Latest / Atmosphere with Emily Gracey / Earthquakes 101: Faults, Forecasts & The Human Impact

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Earthquakes 101: Faults, Forecasts & The Human Impact · Atmosphere with Emily Gracey

• Emily Gracey: The ground under your feet isn't as still as it feels. Deep beneath the ground, rocks are under constant stress. Bending, straining, building pressure over time. And at some point, that bend overcomes the stretch of the rock and it breaks. That's an earthquake. And here's the unsettling part. We still don't know when or where that's going to happen. We've got people traveling around the moon. We can't even figure out when the next small earthquake is gonna be, where it's gonna be. For something that can change everything in under a minute, that's pretty humbling. Today on Atmosphere, we are taking a deep dive underground to learn about what causes earthquakes, why some are triggered by humans, and the question that has stumped scientists for decades: will we ever be able to accurately predict them? I'm meteorologist Emily Gracie and this is Atmosphere, a podcast where science becomes conversation. Each week I sit down with the experts behind the forecasts, the research, and the headlines to explore not just the science, but the human stories behind it. Through natural curiosity, we're making science more understandable, more relatable, and hopefully bringing a little more comfort in how we experience the world around us. Hi everyone, Emily Gracie here. Welcome to Atmosphere. Thank you for joining me today. And I have a special guest in the studio. Can you say hi? Hi. This is my daughter, Addison. Addison wanted to help out with today's episode. And well, this is an episode I wanted to do for a while. And the reason? Okay. You want to know why? Yeah. Because there's a lot we don't know about earthquakes. Yeah, yeah, yeah. We think we know them. You're supposed to drop. cover, hold on, maybe stand in a doorway, right? Yeah, we have we have like an earthqu we have earthquake ⁓ drills like once every two months. At school you do? Yeah. Well that's great. Well some of these are actually myths. We're gonna ⁓ bust some of those myths here today. Really? Yes. Today I'm bringing in a guest that I had on my old show off the radar. We did an episode last year about the swarm of earthquakes in Santorini, Greece. Swarm like swarm of bees? Kind of. So today we're talking about what actually causes earthquakes, why we can forecast them but never truly predict them. Do you know the difference between magnitude and intensity? Nope. You're gonna find out too. Bomb, I'm only in second grade. We're gonna find out what human activity has to do with triggering earthquakes. And what you should do right now, today, to be ready. Are you ready? ⁓ maybe. Okay. we're gonna get ready. Sean is a geologist, an educator, and he runs an incredible YouTube channel for anyone who wants to go even deeper into this topic. You too? I thought we weren't allowed to watch YouTube. You can watch his YouTube channel. Yay. All right, I learned so much today, and I think you will too, Addison. Hey, thanks for joining me. Yeah. All right, let's get into it. Well, I've been wanting to do an earthquake episode for a while. And the last one we did was a little bit more focused on volcanoes. And I know they're related. ⁓ but we're gonna dig into it because I realized how little I know about earthquakes, and I think some things have changed ⁓ education-wise since I was a kid. So I wanna dig into all of the things. So that everybody else can get into that information as well. And you are the guy, ⁓ all things geology, right? Well, I'll I try. You have an awesome YouTube channel. So if anybody wants to dig in a little bit deeper and get kind of like that extended version of some of these things, they should definitely check that out. Let's go to like basic earthquake science. ⁓ some of the basics here about like what what causes an earthquake? Because there's a lot of different things, right? Yeah. I mean, great question. Just with with the basics here. So fundamentally think of an earthquake as rocks breaking, right? So just like you take a s ⁓ a stick off the ground and you apply a force to it. You're trying to bend the stick, you know, depending on if it's, you know, a a dead branch or what type of tree it is or whatever. But at some point you you overcome ⁓ the strength of that material and it snaps and it breaks. And that's similar to what happens when an earthquake the rocks in the subsurface are under stress, could be an active Plate boundary, could be magma that's moving up through the system, could be a lot of factors that cause that stress. But ultimately, when the stress that's applied to the rocks exceeds the strength of the rocks themselves, we get the rocks breaking. And there's usually some small movement that accompanies that. And so that energy then is transmitted out as seismic energy. And that's essentially what an earthquake is. But the quickest definition, I suppose, is to think of An earthquake is caused by rocks breaking. Okay. And that can happen naturally and human induced, correct? Yeah. So I mean, we think we think of earthquakes as a natural phenomenon. Of course, they are. Most earthquakes are caused by, you know, forces along plate boundaries, massive chunks of the earth's crust that are trying to push past each other or move apart or slide past each other. And that's where you see