Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

Summary: It is likely that the U.S. will be hit with a devastating tsunami within the next 50 years.

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TOPICS: Outage, Travel Tech
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Every day, the news reports out of Japan detail more and more horrific conditions. The power of the offshore earthquake, followed by a mega-tsunami, is almost beyond comprehension. The level of devastation and human loss is extreme and the worries over reactor disasters only compound the dispair.

Could it happen here?

And yet, one question -- above all -- keeps running through my head: could it happen here? The short answer is "Yes". In fact, it already has.

Brian Atwater is a geologist for the U.S. Geologic Survey. Atwater has been investigating ruins in the Pacific Northwest that show strong evidence of a previous geological event that took place about 300 years ago.

He found a native American fire pit covered by a layer of tsunami sand from about the year 1700. He also was able to correlate that archeological information with Japanese records of a tsunami hit in or around Honshu, also in 1700. The Japanese records narrow it down. They say it hit in January.

The Earth's lithosphere -- the planet's hard shell -- is made up of a series of tectonic plates. These are enormous slabs of the Earth's crust, running about 60 miles deep and as big as continents. There are seven major plates, and a number of smaller plates across the planet.

These plates move and are subject to subsurface pressure. Over time, they rub against each other and push against each other. Imagine two small boats floating side-by-side in a pond. They might drift slightly into each other, but if the speed of the drift was slow enough, there'd be no harm.

Now imagine two aircraft carriers in the ocean cruising side by side, say just a few yards apart. If a wave came up, it could throw the first carrier into the other, and the harder it was thrown, the more damage would be done.

Tectonic plates

Tectonic plates are like those carriers, except much, much bigger. If one plate is thrown into another because of subterranean forces, the resulting geological event can be felt across much of the world.

This is what happened in Japan last week. Two plates came together and...popped. Basically, a big chunk of underwater planet shot up suddenly, displacing the water that was once in its place. That water displacement became the tsunami.

Just west of Seattle is the Juan de Fuca plate, named after a 16th century explorer who mapped much of America's west coast. The Juan de Fuca plate rubs up against the North American plate, just off the coast of Vancouver, Washington, Oregon, and northern California.

This tectonic bump-and-grind zone is known as the Cascadia subduction zone. In 1700, the two plates didn't just nudge each other, they bashed into each other with tremendous force, causing an earthquake of a similar magnitude to the one in Japan.

And -- just like in Japan -- the megathrust under the ocean's floor displaced a tremendous amount of water. That water exploded over the shores of the Pacific Northwest and -- just as if the Pacific were really a giant bathtub -- also flooded some of Japan.

So, we now know that not only could a devastating megathrust quake/tsunami hit America, we also know it did.

The next obvious question is this: can it happen again?

Next: Why it could happen »

« Previous: Historical proof

There've actually been a number of earthquakes in the Pacific Northwest region, but most have been the more traditional (if no less devastating) deep earth quakes, like those that took place in 1949, 1965, and 2001.

The Cascadia zone has had a regular cycle of major events, happening every 300 to 900 years. Geological information shows that previous megathrust events have taken place (working backwards in time) in the years 1700, 1310, 810, 400, 170 BC and 600 BC.

It's relatively easy, then, to answer our can-it-happen-again question. Based on previous activity, the answer is "almost definitely".

When could it happen here?

So, let's work through what we know. We know the tsunami that's currently devastating Japan was caused by a megathrust quake that took place off the coast and was the result of underwater tectonic action that displaced large amounts of ocean water.

We know that a similar tsunami hit American shores in the year 1700, the result of a similar sort of geological activity as took place in Japan.

We know that the Cascadia subduction zone generates massive geological events every 590 years, on average.

That, of course, brings us to the next question: when could it happen here?

At least two sets of Cascadia events took place only a few hundred years apart. The last known Cascadia event was 300 years ago. The math is not promising.

Let's let U.S. Geologic Survey geologist Atwater bring the story home with the most disturbing of conclusions. This is an interesting video put out some years ago by the BBC. Not only does Atwater talk about the geology, you can also see how the U.S. would respond if the event took place.

The problem is that Atwater isn't some lone wacko predicting the end of the world. He's a well-respected scientist and his work is backed up by other research. For example, research by Oregon State University marine geologist Chris Goldfinger makes a case that the Pacific Northwest is due for another quake, sometime in the next 50 years.

