The Earthquake That Lasted Two Centuries

Natural disasters can be scary, but they can also be awesome. Like literally, like they evoke awe. And maybe some of that  feeling comes from how quickly these events can come and go. Take the Mount Saint Helens eruption. One day it’s chilling, the next it’s back to chilling… with a bunch of destruction in between. But not all volcanic eruptions  are flashes in the pan. And the same can be said for  many other natural phenomena. From fires that keep burning for millennia, to earthquakes that sha

ke  the ground for centuries, here are four natural disasters that lasted way longer than most. [intro jingle] In 1774, the English explorer Captain Cook observed a volcanic eruption in Vanuatu, an island chain to the northeast of Australia. This eruption was new to him, so he recorded it as something remarkable. But the locals may not have been so impressed, because it had been happening  for the past 500 years or so. Some of us may think of volcanic eruptions as being big, explosive, one-time

events. But people who live near volcanoes, like folks in Hawai’i, Sicily, and, yes, Vanuatu, know they can last for a long, long time. The Vanuatu volcano in question  is known as Mount Yasur, or “The Lighthouse of the Pacific”. And written reports suggest it’s been erupting continuously  since Captain Cook’s visit. But written reports aren’t everything. And scientists suspect it’s  actually been happening much longer than that. How can we prove it? Well, back in 2014, one team of scientists pu

blished a treasure trove of geological  information on Mount Yasur. And by applying some clever chemical thinking, they could even deduce what  was going on in the churning, molten heart of the volcano itself. First, the team reasoned that continuous eruptions would mean the volcano had been constantly dumping ash and volcanic rock into the nearby area. And over time, that ash and rock would build up into neat layers. Well, their reasoning was right on point. The team found well-preserved layers

at a lake just to the northwest of the volcano. And by digging down through these layers, they found evidence that the volcano hadn’t just been active since  Captain Cook saw it in the 1700’s. It appears to have been active  for more than 1,500 years. And it’s been maintaining its  current pattern of low-volume but nearly constant eruptions  for the past 630 to 850 years. It Sounds a bit like counting the rings on a tree to figure out how old it is, doesn’t it? But these scientists did more tha

n count. By analyzing the chemical  composition of the different layers, they revealed that the magma has stayed incredibly consistent over time. That means Mount Yasur is  probably a steady-state system. The amount of magma filling it up from deep within the Earth is the same as the amount exiting out the hole in the top. If it weren’t… if the volcano completely emptied itself and then spent years or decades refilling… you’d expect each batch of magma  to have a different composition. But in a

steady-state system, there’s plenty of time for old and new magma to mix together inside the volcano. Now, Mount Yasur isn’t unique. This type of continuous eruption has appeared in a number of different places around the world, like Hawai’i’s Kilauea and Sicily’s Stromboli. But if you go back in time, there are even bigger, longer lasting eruption s in Earth’s history. For example, the Wrangellia eruptions that happened back in the Triassic Period, located around modern British Columbia, may ha

ve lasted for two million years. And their eruption may have had  another disastrous consequence: they made the world a lot wetter. Back in the 1980’s, there were these two scientists. We’ll call them Mike and…Alastair. Because those are their names. Mike had been looking into the  extinction rates of crinoids, a starfish-like sea animal. Alastair was interested in geology. And eventually, they got to talking about some weird observations that scientists kept finding at one specific point in the

geological record. That point was a roughly two million year timespan in the middle of the Triassic Period, between 234 to 232 million years ago. And the first weird thing they kept finding was a bunch of sandstone and mudstone. Now, that might not sound  weird to any of us at first. But the Triassic is generally thought of as a pretty arid time in Earth’s history, at least across what is now Europe and North America. So for a bunch of mud… which takes, you know, water… to show up in the geolog

ical record was definitely weird. Meanwhile, scientists had been measuring  a bunch of other changes that happened around the same point in history, like changes in ocean chemistry, and certain species suddenly going extinct. So as Mike and Alastair were chatting, they realized it wasn’t a coincidence. They came up with one major  event that could connect them: Massive rainstorms. This new, dramatic idea went out into  the scientific world back in 1989… and it kind of flopped. But over the years

