# Why do earthquakes happen?

An episode of [Science for Kids / Science's Not Boring: The Kids Science Podcast](https://invisiblenetwork.ai/podcast/1896928296), 23 Aug 2026, 12 min.

Audio: https://www.buzzsprout.com/2624612/episodes/19652633-why-do-earthquakes-happen.mp3

Have you ever wondered why the ground can suddenly shake, crack, and roll like huge waves on a beach? Join Mira and Finn on an earth-shattering adventure to find out what really causes earthquakes! Did you know the ground beneath your feet is actually broken into giant puzzle pieces called tectonic plates? They are always moving, but usually only as fast as your fingernails grow! But watch out! When these massive, jagged rocky plates get stuck together, the solid rock can actually bend like a giant rubber band. And when the pressure gets too high... SNAP! The rock breaks and releases unbelievable energy, sending super-fast invisible waves shooting through the ground! In this exciting episode of Science is Not Boring, we uncover the mystery of the 1906 San Francisco earthquake and discover how solid rock moved 21 feet in just seconds! We'll learn the big difference between speedy P-waves and destructive S-waves, how scientists use incredible early warning systems to keep people safe, and why places like Florida get to skip the shaking. Plus, explore the famous, volcano-filled Ring of Fire! Get ready to rock and roll!

## Transcript

[0:46] SPEAKER_01: Welcome to Science is Not Boring by Kidopoly.com.
[0:50] SPEAKER_01: I'm Mira! And I'm Finn.
[0:52] SPEAKER_01: Before we start, we have a huge shout-out today.
[0:55] SPEAKER_01: A big hello to Carson, who is seven, in Pensacola, Florida.
[1:00] SPEAKER_01: Hey Carson, thanks for listening.
[1:02] SPEAKER_01: Carson asked an amazing question.
[1:05] SPEAKER_01: What is an earthquake and why does Florida not get them?
[1:09] SPEAKER_01: This entire episode is dedicated to you.
[1:12] SPEAKER_00: Yeah, what exactly is an earthquake?
[1:15] SPEAKER_00: The idea of the ground just suddenly shaking and cracking open is a little freaked out.
[1:20] SPEAKER_00: I mean, a little scary.
[1:22] SPEAKER_01: It is wild! But did you know that the Earth never actually stops moving?
[1:27] SPEAKER_01: The National Earthquake Information Centre locates about 55 earthquakes every single day.
[1:34] SPEAKER_00: Wait, 55 a day?
[1:36] SPEAKER_01: Why aren't we feeling them right now?
[1:39] SPEAKER_01: Because most of them are tiny microquakes happening deep underground or far out in the ocean.
[1:44] SPEAKER_01: But when a big one happens, the ground can literally roll like waves on a beach.
[1:50] SPEAKER_00: Okay, but how does solid rock roll like a wave?
[1:53] SPEAKER_00: And can scientists warn us before it happens?
[1:56] SPEAKER_01: That is exactly what we are going to find out.
[1:59] SPEAKER_01: Let's crack this mystery wide open.
[2:01] SPEAKER_01: Okay, to understand earthquakes, we have to look at the ground we are standing on.
[2:06] SPEAKER_01: It feels solid, right?
[2:08] SPEAKER_00: Yeah, pretty solid to me.
[2:10] SPEAKER_00: I can jump up and down and it doesn't break.
[2:12] SPEAKER_00: Well, the Earth's crust isn't actually one big solid shell.
[2:17] SPEAKER_01: It's broken into giant puzzle pieces, called tectonic plates.
[2:21] SPEAKER_01: Puzzle pieces?
[2:23] SPEAKER_01: How big are we talking?
[2:24] SPEAKER_01: Massive! The North American plate, which is the one we live on, is millions of square miles in size.
[2:32] SPEAKER_01: And these plates are shifting over a layer of super hot, solid rock deep inside the earth, called the mantle.
[2:39] SPEAKER_00: Wait, so the ground we are on is basically sliding over solid rock?
[2:44] SPEAKER_00: Are we moving right now?
[2:46] SPEAKER_01: We are, but very, very slowly.
[2:50] SPEAKER_01: Tectonic plates move about one to two inches a year.
[2:54] SPEAKER_00: Phew! One or two inches a year is nothing.
[2:57] SPEAKER_00: That's so slow.
[2:59] SPEAKER_00: It is! In fact, that's exactly the same speed that your fingernails grow.
[3:04] SPEAKER_00: Whoa, my fingernails?
[3:06] SPEAKER_00: That is a brilliant comparison.
[3:09] SPEAKER_00: But if they move so slowly, why do they cause huge, violent earthquakes?
[3:14] SPEAKER_01: Because the edges of these plates aren't smooth like glass.
[3:18] SPEAKER_01: They are jagged, rocky, and extremely rough.
[3:21] SPEAKER_01: So when two huge tectonic plates slide past each other, their edges catch and get stuck.
