The east coast is also where the vast majority of Japan's population lives, and was previously hit by the 2011 tsunami (Fukushima and all that). We're about to find out the hard way what lessons they have learned.
Update: First detected wave in Nemuro, Hokkaido (northernmost Japan) was only 30cm. There may be more. Waves of 3-4m have apparently already hit Kamchatka in Russia.
Update 2: We're almost an hour in and highest waves to actually hit Japan remain only 40 cm. It looks unlikely that this will cause major damage.
To be fair, most of Japanese TV is like that. I always joke that the primary reason they developed HD TV was to be able to cram more text in every corner xD
I was wondered that. Like from movies or documentaries, etc. Very nice, clear, order, minimalistic. Then I was looking to buy a house and I found a site with "almost" abandoned house for sale.
My God. Everything , everywhre, no design ( haha ), no exceptions. People were actually living there.
I do live in Japan and good god, I have never seen such messy people anywhere else in the world. The offices of all my Japanese colleagues are piles upon piles of documents and boxes without any kind of order.
But the cities themselves are like that. There is zero urban planning, just buildings thrown around in impossible non-Euclidean patterns.
They're a book from the early 1990s called "Tokyo Style" that is packed with photos of real living conditions from back then. Chaos of every variety. Plus some Super Famicom and PC-Engines laying around. A very cool book, most recently reprinted in 2024 with Japanese/English captions.
The transformers are a result of a the lower voltage (also used in America), for efficiency and to keep the required voltage the transformer needs to be nearer to the house.
My favorite is the NHK reporters standing in the middle of absolutely nowhere with their NHK helmets. No matter what the event, there is a reporter wearing a helmet.
Also, the very first thing they say when the camera cuts to them is that they are standing in designated evacuation zone X that's Y meters above sea level.
Then the cameraman zooms at the ocean, which is blurry and shaky because they're in the designated evacuation zone Z km away from the coast.
That’s probably the responsible thing to do. It is always odd to see American weather disaster reporters, like:
“We’re here inside the hurricane, let me go outside so you can see that the wind will push me over. Can’t hear anything because my microphone is getting blasted by the wind. Over there you can see the emergency responders, they appear to be fleeing. Tell my wife I love her, but I’ve got to die for some b-roll.”
That makes sense, though. To do otherwise would be pretty dumb for a tsunami situation.
But yeah, the handheld telephoto zoom from a safe location is definitely on the Japanese Disaster TV bingo card. That said, I appreciate that they just keep repeating the same warnings and data, rather than the ridiculous speculation that the US news media engages in when they get bored.
Also when you visit most japanese websites you can see this phenomenon.
I've read an explanation once that this is because culturally, japanese people perceive a wealth of information and choice as being re-assuring and trustworthy, while most westerners feel more re-assured by seeing less content and choice presented in a more minimalist kind of way.
I actually prefer content style of Japanese websites. I get all the relevant info on one screen instead of having to scroll/click thru tens. The western style websites are very inefficient and hide info (feels scammy with lack of info).
Eg. old people without smartphones or someone just turning their TV on, seeing big letter "Tsunami evacuate" with map and other information.
You instantly know the most important information and you can act on it.
EDIT: Apologies, I misunderstood—a reply to this comment said they were just predictions. (I saw in this video[0] that the first waves had arrived, and assumed the heights would've therefore corresponded to actual measurements. But it's still in the "predictions" section, and I should've noticed that before posting....)
No. That's the predictions. Biggest wave so far has been 60cm (EDIT: as of 6am UTC it's 1m30cm, but that's still relatively small. It came up almost exactly to the top of the pier in Kuji.)
I've updated my comment, I indeed misunderstood what I read.... Unfortunately it's too late for me to delete the comment, so everyone please feel free to flag/downvote it (both to push it down for the sake of clutter, and also to punish my carelessness :-P).
No worries -- the way they present it is confusing, particularly if you're watching the NHK World stream, which layers poorly translated English versions on top of the Japanese.
It'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.
I'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.
Its a wave (or series of waves) with a large wavelength and speed in deep ocean, that becomes a shorter wavelength and very large amplitude by shoaling as it hits shallow water.
Its different from typical wind-driven ocean waves for a lot of reasons; but a big indicator is wavelength -- wind-driven ocean waves have wavelengths up to hundreds of meters, tsunamis have wavelengths (in deep ocean) of hundreds of kilometers.
More like tides than waves, as has been stated elsewhere in the thread, is both technically wrong but substantively (with the caveat that "waves" really means "typical wind-drive waves") correct, in that tides are also manifested through waves, but waves which have wavelengths of thousands of kilometers, and so tsunamis are waves more similar to those making up tides (hence the old colloquial use of "tidal waves", which properly refers to the waves manifesting tides, to refer to tsunamis) than to wind-driven waves.
Not true. As the news reporters here in Japan are repeating every few minutes, there will be many waves and they can get bigger over time. They already have, 20-30cm initial waves had 40-60cm later waves.
Waves can get bigger due to earthquakes not being instantaneous or necessarily a single movement, due to amplification by geography, by reflections, by aftershocks, and many other things. The news is suggesting waves lasted about a day for a previous event in a similar area.
> 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.
I don’t take offence. I’m not the most educated, and I don’t live in or near a tsunami prone area, I know about other natural disasters that are relevant to where I live though, maybe more than the parent poster.
I 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.
The 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.
I appreciate your effort to provide an understandable explanation.
That said, in context the original statement was so extremely misrepresentative of the reality that I felt it left the realm of "inaccurate but effective for communication". I certainly didn't see the objections as pedantic.
A clarification was appropriate because it really did miss the physics, but doubling down on the definition of wave without talking about speed, length, and volume (which is what had confused OP in the first place) was not only suboptimal in teaching useful knowledge to OP, it was also misleading in a way that could (and did, in at least one case of a commenter in this thread) lead to a dangerous misconception about characterising tsunamis.
Perhaps it wasn’t intentionally pedantic, but the way that it was doubled down on later makes me suspect an argument in bad faith, or at least an epic case of missing the opportunity to usefully inform.
I value this site for the general character of people trying to educate more than just troll, and I think it’s important to try to educate trolls as well to understand a more constructive and respectful way to interact here. Ostensibly, we take off our clown shoes and leave them at the door.
OTOH I may have read multiple comments in similar tone that were not all attributed to one poster , giving me a mistaken impression of the intent. In that case, I owe an apology for perhaps overreacting.
Nitpick: while what you say is generally true, there are several scenarios that can create true dramatic “wall of water” tsunami waves that have leading slopes of 45-90 degrees and heights in the tens of meters.
The most obvious (but relatively rare) are tsunamis amplified by submarine canyons and other coastal bathymetry like the Nazare submarine canyon famous for the biggest waves on the planet (50+ footers are common in season). If an earthquake directs a tsunami at that canyon, the resulting waves will be spectacular and probably drown everything north of the cliffs. Unfortunately we don’t have any historical records about what happened at Nazare after the 1755 Lisbon earthquake so we don’t know just how big those waves can get.
Then there’s landslides like the one that caused the 1958 tsunami in Lituya Bay, Alaska which creates a much more sudden displacement than an earthquake. Based on the surrounding mountainsides the wave created from that landslide might have peaked at ~500 meters without the 100+ mile wavelength you’d see in a normal tsunami wave.
The most common however are tidal bores, which can send a 30+ foot vertical wave down rivers and narrow channels. This phenomenon shows up relatively frequently in earthquake youtube videos near rivers, though the wall is usually only 5-10 ft tall.
Oh yes! It’s absolutely true that underwater geography can steepen the wave front and amplify the height, sometimes by orders of magnitude. The deep water height of a tsunami wave is often a lot different from what you will see at the coastline.
An entertaining anecdote from the pre- smartphone era:
I sailed to the site near Chenega bay where the earthquake wiped out the village in 1958. We got permission from the elders at the Chenega bay village to land at the island, and it was extremely humbling to see the high water mark from the coastline, and to see the wreckage of boats far, far up on mountainsides.
I’m not a big believer in supernatural stuff, and there are plenty of alternative explanations, but it still freaks me out a bit that the photos we took (aside from the digital ones) did not develop any images of the village site. It was white as if it had been overexposed, even in the case of 1/2 frames. On both disposable cameras. Other photos from the same day, taken in other directions, turned out fine. The digital camera fell overboard in 500 fathoms, so we lost those photos the next day.
As for how exactly this could happen in any reasonable version of events, I’ve got nothing. I guess sometimes chance events line up just right to make for a good story.
Interestingly, there are big tidal bores frequently in Turnagain arm, with 1-3m being common. I’ve seen people surfing it with wetsuits in the ice cold water, getting a run of several miles lol.
> Interestingly, there are big tidal bores frequently in Turnagain arm, with 1-3m being common. I’ve seen people surfing it with wetsuits in the ice cold water, getting a run of several miles lol.
That’s going on the bucket list! How dangerous is it? If you biff it and get caught by the wave can you just dive under the wavefront and come up behind it like on a beach?
I don’t know much about the dangers involved, but it isn’t (or wasn’t, AFAIK) a big attraction… so maybe it’s crazy or dangerous? I’m not sure. Or it might be because the water is so cold that hypothermia and death is inevitable in less than an hour? Or because there probably is no realistic chance of rescue if something goes wrong?
At any rate, there was enough people willing to try that I saw it a couple of times, and TBF I think windsurfing isn’t too unusual in the arm now. But there is also trees and stuff in the tidal bores sometimes, so maybe debris is a big problem or the area is too shallow to be safe.
But, if it’s doable, I’m sure it would be memorable!
I think you’re out of touch. A tsunami is a wave both from a pedantic perspective and an intuitive one and most people aren’t deceived into thinking that tsunamis aren’t dangerous at all because it’s a wave. That’s just made up garbage.
You’re like coming up to me and saying hurricane is not wind because it’s dangerous to think of a hurricane as only wind.
Dude. Nobody is thinking hurricanes are just chill just because hurricanes are wind. This is a fucking non-issue.
I think what you’re trying to say is that the wave length of a tsunami is much longer than the amplitude even though the amplitude is still epically high. But don’t try to conflate this with a safety issue of people dying because somebody called it a “wave” that’s just garbage.
So, I’m sorry that I evidently didn’t manage to convey my point effectively. The problem is that wave is accompanied by a measurement that deceptively buries the lede.
Everyone knows hurricanes are wind. So they look for the wind speed to understand the threat. And it’s effective at characterizing the threat. A 100mph wind is going to be similarly destructive as any other 100mph wind. It works and is semantically and linguistically accurate.
Everyone knows a tsunami is a wave, and it is a strong intuition to believe that a wave is defined by its height. , and the height of the tsunami is actually one of the most widely reported metrics. But intuition about the effects of a tsunami by wave height is dangerously wrong. A tsunami is not at all similar to the vast, vast majority of waves in character and effect. Its speed and length at way, way out of band, and are seldom reported.