, as people have continued to look at the evidence, it’s gained more and more traction. And today, it’s known as  the Carnian Pluvial Episode. You might have heard it described as “that time in Earth’s history where it rained for two million years.” But the latest research suggests it was more like four distinct episodes in a two million year timeframe, not one two-million year downpour. And each of these episodes wasn’t one long rainstorm, but instead a massive shift in climate. It’s kinda like

if you spent  your whole life in the Sahara and then suddenly found  yourself teleported to India for one of its wet monsoon seasons. You’d still experience sunny days occasionally while you’re there. But on the whole, it’d seem like a disaster. Like your entire world had changed. As for why the Carnian Pluvial Episode happened, scientists still aren’t 100% sure. It was likely due to volcanic emissions from those Wrangellia volcanos I mentioned earlier. But it’s also possible that a new mountai

n range had just formed, and that caused something like a gigantic monsoon weather pattern to emerge. In fact, that’s what the Himalayas  are doing to India right now. But whatever caused the Carnian Pluvial Episode, it did more than bring a bunch more rain to land that hadn’t seen it in a while. It caused environmental  changes all over the globe. From the birth of gigantic river deltas, to the ocean losing much of its oxygen. And of course, all the critters living in these affected regions had

responses of their own. Like dying. Or the opposite of dying. In fact, this is the point in the fossil record that shows dinosaurs finally taking over as a dominant group of animals on land. But we can also see evidence of how much life changed by the appearance of a ton of coal… likely thanks to the rise of big, peaty swamps. And speaking of coal… [3. Mount Wingen Coal Seam Fire] Mount Wingen, or The Burning Mountain, is more of a hill than a proper mountain. It rises only 100 meters or so abo

ve the surrounding countryside, in New South Wales, Australia. But even so, it’s quite a sight. There’s an area which, depending on the source you cite, is either several hundred or several thousand square meters in size and completely devoid of vegetation. But that doesn’t mean it’s starved for color. In some places, the ground is mottled white, red, and purple. And in others you’ll see patches that sport shades of reds, yellows, and grays. But if that’s not enough for you, there’s also a bunch

of steamy fumes escaping up through the rock from meter-long cracks. When westerners came upon  Mount Wingen back in 1828, they thought all this activity may have been volcanic in origin. But today we know it’s actually a coal seam fire. Coal seam fires are pretty much what they sound like: naturally occurring deposits of coal that have somehow caught fire. And they can happen just about anywhere you find coal deposits. But what causes them can vary. Sometimes they start because of human acti

vity. Sometimes they’re caused by Nature itself, like a lightning strike at an exposed seam. They can even self-ignite, which is where geological forces or especially hot weather heat up the ground so much that the coal spontaneously combusts. We don’t know what started the coal seam fire beneath Mount Wingen. But what makes it special is its age. More on that in a minute. The part that’s actively burning is only 5 to 10 meters long at any given time, about 30 meters below the surface. And there

are probably aren’t, like, roaring flames down there. It’s likely a slow, steady smolder that’s been working its way through the coal seam over time. In other words, the fire is slowly moving, which means the hottest part of  the hill above it moves, too. And based on some limited historical records tracking that surface hotspot, the whole fire seems to be moving south by about one meter per year. So by working backwards and looking at the rocks for evidence of previous burning, we think it sta

rted about six kilometers away from its current position. And if you assume that the fire has kept roughly the same pace all this time, that makes the Mount Wingen coal seam fire roughly 6,000 years old. At least those are the numbers you’ll see in most places, including signs around the site itself. But if you search the internet long enough, you’ll find some reports  that claim even older ages, from 15,000 years to over 50,000… to even 500,000 years old. Unfortunately, we don’t have  much more

to go on than that. For such an interesting place, there hasn’t been a lot of peer-reviewed research looking into it. But we do know it was well known by the people who lived in the  area before Europeans arrived. The Wonnarua people had been coming to Mount Wingen for generations. Not only did they take advantage of the heat, but they collected chemicals like sulfur to make a variety of products, like paints and medicine. In fact, the first Westerner to make a fuss about the  landmark reported