[3:28] SPEAKER_00: Uh-oh.
[3:28] SPEAKER_00: So the bottom part of the plate is still trying to move, but the top part is jammed.
[3:34] SPEAKER_01: Exactly.
[3:35] SPEAKER_01: The rest of the plate keeps slowly moving, pushing and pulling, but the edges are locked tightly together.
[3:41] SPEAKER_01: That builds up an unbelievable amount of pressure over decades or even centuries.
[3:48] SPEAKER_01: It's like pushing two pieces of sandpaper together as hard as you can and trying to slide them.
[3:54] SPEAKER_00: So, how did scientists figure out that these massive plates were getting stuck?
[3:58] SPEAKER_00: Did they have to dig a really deep hole into the crust?
[4:01] SPEAKER_01: Actually, they figured it out after a massive disaster.
[4:05] SPEAKER_01: In 1906, a terrifying earthquake struck San Francisco, California.
[4:11] SPEAKER_01: It shook the city so hard, the buildings collapsed and huge fires broke out.
[4:18] SPEAKER_00: Oh no, I bet a lot of people were scared.
[4:21] SPEAKER_00: What did the scientists do after the shaking stopped?
[4:24] SPEAKER_01: A famous geologist named Harry Fielding Reed went out to carefully study the broken ground.
[4:30] SPEAKER_01: He studied the massive rupture along the already named San Andreas Fault.
[4:36] SPEAKER_00: How big was the crack exactly?
[4:38] SPEAKER_00: Like across a whole street?
[4:40] SPEAKER_01: Way bigger! The ground had ripped open for 296 miles! And the craziest part?
[4:48] SPEAKER_01: The land on one side of the crack had slid past the other side by up to 21 feet in just a few seconds.
[4:56] SPEAKER_00: 21 feet?
[4:57] SPEAKER_00: That's longer than a large car.
[5:00] SPEAKER_00: How did solid rock move that far, that fast?
[5:03] SPEAKER_01: Reed came up with something called the elastic rebound theory.
[5:07] SPEAKER_01: He realised that rock is actually elastic under extreme pressure.
[5:11] SPEAKER_00: It can bend.
[5:13] SPEAKER_00: Rock can bend?
[5:14] SPEAKER_00: I thought it would just shatter into dust if you bent it.
[5:18] SPEAKER_00: It takes incredible force, but it does bend.
[5:21] SPEAKER_01: Think of a thick rubber band.
[5:23] SPEAKER_01: If you pull it and pull it, it stretches, storing up potential energy.
[5:28] SPEAKER_00: Yeah, and if you pull it too far, it snaps and hits your finger, which really hurts.
[5:35] SPEAKER_01: Exactly! For decades, the tectonic plates were stuck, but they kept pushing, causing the solid rock to actually bend and warp, storing up all that energy.
[5:47] SPEAKER_00: Oh wow! So the pressure gets higher and higher until finally the rock can't hold on anymore and just explodes forward.
[5:55] SPEAKER_00: SNAP!
[5:56] SPEAKER_01: The rock finally breaks and suddenly shifts back to its normal shape.
[6:00] SPEAKER_01: All that stored energy from decades of bending is released in a split second!
[6:06] SPEAKER_00: And that sudden snap is the earthquake.
[6:09] SPEAKER_00: But how does a snap deep underground shake houses that are miles away?
[6:14] SPEAKER_01: The energy shoots out in invisible ripples called seismic waves, and they are incredibly fast.
[6:21] SPEAKER_00: The first ones to arrive are called P waves or primary waves.
[6:25] SPEAKER_00: How fast are P waves?
[6:27] SPEAKER_00: Like as fast as a supersonic jet airplane?
[6:31] SPEAKER_01: Way faster! P waves travel through solid rock at 3 to 5 miles per second.
[6:37] SPEAKER_00: That's more than 10,000 miles per hour! Miles per second?
[6:43] SPEAKER_00: That is mind-blowing! What do they feel like?
[6:46] SPEAKER_01: They move by squishing and stretching the ground, kind of like pushing and pulling a slinky toy.
[6:52] SPEAKER_01: But the real danger comes right after, with the S-waves or secondary waves.
[6:58] SPEAKER_00: Are S waves even faster?
[7:00] SPEAKER_01: No, they are a little slower, travelling about half a mile to three miles per second.
[7:06] SPEAKER_01: But they move the rock violently side to side, which is what shakes buildings apart.
[7:11] SPEAKER_00: That sounds so dangerous.
[7:14] SPEAKER_00: Is there any way to know an earthquake is coming before the heavy shaking starts?
[7:18] SPEAKER_01: We can't predict them days in advance, but scientists have created incredible early warning systems.
[7:25] SPEAKER_01: Because P waves arrive first, special sensors can detect them instantly.