My understanding is the most deadly/destructive parts of hurricanes are usually:
1. the storm surge, the potential wall of water brought by the continuous winds and waves near the shore, followed by
2. the flooding from heavy rains, then
3. followed by the wind.
So your example might also be hitting the same issue you're trying to avoid.
Note, the worst storm surge is from the eye towards the side where the winds are blowing in the direction of the shore. That's only part of the area with the peak winds.
Good points. Where I am at it’s mostly the wind because I am a well drained higher elevation, so I’m sure that coloured my perception. But you are right, the storm surge and flooding also do a great deal of damage.
Idk. I don't live anywhere where tsunamis are an issue but seeing measurements like a 1m wave does make me wonder about waves I see at the beach that are that high regularly. I find myself going "oh not so bad then" only to read about thousands of people being evacuated and major damage
This doesn't make sense to me intuitively. It must be a wave.
Imagine you have a fault line. There is a left side and a right side to the fault line. If the left side lowers with a shift then that shift MUST be localized to the area around the fault. Because if it wasn't then that means there's an elevation change across the board for everything to the left of the fault. You see how that doesn't make sense? So if the entire country of japan was on the left side of the fault then the entire country of japan shifts in elevation which is unrealistic.
So that means, if what you say is semi-true then the shift in elevation is localized to the area left along the fault but the elevation further left remains the same. It's like a slight dip or bump along the fault line. It must be like this because the alternative is just unrealistic. This MUST be what happens when tectonic plates "shift". You won't see the ENTIRE plate shifting in elevation.
With naive logic, one would think that the water simply fills the localized gap but given how deep the ocean is relative to the actual shift way down in the abyss I'm betting if you were on a boat on top of the fault you wouldn't notice anything. But the movement does create a slight imperceptible "filling" that you don't notice. This is a "wave" but it's invisible.
The wave will translate leftward if the movement of the "shift" was sort of in that direction, but you don't see it. BUT as the sea floor gets nearer and nearer to the surface of the ocean the energy of the wave gets squuezed into less and less ocean water mass (i'm remembering how tsunamis work now) and THEN it becomes visible. Right? Just imagine a sideways cross section. As the tiny wave travels from big ocean with huge depth to coastline with no depth the energy of the wave gets concentrated into a thinner and thinner layer of water.
My intuition just sort of converged with my obscure memory of how tsunamis work so I'm pretty sure this is what's going on.
So it is indeed a "wave" that is acting on wave like phenomena beyond simply "filling a gap". In fact say there's an elevation lowering on the left side of the fault by 1 meter. The resulting wave on the coast line hundreds of miles away will be a wave that extends upward by MORE then 1 meter above sea level which is the opposite of water "filling up a gap." That's totally a wave.
Additionally water from tsunamis always recede. This wouldn't happen if the "wall of water" was simply equalizing. If that's the case the water would never recede.
Any expert who says otherwise, let me know.
edit: Actually why the fuck am I using my intuition to explain it? Just cite a source:
tsunamis are 100% waves as explained in the link. Anyone who says otherwise clearly doesn't know what they are talking about, that includes the person I'm responding to. End of story.
Yes, they are waves, but they are often very long waves. A typical 1m wave might be 20m long. A tsunami wave might be a kilometer long or longer. That is why people say they are like a tide. The wave arrives, then does not recede for several minutes. So, while a 4m wind driven wave might break over a seawall and even wash a car off the road, a 4m tsunami washes ships over that same seawall and floods the city.
It’s a wave, but it is often not at all like a regular ocean wave. I’ve been at sea when a 3m tsunami passed, we barely felt it. If it had been a 3m wind wave in that otherwise calm sea, it would have knocked dinner off the table.
We were about 50 miles offshore, off the continental shelf (in very deep water) we got the information of the wave from our regular meteorological diligence, since it was my job to get our satellite weather and any notices to mariners on a 6 hour rotation.
I saw the wave on radar first, since it lifted ships that were below our horizon up to where they could be seen again for a few sweeps. But it just felt like A gentle lifting. I didn’t even feel the subsidence of the wave. Interestingly, ships 20 miles away from us but near the edge of the shelf reported isolated severe and chaotic waves.
Here's a video of what it looks like from the 2011 event, from the POV of the coast guard approaching it. Waves don't typically look like a sheet has been flapped across one front of the entire horizon of what is visible on the ocean
Yeah that's a wave bro. Notice how the ocean rises above it's own typical sea level? That's not water "filling in a gap" the way tides do it as sea level changes.
That's a huge ass wave as it's a pulse traveling on top of the ocean, above sea level.
That's what it is like out at sea. There's a reason tsunamis are referred to as "tidal waves." For example, watch this video of a tsunami hitting a port today: https://www.youtube.com/watch?v=M1B1J6sgFxk
Yeah, they are waves I think. Just, really incredibly big waves with lots of mass behind them. I think people want to say “not a wave” to emphasize the fact that they are much bigger than the waves that the local environment is used to, so they can be really surprising.
Since we're intuiting, I'm just imagining something like quickly adding a "D.C. offset" of some given height to the crests and troughs you'd measure by sampling ocean waves.
In fact, I'm not sure I should have quotes around that. Isn't your interlocutor saying a tsunami is literally a direct current of water flowing toward the shore?
I guess it is like a step function, or at least a step function on one side and a really long decay on the other. Is a step function a wave? I’m not sure, my signal processing class was too early in the morning. Maybe it depends on who you ask, mathematicians vs engineers. I’ll go along with the ones that might make a taser or something.
Maybe the easiest way is explain it by volume of water coming at you. A 'normal' wave comes at you for maybe 2-5 seconds, then recedes. A tsunami wave might come at you for what, a few minutes? So moves more than 20x-50x the water than an equivalent 'normal' wave, which has no other way to go?
Sure it's a wave, but tides, swells and waves all oscillate just on different frequencies and amplitudes. When they all align you get rogue waves and to the casual observer of a tsunami, a wall of water coming your way.
> If the left side lowers with a shift then that shift MUST be localized to the area around the fault. Because if it wasn't then that means there's an elevation change across the board for everything to the left of the fault. You see how that doesn't make sense
Yo heard of fluid dynamics? Good luck localizing this;) maybe you can build a wall or something real quick
Obviously it is all technically waves. Even if EVERYTHING to the left lowered we would be talking about waves caused by it. But it don't need to be all lowered because waves propagate. And point is these particular waves, tsunami are not the waves you think about because you saw some on the beach. It's an ocean rising for a while. Watch some vids to get a vibe for it.
Despite 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.
This is also in many ways what makes them so deadly in places that aren't used to tsunamis. It often just looks like a regular wave or a tide that will imminently break or recede, but they never do. Here [1] is a video of one of the later waves of Thailand's 2004 tsunami.
Even worse is tsunamis are also often preceded by a 'disappearing coast' effect where the water will recede back into the ocean for hundreds of meters. This often drives tourists or locals who don't know better to go check out the sea bed and the weird behavior of the ocean, then the tsunami comes in and they're right in the middle of it.
If you're ever at a beach where the water starts rapidly disappearing, yell tsunami and get away as fast as you can. Ignore the normalcy bias, because most people, even locals, will be just standing around taking videos or even walking out into it. And don't stop running even when you're well away from the beach. It's nature's warning sign.
On 26 December 2004, at 07:58:53 local time (UTC+7), a major earthquake with a magnitude of 9.2–9.3 Mw struck with an epicentre off the west coast of Aceh in northern Sumatra, Indonesia. The undersea megathrust earthquake, known in the scientific community as the Sumatra–Andaman earthquake,[8][9] was caused by a rupture along the fault between the Burma plate and the Indian plate, and reached a Mercalli intensity of IX in some areas.
A massive tsunami with waves up to 30 m (100 ft) high, known as the Boxing Day Tsunami after the Boxing Day holiday, or as the Asian Tsunami,[10] devastated communities along the surrounding coasts of the Indian Ocean, killing an estimated 227,898 people in 14 countries, violently in Aceh (Indonesia), and severely in Sri Lanka, Tamil Nadu (India), and Khao Lak (Thailand). The direct result was major disruption to living conditions and commerce in coastal provinces of surrounding countries. It is the deadliest natural disaster of the 21st century,[11] one of the deadliest natural disasters in recorded history, and the worst tsunami disaster in history.[12] It is also the worst natural disaster in the history of Indonesia, Maldives, Sri Lanka and Thailand.[13]
It is the most powerful earthquake ever recorded in Asia, the most powerful earthquake in the 21st century, and the third or second most powerful earthquake ever recorded in the world since modern seismography began in 1900.[14][a] It had the longest fault rupture ever observed, between 1,200 km and 1,300 km (720 mi and 780 mi), and had the longest duration of faulting ever observed, at least ten minutes.[18] It caused the planet to vibrate as much as 10 mm (0.4 in),[19] and also remotely triggered earthquakes as far away as Alaska.[20] Its epicentre was between Simeulue and mainland Sumatra.[21] The plight of the affected people and countries prompted a worldwide humanitarian response, with donations totalling more than US$14 billion[22] (equivalent to US$23 billion in 2024 currency).
I was around (in India) at the time, but not near the coast, much further inland and to the north, so was not affected.
Yes, they are waves, but they are often very long waves. A typical 1m wave might be 20m long. A tsunami wave might be a kilometer long or longer. That is why people say they are like a tide. The wave arrives, then does not recede for several minutes. So, while a 4m wind driven wave might break over a seawall and even wash a car off the road, a 4m tsunami washes ships over that same seawall and floods the city.
It’s a wave, but it is often not at all like a regular ocean wave. I’ve been at sea when a 3m tsunami passed, we barely felt it. If it had been a 3m wind wave in that otherwise calm sea, it would have knocked dinner off the table.
Perhaps we can just go back to calling them tidal waves. Which is also ambiguous. I guess if I had any point it's just that it's not colloquial to call tsunami waves, its technical. If anything distinguishing based on how they feel compared to regular wind waves is more colloquial.
Honestly tidal wave, a wave that comes in like the tide, might actually be a better term than tsunami (lit Harbor Wave) A wave that destroys your harbor? A wave found in your harbor(a place where there are usually no waves)? What if you are not in a harbor, do you still get a wave?
I am just having a bit of linguistic fun. Tsunami is a great clear distinct term for what can be a very destructive event.
They are waves, but they don't behave like the sort of waves we are used to. This is the source of all the confusion.
I have heard description of a tsunami being "a temporary rise in sea level", which describes its behavior much more intuitively. A tsunami that tops a sea wall will flood the entire lower-lying area behind it. A usual wave, even a tall one, will only deposit some splashes of water behind the wall and go away immediately.
It's a distinction without value I think. There are waves, and many of them. There is a rise in the sea level. For anywhere affected, both certainly matter. Like you mentioned, tsunami isn't a brief event. And here in Japan, they are talking about tsunami waves, not a singular tsunami. And talking about sea level rise and checking the local power poles for sea level indicators from previous tsunami events and floods.
