Cascadia: The Earthquake that will Destroy Westcoast America

It

will

be one of the largest

earthquake

s in history. When the Big One finally reaches the west coast of the United States, it

will

unleash carnage on a scale rarely seen. Buildings will collapse, burying thousands of people under the rubble. Fires will break out, devastating entire city blocks. There will be landslides, dam failures, chemical spills… things that, taken alone, would qualify as one of the worst disasters this side of Hurricane Katrina; but, together, they will affect millions. And that's just for starters. Minutes after the shaking begins, a massive tsunami will arrive, devastating coastal communities and flooding hundreds of thousands of square kilometers.

By the time the wave recedes, North America will have witnessed the worst natural disaster in its history. The culprit of all this misery? The Cascadia Megathrust Fault, an offshore subduction zone capable of releasing so much energy, would make the legendary San Andreas Big One look like a mere wobble. But rather than being a hypothesis, this mega

earthquake

will soon become a reality. Estimates that this will happen in the next fifty years range from a worrying one in ten to a terrifying one in three. Today we explore both the history of Cascadia... and its apocalyptic future. The wave of orphans The day before the wave arrived, there were no signs that anything was wrong.

It had been a mostly clear afternoon on all the islands. The sun was shining, the air was cold and crisp. Apart from a few patches of cloud here and there, it was as reasonably pleasant a day as could be expected in winter. Significantly, no one in all of Edo-period Japan had felt any tremors. None of the earthquakes that characterized life within the Pacific Ring of Fire had occurred. That meant that when people went to sleep that night, they were completely unprepared for the disaster that would soon befall them. Shortly after passing midnight on the eighth day of the twelfth month of the twelfth year of the Genroku era, or what we would call January 27, 1700 AD, the wave arrived.

It arrived silently, without warning. From tip to tip, it measured something in the region of 600 miles. But it wasn't the length of the tsunami that caused the problems, but its height. At its peak, the water reached 16 and a half feet. The most affected area was the Miyako Bay area. In Kuwagasaki, 13 houses were razed and fires were started that

destroy

ed another 21 buildings. In Tsugaruishi, floodwaters fell half a mile down the main street,

destroy

ing homes and nearly washing away a shrine. Along the eastern coast, rice fields were damaged, houses were flooded and goods stored in government warehouses were destroyed.

The most dramatic moment may have occurred in Tanabe, where the mayor watched in horror as the castle's moat broke. But even in the least affected areas, people continued to flee to the hills. However, once the waters finally receded, people did not focus on the damage. It was that the wave had occurred. Japanese records on the relationship between earthquakes and tsunamis date back to at least the 6th century. It's all part and parcel of surviving in one of the most seismically active countries in the world. But the tsunami of 1700 came without any tremors. He had simply appeared in the night: a god of death rising from the ocean like a totally stupid version of Poseidon.

If Edo period Japan had been less isolationist, they would have realized that they were not the only ones dealing with the mystery. Some 4,600 miles away, native North American tribes struggled to understand what they had just seen. Approximately ten hours before the orphan wave swept across Miyako Bay, the land beneath the feet of the Nuu-chah-nulth people, the Makah, the Yurok, the Tolowa, and hundreds of others had shifted violently, transforming the landscape. However, unlike the Japanese, the indigenous people of the Pacific Northwest did not keep written records. Instead, they recorded their stories orally, telling stories that encoded both legends and great events of the past.

And the events of that night were, without a doubt, some of the greatest any of them had ever seen. Thunderbird's Shadow The night Thunderbird attacked, she gave no warning. It was a dark, miserable afternoon, the kind of afternoon that is a staple of life when you live in the Pacific Northwest and it never seems to stop raining. In the midst of this darkness, Thunderbird suddenly descended from the sky: vast, invisible. She picked up her nemesis Whale with her claws and dragged him through the air. She dropped him high into the night sky and Whale crashed to Earth.

The strength of her body shook the world. In the bay, the waters receded and returned to the ocean. The wiser ones saw what this would mean and got into their canoes. They were the ones who survived. After the battle came the flood. When the waters rose again, the villages disappeared. People were dragged away. Those who survived saw strange scenes afterwards, such as canoes stranded in trees. The battle between Thunderbird and Whale was felt throughout the Pacific coast. For some who later told the stories, Thunderbird was the hero who defeated the evil Whale. For others, she was the evil one and attacked the innocent Whale.

However, others insisted that the battle took place not between Thunderbird and Whale, but between Thunderbird and Transformer, the one who created the world. But the mythical battle between these two great titans was only one of the explanations that emerged for the Earth's shaking and flooding that night, an explanation that focused primarily on modern Oregon. Further afield, very different indigenous tribes came up with very different stories. On Vancouver Island, the Huu-ay-aht First Nations told stories of dwarves who lived on a giant mountain. That night they invited a man to dance around his drum. But the man accidentally kicked the drum and the sound got trapped in his foot.