most earthquakes happening, like the San Andreas Fault or ⁓ Japan, places like that. ⁓ but we also have human-induced earthquakes. So we ⁓ do enough things just in in the course of civilization that we can cause changes. We can induce earthquakes through the stresses or the things that we're doing in the subsurface. So an example of that would be ⁓ like wastewater injection when we're recovering ⁓ oil and gas out of the ground, we actually inject some of that water and material that we don't want that comes up with the oil and gas, pump it back down into the ground, and that causes more pressure. You're actually injecting that water ⁓ at a tremendous ⁓ pressure and that causes the rocks to actually move, slip, and it basically induces ⁓ earthquakes. Wow. Big little earthquakes, what what causes it? Can that create a big or a little? Is a big earthquake gonna be created by like, say, wastewater injection, or does that require more like plate tectonic? Yeah, to get the really big earthquakes, I mean like the truly damaging, destru destructive, you know, cataclysmic earthquakes, those ⁓ are caused by natural processes. So these ⁓ in human-induced earthquakes tend to produce maybe up to like, I think the biggest one is like a five point eight, which is still like an earthquake that's big enough to be felt. ⁓ and it might cause some. local damage, ⁓ you know, to structures, but in terms of like wiping out a whole city, massive collapses and you know, structures failing, usually that would involves stresses and forces beyond what we can do as humans. And so that would be the natural ⁓ caused earthquakes. I think the number one thing I hear people curious about, which I'm sure you've heard a million times, is about earthquake. prediction and I work in weather, which we can predict weather to a certain degree. Is there any sort of earthquake prediction that can be done? Yeah. So I I think it's helpful here to like distinguish prediction from forecasting, right? And so if we kind of dig into what those two terms mean, at least as ⁓ the way I understand them, prediction is knowing when something's going to happen, not just the event, but its magnitude, its location, its time. So if I said There's going to be, you know, a magnitude 6.0 earthquake underneath Santa Barbara on May 13th, 2026 at 815 PM. That that's a prediction. And then that's really what we want, right? As humans, we'd like to know. Please tell me when the earthquake's gonna happen. I'll put it on my phone. I can get an alert, and then I can deal with the earthquake for a few seconds or minutes, and then I can go about my day, right? That's we don't want earthquakes to be A big inconvenience on us. But really, we can't do that with earthquakes. So we can't predict an earthquake. And that's what makes them different from other natural hazards like a hurricane, like something you're familiar with, is we can see the hurricane. We know its size and strength pretty well. We can track it. We can model where it's going to hit the coast. And the closer that earthquake gets, or excuse me, hurried gets to the coast, the better that that prediction or that forecast is. So we can't do that at all with earthquakes. What we can do is forecast them to with some, you know, some level of not even certainty, but just with with some broad parameters. So what we can do is look at a region that's prone to earthquakes and we can say, well, based on all the earthquakes this area has had and what's going on there, we have a forecast maybe of a magnitude six point ⁓ earthquake in the San Francisco Bay region in the next 20 years. And let's say the probability of that event is like 50% or 60% or whatever. Well, that's that's great scientifically, but it's hard for the public to know what to do with that information. So it's like you've given me a big time frame, like, you know, twenty years or whatever. You haven't even given me much certainty. It's like a 60% chance. ⁓ and so forecasting is the best we can do is look at where earthquakes have occurred in the past, where they're likely to occur in the future, and how big those earthquakes might be, and then just model it and play games with that. So in a way it is kind of like the weather, because we don't We don't know for sure what the weather's gonna do. When I open up my weather app, it says, Hey, on Friday when you're having a barbecue, it's fifty percent chance of thunderstorms after three o'clock. And like, do I cancel the barbecue? Do I continue on? And there's no guarantees there. So I don't know if that makes sense, but that's kind of how we think of earthquakes is more forecasting versus prediction. Gotcha. Okay. That makes sense. ⁓ going back to some like terminology when it comes to basics, the Richter scale. ⁓ And this is something it's an interesting scale because of this exponential growth with it. Can you kind of explain what it is and why it is that way? Yeah, basically it was a way, it was invented by Charles Richter, I think, in the early 1900s. ⁓ and it was just a way to compare earthquakes. And he was just looking regionally in Southern California. He did not I d I don't think he intended it for it to be like a worldwide system of comparing earthquakes, but he was just looking at a way to Compare earthquakes in a given region. And so what it does is the Richter scale basically takes the largest magnitude ⁓ or excuse me, amplitude of waves. So a lot of times when we get an earthquake, we have this little