I is absolutely a VERY valuable distinction because the behavior as it affects humans (up to and including killing them) is VERY different.
Regular waves that are a little higher than your seawall might cause some water damage to the buildings right next to it. A tsunami that is a little higher than your seawall will flood your entire town and drown people who are caught in basements.
Sure, but if you insist it's like a tide you downplay the risk of the initial hit of the wavefronts and the potential for it to slam up the coast or a seawall becoming a larger local wave. And if you insist it's like a wave, you downplay the persistent risk of both follow-up waves and ongoing flooding that won't subside quickly.
So saying it's not waves is dangerous, and saying it's not a sea level rise is dangerous. It's not useful to try and delineate between a tsunami being one of the two when it's in reality an event that consists of both.
(Ignoring that a sea level rise and a long-wavelength wave are the same thing)
These things are 100% waves. It's not a misnomer. It fits the scientific definition of waves and it fits our intuition of what waves are. These are NOT tides.
Yes, they are waves, but they are often very long waves. A typical 1m wave might be 20m long. A tsunami wave might be a kilometer long or longer. That is why people say they are like a tide. The wave arrives, then does not recede for several minutes. So, while a 4m wind driven wave might break over a seawall and even wash a car off the road, a 4m tsunami washes ships over that same seawall and floods the city.
It’s a wave, but it is often not at all like a regular ocean wave. I’ve been at sea when a 3m tsunami passed, we barely felt it. If it had been a 3m wind wave in that otherwise calm sea, it would have knocked dinner off the table.
A tsunami absolutely does not fit our intuition of what waves are. It looks like a wave. But it does not stop. It just continues. That little wave goes on an on, farther and farther inland. After an hour it may still go on. It's a nightmare wave, because it doesn't not fit one's intuition of what waves are.
I'm reacting against the word "intuition" here. Nobody said it isn't a wave. But it's not like a wave as our intuition says.
(Though it does not _always_ look like a wave - check out the timelapse video from Kuji harbor: https://www.youtube.com/watch?v=M1B1J6sgFxk - that's why you'll sometimes see people talking about it looking like a (very) high tide.
As an example of the nightmare "wave" which doesn't stop, and is thus un-intuitive.. https://www.youtube.com/watch?v=3618dZoiaPE which is incidentally also from Kuji, but from 2011)
I 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.
Ah, 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.
I seriously wonder if people brains are being cooked these days. One of the blessing of HN used to be it was full of fairly well educated, and most importantly, curious people. Sometimes with a bit too much of a focus of the technical side of things, but at least on most technical topics the comments where a great place to get a richer understanding of a whatever was being discussed.
A 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.
Depends 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.
Same. Japan's earthquake/tsunami preparedness is genuinely unmatched, but earthquakes/tsunamis have the annoying habit of happening in the "wrong" place and the country's overall record of "doing the right thing" can charitably be described as spotty.
My guess is that the wide area simply reflects the uncertainty, and not some apocalyptic scenario. Hopefully this broad warning and plenty of time gets everyone out of danger effectively
Yes, but it would have to be equal and opposite the incoming tsunami, and the amount of energy involved is mind boggling. The recoil would have its own repercussions. Your neighbors on the receiving end of the resulting double tsunami would want to have a word with you.
My wife decided to not travel to Japan due to an impending warning from a manga for July 2025. I have been making fun of her all month only to get this tsunami warning now!
> The 2021 reprint capitalizing off this revived popularity warned of a "real disaster" in July 2025, causing a minor case of mass hysteria in 2025 when summer trips to Japan from East Asia decreased markedly and several airlines even cancelled flights.
That's because the other mangas forgot to adjust by +/- some 1000 km for location, 25 days, 365 days, 1825 days, or some other arbitrary but possibly nicely divisible number, for when and where it strikes.
You also have to conveniently forget the things that don't sell mangas such as annual typhoons, heatwaves, and of course thousands of premature deaths from man-made causes such as pollution and poor lifestyle.
Otherwise, if predicting disasters was easy, everybody would be doing it. No, it takes special, paper-based skills such as mangas , tarot cards, weekly horoscopes, etc.
Reminded of the available $1m award from James Randi’s org that was never claimed b/c no one could ever do anything supernatural under reasonable testing conditions.
(Woo is surely possible but all those who can pull it off were gifted abilities that are deactivated by non-monetary incentives)
Ryo Tatsuki clarified it wasn't her that said July 5th was when the big one will hit but that it was her publisher that pushed that date for marketing and sales.
She along with the Thai clairvoyant and Brandon Biggs all say July is the month when the earthquakes and tsunamis begin.
It is unwise to simply write this off, Ryo Tatsuki said she saw 4:18am in July 2025 which can only mean 14 hours from now we will know if that is it.
It is July 30th 2:14pm, in 14 hours it will be July 31st 4:18am. After that a 20 hour period until the deadline.
Is your wife generally fearful like that or this was a rare occurrence and she can actually have some introspection on that and has a fighting chance of coming on top of that?
I know few folks like that, for them it comes from general lack of understanding of reality, society and human nature, a lot of superstition in various directions and similar traits. Suffice to say its very hard to live up to one's potential in life with such mindset, but such things could be conquered if there is enough resolve.
From videos online so far, it seems the strength of the quake didn't translate to massive lateral movement. There seemed to be lots of intense P-wave wiggling and bumping rather than large S-wave swings back and forth. The big Japan quake was one of those, where you saw offices being slid back and forth and everything flying off shelves.
Not sure what that means for the tsunami - but so far it seems less intense than the 8.8 would imply.
Japan uses a scale that measures the movement[0]. Of course depending on where you are the result changes, but it's a lot more usable for the practical "how much shaking will be involved here/was involved here".
The first list on that page is specifically for the deadliest earthquakes, and so it only includes earthquakes with 100,000+ fatalities. The ranking by magnitude is farther down (and according to that list, a magnitude of 8.8 would make it tied for sixth place).
Multiple lists. On the list of strongest by magnitude, it would be in a three-way tie for 7th if there's no further revision to the magnitude estimate (which there usually is). It would be second by magnitude on the list of deadliest earthquakes, but thankfully due to location will not likely make that list.
Not that it's much use to compare, but the closest DART buoy 21418 to the M9-9.1 2011 Tōhoku earthquake[1] (which had an epicentre just 72km East of Japan's east coast) recorded a water column height variation of ~3m.[2][3] The closest DART buoy to today's M8.7-8.8 earthquake is 21416 and this recorded a water column height variation of ~0.6m back in the M9-9.1 2011 Tōhoku earthquake.[4]
Impressive, glad the alarm chain works. And from what you say the warning message is also clear and understandable. Not tech or geology jargon that people don't understand and then take no or the wrong actions.
Watch has been upgraded to Warning (Aleutian Islands and California from Cape Mendocino to the Oregon border) or Advisory (California from Cape Mendocino south, and pretty much everything from the California/Oregon border to Alaska until you reach the Aleutian Islands, it looks like.)
Has anyone heard how bad it was in Petropovlosk? USGS estimates "severe" shaking with the possibility of moderate to heavy damage and a chance of fatalities.
They have had quite a swarm of quakes there over the last couple of weeks, including one that was M7+ around the 20th.
From what I see in Russian-language news, only relatively minor damage. I've lived in Petropavlovsk, it's an ugly city in various states of disrepair, but they do take seismic reinforcements seriously, like mag 7 should cause zero damage according to plan.
It's basically immune to tsunamis as it's protected by a bay with narrow entrance that extinguishes the waves, also most of the city is raised at least 10m above the sea.
Severo-Kurilsk, an island town destroyed by a similar tsunami in 1956, lost its port again: https://en.wikipedia.org/wiki/Severo-Kurilsk — the rest of the settlement was rebuilt on higher ground, leaving only the port vulnerable.
The settlement is notable as having belonged to the Japanese in late 19th and early 20th centuries, who once relocated islanders there. Russian Wikipedia says they were Ainu.
So far the news here has only shown damage to a school (which apparently was empty due to repair work), and some bad flooding in one part. Let’s hope for the best.
I use MyShake which will let me get alerts based on specific magnitude cutoffs. I actually just ratcheted up my "global" alert from 7.5 to 8 because of all the alerts from the last couple weeks in the pacific.
People tripping over eachother arguing whether a tsunami is a "wave" on a disaster warning submission... If HN was a village everyone would drown in the process.
I have family members who were in Hawaii (Haleiwa) today and they are wondering if they should try to beat the tsunami and get back to their hotel in Waikiki.
I am afraid Waikiki will see flooding. I know Duke's and some other restaurants were closing early.
Do not stay in Haleiwa or go to Waikiki. Consult a map, and find some uphill areas above 100ft to drive to. Drive towards Mililani and wait it out in the upland areas.
My kids are at camp right now on the North Shore and are being evacuated by bus to Mililani.
Talked to the AI which said: MMI 4.5 in the context of an M8.7 quake, for your vessel: Danger level from shaking alone: Very low in open water. Danger from tsunami in the open ocean: Very low (unless extremely close to epicenter). Prime danger: If near shore, from tsunami run-up, NOT the shaking. Actionable advice: Remain in deep water until tsunami warnings have cleared; proceed to port only when officially safe. Monitor official maritime and tsunami alerts closely after any major earthquake.
That's interesting. Mental note, if piloting a vessel in a tsunami, head to deep water.
Neat video. It seems to capture the middle between "super high coastal wave" and "shallow but long duration wave in deep water". That's what you'd get with coastal waters several tens of meters deep.
>Important Context: In the Japanese audio, a TV announcer says they don't know if this incident is related to the earthquake/tsunami: "We have no information indicating a connection with the recent tsunami".
>Also, stranded whales in Tateyama have been observed since yesterday
The USA also has a site that seems to be up at the moment. Without seeing the CA version I'm not sure how it differs, but I suspect it's possible for Canadians to get some useful local information from it: https://www.tsunami.gov/
ah, you're right. I knew that, think I must've looked at it too fast and assumed it was .gov.ca. (which isn't even the TLD that the Canadian government uses, but never mind...)
But our funny-accented cousins can access useful information on the .gov as well (the entire west coast of Canada is under tsunami watch at the moment).
I was parked at Selzer beach in Seaside, Oregon when the earthquake/tsunami news hit around 7:30pm. Within 30 minutes it was impossible to buy gas without queueing and now there is a pretty steady stream of cars heading out of town. As of 9pm it’s been upgraded to a warning up and down the coast.
I was just thinking of tsunamis the two days ago in the Del Rey beach parking lot, where I noticed the locals seemed to park at the exit end of the lot, facing out. I moved my car to match because that just makes sense.
I’ve never thought about a tsunami when visiting the beach in my life. Are they much more common in the Pacific? We go to the Gulf and Atlantic and it’s never something I think about. We usually go in June/July, so we don’t worry much about hurricanes either.
