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How big was the 2011 tsunami? Is 3m bigger or smaller?
by Brystephor 1y ago
How big was the 2011 tsunami? Is 3m bigger or smaller?
- decimalenough 1y agoIt's complicated. Tsunami forecasting is a very inexact science and "3m" means "very large". The average actual height in eastern Japan (Tohoku) was 4-6m, but there were peaks up to 20m in places like Ofunato where the local geography funneled all the water upwards. https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_and_tsunami#Tsunami https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an...
- hsbauauvhabzb 1y agoIs height the only thing that matters? Presumably 1x 2m wave is less impactful than 10 x 1m waves spread 20 seconds apart?
- edoceo 1y agoVelocity of wave as well.
- brewdad 1y agoDepends on topography and protections in place. 10 1m waves against a sound 1.5m seawall is no big deal. 1 2m wave against the same seawall could be a problem.
- idontwantthis 1y agoA tsunami is a gigantically long wave. I don’t think what you’re describing describes a tsunami.
- leptons 1y agoThat is not really a good description of a tsunami. Tsunamis can occur in very narrow areas too, like when landslides happen in fjords.
- idontwantthis 1y agoI mean long as in wavelength. You wouldn’t have a series of tsunami waves.
- TylerE 1y agoDespite the common vernacular calling them "waves" they're really more like really really high tides. You're talking about something that happens over, say, 10-90 minutes, not seconds.
- bgwalter 1y agoAgain the only correct comment is downvoted. Watch Tsunamis on Youtube. The water just keeps coming and coming. They are like high tides.
- foobarian 1y agoAh, and here I was wondering if it would be possible to surf one of these for miles in if the timing were right. The grandparent answers that question.
- VintageCool 1y agoI remember in 2015 watching this great tsunami video at a harbor. It was about 11 minutes long. At the start, there's just a white line at the horizon. Then the fishing boats in the harbor start rocking and jangling. Then water starts pouring over some walkways and sea walls. Eventually the cameraman backs away and starts climbing a concrete tower; water starts to flood over the area where they had been standing. I think they climb a couple stories and are safe up there. I haven't been able to find the video in years, but I remember being fascinated by it and I'd love to watch it again. Edit: I never expected to find that video again, but here it is. A little more terrifying than I remember. https://youtu.be/PvJs2iWQuFs https://youtu.be/PvJs2iWQuFs
- crystal_revenge 1y agoI'm surprised so many people don't understand what tsunamis are. It's a "wave" created by a sudden shift in the Earth's crust. Imagine, suddenly, water on each of side of that split is now at different heights and has to equalize. It's much closer to just removing a dam that is holding back water equal in height to the new difference between the sea floors. What you get is not a "wave" but a wall of water.
- dgfitz 1y ago> I'm surprised so many people don't understand what tsunamis are. “I’m Surprised so many people don’t know what ‘X’ is/are isn’t a very nice thing to say. Your comment could have done without that, the rest of it would have been fine.
- dotancohen 1y ago[flagged]
- nathos 1y agoObligatory https://xkcd.com/1053/ https://xkcd.com/1053/
- ninetyninenine 1y agoI don't think he's even right. Like what he is saying is in actuality wrong. He's surprised because he's ignorant. I'm all for people saying stuff the way he says it. He believes it's true, then he should stand behind. But then the consequence is that he needs to be accepting of when people call him out for being utterly wrong.
- K0balt 1y agoThe difference is that people know what 2m (wind driven) waves look like at their cities seawall. A 2m tsunami is a -completely- different phenomenon, because of its length. Depending upon the underwater geography, a 2m tsunami might flood right over their 3m seawall, and wipe out entire parts of the city, sweeping hundreds of people out to sea. A 2m wind wave will get saltwater spray on cars driving by. They are both waves, but they share very little in characteristics other than their fundamental physics. It’s like saying that a slingshot fires a 12mm projectile, and so does a 50 caliber anti material rifle. The fact that they are both projectiles, of the same size, is much, much less informative than other facts about their nature. Saying that tsunamis are waves is easy to equivocate into tsunamis are waves, like other waves. This is an equivocation that is very misleading and can get people killed. Insofar as the goal of communication is to communicate meaningful information, it is less accurate to say “tsunamis are waves” than it is to say “tsunamis are nothing like normal waves”, or to say “tsunamis are like a wall of water, not like a wave” or “tsunamis are more like tides than waves”. So yes, tsunamis are waves, but insisting that tsunamis are waves without qualification that their effective characteristics are fundamentally much different and more dangerous than a regular wave is misleading through omission in a way that could directly put people’s lives in jeopardy. Being pedantic about definitions and being accurate in conveying meaning are not the same thing, and communicating in good faith normally is about conveying meaning in an accurate manner, not just using words in an accurate manner. FWIW I also believe that meanings are important, but there is a point where pedantry falls into bad-faith territory.
- javcasas 1y agoA tsunami is not a "bigger" wave like the ones that crash on the beach every minute. A tsunami is a single wave that crashes and crashes and adds more and more and more water for several minutes non stop, not pausing or pulling back for a single second. It is a sudden flood coming from the sea.
- timr 1y agoFor perspective, the tsunami that topped the seawall at Fukushima Dai-ichi had a peak height of ~14m. The seawall was 5.7m.