up and down line, what we call a seismogram, kind of like a, you when you go to the doctor, you get a cardiogram that shows just the rhythmic beating of your heart. And so that seismogram, we just look for the largest amplitude sort of spike on that. And then he just had a mathematical formula that would spit out a magnitude based on that. And it is, like you said, it's a it's a logarithmic scale. So it's not a linear scale. It's basically exponential. ⁓ so a magnitude five, for example, ⁓ has is 10 times bigger in terms of wave amplitude, but that's not important to humans. What's really important is it's 32 times the energy. So if you compare a magnitude five to a magnitude four. It's 32 times more energy that's being released and that's being transmitted as shaking. ⁓ so that's a lot. I mean, it's basically like saying if you take 32 magnitude fours, that equals one magnitude five. And so that's kind of the way that's that scale works. ⁓ and I think people intuitively over time, if you're in California or an earthquake-prone region, you kind of know, like, ⁓ you know, a 6.3 is way worse than a 5.6 or something like that. You kind of get a feel. For these kind of subtleties there, but that's actually sort of mathematically how that works. It's energy release and it's a 32-fold increase with each number. Okay. So then there's a difference between like magnitude and intensity. Yeah. So magnitude is the way we think about earthquakes in terms of ⁓ quantifying their energy. So this is based on just a mathematical formula. We measure the earthquake like on a seismogram, we figure out how far it is away, we figure out some. factors in terms of like the rocks it moves through and that and it spits out a number, right? ⁓ so the magnitude of any quake should be the same. If you and I live in the same town and I'm, you know, south of the tracks and you're north of the tracks and we both feel the same earthquake, the earthquake's the same. It's maybe a magnitude 6.3 or something like that. But the intensity is different because maybe you live in a home that is modern, wood wood frame construction is up to seismic codes. and maybe I live in a different home that is 100 years old, made out of bricks. Maybe I live in a part of town that has a lot of sand and mud sediments underneath the home. Maybe there's a high water table. Maybe your home is over solid rock. And so you and I experience a very different earthquake. I would s would feel a lot more intense shaking, all things being equal, than you would based based on the construction style of our homes. the geology under our homes. ⁓ so there's a lot of factors that go into that. So the intensity is how the earthquake's shaking was manifest and all the data that we use for intensity is based on human reports. And so if it's just you and I reporting it, well, you know, we're we're questionable characters maybe. So maybe that's not reliable. But you get a hundred of these or a thousand of these or 10,000 of these reports. And then you start to get a feel for ⁓ you know, how that earthquake actually affected a given area. Does it look at damage too in the way that weather disasters do? Yeah, it looks at damage. And so, you know, after an earthquake, you can go on to like the USGS site. And obviously, you know, if you do experience a s a serious earthquake, you should make sure your home's okay, your loved ones. But after all that's done and maybe your your heart rate's back down, you can go into the USGS site and there's a a did you feel it form that you can fill out and you could say, I was awake, I was in my house, I was on the second floor. Do you, you know, was there damage to your home? And it asks very specific questions and it's multiple choice for the most part. You just click the boxes that are appropriate. And then from that, it takes all those reports from you and others and aggregates all that. And it puts together what we call a shake map. And so the intensity level, it's a different scale than the Richter scale. It's called the modified Mercali. intensity scale and we use Roman numerals instead of numbers. So let's say for example you and I both felt a magnitude 6.3 quake, but your house, wood frame construction on top of solid rock, maybe your intensity level for that earthquake was, you know, ⁓ intensity level six. And maybe my report of that earthquake, because I had a lot more damage to my home and it was really scary. Maybe mine is intensity level eight or nine or something like that. So that's kind of the way it works. Two Very different ways to address how the earthquake affected a region, magnitude and intensity. What are the instruments like that do measure magnitude? And where are they? Are they frequent everywhere? Yeah. I mean, there's different types of like seismometers that are in place. Sometimes they're at ground level, sometimes they're ⁓ you know, ⁓ below ground a bit, usually it's attached to the earth. There's different ⁓ different ones that that record different ⁓ frequencies or has different sensitivities. ⁓ and so it depends on what you're trying to capture. And obviously the more of those instruments you have, the better data you have in terms of like knowing exactly where the earthquake is. ⁓ so if we have, you know, a nice spacing of those over an area, we can not only calculate the location, but we actually can also calculate the depth, how deep it is. ⁓ and so you can get a lot of analysis from that. For the intensity