There is no Atlantic ring of fire, is there. What little places like Iceland show is nothing compared to what pacific has to offer in much larger area.
While the Atlantic doesn't really have many faults that will generate earthquakes causing tsunamis there is always a risk of landslides creating large tsunamis up to what we'd consider mega-tsunamis. This said this is something that may have thousands of years between incidents.
Reading the news, it seems there was no significant impact in the neighbouring societies, except the death of sea life (whales in Chiba), is that right?
I’m in Costa Rica on vacation, hotel said the beach is closed but they didn’t know why (lol yeah right). Per tsunami alerts it should be hitting right now at 1-3M above tide, I don’t see any evidence on various beach livecams like Taramindo. I’m in puerto Jimenez which is on the inland side of a small peninsula in southern CR so not expecting much.
All the tectonics and volcanos that are underground are linked, these seismic events aren't just isolated on islands.
I hate to say this but we can expect a major event in August. All I can tell people is to prepare but I see people just with blank expression, there is almost no concern at all which reminds me very much of November 2019.
I happened to be visiting Miyagi just before the tsunami struck, and I was really panicked.
When I got out of the car, everyone's smartphones nearby suddenly started beeping.
A message in Japanese, saying something like "TSUNAMI EVACUATE NOW," sounded throughout the area. At the time, my phone displayed a warning that a three-meter tsunami would hit the area within an hour.
I waited on slightly higher area for about two hours, but the locals kept going about their usual business, and there were no announcements from the nearby police.
Fortunately, nothing happened, but it's difficult to know which information to trust. Still, it's good that there's a system in place for evacuation alerts.
Just when I am about to depart on vacation to Sulawesi in Indonesia, mostly for diving and some culture and adventure... well at least Togian islands are not directly exposed to part of pacific ocean that generated this.
I guess I will have to sleep with a big wooden log.
Can the wave be seen and tracked from planes above? I know they can travel at upwards of 300+mph but given the distance from Russia to the west coast seems like it should be able to be tracked.
No. When they travel at that speed they are not visible. Only when they hit shallow water (a necessary , but not sufficient, condition) do they slow down and become a threat.
There are planes, buoys and other things being mentioned on the news here in Japan as ways things are being tracked. Maybe not what you meant, but tracking the wave isn't necessarily correct. There are many waves, and the initial wave is often (in this case also) not the largest.
The news mentioned a previous similar event where the largest wave was 4 hours later.
I don’t think there’s a high false positive rate on these. They do happen pretty rarely, and a false negative is far worse than a false positive. Due to the tsunami wave propagation, it can sometimes take hours for significant waves to reach the coastline.
to put this in perspective, and please, if you work for USGS or whatever, correct me if i am wrong: this is roughly the same magnitude of the 1994 Northridge earthquake in California.
i think i got the scale the wrong way around, the magnitudes reported now are only larger (than Richter) with smaller quakes compared to the Richter; it looks like 8.8ML ~= M8.8. Sorry, i looked at the chart the wrong way around.
Each incremental increase in magnitude is 10^1.5 in power. The difference between 1994 Northridge and this one is 2.1, so roughly 10^3 difference in power.
The Richter Scale is a logarithmic scale, based on shaking measurements (think of the old pencil-based seismograph!). Power. (10^1).
The Moment Magnitude Scale (the more modern/replacement of Richter Scale) is based on energy. Geological organisations reporting on an earthquake will usually show this as "M <number>" or "Mw <number>".
Richter works well for small-to-medium earthquakes, and it's not accurate for really large or distant earthquakes.
The energy released in an earthquake increases exponentially, not just linearly.
AFAIK, it was done that way to maintain rough congruence with historical seismic magnitude scales, which were more qualitative in nature. Modern seismic scale systems are significantly more scientific and quantitative but you can kind of retcon the historical systems if you set the exponential strength scale to 10^1.5 in the modern systems.
I'm actually not sure the Northridge earthquake was cited in the Richter scale, most references I see have it as about a 6.7, which based on the USGS catalog, was it's moment magnitude 6.7 Mw
Japan forecasting tsunamis up to 3m across basically the entire eastern coast. First waves will hit within 10 minutes.
https://www.nhk.or.jp/kishou-saigai/tsunami/
https://www3.nhk.or.jp/news/live/ (live, Japanese)
https://www3.nhk.or.jp/nhkworld/en/live/ (live, English)
The east coast is also where the vast majority of Japan's population lives, and was previously hit by the 2011 tsunami (Fukushima and all that). We're about to find out the hard way what lessons they have learned.
Update: First detected wave in Nemuro, Hokkaido (northernmost Japan) was only 30cm. There may be more. Waves of 3-4m have apparently already hit Kamchatka in Russia.
Update 2: We're almost an hour in and highest waves to actually hit Japan remain only 40 cm. It looks unlikely that this will cause major damage.
Here are some live streams.. No action yet. Fingers crossed!
From a helicopter Japanese KATU news https://www.youtube.com/live/mBQHNV7cqrM?si=lwqB5YHknA7KUTY_
Webcams https://www.youtube.com/live/5pTPKHJxQ4g?si=xWe5MkLKIZ3N5I8D
Hawaii news https://m.youtube.com/watch?v=lVy5nLWruu0&pp=ygUSSmFwYW4gdHN...
Now that things have calmed i can say that the webcam chats were very entertaining
Japanese news reporting during disaster scenarios is something to behold.
The screen is filled with data and blinking like a Bloomberg Terminal.
To be fair, most of Japanese TV is like that. I always joke that the primary reason they developed HD TV was to be able to cram more text in every corner xD
haha, makes a lot of sense!.
But then again, take a stroll around a shop-laden street in Japan and you'll see the exact same thing. They just like it that way.
Funny thing is how for interior design they do a full 180 and typically go very minimalistic.
> Funny thing is how for interior design they do a full 180 and typically go very minimalistic.
Only if they are well to do. Most family houses in Japan are crammed full of stuff with very little "design".
I was wondered that. Like from movies or documentaries, etc. Very nice, clear, order, minimalistic. Then I was looking to buy a house and I found a site with "almost" abandoned house for sale.
My God. Everything , everywhre, no design ( haha ), no exceptions. People were actually living there.
Had a cultural shock.
I do live in Japan and good god, I have never seen such messy people anywhere else in the world. The offices of all my Japanese colleagues are piles upon piles of documents and boxes without any kind of order.
But the cities themselves are like that. There is zero urban planning, just buildings thrown around in impossible non-Euclidean patterns.
They're a book from the early 1990s called "Tokyo Style" that is packed with photos of real living conditions from back then. Chaos of every variety. Plus some Super Famicom and PC-Engines laying around. A very cool book, most recently reprinted in 2024 with Japanese/English captions.
Here's the full book "Tokyo: a certain style" by Kyoichi Tsuzuki (same author), https://archive.org/details/tokyo-a-certain-style
I believe that's essentially the first English edition.
and the cables, the cables hanging from everywhere!
( btw, has anyone noticed in anime there are always frames of street cabling? Like those cylindrical transformes and thick cables. Almost cyberpunk! )
The transformers are a result of a the lower voltage (also used in America), for efficiency and to keep the required voltage the transformer needs to be nearer to the house.
We also have transformers in Europe, but they are hidden. Which incidentally makes them more reliable, as they are not exposed to the elements.
I know, I live in Japan, shopping streets are seizure-inducing here xD
"content is beautiful"
And most Japanese websites.
Yeah, shopping in Rakuten or Yahoo Auctions is quite an experience...
My favorite is the NHK reporters standing in the middle of absolutely nowhere with their NHK helmets. No matter what the event, there is a reporter wearing a helmet.
Also, the very first thing they say when the camera cuts to them is that they are standing in designated evacuation zone X that's Y meters above sea level.
Then the cameraman zooms at the ocean, which is blurry and shaky because they're in the designated evacuation zone Z km away from the coast.
That’s probably the responsible thing to do. It is always odd to see American weather disaster reporters, like:
“We’re here inside the hurricane, let me go outside so you can see that the wind will push me over. Can’t hear anything because my microphone is getting blasted by the wind. Over there you can see the emergency responders, they appear to be fleeing. Tell my wife I love her, but I’ve got to die for some b-roll.”
That makes sense, though. To do otherwise would be pretty dumb for a tsunami situation.
But yeah, the handheld telephoto zoom from a safe location is definitely on the Japanese Disaster TV bingo card. That said, I appreciate that they just keep repeating the same warnings and data, rather than the ridiculous speculation that the US news media engages in when they get bored.
I mean, they could at least fly some drones over to the beach for some B-roll.
It would take too long to fax back the Ultra HD footage taken with optics we can't even comprehend exist.
Self-satisfaction or more professional?
Also when you visit most japanese websites you can see this phenomenon.
I've read an explanation once that this is because culturally, japanese people perceive a wealth of information and choice as being re-assuring and trustworthy, while most westerners feel more re-assured by seeing less content and choice presented in a more minimalist kind of way.
I actually prefer content style of Japanese websites. I get all the relevant info on one screen instead of having to scroll/click thru tens. The western style websites are very inefficient and hide info (feels scammy with lack of info).
Can you point to some japanese websites that have an english version and are a good example of this?
oh I hate minimalistic UIs, I think I might have just found my people
Yes, but it does make sense.
Eg. old people without smartphones or someone just turning their TV on, seeing big letter "Tsunami evacuate" with map and other information. You instantly know the most important information and you can act on it.
Pachinko!
A̶F̶A̶I̶C̶T̶,̶ ̶N̶T̶V̶ ̶i̶s̶ ̶r̶e̶p̶o̶r̶t̶i̶n̶g̶ ̶t̶h̶a̶t̶ ̶3̶m̶ ̶w̶a̶v̶e̶s̶ ̶h̶a̶v̶e̶ ̶j̶u̶s̶t̶ ̶s̶t̶a̶r̶t̶e̶d̶ ̶t̶o̶ ̶h̶i̶t̶ ̶J̶a̶p̶a̶n̶.̶
EDIT: Apologies, I misunderstood—a reply to this comment said they were just predictions. (I saw in this video[0] that the first waves had arrived, and assumed the heights would've therefore corresponded to actual measurements. But it's still in the "predictions" section, and I should've noticed that before posting....)
[0] https://www.youtube.com/watch?v=YbRCvDZO5Zk
No. That's the predictions. Biggest wave so far has been 60cm (EDIT: as of 6am UTC it's 1m30cm, but that's still relatively small. It came up almost exactly to the top of the pier in Kuji.)
I've updated my comment, I indeed misunderstood what I read.... Unfortunately it's too late for me to delete the comment, so everyone please feel free to flag/downvote it (both to push it down for the sake of clutter, and also to punish my carelessness :-P).
No worries -- the way they present it is confusing, particularly if you're watching the NHK World stream, which layers poorly translated English versions on top of the Japanese.
