Tag: tsunami

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

Japan's nuclear reactor overreaction

By Phil Plait | March 14, 2011 4:49 pm

[UPDATE: Wow, minutes after I posted this, an explosion is being reported at the third reactor site. I mentioned in this post the third reactor was in trouble, so this may be another hydrogen combustion explosion as happened in the other two. I’ll put more updates here as I find them.]

[UPDATE 2: The comments being posted below are contradictory, as I expected; news is coming quickly about the third explosion and speculation is flowing. I’ll add that I freely admit things I wrote below may be in error; but they are based on what I’ve read and heard over the past few days. With news being as spotty as it is, that’s inevitable. That’s why I made the disclaimer I did in the post.]

[UPDATE 3: Alan Boyle at Cosmic Log has an excellent and calm discussion of what happened, including best and worst case scenarios.]

[UPDATE 4 (20:30 Mountain time): Yikes. The New York Times — not generally known for breathless overreaction — is reporting that the explosion from reactor 2 may have damaged the containment vessel of the nuclear core. The exact situation is still maddeningly unclear. Both best and worst case scenarios are being spun, but as usual I will wait for more information before drawing any conclusions. In the meantime, there may be evacuations of personnel from the plant. I hope that’s not true; those people are the ones heroically working to keep this matter under control.]

[UPDATE 5 (March 15, 22:00 Mountain Time): I haven’t updated today because until now not much news was coming out about the reactors, and some of the news I did see was clearly contradicted by other reports. However, The Associated Press is reporting that all the workers at the plant have been evacuated. This is bad news. Those people have been working heroically to keep things under control, despite some temporary but scary surges in radiation levels around the plant. The AP article itself has contradictory statements by experts — one saying it’s a matter of time now, and another saying there is minimal risk to the population. It was reporting like this that led me to write this article in the first place, and clearly some of the things on which I was basing my conclusions have changed. If there are any major developments, good or bad, I’ll update here and most likely write a new post given what we’ve learned in the past few days.]

After the earthquake and tsunami in Japan, things over there are very, very bad. The pictures and video of the devastation are incredible… and before I go any further I will note that science and engineering mitigated this disaster by orders of magnitude. The Japanese have prepared for this type of event for decades, and it’s paid off. At this time, the number of dead is in the thousands… not the hundreds of thousands. I will not downplay the tragedy and loss, but it could’ve been far worse.

Still, there are many problems. One of the biggest* is the Fukushima Daiichi nuclear plant, which is facing a crisis with its reactors. While this situation is serious, let me be very clear: we are not facing a nuclear explosion, nor are we facing the release of a huge, deadly radioactive cloud (more on both of these below). The fear-mongering and misinformation on the web and in the news is rampant, and the last thing we need is people panicking because of it! The news is bad enough without exaggeration of it.

The best analysis I’ve seen so far is at Slate. An excellent summary is also on The Market Ticker. At reddit, a commenter gave a very short description, and Boing Boing also has a good piece. [Update: My friend Evelyn Mervine, who is a PhD candidate in geology, has a series of interview with her nuclear engineer father on her website.]

This situation is changing all the time, so please be aware that what I write here is based on what I’ve read in those articles, what I’ve seen in the news, and my own knowledge. With things being so fluid, caveat lector.

Here’s what happened: The plant has six reactors. The earthquake and subsequent tsunami severely damaged some of the reactors and hampered attempts to fix them. An explosion rocked the plant on Saturday, and another about a day later. These were not nuclear explosions! That is literally impossible from a fission reactor; the fuel is the wrong kind and doesn’t have sufficient quantities to explode like an atomic bomb. Instead, the explosions were due to hydrogen combustion, created when water came into contact with the extremely hot fuel cells. The cooling system was down, allowing the fuel cells to heat up. Hydrogen was released, and is extremely volatile. It volatilized.

The explosions destroyed the reactor buildings (basically an enclosure around the reactor itself to protect it from the elements), but far more importantly it appears the reactor housings are intact. Engineers are now using seawater to cool the reactors, which will ruin them for future use but should safely cool the fuel rods. This situation isn’t over yet (a third reactor is in trouble as well), but I’m cautiously optimistic this plant will be shut down safely. Ironically, it was two weeks from its scheduled 40 year decommissioning as it was.

That isn’t stopping the rampant speculation fueled by fear and ignorance of the real situation. For example, I’ve seen some people calling that blast a nuclear explosion, but it wasn’t. Again, it was hydrogen exploding when it reacted with air. A huge explosion, but not a nuclear one.

Far worse, in my opinion, is the person who created a map claiming to show the spread of a radiation cloud from fallout. This map is a fraud: totally fabricated and complete garbage. Read More

CATEGORIZED UNDER: Alt-Med, Antiscience, Debunking, Science

Magnitude 8.8 earthquake off Chile coast

By Phil Plait | February 27, 2010 9:59 am

Last night at 06:34 UTC, a huge earthquake struck on the coast of Chile, with a reported magnitude of a numbing 8.8 — making it one of the largest earthquakes recorded on Earth since 1900.

A tsunami warning has been issued for the entire Pacific ocean. This is no joke; the tsunami gauges in the deep ocean have registered a wave spreading from the quake. I don’t know how big the amplitude is, but there have been confirmed reports of waves a meter high in Chile. That may not sound like much, but water weighs a ton per cubic meter/yard, so a wave that high has a lot of destructive power.

The tsunami should hit Hawaii around 11:05 local time, and it’s not clear at all how big it will be. In 1960, a larger earthquake happened off Chile and a tsunami hit Hilo, Hawaii causing quite a bit of damage. If you live anywhere near a Pacific coast, please check the local news and the Pacific Tsunami Warning Center. Also, a live stream of news from Hawaii is on HawaiiTsunami.com. I’ve been listening and the coverage is pretty good.

If you live in Hawaii, now might be a good time to check out that higher ground you hear so much about. At the very least, stay away from the beaches! People are already starting to evacuate the coasts, so if you choose to get out, the earlier you get moving, the better. Traffic is bound to get snarled. Please please please don’t panic. Stay calm, and keep focused.

It’s unclear if this will be a big wave or not. But if you’re in Hawaii you should consider moving to higher ground.

Here is a map by the NOAA of the modeled energy wave expected from the earthquake:

noaa_2010_quakeenergy

It’s unclear to me just how big a wave this means in terms of real height (it’s a model, not an actual measurement), but it should bring home that you should take this seriously.

I’ll note that the magnitude scale doesn’t translate perfectly to energy released, but roughly speaking an 8.8 quake releases the energy equivalent of 20 billion tons of TNT, or 400 time the largest nuclear weapon ever detonated (Tsar Bomba, a 50 megaton test done by the USSR in 1961). If the measurement hold up, this will be the fifth or sixth strongest earthquake recorded since 1900. The strongest ever recorded, in 1977 1960, was magnitude 9.5, also in Chile — the one that caused the tsunami in Hilo.

Thanks to Sean Carroll for the link to the energy map. Note also, in this post I referred to the Richter scale, which is no longer used. I corrected that.

CATEGORIZED UNDER: Science
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