though, what you would want is a lot of people in a lot of places. ⁓ and so if we have a sparsely populated area and there's a major earthquake, a lot of times we don't have a good handle on the intensity. And you could argue it doesn't matter much because there's not a lot of people there. So it doesn't matter how maybe strong that that shaking was per se. So one relies on instruments, one relies on on people and damage, like you talked about with with tornadoes. So what should you do if the world started shaking because I I remember as a kid someone saying like go to a door frame, but then I heard somebody else say that's like outdated information. So can you give me like the latest safety information? Yeah, I hit my students with this question every semester. We kind of like go through this because there is a lot of ⁓ you know, urban legends or misinformation, or it just depends on where you grew up and what you were taught. Your your grandparents told you this or the the school teacher told you to do something. ⁓ It is a bit situational. So, like, you know, obviously, but because most of us spend our time indoors, then we sort of the best place to have an earthquake. If you're gonna, if I said, Hey, Emily, there's gonna be an earthquake in five minutes, go do what you need to do to be as safe as possible. You would obviously go outside, you'd get away from any tall buildings or power poles or even trees, and you would sit down in maybe a big grassy field somewhere, ⁓ you know, the soccer field or something like that. And the earthquake would come and you would. Shake side to side and maybe you get a little scared, and that would kind of be it. ⁓ so it's the structures failing that cause the damage during an earthquake. So what what we advise people to do is to get under some object. Usually, you know, with schools, we we have kids get under desks. That's their earthquake drill protocol, is getting underneath their desk and holding on, or getting underneath a table. ⁓ the doorway is a bit of a fallacy. I'm not sure. There's there's some different ideas about how that kind of Crept into there's Hollywood that's to blame. And there's some different like different things we could point to. ⁓ you know, structurally, the doorway is not the worst place to be. So if I found myself like hanging out in a doorway, you know, maybe having a conversation or whatever with someone, and an earthquake began and the table was like 20 feet away, it probably would make sense to stay in the doorway, but most people are hanging out in doorways during their their day. ⁓ so structurally it's okay, but the doorway has a couple flaws. It's really narrow. ⁓ there's a door on it, so it'll swing back and forth on hinges, might squish your fingers. And you definitely wouldn't want the doorway to be the evacuation location that's in everyone's mind. Cause what if you're in a meeting, conference room with 15 people and there's an earthquake and everyone runs for the same doorway? You're all not gonna fit in that doorway. And then the other problem is you have to get to the doorway. So while you're trying to get to the doorway, the earth is moving in different directions. ⁓ you're maybe you're gonna fall down. There's stuff that could be falling on you. So there's a variety of reasons why we should not be teaching or preaching that the the doorway is the, you know, the the the sacred haven during an earthquake. Just get underneath a sturdy object, your bed, a desk, a table that's close by, hold on, and then that's the best thing you can do. Okay. I have experienced one earthquake in my life and I was in a pool when it happened. ⁓ interesting. So that was really wild. Yeah. So you saw the water slosh back and forth. It didn't really slosh back and forth. I felt the ground moving. And I remember I I was like, I I don't know what's happening here. Like it has to be an earthquake, right? And everybody kind of looked around like earthquake. And then they started yelling, out of the pool. But nobody knew what to do on an earthquake. It was Maryland in like I don't know, whatever that Maryland one was. Yeah. And they probably, you know, maybe they do now, but at at some point I imagine they weren't doing, you know, earthquake drills at schools and now. And that's why we do, you know, whether back to weather, whether it's a tornado or a hurricane, if we don't practice the protocols for what to do when these things happen, then people are lost and then kind of chaos ensues. Mm-hmm. Yeah, it's ⁓ it's interesting that this is the one natural disaster where you do want to be outside. Everything else, it's like you have to take shelter. Yeah, I've never thought of that before. That's ⁓ that that is true. I mean, for the most part, yeah. the exact opposite of what you want to do in a lightning store. Yeah, like you know, like you're if an earthquake starts up when you're playing soccer, like great. Like, you know, I'm just gonna sit down and and deal with that. But yeah. But most of us are indoors for a large portion of the day. So that's why we kind of think about what to do. When we're indoors. Yeah. ⁓ okay, let's talk about like parts of the country and parts of the world that are most at risk for earthquakes and why. Yeah. So definitely ⁓ first and foremost, in terms of just earthquake risk around the world, is going to be these active plate boundaries. So places where we have the edges of these tectonic plates. These are the places where Probably 