How big was the 2011 tsunami? Is 3m bigger or smaller?
It'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_an...
For perspective, the tsunami that topped the seawall at Fukushima Dai-ichi had a peak height of ~14m.
The seawall was 5.7m.
Is height the only thing that matters? Presumably 1x 2m wave is less impactful than 10 x 1m waves spread 20 seconds apart?
I'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.
> What you get is not a "wave" but a wall of water.
Its a wave (or series of waves) with a large wavelength and speed in deep ocean, that becomes a shorter wavelength and very large amplitude by shoaling as it hits shallow water.
Its different from typical wind-driven ocean waves for a lot of reasons; but a big indicator is wavelength -- wind-driven ocean waves have wavelengths up to hundreds of meters, tsunamis have wavelengths (in deep ocean) of hundreds of kilometers.
More like tides than waves, as has been stated elsewhere in the thread, is both technically wrong but substantively (with the caveat that "waves" really means "typical wind-drive waves") correct, in that tides are also manifested through waves, but waves which have wavelengths of thousands of kilometers, and so tsunamis are waves more similar to those making up tides (hence the old colloquial use of "tidal waves", which properly refers to the waves manifesting tides, to refer to tsunamis) than to wind-driven waves.
Not true. As the news reporters here in Japan are repeating every few minutes, there will be many waves and they can get bigger over time. They already have, 20-30cm initial waves had 40-60cm later waves.
Waves can get bigger due to earthquakes not being instantaneous or necessarily a single movement, due to amplification by geography, by reflections, by aftershocks, and many other things. The news is suggesting waves lasted about a day for a previous event in a similar area.
> 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.
I don’t take offence. I’m not the most educated, and I don’t live in or near a tsunami prone area, I know about other natural disasters that are relevant to where I live though, maybe more than the parent poster.
I 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.
The 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.
I appreciate your effort to provide an understandable explanation.
That said, in context the original statement was so extremely misrepresentative of the reality that I felt it left the realm of "inaccurate but effective for communication". I certainly didn't see the objections as pedantic.
A clarification was appropriate because it really did miss the physics, but doubling down on the definition of wave without talking about speed, length, and volume (which is what had confused OP in the first place) was not only suboptimal in teaching useful knowledge to OP, it was also misleading in a way that could (and did, in at least one case of a commenter in this thread) lead to a dangerous misconception about characterising tsunamis.
Perhaps it wasn’t intentionally pedantic, but the way that it was doubled down on later makes me suspect an argument in bad faith, or at least an epic case of missing the opportunity to usefully inform.
I value this site for the general character of people trying to educate more than just troll, and I think it’s important to try to educate trolls as well to understand a more constructive and respectful way to interact here. Ostensibly, we take off our clown shoes and leave them at the door.
OTOH I may have read multiple comments in similar tone that were not all attributed to one poster , giving me a mistaken impression of the intent. In that case, I owe an apology for perhaps overreacting.
Nitpick: while what you say is generally true, there are several scenarios that can create true dramatic “wall of water” tsunami waves that have leading slopes of 45-90 degrees and heights in the tens of meters.
The most obvious (but relatively rare) are tsunamis amplified by submarine canyons and other coastal bathymetry like the Nazare submarine canyon famous for the biggest waves on the planet (50+ footers are common in season). If an earthquake directs a tsunami at that canyon, the resulting waves will be spectacular and probably drown everything north of the cliffs. Unfortunately we don’t have any historical records about what happened at Nazare after the 1755 Lisbon earthquake so we don’t know just how big those waves can get.
Then there’s landslides like the one that caused the 1958 tsunami in Lituya Bay, Alaska which creates a much more sudden displacement than an earthquake. Based on the surrounding mountainsides the wave created from that landslide might have peaked at ~500 meters without the 100+ mile wavelength you’d see in a normal tsunami wave.
The most common however are tidal bores, which can send a 30+ foot vertical wave down rivers and narrow channels. This phenomenon shows up relatively frequently in earthquake youtube videos near rivers, though the wall is usually only 5-10 ft tall.
Oh yes! It’s absolutely true that underwater geography can steepen the wave front and amplify the height, sometimes by orders of magnitude. The deep water height of a tsunami wave is often a lot different from what you will see at the coastline.
An entertaining anecdote from the pre- smartphone era:
I sailed to the site near Chenega bay where the earthquake wiped out the village in 1958. We got permission from the elders at the Chenega bay village to land at the island, and it was extremely humbling to see the high water mark from the coastline, and to see the wreckage of boats far, far up on mountainsides.
I’m not a big believer in supernatural stuff, and there are plenty of alternative explanations, but it still freaks me out a bit that the photos we took (aside from the digital ones) did not develop any images of the village site. It was white as if it had been overexposed, even in the case of 1/2 frames. On both disposable cameras. Other photos from the same day, taken in other directions, turned out fine. The digital camera fell overboard in 500 fathoms, so we lost those photos the next day.
As for how exactly this could happen in any reasonable version of events, I’ve got nothing. I guess sometimes chance events line up just right to make for a good story.
Interestingly, there are big tidal bores frequently in Turnagain arm, with 1-3m being common. I’ve seen people surfing it with wetsuits in the ice cold water, getting a run of several miles lol.
> Interestingly, there are big tidal bores frequently in Turnagain arm, with 1-3m being common. I’ve seen people surfing it with wetsuits in the ice cold water, getting a run of several miles lol.
That’s going on the bucket list! How dangerous is it? If you biff it and get caught by the wave can you just dive under the wavefront and come up behind it like on a beach?
I don’t know much about the dangers involved, but it isn’t (or wasn’t, AFAIK) a big attraction… so maybe it’s crazy or dangerous? I’m not sure. Or it might be because the water is so cold that hypothermia and death is inevitable in less than an hour? Or because there probably is no realistic chance of rescue if something goes wrong?
At any rate, there was enough people willing to try that I saw it a couple of times, and TBF I think windsurfing isn’t too unusual in the arm now. But there is also trees and stuff in the tidal bores sometimes, so maybe debris is a big problem or the area is too shallow to be safe.
But, if it’s doable, I’m sure it would be memorable!
I think you’re out of touch. A tsunami is a wave both from a pedantic perspective and an intuitive one and most people aren’t deceived into thinking that tsunamis aren’t dangerous at all because it’s a wave. That’s just made up garbage.
You’re like coming up to me and saying hurricane is not wind because it’s dangerous to think of a hurricane as only wind.
Dude. Nobody is thinking hurricanes are just chill just because hurricanes are wind. This is a fucking non-issue.
I think what you’re trying to say is that the wave length of a tsunami is much longer than the amplitude even though the amplitude is still epically high. But don’t try to conflate this with a safety issue of people dying because somebody called it a “wave” that’s just garbage.
So, I’m sorry that I evidently didn’t manage to convey my point effectively. The problem is that wave is accompanied by a measurement that deceptively buries the lede.
Everyone knows hurricanes are wind. So they look for the wind speed to understand the threat. And it’s effective at characterizing the threat. A 100mph wind is going to be similarly destructive as any other 100mph wind. It works and is semantically and linguistically accurate.
Everyone knows a tsunami is a wave, and it is a strong intuition to believe that a wave is defined by its height. , and the height of the tsunami is actually one of the most widely reported metrics. But intuition about the effects of a tsunami by wave height is dangerously wrong. A tsunami is not at all similar to the vast, vast majority of waves in character and effect. Its speed and length at way, way out of band, and are seldom reported.
My understanding is the most deadly/destructive parts of hurricanes are usually:
1. the storm surge, the potential wall of water brought by the continuous winds and waves near the shore, followed by 2. the flooding from heavy rains, then 3. followed by the wind.
So your example might also be hitting the same issue you're trying to avoid.
Note, the worst storm surge is from the eye towards the side where the winds are blowing in the direction of the shore. That's only part of the area with the peak winds.
Good points. Where I am at it’s mostly the wind because I am a well drained higher elevation, so I’m sure that coloured my perception. But you are right, the storm surge and flooding also do a great deal of damage.
Idk. I don't live anywhere where tsunamis are an issue but seeing measurements like a 1m wave does make me wonder about waves I see at the beach that are that high regularly. I find myself going "oh not so bad then" only to read about thousands of people being evacuated and major damage
Obligatory https://xkcd.com/1053/
This doesn't make sense to me intuitively. It must be a wave.
Imagine you have a fault line. There is a left side and a right side to the fault line. If the left side lowers with a shift then that shift MUST be localized to the area around the fault. Because if it wasn't then that means there's an elevation change across the board for everything to the left of the fault. You see how that doesn't make sense? So if the entire country of japan was on the left side of the fault then the entire country of japan shifts in elevation which is unrealistic.
So that means, if what you say is semi-true then the shift in elevation is localized to the area left along the fault but the elevation further left remains the same. It's like a slight dip or bump along the fault line. It must be like this because the alternative is just unrealistic. This MUST be what happens when tectonic plates "shift". You won't see the ENTIRE plate shifting in elevation.
With naive logic, one would think that the water simply fills the localized gap but given how deep the ocean is relative to the actual shift way down in the abyss I'm betting if you were on a boat on top of the fault you wouldn't notice anything. But the movement does create a slight imperceptible "filling" that you don't notice. This is a "wave" but it's invisible.
The wave will translate leftward if the movement of the "shift" was sort of in that direction, but you don't see it. BUT as the sea floor gets nearer and nearer to the surface of the ocean the energy of the wave gets squuezed into less and less ocean water mass (i'm remembering how tsunamis work now) and THEN it becomes visible. Right? Just imagine a sideways cross section. As the tiny wave travels from big ocean with huge depth to coastline with no depth the energy of the wave gets concentrated into a thinner and thinner layer of water.
My intuition just sort of converged with my obscure memory of how tsunamis work so I'm pretty sure this is what's going on.
So it is indeed a "wave" that is acting on wave like phenomena beyond simply "filling a gap". In fact say there's an elevation lowering on the left side of the fault by 1 meter. The resulting wave on the coast line hundreds of miles away will be a wave that extends upward by MORE then 1 meter above sea level which is the opposite of water "filling up a gap." That's totally a wave.
Additionally water from tsunamis always recede. This wouldn't happen if the "wall of water" was simply equalizing. If that's the case the water would never recede.
Any expert who says otherwise, let me know.
edit: Actually why the fuck am I using my intuition to explain it? Just cite a source:
https://www.noaa.gov/explainers/science-behind-tsunamis
tsunamis are 100% waves as explained in the link. Anyone who says otherwise clearly doesn't know what they are talking about, that includes the person I'm responding to. End of story.
Yes, they are waves, but they are often very long waves. A typical 1m wave might be 20m long. A tsunami wave might be a kilometer long or longer. That is why people say they are like a tide. The wave arrives, then does not recede for several minutes. So, while a 4m wind driven wave might break over a seawall and even wash a car off the road, a 4m tsunami washes ships over that same seawall and floods the city.
