The Next Megaquake Is Coming, Scientists Warn

On January 26, 1700, one of the biggest earthquakes in history hit off the coast of the United States.

It had a magnitude of 9, which puts it in the top 10 most powerful earthquakes ever recorded.

This earthquake triggered a huge tsunami and changed the coastline all the way from southern British Columbia down to northern California forever.

In fact, then the area wasn't very popular, but thanks to some clever research, scientists figured out exactly what happened that day by looking at old geological records, tree rings, and even some history from Japan.

On the same day as the earthquake, a massive tsunami also hit Japan's eastern coast.

For a long time, no one connected the two, but in the 1980s and 90s, researchers realized the tsunami in Japan had been caused by the earthquake in the Pacific Northwest.

They were also able to pinpoint the exact day, January 26, 1700.

They even found old trees in coastal Washington that had all perished around the winter of 1700, which matched up perfectly with the timing of the earthquake.

The earthquake came from the Cascadia Subduction Zone, a fault where the Wanda Fuca plate slides under the North American plate.

This fault stretches about 700 miles, from northern Vancouver Island in British Columbia to Cape Mendocino in California.

The pressure from the moving plates builds up over time, and eventually another big, devastating earthquake will hit the same region. It's just a matter of time.

By looking at the geological records, past tsunami deposits and signs of land-level changes, scientists can figure out how often these huge earthquakes happen.

Emergency planners have been preparing for the next big quake, often calling it the big one.

Scientists believe earthquakes in the Cascadia Subduction Zone happen every 200 to 1000 years, and since the last major one was over 300 years ago,

the Pacific Northwest is definitely due for another.

When it happens, the earthquake is expected to be as big as the one from 1700, but this time it'll affect around 15 million people.

The devastation will be severe, buildings will collapse, roads and runways will crack, and bridges will fall.

Communication in and out of the area will be cut off, but the worst part?

The earthquake will trigger a massive tsunami that might hit parts of the Washington coast in as little as 10 minutes.

It's not a matter of if, but when the Cascadia Subduction Zone will break, when it happens, it will be the worst disaster the US has ever faced, worse than the Hurricane Katrina or Superstorm Sandy.

It'll impact an enormous area, stretching from southern British Columbia all the way down through Oregon to Northern California.

That means millions and millions of people will be affected.

Fairchild is considered a backup staging area for handling the aftermath of the earthquake, with Grant County International Airport in Moses Lake being the main one.

For those who will survive the initial quake and tsunami, the aftermath could be just as disastrous.

Aftershocks will follow and transportation will be on mess.

Roads will be damaged or completely blocked, airports will shut down, and most of the main routes, like Interstate 5, will have bridges destroyed.

This means food and water supplies will be cut off, and it will be incredibly difficult for help to get in or for people to escape.

Gas pipelines will most likely be damaged too, and restoring them could take anywhere from a few days inland to weeks or even months along the coast.

Power outages will be widespread within 100 miles of the coast throughout the entire Pacific Northwest, and water could be out for three to seven months.

Even telecommunications will be down for two to three months across the Pacific Northwest, Alaska, and even parts of East Asia.

The good news for Eastern Washington is that it will mostly avoid the worst of it, thanks to natural barriers between the west and east sides of the state.

The tsunami may hit the Columbia River Gorge, but it will lose energy quickly because of a sand bar under the river.

The Cascade Mountains will absorb much of the earthquake's impact, so the east side won't feel it as strongly.

And since Eastern Washington won't get hit as hard, it'll be up to them to handle the aftermath of the quake.

That means helping Western Washington, taking in refugees from the areas that got destroyed, and delivering supplies to where they're needed.

Scientists have looked at other major 8.0 to 9.0 magnitude earthquakes like the ones in Chile in 1960, Alaska in 1964, and Sumatra in 2004, and Japan in 2011.

These kinds of quakes can shake the ground for anywhere between six to ten minutes, and that's a long time for the ground to be shaking.

Such quakes are super intense because they happen close to Earth's surface, so it's not just a quick shake.

It's a long, strong one that can cause a lot of damage.

If the Cascadia earthquake and tsunami were to hit tomorrow, over 13,800 people could lose their lives, and about 107,000 people could be injured.

The economic toll in Washington, Oregon, and California could top 70 billion. To put that into perspective, we can compare these numbers with some other major earthquakes.

In Chile's 1960 earthquake, about 1,650 people lost their lives. The 1964 Alaska quake resulted in around 140 lives lost.

The 2004 Sumatra earthquake and tsunami took the lives of an estimated 280,000 people.

And the 2011 Japan earthquake and tsunami caused over 20,000 casualties.

Authorities know about the dangers of the Cascadia fault, but even with all the planning, no one can say for sure what will be needed when the big quake hits.

Right after the earthquake and tsunami, the areas outside the immediate disaster zone won't be able to help much because roads and airports will be destroyed, and resources will be limited.

How can we deal with this kind of disaster and its effects? We don't have all the answers yet.

Right now, let's focus on the Cascadia subduction zone. It's a huge fault line that stretches about 620 miles from Vancouver Island to Cape Mendocino in California, sitting about 93 miles off the coast.

It's like one tectonic plate is slowly sliding under another. When the plates are close to the surface, about 18 miles deep or less, they get stuck because of friction, kind of like pushing two rocks together.

Over time, this creates a lot of pressure. When the pressure finally becomes too much, the plate slip, causing a massive earthquake. This is called a mega thrust earthquake, and it can be huge.

Below the area where the plates are stuck, there's a zone where the plates move really slowly. We're talking about just a few inches every few months.

This slow movement helps to release some of the pressure, but it also builds up more pressure on the parts of the fault that are still stuck.

This means that over time, it increases the chances of a huge earthquake happening. These massive quakes, called great subduction zone earthquakes, can be stronger than magnitude 8.5.

Mega thrust earthquakes are the biggest earthquakes that happen. They can go over a magnitude of 9.0, which is insanely powerful. Just to put it in perspective, a magnitude 9.0 earthquake releases 1,000 times more energy than a 7.0 and a million times more energy than a 5.0.

These earthquakes happen when a lot of pressure builds up in a part of the fault that's locked, which means the plate can't move past each other.

When that pressure gets too high, the fault finally ruptures, releasing all that built up energy in one massive shake.

The Cascadia subduction zone is super long. That's why if it were to rupture all at once, it could produce a large earthquake.

Scientists have studied this region and found that about 18 miles below the surface, the fault is completely locked.

The plates there aren't sliding past each other, but deeper down, the plates start to slide more smoothly, causing less friction.

This is important because it tells us how much stress is building up in that locked zone and how it could eventually lead to a major earthquake.

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