90 or more percent of all of our earthquakes in a given year are happening. They're also the places where we have typically the most destructive and damaging earthquakes. Some countries are entirely located on these plate boundaries, places like Japan or Chile or Indonesia. other countries, ⁓ not so much, ⁓ like Australia. Although ironically enough, I I did a video this past week and there was an earthquake in right in the middle of Australia. Like, you know, it's far away from The coast as you can get, about as far away from a plate boundary in Australia as you can get. And there was a magnitude 5.5 there. So I guess the lesson is earthquakes can happen anywhere. They do happen literally just about everywhere, but they certainly happen with more frequency and with greater magnitudes on or close to these plate boundaries. So those countries and communities need to be a lot more vigilant ⁓ about, you know, earthquake codes for buildings. ⁓ Just earthquake protocols, like we talked about with you know what to do in an earthquake and places like Japan where they have the resources and ⁓ the technology and the means, they definitely have educated their residents on what to do. And then there's other countries that ⁓ maybe don't have those resources where earthquakes tend to be a lot more fatal, unfortunately. I live in South Carolina now, and there have been A lot of little earthquakes recently. Do you have any information about that? Or if people in South Carolina should be concerned about this? I mean, certainly there's some states in the US that are more active than others. When would as soon as you said South Carolina, my my immediate thought was like, I think there was one in Charleston in like 1883. So like there was there. So the fact that you've had a fairly significant earthquake in South Carolina at some point in the past suggests that you could have that again. ⁓ I don't know what parts of that state, you know, would be the most prone to earthquakes. Interestingly, the East Coast, ⁓ the earthquakes, you could make ⁓ an argument that East Coast earthquakes, including the entire eastern U.S., are not necessarily bigger than West Coast quakes, but they are felt over a bigger area. So if I took, like, let's say, a magnitude seven earthquake on the San Andreas fault, that would certainly cause a lot of shaking and damage, but it would be pretty localized to maybe a couple hundred miles radius, like it wouldn't be felt that far. And that's because in the western US, the rocks that that seismic energy is moving through, ⁓ there's there's places there's other faults, there's different rock types, there's places that where the rocks are hotter. And so that seismic energy doesn't get very far. So people in Las Vegas might not even feel it or just barely feel it. Versus if you take that same earthquake, magnitude seven, and put it in South Carolina or Memphis or someplace like that. Because you have mostly rocks in the eastern US that are very old and brittle and cold and dense, that energy would travel over a much bigger area and people would fill it several hundred miles away with significant intensity and shaking going on there. And so you could argue that a magnitude seven, although less, you know, it'd be less likely to occur back east, and maybe a magnitude five or six would be, you know, something, but even that size earthquake would have a greater impact. On more people than something in the Western US. Interesting. Yeah, that one in the mid-Atlantic back when it was P everybody thought it was in their backyard, but it was like hundreds of miles. ⁓ last time I spoke to you, we were talking about Santorini and the ⁓ swarm of earthquakes that was happening during that time. Can you follow up on what happened there? And then also, can you tell me what swarm actually means? Because I hear that thrown a lot. out of love, but I don't know what it means. I don't know that I've seen a good definition for a swarm. ⁓ sounds like bees. Yeah. Yeah. How many how many bees is a swarm, right? If there's 10 bees buzzing around my head, is that am I being attacked by a swarm of bees? And the same is true with an earthquake. Like what what is the threshold that we would define it as as a swarm? ⁓ certainly I we can say a swarm is a A a series of earthquakes. I don't know how many, but let's say, I don't know, more than 20, 30, whatever the number might be. But they're happening in a very tight geographic area and over a fairly condensed period of time. So you're getting, you know, a bunch of quakes in one area within hours, days, maybe weeks, maybe months, ⁓ like we saw with Santorini. The Santorini one, ⁓ I didn't read all the papers and dig in too much, but the things I did learn after you and I spoke was that. ⁓ there actually was magma. There they did document that magma had moved through the seafloor in the subsurface, some distance. Now it was quite deep though. So it didn't necessarily mean that an eruption was going to take place, but ⁓ it was a combination of fluids and magma movement ⁓ that sort of precipitated a lot of those earthquakes, from what I remember. So ⁓ and now it's quieted down and it's not on the news anymore. And ⁓ this Generally, this is the way things work. And all the doomsday people that thought it was going to erupt, where are they now? Like, you know, those people are they're on to something else. They're looking for some other thing to get us all kind of up in arms about. And that's