That means that if you live in the northwestern part of the United States or western Canada -- near Seattle, Portland, Vancouver, Victoria, or Tacoma -- either you or your kids will experience a tsunami of the magnitude that just hit Japan.

Reactors and reactions

There is one piece of good news in all of this. Unlike Japan, the U.S. has no operating nuclear reactors within the Cascadia subduction zone area of effect. That's something, at least.

If Katrina taught us anything, it's why disaster planning is so important. It's also why developing and building to disaster-aware building codes can be a life-saving practice.

It is likely that the U.S. will be hit with a devastating tsunami within the next 50 years. How much it hurts depends on how well we prepare.

Wayne's world

Update: My colleague, Wayne Rash, former Executive Editor at eWEEK, had some very interesting additional notes. These are his words:

If you have room for an update, that tsunami in 1700 was probably much worse than the one that struck Japan. The configuration of the sea floor in that area resulted in waves that were much higher, and in some cases significantly higher than what hit Japan.

But that doesn’t hold a candle to a tsunami that hit Alaska that in one area had waves around a thousand feet high. Yes, it was in a bay with an unusual sea floor configuration, but still…

The other tsunami zone that mostly goes ignored by emergency planners is the area of the mid-Atlantic ridge. The ridge in the North Atlantic is subject to large underwater landslides that can generate tsunamis. One of the areas of concern – Manhattan. But that would just scare everyone so we don’t want to plan for that possibility.

Thanks, Wayne!

Topics: Outage, Travel Tech

About

David Gewirtz, Distinguished Lecturer at CBS Interactive, is an author, U.S. policy advisor, and computer scientist. He is featured in the History Channel special The President's Book of Secrets and is a member of the National Press Club.

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36 comments
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  • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

    All of this has happened before, and all of it will happen again. And again. And again. And again.


    I think one thing you forgot to mention, is the East Coast. The East Coast too, has a tsunami threat from the Cumbre Vieja volcano on the Canary Islands off the coast of Africa. An eruption in 1949 causes the volcano's west side to slide 2m toward the sea. If that landmass decides it wants to go into the sea in a future eruption, the East Coast is in for a rude awakening.
    The one and only, Cylon Centurion
    • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

      @Cylon Centurion 0005

      That's what I was thinking when I was reading through the article. Going back ten years or so, but I think it was mentioned in our Geography class that should Cumbre Vieja collapse into the Atlantic then most areas within 10km of the Eastern seaboard would be inundated.

      With a bit of luck Vancouver Island will shield Vancouver from the worst of any Cascadian tsunami, but maybe it will just funnel the water between the island and the mainland and make it stronger :p
      OffsideInVancouver
      • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

        @OffsideInVancouver <br><br>6 Miles would be devastating to the East Coast considering we're nothing but lowlands at or slightly above sealevel. Coastal cities like New York, Miami, Boston, Norfolk, Cape May, Charleston, Savanna, Outer Banks, etc would be all but wiped out. Those cities are nothing but reclaimed land! They would literally sink!<br><br>The death toll alone there would be greater than what Japan faces now. No one here on the East Coast is even the slightest bit prepared for an evac of that scale. I'm not entirely sure if even there is evac plans in place. It would be mass confusion for sure.
        The one and only, Cylon Centurion
      • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

        @OffsideInVancouver

        Reading up on the Wikipedia article. The article claims the worst case scenario would be that the tsunami generated could travel *16 miles* inland.

        The Japan tsunami would look like childs play compared with that.
        The one and only, Cylon Centurion
    • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

      @Cylon Centurion 0005

      Just took a read of that article on wiki, at least the US gets six hours warning, the UK gets three! I can't see the Thames Barrier in London being much use in that situation...
      OffsideInVancouver
      • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

        @OffsideInVancouver

        6 hours still isn't much considering how many live along the coast. People in NYC, Boston, etc can forget evac, all they can hope is that the tunnels underneath them don't give way, and collapse the streets/buildings above them. :(
        The one and only, Cylon Centurion
      • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