It’s a wave, but it is often not at all like a regular ocean wave. I’ve been at sea when a 3m tsunami passed, we barely felt it. If it had been a 3m wind wave in that otherwise calm sea, it would have knocked dinner off the table.
> I’ve been at sea when a 3m tsunami passed, we barely felt it.
How far out at sea were you? And how did you know at the time?
We were about 50 miles offshore, off the continental shelf (in very deep water) we got the information of the wave from our regular meteorological diligence, since it was my job to get our satellite weather and any notices to mariners on a 6 hour rotation.
I saw the wave on radar first, since it lifted ships that were below our horizon up to where they could be seen again for a few sweeps. But it just felt like A gentle lifting. I didn’t even feel the subsidence of the wave. Interestingly, ships 20 miles away from us but near the edge of the shelf reported isolated severe and chaotic waves.
https://www.youtube.com/watch?v=wAFYVpX45xs
Here's a video of what it looks like from the 2011 event, from the POV of the coast guard approaching it. Waves don't typically look like a sheet has been flapped across one front of the entire horizon of what is visible on the ocean
Yeah that's a wave bro. Notice how the ocean rises above it's own typical sea level? That's not water "filling in a gap" the way tides do it as sea level changes.
That's a huge ass wave as it's a pulse traveling on top of the ocean, above sea level.
That's what it is like out at sea. There's a reason tsunamis are referred to as "tidal waves." For example, watch this video of a tsunami hitting a port today: https://www.youtube.com/watch?v=M1B1J6sgFxk
Yeah, they are waves I think. Just, really incredibly big waves with lots of mass behind them. I think people want to say “not a wave” to emphasize the fact that they are much bigger than the waves that the local environment is used to, so they can be really surprising.
Since we're intuiting, I'm just imagining something like quickly adding a "D.C. offset" of some given height to the crests and troughs you'd measure by sampling ocean waves.
In fact, I'm not sure I should have quotes around that. Isn't your interlocutor saying a tsunami is literally a direct current of water flowing toward the shore?
I guess it is like a step function, or at least a step function on one side and a really long decay on the other. Is a step function a wave? I’m not sure, my signal processing class was too early in the morning. Maybe it depends on who you ask, mathematicians vs engineers. I’ll go along with the ones that might make a taser or something.
Maybe the easiest way is explain it by volume of water coming at you. A 'normal' wave comes at you for maybe 2-5 seconds, then recedes. A tsunami wave might come at you for what, a few minutes? So moves more than 20x-50x the water than an equivalent 'normal' wave, which has no other way to go?
Sure it's a wave, but tides, swells and waves all oscillate just on different frequencies and amplitudes. When they all align you get rogue waves and to the casual observer of a tsunami, a wall of water coming your way.
Tsunamis are waves the same way a step function is the sum of a series of waves.
> If the left side lowers with a shift then that shift MUST be localized to the area around the fault. Because if it wasn't then that means there's an elevation change across the board for everything to the left of the fault. You see how that doesn't make sense
Yo heard of fluid dynamics? Good luck localizing this;) maybe you can build a wall or something real quick
Obviously it is all technically waves. Even if EVERYTHING to the left lowered we would be talking about waves caused by it. But it don't need to be all lowered because waves propagate. And point is these particular waves, tsunami are not the waves you think about because you saw some on the beach. It's an ocean rising for a while. Watch some vids to get a vibe for it.
Despite 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.
This is also in many ways what makes them so deadly in places that aren't used to tsunamis. It often just looks like a regular wave or a tide that will imminently break or recede, but they never do. Here [1] is a video of one of the later waves of Thailand's 2004 tsunami.
Even worse is tsunamis are also often preceded by a 'disappearing coast' effect where the water will recede back into the ocean for hundreds of meters. This often drives tourists or locals who don't know better to go check out the sea bed and the weird behavior of the ocean, then the tsunami comes in and they're right in the middle of it.
If you're ever at a beach where the water starts rapidly disappearing, yell tsunami and get away as fast as you can. Ignore the normalcy bias, because most people, even locals, will be just standing around taking videos or even walking out into it. And don't stop running even when you're well away from the beach. It's nature's warning sign.
[1] - https://www.youtube.com/watch?v=WO7TZFBAlaE
>Here [1] is a video of one of the later waves of Thailand's 2004 tsunami
If that is the one of December 2004, it affected not just Thailand, but also many other countries around the Indian Ocean:
https://en.m.wikipedia.org/wiki/2004_Indian_Ocean_earthquake...
Excerpts:
2004 Indian Ocean earthquake and tsunami
On 26 December 2004, at 07:58:53 local time (UTC+7), a major earthquake with a magnitude of 9.2–9.3 Mw struck with an epicentre off the west coast of Aceh in northern Sumatra, Indonesia. The undersea megathrust earthquake, known in the scientific community as the Sumatra–Andaman earthquake,[8][9] was caused by a rupture along the fault between the Burma plate and the Indian plate, and reached a Mercalli intensity of IX in some areas.
A massive tsunami with waves up to 30 m (100 ft) high, known as the Boxing Day Tsunami after the Boxing Day holiday, or as the Asian Tsunami,[10] devastated communities along the surrounding coasts of the Indian Ocean, killing an estimated 227,898 people in 14 countries, violently in Aceh (Indonesia), and severely in Sri Lanka, Tamil Nadu (India), and Khao Lak (Thailand). The direct result was major disruption to living conditions and commerce in coastal provinces of surrounding countries. It is the deadliest natural disaster of the 21st century,[11] one of the deadliest natural disasters in recorded history, and the worst tsunami disaster in history.[12] It is also the worst natural disaster in the history of Indonesia, Maldives, Sri Lanka and Thailand.[13]
It is the most powerful earthquake ever recorded in Asia, the most powerful earthquake in the 21st century, and the third or second most powerful earthquake ever recorded in the world since modern seismography began in 1900.[14][a] It had the longest fault rupture ever observed, between 1,200 km and 1,300 km (720 mi and 780 mi), and had the longest duration of faulting ever observed, at least ten minutes.[18] It caused the planet to vibrate as much as 10 mm (0.4 in),[19] and also remotely triggered earthquakes as far away as Alaska.[20] Its epicentre was between Simeulue and mainland Sumatra.[21] The plight of the affected people and countries prompted a worldwide humanitarian response, with donations totalling more than US$14 billion[22] (equivalent to US$23 billion in 2024 currency).
I was around (in India) at the time, but not near the coast, much further inland and to the north, so was not affected.
They are very literally long wavelength waves though.
Yes, they are waves, but they are often very long waves. A typical 1m wave might be 20m long. A tsunami wave might be a kilometer long or longer. That is why people say they are like a tide. The wave arrives, then does not recede for several minutes. So, while a 4m wind driven wave might break over a seawall and even wash a car off the road, a 4m tsunami washes ships over that same seawall and floods the city.
It’s a wave, but it is often not at all like a regular ocean wave. I’ve been at sea when a 3m tsunami passed, we barely felt it. If it had been a 3m wind wave in that otherwise calm sea, it would have knocked dinner off the table.
So are tides.
Perhaps we can just go back to calling them tidal waves. Which is also ambiguous. I guess if I had any point it's just that it's not colloquial to call tsunami waves, its technical. If anything distinguishing based on how they feel compared to regular wind waves is more colloquial.
Honestly tidal wave, a wave that comes in like the tide, might actually be a better term than tsunami (lit Harbor Wave) A wave that destroys your harbor? A wave found in your harbor(a place where there are usually no waves)? What if you are not in a harbor, do you still get a wave?
I am just having a bit of linguistic fun. Tsunami is a great clear distinct term for what can be a very destructive event.
They are waves, but they don't behave like the sort of waves we are used to. This is the source of all the confusion.
I have heard description of a tsunami being "a temporary rise in sea level", which describes its behavior much more intuitively. A tsunami that tops a sea wall will flood the entire lower-lying area behind it. A usual wave, even a tall one, will only deposit some splashes of water behind the wall and go away immediately.
It's a distinction without value I think. There are waves, and many of them. There is a rise in the sea level. For anywhere affected, both certainly matter. Like you mentioned, tsunami isn't a brief event. And here in Japan, they are talking about tsunami waves, not a singular tsunami. And talking about sea level rise and checking the local power poles for sea level indicators from previous tsunami events and floods.
I is absolutely a VERY valuable distinction because the behavior as it affects humans (up to and including killing them) is VERY different.
Regular waves that are a little higher than your seawall might cause some water damage to the buildings right next to it. A tsunami that is a little higher than your seawall will flood your entire town and drown people who are caught in basements.
Sure, but if you insist it's like a tide you downplay the risk of the initial hit of the wavefronts and the potential for it to slam up the coast or a seawall becoming a larger local wave. And if you insist it's like a wave, you downplay the persistent risk of both follow-up waves and ongoing flooding that won't subside quickly.
So saying it's not waves is dangerous, and saying it's not a sea level rise is dangerous. It's not useful to try and delineate between a tsunami being one of the two when it's in reality an event that consists of both.
(Ignoring that a sea level rise and a long-wavelength wave are the same thing)
These things are 100% waves. It's not a misnomer. It fits the scientific definition of waves and it fits our intuition of what waves are. These are NOT tides.
https://www.noaa.gov/explainers/science-behind-tsunamis
Yes, they are waves, but they are often very long waves. A typical 1m wave might be 20m long. A tsunami wave might be a kilometer long or longer. That is why people say they are like a tide. The wave arrives, then does not recede for several minutes. So, while a 4m wind driven wave might break over a seawall and even wash a car off the road, a 4m tsunami washes ships over that same seawall and floods the city.
It’s a wave, but it is often not at all like a regular ocean wave. I’ve been at sea when a 3m tsunami passed, we barely felt it. If it had been a 3m wind wave in that otherwise calm sea, it would have knocked dinner off the table.
A tsunami absolutely does not fit our intuition of what waves are. It looks like a wave. But it does not stop. It just continues. That little wave goes on an on, farther and farther inland. After an hour it may still go on. It's a nightmare wave, because it doesn't not fit one's intuition of what waves are.
>It looks like a wave.
and it IS a wave. I don't understand the resistance here. It BOTH is a wave and looks like a wave.
But because it does not stop, it is not a "wave". Let's just stop with the strange pedantism.
I'm reacting against the word "intuition" here. Nobody said it isn't a wave. But it's not like a wave as our intuition says.
(Though it does not _always_ look like a wave - check out the timelapse video from Kuji harbor: https://www.youtube.com/watch?v=M1B1J6sgFxk - that's why you'll sometimes see people talking about it looking like a (very) high tide. As an example of the nightmare "wave" which doesn't stop, and is thus un-intuitive.. https://www.youtube.com/watch?v=3618dZoiaPE which is incidentally also from Kuji, but from 2011)
I know what you’re talking about. But intuitively it’s still a wave.
Again the only correct comment is downvoted. Watch Tsunamis on Youtube. The water just keeps coming and coming. They are like high tides.