[7:30] SPEAKER_00: Oh, and since S-waves are slower, the computers can send out a warning before the heavy destructive waves arrive.
[7:38] SPEAKER_01: Exactly! Systems like Shaker can send emergency warnings to mobile phones, seconds or even a minute before the damaging S waves hit.
[7:48] SPEAKER_01: That gives people precious time to drop, cover, and hold on.
[7:53] SPEAKER_00: For you, I'm glad scientists are using those super fast P waves to keep people safe.
[7:58] SPEAKER_00: But wait, what about Carson in Florida?
[8:01] SPEAKER_00: Will he get an earthquake warning?
[8:04] SPEAKER_01: Great point! Carson asked why Florida doesn't get earthquakes.
[8:08] SPEAKER_00: It all comes back to those giant puzzle pieces, the tectonic plates.
[8:12] SPEAKER_00: Is Florida not sitting on a tectonic plate?
[8:15] SPEAKER_01: It is, but Florida sits in the stable interior of the North American plate.
[8:21] SPEAKER_01: Remember how earthquakes happen where the edges of the plates grind together.
[8:25] SPEAKER_00: Oh, because Florida is safely in the stable interior of the giant puzzle piece, it's super far away from the jagged edges where the plates are getting stuck.
[8:34] SPEAKER_01: You got it! Places like California are right on the western edge where the North American plate meets the Pacific Plate, which is why they get so many quakes.
[8:44] SPEAKER_00: Florida is in a very stable, peaceful spot geologically.
[8:48] SPEAKER_00: That's awesome news for Carson.
[8:50] SPEAKER_00: So Florida is basically just going along for a very smooth ride.
[8:55] SPEAKER_00: Okay, what is the biggest earthquake ever recorded in human history?
[9:00] SPEAKER_01: That absolute monster of a quake was in Valdivia, Chile in 1960.
[9:05] SPEAKER_01: It was a staggering magnitude 9.5, which released an unimaginable amount of energy.
[9:12] SPEAKER_01: The shaking lasted for an entire 10 minutes.
[9:21] SPEAKER_01: It really would.
[9:22] SPEAKER_01: Chile is located on a very active plate boundary.
[9:26] SPEAKER_01: In fact, almost 90% of all the world's earthquakes happen in a massive ring completely surrounding the Pacific Ocean.
[9:34] SPEAKER_00: Does this famous earthquake ring have a cool name?
[9:37] SPEAKER_01: It sure does.
[9:38] SPEAKER_01: Scientists call it the Ring of Fire, because it's completely lined with hundreds of active volcanoes and deep ocean trenches.
[9:47] SPEAKER_01: Alright Finn, time for the quiz.
[9:49] SPEAKER_01: Are you ready?
[9:50] SPEAKER_01: Okay, I'm ready.
[9:53] SPEAKER_01: First question.
[9:54] SPEAKER_01: What are the giant jigsaw puzzle pieces of Earth's crust called?
[10:02] SPEAKER_01: Next one, what speed do tectonic plates move at?
[10:10] SPEAKER_01: Question three.
[10:11] SPEAKER_01: Who discovered the elastic rebound theory after the 1906 San Francisco earthquake?
[10:20] SPEAKER_01: Here's number four.
[10:22] SPEAKER_01: Which seismic waves travel faster, P waves or S waves?
[10:30] SPEAKER_01: Last question.
[10:32] SPEAKER_01: Why doesn't Florida get many earthquakes?
[10:38] SPEAKER_01: Great job! Let's see how you did.
[10:41] SPEAKER_01: The first answer is they are called tectonic plates.
[10:45] SPEAKER_01: For question two, they move at the speed your fingernails grow, about one to two inches a year.
[10:52] SPEAKER_01: Number three, the answer is Harry Fielding Reed.
[10:56] SPEAKER_01: Question four, P waves travel much faster, up to five miles per second.
[11:03] SPEAKER_01: And the final answer is Florida is safely in the stable interior of a tectonic plate, far from the edges.
[11:11] SPEAKER_00: I still can't believe the ground beneath us is constantly moving, even if it's just the speed of a growing fingernail.
[11:18] SPEAKER_01: I know! And the fact that solid rock can bend like a rubber band before snapping is so incredibly cool.
[11:25] SPEAKER_00: If you loved learning about tectonic plates today, please leave us a five-star review.
[11:31] SPEAKER_00: Tap those stars faster than a P wave.
[11:33] SPEAKER_00: Just scroll down and tap the stars.
[11:36] SPEAKER_01: Oh, and don't forget to check out our site kidopoly.com.
[11:39] SPEAKER_00: We've got tons of fun learning games and activities there.
[11:43] SPEAKER_00: Want your name on the show like Carson?
[11:45] SPEAKER_00: Send us an email at hello at kidopoly.com.
[11:49] SPEAKER_01: See you next time on Science Is Not Boring.
[11:52] SPEAKER_01: Bye, everyone.
[11:53] SPEAKER_01: Bye.

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