        @Cylon Centurion 0005 <br><br>tsunami wouldn't collapse buildings in NYC, they're not made of wood like those Japanese houses (maybe here and there those that are in really bad shape anyway). It did not collapse cheap hotels in Thailand in 2004, it won't in NYC, also NYC si further away from potential danger, so the tsunami would be much weaker. Tall buildings in NYC would actually be the best bet for the majority of people living nearby. Hiding in the tunnels underneath seems like the dumbest bet from all the possibilities. Even if it was somehow waterproof and they managed not to screw up, somehow had electricity and fresh air it'd take weeks to dig them out.
        CarboneCZ
      • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

        @CarboneCZ

        I don't think the buildings would collapse on their own, but at the same time, I don't think NYC's aging water pumps would be able to handle a potential tsunami like the one they think the landslide would produce.
        It seems as if the pumps would overload and cease functioning. I'm not sure what kind of damage that water would do to the support structure of the tunnels.
        The one and only, Cylon Centurion
    • I don't think so ...

      @Cylon Centurion 0005 ... first, land mass sliding into the sea is much different than a land mass displacement at the bottom of the sea. Displacing a column of water thousands of feet deep is far worse than an above-ground landslide into the see.

      Plus, as the Janases Tsunami should have proved to us, a Tsunami taking place on one side of the Atlantic will have a minimal effect on the other side of the Atlantic - just as it did with the Pacific quake that brought so much death and distruction to the Japanese.
      M Wagner
    • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

      @Cylon Centurion 0005 ... Rude awakening? I saw nothiing about complacency of the east coast in the article; what do you think about the northern mid-west? Right up the mississippi, into the great lakes and on down to the Pacfic Ocean is a possible route. Water, like electricity seeks the path of least resistance and one more path for it is underground, erupting above ground many miles away. There are so many possibilities they're actually uncountable IMO. And why does a plate always seem to "lift"? Why not "sink"?
      tomaaaaaa1
    • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

      @Cylon Centurion 0005 ... I don't think the missing east coast is a big deal although it could of course also be hit by the same effects. Quakes are interesting stuff. Ever wonder about a really huge one, say 15 on the scale happening on the opposite side of the earth? We'd have tsunamis headed for both costs, trying to meet in the middle of the country.
      Look at the land and ocean contours on both coasts and how they would tend to force water southward, possible causing Central America to just disappear for all practical purposes.
      Then, since the article says "America", how about South America? New Zealand, OZ, and so on.
      Why do tsunamis always go east/west but not north/south. Why are the cracks in the earth's shell almost all have a much longer N-S dimension than and E-W direction?

      Food for thought for the editors. Basically, this was a good article with pretty good analogies IMO; only the title was misleading and didn't even mention our neighbor to the North, Canada. Perhaps on one of the following pages .... haven't read them yet.
      tomaaaaaa1
  • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

    I love these "in the next 50 years perdictions". I live in a earthquake zone not on the west coast and they have been saying the next big one will come in the next 50 years for about 60 years.
    bjs_z
    • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

      @bjs_z May you be sitting right on top of it when it happens.
      dixonrf
  • My thoughts (and fear)

    are of the San Andreas Fault that runs thru heavily populated California.

    Japan has planned for destructive earthquakes and unfortunately it's proven it wasn't enough.

    How well prepared is California and other west coast areas for a similar event???
    MacCanuck
    • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

      @MacCanuck The San Andreas fault is a transform fault, meaning the two plates are travelling parallel from each other. Transform faults create a lot of small earthquakes but don't have the ability to create the giant earthquakes like Japan's. You need the two plates to be on a collision course for the big ones.
      Aerowind
    • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

      @MacCanuck Calif is not prepared. The Calveras fault follows the creek for 2+ miles. My home is 300' away and 100' above. Did you know earthquakes sound like a train coming at you?
      LostValley
    • It wasn't enough because it is much harder to mitigate ...

      @MacCanuck ... the effects of a Tsunami than to build tall building that can stand having the easrth move below them.

      Water is a remakable substance. It does not compress. It floats when it freezes. It is very dense. And, as a result, it is virtually impossible to stop once it starts moving.
      M Wagner
  • OK then. You have a great day.

    nt
    Dietrich T. Schmitz, ~ Your Linux Advocate
    • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

      @Dietrich T. Schmitz, Your Linux Advocate

      Because tsunami's only affect Windows? :p
      OffsideInVancouver
  • RE: Could a Japan-like mega-tsunami hit America? Yes, and there's proof.

    Let us not forget meteor strike Tsunamis.
    hayneiii