kind of the way this, you know, sensationalist kind of thing works. Okay. Well, maybe they've moved on to the ones in the middle of the country too, that are happening because of fracking. Can you address those and the different types as well and how they affect what kind of earthquake it creates? Yeah. if you were to look at a earthquake map of the US, you know, ⁓ 50, 60 years ago, you would see, you know, Alaska, California, Pacific Northwest, a big chunk of the Western US, a few kind of where you are, maybe a few in ⁓ you know, South Carolina, ⁓ mid-Atlantic region, whatever. But in the Texas, Oklahoma area, there were essentially very few. There wasn't a lot of earthquakes happening there. But then as we got better with technology, At extracting oil, we came up with new ways to get more of the oil pumped to the surface. And that involved this thing called fracking. And fracking is just hydraulic fracturing, basically creating more fractures and spaces in the rock ⁓ that allows the oil to move through it. We knew the rocks had a certain amount of oil and gas in them, but we couldn't get it all out because the pore spaces that that that material had to move through were very, very small. So by by fracking it or fracturing it, you can cause more of those pores to get intersected. And so it increases the permeability and it allows more you to extract more material. But fracking, it turns out, only lasts for usually when you're developing a well, it's maybe a day or two. So you're not doing it for a very long time. it doesn't really cause that many earthquakes. It there is an uptick for sure in earthquakes, but they tend to be smaller. ⁓ and so the main thing that we see Correlating with the earthquakes we see in like Oklahoma and parts of Texas and these ones recently in northwest Louisiana is this thing called ⁓ wastewater injection. So while we're pumping the well, now when we pump an oil well or gas well, that can go on for years, maybe decades, because it's a productive well. It's continuously supplying us with ⁓ oil and gas. And injection, and as we're pumping that oil and gas to the surface, It's not just oil and gas. The other thing that comes up with it, because it's trapped and mixed with that material, is brackish water or salty water. And we can't just like leave that stuff out at the surface. ⁓ and so the the remedy for that is to inject it back into the ground somewhere nearby, usually deeper than where we're pr producing the material. So we inject it past, you know, the aquifers and the drinking water supplies we might be getting, but that water that's injected back into the ground. ⁓ we we pump it into a layer that has a lot of porosity, a lot of space for that to go into. And that can move out laterally and possibly intersect a fault that's already down there, an old fault that's been that was active maybe millions of years ago. So this fault hasn't done anything for millions of years, but now you're basically pumping this fluid into it and it's like you're lubricating it. It's like the USGS makes a fun analogy. It's like turning on the air hockey table, right? So the puck slides around a lot easier. When the air is blowing through it and the faults can move and slip and produce earthquakes a lot easier when water is injected into it. Cause basically you're you're causing an increase in what we call pore pressure. Basically, the two sides of the fault are being pushed apart by the water injected into it, and that allows them to slide back and forth a little bit easier. Is that like concerning to you? It sounds concerning. I mean, it's sort of a a cause and effect thing. I mean, if you're going to extract as much ⁓ of the oil and gas as you can from a given well and ⁓ fracking and injection is part of that strategy, then that's sort of the the consequence or the effect of that. ⁓ luckily so far we haven't seen anything bigger than like a five point eight, which is kind of a moderate size earthquake. It's enough to cause, you know, potentially some damage of homes, but not enough to like cause fatalities or collapse buildings or or ⁓ roadways or anything like that. So yeah, everything, you know, there's consequences with all actions and and obviously probably a little bit unintended. And I I don't know where all like the regulations are that surround this this practice, but it's but it's ⁓ it's very well documented. So we know what aftershocks are. but what about foreshocks? Are these indicators of something bigger to come? Yeah. So all earthquakes ⁓ have an aftershock sequence, right? So you have ⁓ this buildup of stress, the rocks break, like we talked about, that reverberates out of seismic energy. And now you've created new stress conditions, right? The rocks were in one position. Now, after this big earthquake, or this moderate size earthquake, doesn't matter how big it is, now the rocks have shifted and moved and everything's kind of in a different spot. And so now as as the earth kind of adjusts to this new position, We get aftershocks, but occasionally, it doesn't happen very often. Maybe one out of every 10 or 20 or so earthquakes might have an earthquake before the main shock. It's what we would call a foreshock that precedes it. ⁓ the tricky thing is we can't tell. So let's say it's it's all quiet in South Carolina, and then tomorrow there's a magnitude 4.5. Like you feel it, no damage done, but it got your attention. Well, was that a main shock or is that a foreshock? We don't