I 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
It never got above the boats, cant be more than a few feet tall
The port's wall slow down the entry of the water and the boats can float. The "tide" caused by the tsunami was several meters.
I feel like you're making a bad joke. Did you drop your /s?
Ah, 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.
> Again the only correct comment is downvoted.
I seriously wonder if people brains are being cooked these days. One of the blessing of HN used to be it was full of fairly well educated, and most importantly, curious people. Sometimes with a bit too much of a focus of the technical side of things, but at least on most technical topics the comments where a great place to get a richer understanding of a whatever was being discussed.
A 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.
A tsunami is a gigantically long wave. I don’t think what you’re describing describes a tsunami.
That is not really a good description of a tsunami. Tsunamis can occur in very narrow areas too, like when landslides happen in fjords.
I mean long as in wavelength. You wouldn’t have a series of tsunami waves.
Depends 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.
Velocity of wave as well.
Don’t worry, if there’s one nation we can trust to have done the right thing, it’s Japan.
I honestly can’t tell if this is satire.
Same. Japan's earthquake/tsunami preparedness is genuinely unmatched, but earthquakes/tsunamis have the annoying habit of happening in the "wrong" place and the country's overall record of "doing the right thing" can charitably be described as spotty.
I've been monitoring the situation, but it appears nothing ever happens.
My guess is that the wide area simply reflects the uncertainty, and not some apocalyptic scenario. Hopefully this broad warning and plenty of time gets everyone out of danger effectively
Question: Could you cancel out a tsunami with a underwater explosion, similar to active noise canceling ?
Yes, but it would have to be equal and opposite the incoming tsunami, and the amount of energy involved is mind boggling. The recoil would have its own repercussions. Your neighbors on the receiving end of the resulting double tsunami would want to have a word with you.
Yike!!
My wife decided to not travel to Japan due to an impending warning from a manga for July 2025. I have been making fun of her all month only to get this tsunami warning now!
https://en.wikipedia.org/wiki/July_2025_Japan_megaquake_prop....
> The 2021 reprint capitalizing off this revived popularity warned of a "real disaster" in July 2025, causing a minor case of mass hysteria in 2025 when summer trips to Japan from East Asia decreased markedly and several airlines even cancelled flights.
Sadly we won’t hear from the partners of everyone whose manga didn’t successfully predict a real disaster in a month.
That's because the other mangas forgot to adjust by +/- some 1000 km for location, 25 days, 365 days, 1825 days, or some other arbitrary but possibly nicely divisible number, for when and where it strikes.
You also have to conveniently forget the things that don't sell mangas such as annual typhoons, heatwaves, and of course thousands of premature deaths from man-made causes such as pollution and poor lifestyle.
Otherwise, if predicting disasters was easy, everybody would be doing it. No, it takes special, paper-based skills such as mangas , tarot cards, weekly horoscopes, etc.
I’m pretty sure they sell mangas about deaths from man made causes. I’m not an expert but I am fairly certain about this
Reminded of the available $1m award from James Randi’s org that was never claimed b/c no one could ever do anything supernatural under reasonable testing conditions.
(Woo is surely possible but all those who can pull it off were gifted abilities that are deactivated by non-monetary incentives)
[late correction: "non-monetary" -> "monetary"]
Well, you can continue to make fun of her because, fortunately, this has turned out to be basically nothing (for Japan, anyway).
> The statement was revised later to specify the date "July 5, 2025" as that of an asteroid impact,[8] or even the end of the world.[9]
Ryo Tatsuki clarified it wasn't her that said July 5th was when the big one will hit but that it was her publisher that pushed that date for marketing and sales.
She along with the Thai clairvoyant and Brandon Biggs all say July is the month when the earthquakes and tsunamis begin.
It is unwise to simply write this off, Ryo Tatsuki said she saw 4:18am in July 2025 which can only mean 14 hours from now we will know if that is it.
It is July 30th 2:14pm, in 14 hours it will be July 31st 4:18am. After that a 20 hour period until the deadline.
This article states that that the book references the 5th day: https://www.newsweekjapan.jp/akane_t/2025/05/202575jaxa.php
Is it wrong? Did the book actually just call the time and month, not day?
> It is unwise to simply write this off
No it isn't
Is your wife generally fearful like that or this was a rare occurrence and she can actually have some introspection on that and has a fighting chance of coming on top of that?
I know few folks like that, for them it comes from general lack of understanding of reality, society and human nature, a lot of superstition in various directions and similar traits. Suffice to say its very hard to live up to one's potential in life with such mindset, but such things could be conquered if there is enough resolve.
the manga was about a mega quake in Japan, not a tsunami from Russia
Thats well within acceptable cleirvoyant margins of error.
a P value of 1.00?
That is _really_ big. It will likely crack the top 8 ever recorded. https://en.wikipedia.org/wiki/Lists_of_earthquakes
From videos online so far, it seems the strength of the quake didn't translate to massive lateral movement. There seemed to be lots of intense P-wave wiggling and bumping rather than large S-wave swings back and forth. The big Japan quake was one of those, where you saw offices being slid back and forth and everything flying off shelves.
Not sure what that means for the tsunami - but so far it seems less intense than the 8.8 would imply.
Japan uses a scale that measures the movement[0]. Of course depending on where you are the result changes, but it's a lot more usable for the practical "how much shaking will be involved here/was involved here".
[0]: https://en.wikipedia.org/wiki/Japan_Meteorological_Agency_se...
Holy crap. That scale definitely makes it pretty clear what the effect of a quake is! Here's the highest level:
Intensity: 7
Category: Brutal
Description: Standing or moving is only possible by crawling. People may be thrown through the air.
I think it has been revised to 8. Earth is going off today. Edit my mistake, 8.8 now!
USGS still has it listed as magnitude 8.7.
(Update: It was just revised upward to 8.8.)
https://earthquake.usgs.gov/earthquakes/eventpage/us6000qw60...
The other way around it seems, on `07-29-2025 23:24:56 UTC` went from 8 to 8.7 [1]
[1] Table on https://www.tsunami.gov/
Looks like it was just updated to 8.8?
The 1960 Valdivia quake released about 1.5e23 J, or about 1000 hurricanes, or about 25% of the total energy of all earthquakes in the past 100 years.
Wow. The same region had a 9.0 in 1952
By magnitude it would be the second largest on that list
The first list on that page is specifically for the deadliest earthquakes, and so it only includes earthquakes with 100,000+ fatalities. The ranking by magnitude is farther down (and according to that list, a magnitude of 8.8 would make it tied for sixth place).
Multiple lists. On the list of strongest by magnitude, it would be in a three-way tie for 7th if there's no further revision to the magnitude estimate (which there usually is). It would be second by magnitude on the list of deadliest earthquakes, but thankfully due to location will not likely make that list.
~1.3m water column height variation observed by the closest DART buoy at 48°7'34" N 163°22'35" E (5787m nominal water depth).[1]
[1] https://www.ndbc.noaa.gov/station_page.php?station=21416&typ...
Is that a lot?
Not that it's much use to compare, but the closest DART buoy 21418 to the M9-9.1 2011 Tōhoku earthquake[1] (which had an epicentre just 72km East of Japan's east coast) recorded a water column height variation of ~3m.[2][3] The closest DART buoy to today's M8.7-8.8 earthquake is 21416 and this recorded a water column height variation of ~0.6m back in the M9-9.1 2011 Tōhoku earthquake.[4]
[1] https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an...
[2] https://www.ngdc.noaa.gov/hazard/data/DART/20110311_honshu/j...
[3] https://www.ngdc.noaa.gov/hazard/dart/2011honshu_dart.html
[4] https://www.ngdc.noaa.gov/hazard/data/DART/20110311_honshu/j...
Quick link to the tsunami view: https://www.tsunami.gov/
Just “watch” level for US west coast, but warning level for Hawaii and Alaska.
Air alarms are going off in Hawaii. Still a few hours away, but they are not joking around. Saying it can wrap around all the islands and hit anywhere
Phone just went off screaming with a warning here in NZ - more a "stay away from the water" warning than a "head for the hills" one
Impressive, glad the alarm chain works. And from what you say the warning message is also clear and understandable. Not tech or geology jargon that people don't understand and then take no or the wrong actions.
It will arrive in California in the middle of the night. Hope they don’t materialize.
I have family staying in Waikiki
Watch has been upgraded to Warning (Aleutian Islands and California from Cape Mendocino to the Oregon border) or Advisory (California from Cape Mendocino south, and pretty much everything from the California/Oregon border to Alaska until you reach the Aleutian Islands, it looks like.)
Upgraded to an "advisory" for the California coast.
Has anyone heard how bad it was in Petropovlosk? USGS estimates "severe" shaking with the possibility of moderate to heavy damage and a chance of fatalities.
They have had quite a swarm of quakes there over the last couple of weeks, including one that was M7+ around the 20th.
From what I see in Russian-language news, only relatively minor damage. I've lived in Petropavlovsk, it's an ugly city in various states of disrepair, but they do take seismic reinforcements seriously, like mag 7 should cause zero damage according to plan.
It's basically immune to tsunamis as it's protected by a bay with narrow entrance that extinguishes the waves, also most of the city is raised at least 10m above the sea.
it's not That ugly :)
but yeah I totally get what you mean, better watch volcanoes and nature than the urban scape around
indeed thankfully not that much damage there
Severo-Kurilsk, an island town destroyed by a similar tsunami in 1956, lost its port again: https://en.wikipedia.org/wiki/Severo-Kurilsk — the rest of the settlement was rebuilt on higher ground, leaving only the port vulnerable.
The settlement is notable as having belonged to the Japanese in late 19th and early 20th centuries, who once relocated islanders there. Russian Wikipedia says they were Ainu.
https://www.google.com/maps/place/50°40'00.0"N+156°07'00.0"E...
That port right next to the water has probably disappeared.
So far the news here has only shown damage to a school (which apparently was empty due to repair work), and some bad flooding in one part. Let’s hope for the best.
It's a very remote, very thinly populated area. The entire Kamchatka peninsula has under 300,000 people, who (statistically) have 1 km2 each.
Sure but a bunch of those people live in Petropavlovsk and surroundings
Current official news:
Around 3k were evacuated in the region to safe areas as a precaution: aftershocks are expected for a month.
Some buildings (including hospitals) have cracks due to an earthquake.
Some minor damage to power lines, some near-shore flooding at some businesses.
All in all, it’s ok.
On Twitter, a search for Russia brings up some videos of pretty severe shaking
Officials report M5-6 in the area, minor damage, several injuries, tell locals not to go to the beach in the next few weeks. They are used to it…
That area of Russia has seen quite a bit of massive seismic activity over the last couple of weeks. I keep getting earthquake alerts about each one.
What do you use for alerts?
