A tsunami's icy reach

By Phil Plait | August 14, 2011 7:09 am

The March 2011 earthquake and subsequent tsunami off the coast of Japan did unimaginable damage. The tsunami was several meters high, marching a long way inland, and wiped out entire towns.

It also swept out to sea, expanding across the planet. By the time it hit the Antarctic ice shelf — 13,000 km away, taking less than a day — it was well under a meter high. But water is dense (a cubic meter weighs a ton!) and that much of it hitting the ice can cause it to flex and break.

And that’s precisely what happened:

[Click to antarcticenate.]

That’s the Sulzberger ice shelf on the coast of Antarctica and the Ross Sea. A few days before this image was taken those gigantic blocks of ice were still part of the shelf (though cracks were already present), and in fact the big one had been part of the shelf for over four decades at least. The pounding wave of the tsunami broke up the shelf, sending those blocks into the sea.

Mind you, that big rectangular block of ice is about 11 km (6.6 miles) across — about the size of Manhattan! The total ice broken off probably doubles that amount. It was about 80 meters (260 feet) thick from top to bottom, too, so we’re talking a lot of ice — about 100 billion tons worth all told!

This image, but the way, is not an optical photo. It’s actually a radar map from Europe’s Envisat Earth-observing satellite. Radar bounces off of water differently than it does off ice, distinguishing the two in images. Maps like this are critical in understanding how the ice changes in the south polar regions, and that of course is critical in understanding the changing environment of our planet.

[Note: after I drafted this post, I found that NASA made a video explaining it:

Nice, and really shows how massive this event was.]


Related posts:

- Ice island heading south off Labrador
- Enormous glacier calves in largest arctic even seen in 48 years
- As arctic ice shrinks, so does a denier claim
- Sign of the apocalypse: blood waterfalls

CATEGORIZED UNDER: Miscellaneous, Pretty pictures

Comments (10)

  1. VinceRN

    Ain’t nature just freakin’ amazing?

  2. lqd

    I just saw Envisat the other night.

  3. JakeR

    Um, Phil,

    I hate to be pedantic, but I’m an SI fan. A cubic meter of seawater weighs about 1.025 tonne, or about 1.1275 tons. That is to say that a cubic meter of moving seawater has about 13% _more_ kinetic energy than a ton of seawater has and consequently about 13% more damage potential.

  4. Jim Starluck

    Man, now I’m imagining what it would be like to be down there, standing on that iceberg when the wave hit; the ice beneath your feet flexing a little and then shuddering as it broke free, cracks racing along the ice where it splits from the shelf.

  5. Nigel Depledge

    Jake R (4) said:

    I hate to be pedantic,

    Hah! You should revel in it. I do!

    but I’m an SI fan. A cubic meter of seawater weighs about 1.025 tonne, or about 1.1275 tons.

    Then you should be aware that there are three kinds of “ton”, not just two as you seem to imply.

    The “metric” tonne is 1000 kg or 2200 lb.
    The Imperial ton (known in the US as the “long ton”) is 20 cwt or 2240 lb.
    The “short” ton is 2000 lb, and, AFAICT is used only in the US.

    So, it seems to me as if, when you say “ton” you mean “US ton” or “short ton”. Maybe Phil was referring to Imperial tons (in the which case, he would have been pretty close)?

    Also, the mass of a cubic metre of sea water varies with temperature and salinity – it is not always about 1025 kg.

    That is to say that a cubic meter of moving seawater has about 13% _more_ kinetic energy than a ton of seawater has and consequently about 13% more damage potential.

    Yes, if you guessed the correct usage of “ton”.

  6. Davy Jones

    I’m surprised Phil didn’t blame this on global warming! And shriek about “deniers”.

  7. DennyMo

    Since we’re quibbling over how much a ton of water weighs, I’ll pick my own nit:
    “This image, but the way, is not an optical photo.”
    Pretty sure you meant to say “by the way”.

    But wait, hadn’t you heard that the earthquake and tsunami was all just a carefully orchestrated “false flage nuclear attack”?!? No, wait, it was HAARP!!! Or, actually it was…

    No, I’m pretty sure it was an earthquake.

  8. marc

    click to dephilinate

  9. icemith

    Now that those icebergs are free, could somebody please arrange to have them towed to all the hotter spots on our world, for use in icy drinks?

    I suggest that that action would be helping against “Global Warming”, as it would prevent having to cool water to make ice, for our drinks, provide cooling for our homes and workplaces, and also provide water for areas that are deprived due to drought etc. All of those activities rely on having to generate electricity, by whatever means, to run refrigeration plants, cooling systems and pumps to distribute the “coolth”!

    (In a thousand years time we will really miss the “coolth”, and they may as well have a word to describe it, as it could be quite rare.)

    Now for the logicians out there, can we really achieve this towing idea?

    Ivan.

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