know. We won't know until we watch over the next few days and weeks ⁓ and maybe months and see what happens. If that 4.5 earthquake was the biggest one and everything that came after was smaller, then we would say, ⁓ a main shock and a bunch of aftershocks. But if the 4.5 occurred and maybe there was a few aftershocks, and then two or two days later there's a 5.3, well, now we can go back, kind hindsight, and look at it and say, ⁓ it was a foreshock. So there's no way of knowing. In the moment that a given earthquake is a foreshock for something bigger. But the big takeaway here is very few earthquakes have a foreshock sequence. It's it's pretty rare. It does occur, but it's pretty rare. ⁓ so we should always assume that the initial earthquake, the bigger of the biggest one typically is the main event, and then you get the smaller ones after. It has to be so frustrating to people not. To be able to predict these because we just live in a time of like controlling everything and everybody gets mad when you don't forecast the exact right amount of snow or exact landfall of a hurricane. So, like, is there still is there progress to be made here or is this kind of the end of the science when it comes to earthquakes? In fifty years, are we gonna be like, Yes, this is where one's happening? Yeah, I mean, ⁓ it's it's it i it is tricky. And as scientists, we of course want to give the most accurate information we can. Our credibility is on the line. So the last thing we want to do is ⁓ you know, make a prediction or make an a ⁓ assumption or some statement that then ⁓ is proven wrong. Cause then it's like, you know, well, they they didn't have that figured out. ⁓ in terms of like, will we ever figure it out? I d I don't know. So if you like dropped yourself back in a time machine in the 50s and sixties and eighties. And looked at the landscape of earthquake prediction, you'd end up with different conclusions. You'd say either like, ⁓ we're 100% we're going to figure this out. We're like right on the cusp. And then other times you'd be like, no, we're never going to figure this out. So, ⁓ so it's it's it's the holy grail of earthquake science is figuring out if we can predict an earthquake, but nothing so far has proven to be a reliable indicator, something that that happens each time that we can use. To predict earthquakes. And we've got all sorts of sensors in the ground. And again, you think like you said, like right now we're we got people traveling around the moon and we can we can't figure out we can't even figure out when the next small earthquake is gonna be, where it's gonna be. Yeah, all those things are still so the best thing we do is ⁓ we go for ⁓ mitigation. We we look to see like, okay, let's just prepare people. We we don't know when this is gonna happen, but it clearly happens in certain places with certain level of intensity and so let's just have people ready at all times. So Okay. So how do we get ready? Yeah. So I think if you live in earthquake country and that could be, you know, most people might think, okay, that's California, that's Japan, that's these, you know, yet yes. But also like you said, you're there in South Carolina and you felt an earthquake and we have a seismic history. You know, your state's not that old. Maybe our country's not even that old. Two hundred and fifty years. And yet we know earthquakes have happened there. So I think ⁓ as a citizen, just knowing where where you sit in terms of the seismic hazard, every state, I believe, has a seismic hazard map and it's color-coded from blue to or green at where where it's a low risk up to red where the risk is high. So I don't know what yours is for South Carolina, but it's probably different in different parts of South Carolina. Maybe the coast is like not so high risk in other parts that are inland where there's rocks beneath there. Higher risk. So people can look at that. They can look at their house and how it's situated. They could find out more about what their house is built on. Certain types of materials fare better in earthquakes than others. And then you can do things like, you know, the simple things. You should have just like with any disaster, having water on hand, some emergency supplies, just kind of being ready, ⁓ having a protocol with your family and friends. Like, okay, what if there's a big earthquake? We can't reach each other by cell phone. Is there gonna be a meeting place we're gonna have? How are we gonna get in touch with each other? yeah, just kind of discussing those things with your kids and and family and and not making it like a lesson in fear, but just like, hey, this could happen. And if we're ready, it's it's no big deal, right? It's like when the power goes out, like, ⁓ bummer, but we can handle this. Mm-hmm. Is there any work being done with AI when it comes to either the prediction of earthquakes or the mitigation? I'm sure I'm not privy to that. And so but I'm sure with just how, you know, ⁓ rampant and and useful AI is today, I have no doubts that there's people using that to see if we can build better models. ⁓ certainly AI is good at like taking huge data sets and like looking for trends. And so I that might be the next big thing in science and geology is like looking at, you know, the earthquakes that I mean you think about all the earthquakes that maybe have happened in Southern California. For a hundred years, like every earthquake of every magnitude. That's an incredibly large number