I use MyShake which will let me get alerts based on specific magnitude cutoffs. I actually just ratcheted up my "global" alert from 7.5 to 8 because of all the alerts from the last couple weeks in the pacific.
People tripping over eachother arguing whether a tsunami is a "wave" on a disaster warning submission... If HN was a village everyone would drown in the process.
Didn't it take years to solve the debate about light being a particle or a wave?
..I'll show myself out :)
Waves at Midway Atoll and Guam are reported to be 3ft (1m) amplitude by Hawaii Governor Josh Green as of 6:24pm Hawaii Time
I have family members who were in Hawaii (Haleiwa) today and they are wondering if they should try to beat the tsunami and get back to their hotel in Waikiki.
I am afraid Waikiki will see flooding. I know Duke's and some other restaurants were closing early.
Do not stay in Haleiwa or go to Waikiki. Consult a map, and find some uphill areas above 100ft to drive to. Drive towards Mililani and wait it out in the upland areas.
My kids are at camp right now on the North Shore and are being evacuated by bus to Mililani.
I'm sorry you're going through that, it sounds like they will be safe in Mililani.
AIS map of vessels in the area: https://www.marinetraffic.com/en/ais/home/centerx:166.7/cent...
A fairly small US fishing vessel is in relative proximity... https://www.marinetraffic.com/en/ais/details/ships/shipid:43...
Talked to the AI which said: MMI 4.5 in the context of an M8.7 quake, for your vessel: Danger level from shaking alone: Very low in open water. Danger from tsunami in the open ocean: Very low (unless extremely close to epicenter). Prime danger: If near shore, from tsunami run-up, NOT the shaking. Actionable advice: Remain in deep water until tsunami warnings have cleared; proceed to port only when officially safe. Monitor official maritime and tsunami alerts closely after any major earthquake.
That's interesting. Mental note, if piloting a vessel in a tsunami, head to deep water.
> That's interesting. Mental note, if piloting a vessel in a tsunami, head to deep water.
E.g. the 2011 tsunami may have had a height of 1.2m or so in open ocean, but when concentrated by shallower water and a bay inlet reached 40m.
Here's a visual of your thoughts from the Fukushima event:
https://m.youtube.com/watch?v=-VcWF8dIDj4
Japan, Tsunami. Coast Guard ship rides over the tsunami waves. 日本 - 津波 4.1M views · 14 years ago
Neat video. It seems to capture the middle between "super high coastal wave" and "shallow but long duration wave in deep water". That's what you'd get with coastal waters several tens of meters deep.
Makes sense. More cushion for the pushin.
There's some interesting visualizations of the quake here
Nearby quakes, faults, movement visualization, etc.
https://earthquakes.builtbyvibes.com/quake/m8.8-119-km-ese-o...
Dutchsinse coverage. https://youtu.be/58ab1phrFF0?si=gb_gpEld8uLTDu8M
It is the sixth strongest earthquake ever recorded on the planet.
Whales have been washed ashore in Chiba https://x.com/AZ_Intel_/status/1950395615944511821
Community Notes says:
>Important Context: In the Japanese audio, a TV announcer says they don't know if this incident is related to the earthquake/tsunami: "We have no information indicating a connection with the recent tsunami".
>Also, stranded whales in Tateyama have been observed since yesterday
https://www.conservation.ca.gov/cgs/tsunami/maps is getting a hug of death :(
If anyone gets on, please post a screenshot.
The USA also has a site that seems to be up at the moment. Without seeing the CA version I'm not sure how it differs, but I suspect it's possible for Canadians to get some useful local information from it: https://www.tsunami.gov/
Anything that ends in .gov is related to a government entity in the US. Other countries don’t get access to that TLD.
I'm not sure if understood correctly, but https://www.tsunami.gov/ works without any problems even from Europe, Poland.
The US government controls who gets .gov domain names, but the websites are available to anyone.
ah, you're right. I knew that, think I must've looked at it too fast and assumed it was .gov.ca. (which isn't even the TLD that the Canadian government uses, but never mind...)
ca.gov is California, not Canada.
But our funny-accented cousins can access useful information on the .gov as well (the entire west coast of Canada is under tsunami watch at the moment).
Yeah but for how much longer? It’s a fire sale on anything intellectual down there.
I can't wait for Wexit to secede/succeed so we can welcome our beloved new territories with open arms.
This also happened during the tsunami last year.
Does anyone know of a map app that works offline and can save overlays like this?
No, but an archive.org for US govt webpages like tsunami.gov (including dynamic content) seems like something that is currently needed.
Interactive map: https://earthquake.usgs.gov/earthquakes/eventpage/us6000qw60...
I was parked at Selzer beach in Seaside, Oregon when the earthquake/tsunami news hit around 7:30pm. Within 30 minutes it was impossible to buy gas without queueing and now there is a pretty steady stream of cars heading out of town. As of 9pm it’s been upgraded to a warning up and down the coast. I was just thinking of tsunamis the two days ago in the Del Rey beach parking lot, where I noticed the locals seemed to park at the exit end of the lot, facing out. I moved my car to match because that just makes sense.
I’ve never thought about a tsunami when visiting the beach in my life. Are they much more common in the Pacific? We go to the Gulf and Atlantic and it’s never something I think about. We usually go in June/July, so we don’t worry much about hurricanes either.
There is no Atlantic ring of fire, is there. What little places like Iceland show is nothing compared to what pacific has to offer in much larger area.
While the Atlantic doesn't really have many faults that will generate earthquakes causing tsunamis there is always a risk of landslides creating large tsunamis up to what we'd consider mega-tsunamis. This said this is something that may have thousands of years between incidents.
Reading the news, it seems there was no significant impact in the neighbouring societies, except the death of sea life (whales in Chiba), is that right?
I wonder how they died.
I'd expect they are safe from a bit of shaking. Are there shock waves involved?
Here is a 2 minute compilation video from a helicopter and other vantage points showing the waves crashing into the shores of Japan.
https://old.reddit.com/r/interestingasfuck/comments/1mcwvpw/...
I’m in Costa Rica on vacation, hotel said the beach is closed but they didn’t know why (lol yeah right). Per tsunami alerts it should be hitting right now at 1-3M above tide, I don’t see any evidence on various beach livecams like Taramindo. I’m in puerto Jimenez which is on the inland side of a small peninsula in southern CR so not expecting much.
each Live cam.
<https://www3.nhk.or.jp/news/html/20250730/k10014878741000.ht...>
What happens to the US West coast?
It moves to Arizona? Or is that the other "big one"?
All the tectonics and volcanos that are underground are linked, these seismic events aren't just isolated on islands.
I hate to say this but we can expect a major event in August. All I can tell people is to prepare but I see people just with blank expression, there is almost no concern at all which reminds me very much of November 2019.
Okay Charlie Frost
Evidence?
I happened to be visiting Miyagi just before the tsunami struck, and I was really panicked. When I got out of the car, everyone's smartphones nearby suddenly started beeping. A message in Japanese, saying something like "TSUNAMI EVACUATE NOW," sounded throughout the area. At the time, my phone displayed a warning that a three-meter tsunami would hit the area within an hour. I waited on slightly higher area for about two hours, but the locals kept going about their usual business, and there were no announcements from the nearby police.
Fortunately, nothing happened, but it's difficult to know which information to trust. Still, it's good that there's a system in place for evacuation alerts.
Agenda-free TV channel on YouTube has pretty good live/current coverage right now
Which TV channel please? Link or name?
He doesn't look to be live right now, but here is the channel: https://youtube.com/@agendafreetv?si=ROE1VAC1D6IlCcXl
Oh that's actually the name, I thought it was a diss on most media! Thanks.
Shanghai has relocated 280.000 people from its coast according to this article: https://mp.weixin.qq.com/s/HLf3PM29IqaWajMhflo_uA
Unclear if its related to the tsunami that is about to hit or the typhoon it is currently experiencing. Wild. Stay safe everyone!
Update: The yellow warning has been lifted
Also, a volcano,
https://www.newsweek.com/russia-klyuchevskoy-volcano-erupts-... ("Russia's Klyuchevskoy Volcano Starts Erupting after Earthquake")
Wow! I hope they stay safe. As others have pointed out it will break records [1] https://en.wikipedia.org/wiki/List_of_earthquakes_in_Japan
Just when I am about to depart on vacation to Sulawesi in Indonesia, mostly for diving and some culture and adventure... well at least Togian islands are not directly exposed to part of pacific ocean that generated this.
I guess I will have to sleep with a big wooden log.
Russian media has some videos of the earthquake (RT, etc.), telegram channels have some tsunami videos, eg: https://t.me/Slavyangrad/136436
Nothing yet from japan
Any supervolcanoes nearby? How is https://en.wikipedia.org/wiki/Paektu_Mountain holding up?
Map on USGS:
https://earthquake.usgs.gov/earthquakes/eventpage/us6000qw60...
Can the wave be seen and tracked from planes above? I know they can travel at upwards of 300+mph but given the distance from Russia to the west coast seems like it should be able to be tracked.
No. When they travel at that speed they are not visible. Only when they hit shallow water (a necessary , but not sufficient, condition) do they slow down and become a threat.
You can see bouys displaced by the seismic event, some up to one foot close by. Pretty crazy
There are planes, buoys and other things being mentioned on the news here in Japan as ways things are being tracked. Maybe not what you meant, but tracking the wave isn't necessarily correct. There are many waves, and the initial wave is often (in this case also) not the largest.
The news mentioned a previous similar event where the largest wave was 4 hours later.
Space-based assets.
6th largest in the measurement history.
hope everyone is safe
The National Weather Service wants you to know that "There is no threat for tsunami impacts in North Dakota", https://x.com/NWSGrandForks/status/1950377134565785933.
Just downgraded to advisory in Hawaii (10:44pm HST)
The US still has a National Earthquake Information Centre?
Wow!
Why are the predictions of the tsunami experts so poor? What can be done to get higher accuracy?
I don’t think there’s a high false positive rate on these. They do happen pretty rarely, and a false negative is far worse than a false positive. Due to the tsunami wave propagation, it can sometimes take hours for significant waves to reach the coastline.
We just had another one in the SF Bay Area a few months ago where they were wildly off.
to put this in perspective, and please, if you work for USGS or whatever, correct me if i am wrong: this is roughly the same magnitude of the 1994 Northridge earthquake in California.
i think i got the scale the wrong way around, the magnitudes reported now are only larger (than Richter) with smaller quakes compared to the Richter; it looks like 8.8ML ~= M8.8. Sorry, i looked at the chart the wrong way around.
You are off by about a factor of 1,000.
Each incremental increase in magnitude is 10^1.5 in power. The difference between 1994 Northridge and this one is 2.1, so roughly 10^3 difference in power.
I thought that it was a log10 scale, so each increment of 1 on the scale is a 10-fold power increase, not a 10^1.5-fold.
This is power vs. energy.
The Richter Scale is a logarithmic scale, based on shaking measurements (think of the old pencil-based seismograph!). