Wednesday, October 11, 2017

Hurricanes are Nowhere Near as Scary As This

Lost in 24/7 news cycle about a big name Hollyweird producer playing casting couch with any hot young aspiring actress he came across - not to mention assorted fruits, vegetables and barnyard animals - was a scary story out of the Canary Islands.  The Canary Islands, off the NW coast of Africa, are the home to La Palma a volcano that ought to scare the snot out of you if you live anywhere in the Western Hemisphere that's on the Atlantic or on water connected to it and under a few hundred feet in elevation.  If you live inland, and there's a ridge that high between you and the ocean, you're probably OK; otherwise, you might want to pay attention.
The islands of La Palma, Tenerife and Gran Canaria have now been rocked by 50 tremors after a “swarm of seismic” movement of low magnitude between 1.5 and 2.7 were measured. 

Express.co.uk reported on Tuesday the islands, popular holiday destinations with Britons, had been struck by 40 earthquakes in just 48 hours.
This is reminiscent of the earthquake swarms in Yellowstone over the last few months, which prompted a lot of "what if the Yellowstone volcano blows?" speculation.  Similar thoughts go here, but the threat is entirely different. 

The shape of La Palma hints that a likely scenarios is for the southwest slope of the volcano to slide into the sea.  This would create a tsunami that puts the 2011 Japanese tsunami into the "tiny" category.  Perhaps millions of cubic feet of rock and dirt sliding into the Atlantic at hundreds of miles per hour.  Displacing millions of cubic feet of water. 
The physics-based simulations of what would happen have yielded predictions for much of the Atlantic coast line.  Tsunamis behave differently in the open ocean than along beaches and shorelines and the shape of the underwater slopes cause the local effects that will be experienced.  The calculations predict tsunamis of 20 to 30 meters high along the entire US east coast, followed shortly by tsunamis of 10 - 20 meters along the gulf coast.  All this transpires about 7 to 9 hours after the volcano slides into the ocean.


Over the years, there have been many big budget movies based on the idea that some number of people suddenly find out they had days or hours left to live. The one kids talked about when I was in 8th or 9th grade was "On the Beach", about Australians waiting around after a thermonuclear war, knowing they all would die.  Much more recently, "Armageddon" and "Deep Impact" both showed society waiting for Earth to be hit by a recently discovered comet.  The reality of a big slide is something like the last two, waiting for the impact tsunami to hit.

Are you in a position where you could get to a couple of hundred feet elevation in a short drive?  How about in under 8 hours?  You'd have to be ready to hit the road the moment you heard the volcano blew.  Every reporting station in the area would be wiped out, but other seismographic stations would report quickly.  Like so many other situations, it would be better to leave an hour early than a minute late.  We've just seen the problem in Florida during the Irma evacuation.  There's really only two highways out of the state.  It seems that being on one of Florida's highest elevations might be enough to survive. 

Either that, if you have a boat, get in the boat and prepare to be buffeted around by currents and floating debris.  From what I recall seeing of the Japanese tsunami in 2011, the "seas" in the sense of waves are not a problem, it's the floating crap and obstacles.  Those are NOT trivial, but nothing about this scenario is. 


18 comments:

  1. I remember reading about this when it was mentioned on a show about the huge landslides that the Hawaiian islands created. There are huge debris fields underwater that have been mapped with modern sonar. La Palma is very scary indeed. On a side note. I was just looking at the live seismic map of Yellowstone prior to scrolling my blog roll and stopping by here. :-)

    Those two possibilities of disaster will change the world. I wonder how close one of the other is.

    ReplyDelete
  2. Those two possibilities of disaster will change the world. I wonder how close one of the other is. That's the billion dollar question.

    I think a volcano has to be on the verge of erupting before the geologists can predict it. Nobody could say, "this one is going in 25 years and that one is going in 26". If it's not ready to erupt soon, I don't think they could say anything.

    It's just a risk out there.

    ReplyDelete
  3. I question the sheer magnitude of the land being displaced. This due to the relatively small size of the island as a whole. This would be like dropping a pebble in a swimming pool.