of quakes, knowing that its position, like in three dimensions, knowing its size. and then it might look for patterns and it might help us not necessarily predict an earthquake, but maybe our forecasts become a little bit more ⁓ tight and more detailed. So now it's not 20 years with a 60% probability, but maybe it's something like, hey, in the next three years. There's an 80% probability. Maybe it helps us in that way. Yeah, for sure. Is there anything that you think people are getting wrong when it comes to understanding earthquakes? Anything you just see that's a major misconception with the public? ⁓ boy. There's there's a few things out there. ⁓ I think mechanisms, a lot of people think earthquakes are are triggered by Tidal forces, the position of the the stars, the sun and the moon, those are actually, you know, th those do cause, those are a factor, but they're like, it's so far down, right? It's like you know, like I don't know what a good analogy would be, but it's it's you know, it's a very small ⁓ force that's exerted on ⁓ that generates an earthquake, right? Earthquakes are generally controlled by subsurface forces, stresses between plates, maybe if it's magma movement, it could be fluids in the subsurface. ⁓ and there's no correlation really between, you know, these. So do do do those tidal forces and ⁓ celestial forces are those real and can they be quantified? Absolutely. But they're they're so minute and so small. But a lot of people think that they're triggering the earthquakes. Like, ⁓ yeah, of course you had a magnitude seven point two. There was sunspots yesterday and the the moon was in its this phase or whatever. And ⁓ those just don't hold up under scrutiny when you actually look at the full the full set of data. It's more, you know, correlative kind of ⁓ you know, correlation versus causation, that kind of thing. I have never even heard that. So Yeah. No, if you deep dive, just ⁓ all sorts of the the pseudoscience around earthquakes. ⁓ that's definitely one that I think that's out there that's that's pretty common these days. something I fight, well, I wouldn't say fight, that's the wrong verb, but ⁓ something I contend with ⁓ with a lot of people in Iceland where I I monitor the volcanic situation there is we've had, you know, several eruptions near the capital Reykjavik over the past couple of years. But Every time there's a little flurry of earthquakes, what you and I would call a swarm, like people immediately jump to the conclusion that ⁓ the the there's gonna be an eruption. Like, ⁓ be so just because we have volcanoes erupting in a region, doesn't mean that every earthquake is related to that. Iceland has a plate boundary, an actual divide between two tectonic pieces of crust. And most of those earthquakes are tectonic earthquakes, but there's so many people that think Each earthquake is is the, you know, the harbinger of a volcanic event that's going to take place any in the next day or two. ⁓ and then that that passes and they let it go. And then a couple of days go by and then there's more earthquakes and they're like, ⁓ this this is the one. And so they kind of jump to jump to conclusions a little bit. I kind of understand. I I went to Iceland recently and like the the ground is just boiling everywhere. So the ground's starting to shake. I would be nervous. No, I get it. And it's recency bias. You know, it would be interesting to think, you know, if we went back When was the first eruption? Twenty twenty one was the first actual eruption in Iceland. And then for hundreds of years, 700 years or whatever it was, that there hasn't been any activity in that area. So if we went back to like nine ⁓ twenty nineteen or something like that, would people be as, you know, likely to associate earthquakes with volcanoes when there's no volcanic activity in that area? So I think it's, you know, it's kind of how our brains work and and I understand it. it's harder to be objective. It's easier to kind of You know, and we like it, right? Like, ⁓ like what sounds more exciting. Yeah, when a volcano to erupt. Yeah. Sean, this is awesome. Is there anything else you want to add? Anything we didn't touch upon? Earthquakes happen, can happen anywhere, ⁓ but they're generally concentrated on these plate boundaries and that's where the big ones are. Be aware. Be earthquake aware. Awesome. Sean Wilsy, thank you so much for all of this great information today. I learned so much. Yeah, happy to share. It was fun. A big thanks to Sean Wilsy for joining me on this episode of Atmosphere. I love Sean's energy and the way he explains geology is so understandable. Make sure you check out his YouTube channel. It's called Geology Explained. He has 181,000 subscribers, so you know it's good. If you have any questions about today's show or weather in general, you can always find me on social media. On Facebook, I'm Meteorologist Emily Gracie. On Instagram, just search Atmosphere Podcast. And guess what guys? I'm now on Substack. So if you want to take a deeper dive into the content that I put out in the podcast every week, please subscribe. If you enjoyed today's episode, please follow Atmosphere on YouTube, Spotify, or Apple Podcasts so you never miss a new conversation. And if you have a moment, leaving a rating or review can really help support the show. Atmosphere is a production of Mike Burst. It's produced, edited, and hosted by me, Emily Gracie. 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