ly only did so after some locals told him it was a burning hill. But just like the lack of research into the coal seam fire itself, there also doesn’t appear to be much literature about the Aboriginal history  and archaeology of the site. If we ever do learn more about Mount Wingen, let’s hope we don’t have to wait 6,000 years. For our final natural disaster, we’re staying underground, but we have to change hemispheres. And we’re switching over to what’s probably the most obvious kind of ground-

based disaster. Earthquakes. Back in 1811 and 1812, three big earthquakes struck New Madrid, a Seismic Zone that straddles several states like Missouri and Tennessee. Locally, these quakes had magnitudes between 6.7 and 8.8. They were powerful enough to knock down chimneys and open up some fissures in the ground. But since the region wasn’t super populated, the overall damage wasn’t too severe. And yet, the effects of these quakes radiated out to the rest of the US. Reports tell of church bells

ringing all the way in Boston, over 1,700 kilometers away! And for the past two centuries, earthquakes have been a somewhat regular occurrence in New Madrid. But is each one a new earthquake? Or are they just the aftershocks of those original big 1800’s quakes? To begin to answer that question, we need to understand what an aftershock even is. Earthquakes happen when stress builds up in the rocks beneath our feet, like when two tectonic plates are trying and failing to slide past each other. It

builds up and up and up, and then suddenly gets released all at once. But much like my body after a half hour massage, not all of the stress goes away. Some of it’s left behind. And not only that, the pushing and twisting of  the rock during the quake can add stress to rocks over yonder just minding their own business. So when the original rocks readjust again, or the rocks nearby end up doing a bit of slipping themselves, that’s an aftershock. And it’s important to know how much of your seismic

activity is due to new quakes or aftershocks. Because aftershocks eventually fade over time. Even if they’ve been going for 200 years, the New Madrid zone would eventually quiet down. At least until the next “big one”. But if it’s mostly new earthquakes, it probably means this seismic activity is here to stay. And if you’re a bunch of  humans living in the area… you should probably consider making a few policy changes. As such, some municipalities within the New Madrid area have invested in com

ing up with specific earthquake disaster plans and stricter building codes. Now, scientists might not feel comfortable judging whether or not those  investments are worth it. But they can try to figure out how many of the proverbial squiggles  on their charts are aftershocks. And one team did just that, in a 2023 paper published in the Journal of Geophysical  Research: Solid Earth. They looked at seismic activity from the New Madrid Seismic Zone between 1980 and 2016, and used a statistical anal

ysis they call the “nearest neighbor” method. It’s pretty math-y, but it basically looks at how big and how close in time, distance, and magnitude any given earthquake’s neighbors are… and then compares that data against what we expect of big earthquakes to see  if any of them are related. It takes into account things like the fact that aftershocks tend to happen close to the original quake. And that a new earthquake’s biggest aftershock tends to be 1 to 1.2 units of  magnitude weaker than its p

arent. Based on their fancy nearest neighbor math, most of the modern New Madrid  quakes appear to be new. But that would make about 23% of them aftershocks with a shared origin over two centuries old. Unfortunately, that math can’t say exactly  what’s happening underground to cause all these aftershocks. And it leaves a pretty  important question unanswered. Why is this part of North  America so seismically active? Missouri isn’t exactly what we normally think of as earthquake country. It’s now

here near any big tectonic rift systems. So scientists have a lot of ideas. But one of the more compelling is that this New Madrid activity may stem from the nearby, 500-million year old Reelfoot Rift. This rift is a geological scar that formed after the North American plate started to pull itself into two halves… and for whatever reason just…stopped. Which is a thing that is so cool, that it has its own SciShow episode!] And if Reelfoot really is what’s behind New Madrid’s quakes, including the

ones from the early 1800s, then we’re looking at a set of natural disasters that were half a billion years in the making! And that’s long enough for the Earth itself, with its four and a half billion year lifespan, to think is pretty awesome, too. Thanks for watching this episode of SciShow. Today, we’re brought to you by our very own merch. But not just any merch. We’ve got a couple of items to help you celebrate an event that’s basically going to be the opposite of what we’ve talked about thi

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