560 you change how much fluids are in the fault, you 0:19:05.800 --> 0:19:09.480 change if you put a bunch of water in, you're 0:19:09.640 --> 0:19:13.639 effectively reducing that stress that's holding the two sides. 0:19:13.359 --> 0:19:14.119 Of the fault together. 0:19:14.240 --> 0:19:16.000 I see, you're making it slippery, or. 0:19:16.080 --> 0:19:19.760 You're making it easier for the stresses to be larger 0:19:19.760 --> 0:19:21.240 than the stress is holding. 0:19:20.960 --> 0:19:21.760 The fault together. 0:19:21.880 --> 0:19:23.359 So it's like if I was pushing down on the 0:19:23.359 --> 0:19:26.080 table super hard, it makes it really hard for me 0:19:26.160 --> 0:19:27.720 to move my hand sideways. 0:19:27.840 --> 0:19:28.760 But if I. 0:19:28.560 --> 0:19:32.359 Put a bunch of water in here, it's pushing back 0:19:32.440 --> 0:19:34.960 on my hand and making it so it's then easier 0:19:35.000 --> 0:19:38.240 for my hand to move. So one idea is that, well, 0:19:38.359 --> 0:19:41.800 if we could trigger an earthquake, uh huh, then we 0:19:41.920 --> 0:19:46.840 would actually be able to study in detail what happens. 0:19:48.080 --> 0:19:52.359 Yes, that's right. Scientists have actually considered drilling holes and 0:19:52.400 --> 0:19:55.359 pumping a lot of water into a fault in order 0:19:55.640 --> 0:19:57.320 to start an earthquake. 0:19:58.320 --> 0:20:01.239 So this is not just a of idea that we 0:20:01.320 --> 0:20:02.600 came up with today. 0:20:02.720 --> 0:20:04.760 Right, There was actually a meeting. 0:20:04.440 --> 0:20:08.879 A few years ago of folks working on earthquake physics 0:20:09.240 --> 0:20:12.800 where we actually talked about whether it would be possible 0:20:13.000 --> 0:20:17.479 to have an earthquake experiment where we actually would create 0:20:17.560 --> 0:20:18.320 an earthquake. 0:20:18.640 --> 0:20:21.360 It just seems like a terrible idea. 0:20:21.800 --> 0:20:25.280 Most of the workshop consisted of people talking about where 0:20:25.359 --> 0:20:27.920 we would do this because it had to be away 0:20:27.920 --> 0:20:28.880 from people, right. 0:20:29.400 --> 0:20:31.760 I think ideally we would want to have like a 0:20:31.840 --> 0:20:34.000 ranch of magnitudes, Like we're talking about a three or four, 0:20:34.000 --> 0:20:36.080 but if we could create a six or seven, that'd 0:20:36.119 --> 0:20:38.320 be great. Like, there's plenty of earthquakes that happened really 0:20:38.320 --> 0:20:41.040 far away from more people are and like nobody feels them, 0:20:41.119 --> 0:20:43.000 so like it'd be like one of those like. 0:20:44.680 --> 0:20:47.600 Well wait, this is just an idea, right, they haven't 0:20:47.640 --> 0:20:50.000 actually done it, have they. 0:20:51.280 --> 0:20:53.240 Well, yes, I know, we've started lots of little ones. 0:20:53.320 --> 0:20:56.600 Oh yeah, well, I mean the geo thermal regions and stuff. 0:20:56.600 --> 0:20:57.600 They're doing it all the time. 0:20:57.680 --> 0:21:02.840 And there was a purposeful experiment a KTB borehole in Germany. 0:21:03.359 --> 0:21:07.520 So this was think in the nineties where a deep 0:21:07.560 --> 0:21:11.080 borehole was drilled and then they injected fluids and they 0:21:11.119 --> 0:21:15.240 triggered a number of earthquakes, small earthquakes. These were kind 0:21:15.240 --> 0:21:16.480 of magnitude one to two. 0:21:16.880 --> 0:21:20.640 Yeah, okay, So the idea would be to create an 0:21:20.680 --> 0:21:24.720 earthquake in order to get more data and understand them better. 0:21:25.160 --> 0:21:28.240 But we also talked about starting an earthquake to make 0:21:28.280 --> 0:21:30.280 it more predictable. 0:21:31.600 --> 0:21:34.000 Another thing along those lines, if you wanted to say 0:21:34.000 --> 0:21:37.440 we can't predict earthquakes, but we could generate one. Let's say, 0:21:37.440 --> 0:21:39.560 if we think we could generate a magnitude seven or 0:21:39.600 --> 0:21:42.720 eight on the San Andreas. Essentially we would kind of 0:21:42.720 --> 0:21:44.479 speed up the clock for when it would happen. 0:21:45.600 --> 0:21:48.080 What our experts are saying here is if we can 0:21:48.200 --> 0:21:52.080 induce earthquakes, and it looks like we can, then maybe 0:21:52.119 --> 0:21:55.199 for a region like Los Angeles where we know a 0:21:55.240 --> 0:21:58.679 big earthquake is coming, the best thing to do is 0:21:59.200 --> 0:21:59.800 to get it. 0:22:00.080 --> 0:22:03.640 We're with and so we could, you know, evacuate LA 0:22:04.119 --> 0:22:06.440 for a while, pump it as hard as we could, 0:22:06.440 --> 0:22:08.320 and see if we can create a giant earthquake on 0:22:08.359 --> 0:22:11.240 the San Andreas fault, uh huh, and then we've alleviated 0:22:11.240 --> 0:22:13.000 it now for a while, and so people can move 0:22:13.040 --> 0:22:14.959 back into La and like feel safer. 0:22:16.960 --> 0:22:21.920 In other words, we could potentially schedule earthquakes. I mean, 0:22:22.240 --> 0:22:25.360 it doesn't get more predictable than that. Of course, there 0:22:25.400 --> 0:22:27.720 are a few problems with this idea. 0:22:28.880 --> 0:22:31.679 The problem with that is that every large earthquake is 0:22:31.680 --> 0:22:36.199 then followed with many, many aftershocks. So and typically the 0:22:36.280 --> 0:22:40.320 largest aftershock is about only one magnitude unit less than 0:22:40.359 --> 0:22:42.960 the main shock. So if we trigger an eight, we're 0:22:42.960 --> 0:22:47.600 then going to have a magnitude seven aftershock. Plus you 0:22:47.640 --> 0:22:52.679 know many six's, hundreds of five, you know, thousands of fours, 0:22:52.760 --> 0:22:57.440 So how long four years? So in general, aftershock sequences 0:22:57.440 --> 0:23:00.960 can go on for decades, and so just alleviating the 0:23:01.040 --> 0:23:04.200 stress means that you're then stressing all of the other 0:23:04.280 --> 0:23:07.119 faults around it in new ways, and so then those 0:23:07.440 --> 0:23:11.359 can have their own earthquakes. And so maybe it's maybe 0:23:11.359 --> 0:23:12.840 it's not the best. 0:23:12.359 --> 0:23:18.240 Yeah, let's think about that one a little more, all right. 0:23:18.320 --> 0:23:20.840