    ReplyDelete
  4. I don't spend a lot of time worrying about disasters on this scale.

    There's BLEEP all you can do about them and since they're civilization killers, little that you can realistically do to prepare.

    But if that map is accurate, I just have to go about half a mile to get above the 10m level, or stand on my roof and pray the foundation holds. Only about thirty miles to get above even the 30m mark, which the map doesn't predict for me.

    However, having been in on a simulation for a meteor strike mid-atlantic, I don't think they modeled the effects on the Gulf side of FL correctly. There's nothing that reflects back at us like that before it expends a lot of energy on Texas and Mexico.

    ReplyDelete
  5. I needed that bit of morning sunshine...

    ReplyDelete
  6. While thinking about this I suggest reading Lucifer's Hammer by Niven and Pournelle, and then read Footfall by the same authors.
    The internet says I am at 167 feet above sea level.

    ReplyDelete
  7. Just a skosh under 600' ASL, my parents are about 800'ASL.
    I should be good.
    Just think, about 40% of the country's Demoncrat voting stock douched away in one foul swoop....... Thanks for the pleasant image SiG.

    Leigh
    Whitehall, NY

    ReplyDelete
    Replies
    1. To be honest, that occurred to me, too. I can see NYC, Boston and much of the NE megalopolis getting really hammered. And that's where all the trucks will be going to fix things, because that's where the media will be with dramatic video of all the horror stories going on.

      Delete
  8. When we sold our sailboat, we kept all the offshore safety gear. Along with our hard dinghy / lifeboat. It is unsinkable and has a master self bailing too. Figure just put the offshore life vests and harnesses on and strap in. Wearing full motocross protection including helmet and hang on tight.

    ReplyDelete
    Replies
    1. Has mast, and self bailing. Frking autocorrect

      Delete
  9. I saw a BBC documentary about this a decade or so ago. One of those islands had a bottomless crack 300 feet wide running the length of the island. They said that WHEN, (not "IF") it let go, it would displace several dozen cubic MILES of earth, creating a wave that would be between 900 and 1800 feet high when it hit the east coast of north America, and would wash inland as far as the Appalachian mountains in the north and half way up the Mississippi river in the south. Scary stuff. Looking at the bright side. If some bright boy were to disable the congressional warning system............ Ray

    ReplyDelete
  10. So, this potential landslide will destroy the coastlines of all the continents, just like happens every few years when an ice shelf the size of Rhode Island breaks off of Antarctica and falls into the sea, displacing dozens of cubic miles of seawater in mere moments.

    ReplyDelete
  11. Something is wrong with the math on this. There is no possible way that such a small island landslide can create a 50 M wave 4000 miles away in a large ocean like the Atlantic that would dissipate that energy. Yes in a funnel shaped bay but not on the entire coast of Eastern America. Try it yourself. Pick up a huge boulder and big as you can lift and drop it into a lake and measure the wave on the opposite side of the lake. Someone is exaggerating this risk for whatever reason.

    ReplyDelete
  12. Please see:

    http://blogs.agu.org/landslideblog/2013/12/13/canary-islands-tsunami/

    ReplyDelete
    Replies
    1. Interesting. I like the observation that if this had happened before, we'd see evidence along the entire eastern seaboard and we don't. Unlike the west coast where there is evidence of previous tsunamis.

      Delete
  13. Heres a link about Hawaii.

    https://hilo.hawaii.edu/~kenhon/GEOL205/Landslides2/default.htm

    ReplyDelete
    Replies
    1. There is well-documented evidence of tsunamis on the west coast.

      http://www.oregongeology.org/sub/earthquakes/oraltraditions.htm

      I can find evidence of only two on the east coast, and neither of them was from what appears to be a transatlantic event.

      https://soundwaves.usgs.gov/2005/01/fieldwork2.html

      It really looks like this is a vanishingly small probability.

      Delete
    2. I agree, most of the northeast has been eroded by glaciers and weather. There is a long chain of seamounts that stretch across the Atlantic basin and there are very old volcanoes here that were formed over the hotspot.

      Delete