From that moment on, wherever he walked, his every step created an earthquake. As soon as he set foot off the mountain, it caused an earthquake and a flood that wiped out entire towns. In Northern California, the Yurok people told a similar story. They claimed that a being called Earthquake that had large, heavy feet ran up and down the coast. Each step caused the earth to open and the ocean to flood. According to an oral history collected more than 150 years later, the Yurok had gathered on a large hill and performed a jumping dance to ward off the earthquake.

But although he eventually left, the devastation remained. When they descended the hill again, the Yurok found everything they had known lost beneath a sheet of water. The story told by the Tolowa people was even more terrifying. They focused not on the earthquake or the shaking ground, but on the waters that followed. Everyone the water touched immediately turned into a mass of coiled snakes. The only Tolowa survivors were a teenage boy and girl who managed to escape the flood by climbing a hill. When they fell ten days later, the entire world had been swept away and replaced with sand, and it was only their children who kept the human race from going extinct.

There are dozens more stories like this, and probably hundreds more that were lost to history. But they all have one thing in common. They are the only surviving accounts of what happened that night. What happened when the Cascadia Megathrust fault unleashed its last massive earthquake in 1700, off the coast of the Pacific Northwest? Registering at least 9.0 on the Richter scale, and probably higher, it transformed the land from California to British Columbia and unleashed the orphan wave that would so shock Edo Japan. However, although these stories would still be told well into the 20th century, no one would think of taking them seriously as part of history.

No one would ever assume they were anything more than legends. By the time modern scientists discovered the truth behind them, it would be too late. The Beast Below Now that we've seen what the Cascadia Subduction Zone is capable of, at least in mythologized form, it might be a good time to discuss what it really is. Where did it come from and how on earth is it able to generate earthquakes powerful enough to create its own mythological cycles? The first part of that question is easy. Just off the west coast of the United States, the vast North American tectonic plate comes into contact with the much smaller Juan de Fuca oceanic plate.

However, this is “minor” on a relative scale. Juan de Fuca still measures ninety thousand square miles. Plates like these are always in motion. Advancing and reorganizing over millions and millions of years, taking us from a world where there are supercontinents like Gondwana, to one where we have the continents of today. In an ideal world, all of this super-slow movement would be accomplished without a hitch. The tectonic plates would slowly advance over the centuries and we wouldn't even notice. But this is not an ideal world. And, in our less than ideal world, these plates often get stuck.

When they get stuck, failures arise. And where there are faults, earthquakes often occur. The most famous fault of all is probably the San Andreas Fault in California. That fault is caused by two plates moving parallel in opposite directions (in this case, the North American and Pacific plates) and getting stuck together. When enough pressure builds up, the plates eventually move forward, called a strike-slip fault. But there are other types of faults that operate in completely different and more dangerous ways. Cascadia is one of those failures. Off the Oregon coast, the Juan de Fuca plate is doing its best to push its way under the North American plate, a process known as subduction.

It should carefully slide underneath, but instead it got stuck. As a result, the North American plate is compressing, and the entire land mass is compressing about an inch and a half per year. As the plate compresses, the pressure increases. When the Earth finally becomes too much to support, the plate will suddenly shift and all that energy will be unleashed. The result? Well, let's look at a list of famous earthquakes caused by subducting plates: Alaska, 1964. Death toll: 131. Chile, 1960. Death toll: up to 7,000. Japan, 2011. Death toll: more than 18,000. In other words, there is a chance that the Cascadia earthquake could turn out to be a big deal.

But that's just its potential. Although the fault extends between 600 and 700 miles (from Cape Mendocino, California, to Vancouver Island), not all regions are equally active. The central area is quite quiet. Almost silent. On the other hand, the northern and southern areas show constant activity. This is interesting and, in some ways, relieving, because failures do not necessarily manifest themselves all at once. The most likely chance for the next big Cascadia earthquake is for only the southern section, centered around northern California, to disappear. In that case, the resulting earthquake would register around 8.0 or 8.6 on the Richter scale. That's still great.

Almost as big as the legendary San Andreas Big One will be. But it is not an event of the magnitude of Armageddon. In modern history, the United States has had at least four larger earthquakes, although none of them took place outside of Alaska. On the other hand, it is possible that the entire Cascadia fault will give way. This, known as full margin rupture, could produce an earthquake with a magnitude of 9.2. Because the Richter scale is logarithmic, a Cascadia megaquake would be about 30 times larger than anything the San Andreas Fault could produce. It would be the joint largest earthquake in United States history, along with the 1964 Alaska earthquake, and the second largest earthquake the world has ever seen.

But the strange thing is that Cascadia almost never produces small earthquakes. If you live in the Pacific Northwest, you've probably never felt even a moderate 4.0 earthquake—the kind that wakes you up wondering if your bedmate ate too many chili burritos the night before. This lack of severe earthquakes is almost the opposite of what would be expected to happen in a subduction zone. And it's why no one discovered what Cascadia was capable of until the 1980s. By then, we'd already spent centuries building alongside it some of the most earthquake-vulnerable cities in American history. Finding the Flaw That we discovered Cascadia is due to pure dumb luck.

When Lewis and Clark arrived in Oregon in 1805, more than a century had passed since the last complete breach of the margin in 1700. The land they found was peaceful and quiet. Apparently the ideal place to build new settlements. Never mind all those persistent Native American and First Nations stories about the land becoming unstable. That was just a lot of buffalo dung, right? White settlers continued to think that well into the 20th century. Even when theGeologists identified the Cascadia subduction zone in the 1970s, everyone said, “Well, there's never been a serious earthquake in Oregon. It must be a seismic fault!

In fact, they were so sure Cascadia was idle that the U.S. Nuclear Regulatory Commission began planning a series of nuclear power plants in the region. Just before giving the green light, the Commission decided to consult with the United States Geological Survey and make sure that the fault was as harmless as everyone assumed. The USGS came back with two possibilities. Possibility one: Cascadia really was a super silent failure. Possibility two: it was a Chile-style foul. This made everyone immediately sit up and start paying attention. Chile is a big problem in the earthquake field, because it is home to some of the worst on Earth.

The largest earthquake in recorded history occurred off the coast in 1960 and killed about 7,000 people. That earthquake was also caused by a subduction fault. If Cascadia really was like Chile (mostly peaceful, but occasionally apocalyptic), who knew what it might be capable of? Over the next few years, scientists began seriously studying the Pacific Northwest for signs of a previous megaquake. In 1984, they began to find evidence of huge floods, landslides and tsunamis. But not enough to declare Cascadia active. Finally, geologist Ruth Ludwin of the University of Washington had an intriguing idea. There may be no written records of a pre-European earthquake in the region, but what about native oral histories?

So they checked West Coast stories for potential candidates. What they found was terrifying. There were over 40 myths, spread across various tribes, that seemed to record a massive earthquake and tsunami. When an approximate range was given to those that could be dated, it was found that they all clustered around 1700. Clearly, something was happening. Over the next few years, increasingly rigorous analyzes were conducted and more surveys were conducted. Finally, in 1996, scientists writing in Nature discovered the last time Cascadia had unleashed the Big One. At 9 p.m. on January 26, 5:00 p.m., a magnitude 9.0 earthquake shook the Pacific. Two incredibly large waves had formed, one of them rushed towards America and drowned countless native tribes; the other quickly headed towards Japan, where it would attack ten hours later.

But the worrying news did not end there. By analyzing deposits left by tsunamis, other researchers were able to calculate how many times in history Cascadia had ruptured. The figure they arrived at was 41 megaearthquakes in 10,000 years. It may seem like a long time, but when you average it out, you find that it means a breakup every 250-odd years. No, your math doesn't fool you. 1700 plus 250 means we should have expected an earthquake around 1950. In other words, we are already long overdue for another big Cascadia earthquake. So let's find out what will happen when it finally arrives. Disaster As we mentioned above, there are several ways Cascadia could break, from "argh!" to "AAAAARGH!" For the sake of simplicity, this section will assume an “AAAARGH!” scenario, which measures 9.2 on the Richter scale.

So, here's how it could happen. The first thing you'll notice is that all the dogs are acting crazy. This is because the compression wave has just arrived, a kind of early warning system built into earthquakes, but which only certain animals can detect. Unfortunately, humans are not among those animals, so you'll be left thinking, "Okay, this is weird, all the dogs are freaking out." Enjoy those long seconds of confusion while they last. It may be the last time you enjoy something again. About 30 seconds after Fido starts going crazy, the seismic waves will arrive. At first it will be strange.

But then the shaking will last longer and longer and become more and more powerful, going from worrying to actively threatening to life. Unlike California, the Pacific Northwest did not introduce strict building codes until 1994. That means any structure built before the 1990s will be in danger of immediate collapse. As the shaking increases, houses will begin to fall on their occupants. Schools will collapse. Airports. Fire stations. In total, it is believed that up to a million buildings in the region could collapse. Three thousand schools could collapse, along with two-thirds of all hospitals. Thousands of people will be crushed to death.

Tens of thousands will be trapped in the rubble. And this is just the beginning. As gas pipes break, fires will break out. The electrical grid will fail. Up to half of all highway bridges will fall. Remember that terrible bridge collapse in Italy in 2018 that traumatized the nation? Well, now let's imagine that scenario is repeated not dozens, but hundreds of times, from Northern California to British Columbia. Elsewhere, the earthquake will trigger deadly landslides, up to 30,000 of them in the Seattle area alone. Inland, dams will fail and cause flooding. There will be chemical spills, gas leaks, explosions. By the time the shaking subsides, 6 minutes after the dogs started howling, the Pacific Northwest will be unrecognizable.

Up to 75 percent of buildings will have been compromised. There will be a cascade of different disasters to deal with, from fires to hazardous waste spills. In short, the consequences of the earthquake will be miserable. But you won't have time to stop and think about it. By the time the fault ruptured, the northwestern edge of North America will have fallen two meters and bounced up to thirty meters to the west. Much of this movement will have occurred under the ocean, creating a 600-mile-long wave in the sea that is now hurtling towards the western coast. Those stunned minutes of horror after the ground stops moving will be your last chance to run.

And trust me, running is exactly what you'll need to do. No matter how bad the earthquake itself is, it will have nothing to do with what comes next. When the tsunami hits, everything will be a million times worse. Drowning Man When the Cascadia tsunami hits, you'll have no trouble spotting it. At its lowest point, the water will reach a height of 20 feet. At its highest point, it will reach a height of more than 100 feet. When it reaches the coast, it will move at 12 miles per hour, dragging with it everything from boats to cars to human bodies.

At this point, our narrative branches into different parallel universes, depending on when the earthquake occurs. If this occurs in winter, the maximum possible death toll is around 71,000, the number of people living in the flood zone. Since many of them will flee to higher ground, the actual death toll will be much lower. But even in this best-case scenario, it is still estimated that a third of the population will be too old or disabled to escape the wave. But if the earthquake hits during a summer holiday, like, say, the Fourth of July weekend, we could be looking at carnage on an unprecedented scale.

In Oregon alone, it is estimated that more than 150,000 people could be on the beaches; and another 17,000 at risk in Washington state. That's not including those on Vancouver Island. In total, almost 200,000 people could be found in the path of the tsunami. Some would escape. Most wouldn't. As seawater moves inland, more than 100,000 square miles will be inundated. Buildings that survived the earthquake will be razed. Entire towns will drown. When the New Yorker interviewed Fema regional director Kenneth Murphy in 2015 about the aftermath of the tsunami, he cheerfully responded, “Our operating assumption is that everything west of Interstate 5 will be destroyed.” For those not into American geography, this includes not only Seattle and Portland, but also Eugene, Salem, and, in Canada, Victoria and Vancouver itself.

About half an hour after the compression wave hits, the tsunami advance will end. By then, seven million people will have been affected and the Pacific Northwest will have been wiped out. The statistics will be brutal. Fema estimates that in the event of a winter earthquake, about 13,000 people will be directly killed and another 27,000 injured, making it easily the worst natural disaster in US history. Additionally, up to a million people will have lost their homes; and another 2.5 million urgently need food and fresh water. But this is only in winter. If the wave were to hit when Oregon beaches are at their peak, in the middle of a hot summer holiday, then the death toll could skyrocket.

At the time of this writing, the worst disaster on record in North America is the 2010 Haiti earthquake, which killed between 100,000 and 160,000 people. As horrible as it sounds, a summer earthquake in Cascadia could surpass even that. But before you rush to build an earthquake-proof shelter on the highest hill you can find, remember: this probably won't happen in your lifetime. The odds of Cascadia unleashing its full power in the next fifty years are one in ten. That's about ten times higher than we'd like it to be, but it's still low. A damaging magnitude 8.0 earthquake is much more likely to occur, but with a death toll in the hundreds rather than thousands.

So yes. Realistically, the Cascadia probably won't unleash hell on your butt. Still, in case we live in that unfortunate universe with a ten percent chance, there's something else you should probably know. We have long been aware that the Cascadia and San Andreas Faults connect; grazing near the coast of Mendocino County. A couple of years ago, researchers decided to see if the two affected each other. By dating geological remains from previous San Andreas earthquakes and comparing them to remains from the Cascadia earthquakes, they were able to make a disturbing discovery. In the last 3,000 years, a large earthquake in Cascadia caused the San Andreas Fault to also rupture between 9 and 11 times.

That means that almost every time Cascadia unleashes the Big One, it's followed by San Andreas, which also triggers the earthquake apocalypse. Just think. The huge and staggering death toll seen in this video may be just the beginning. If they were not affected by Cascadia, Los Angeles and San Francisco could be hit by a devastating earthquake. Such a double whammy would affect everyone living on the West Coast. It would cause chaos from Canada to Mexico. And there is just under a one in ten chance of this happening by 2070. At the end of this video, we will leave you with the following thought: It is often said that we should live each day as if it were our last.

It's a somewhat trite saying, which essentially means that you should try to take advantage of opportunities and make the most of what you have. Well, if you live on the west coast of the United States, you might want to start taking it literally. Because if Cascadia blows up, it really will be the end. The end of everything you've ever known.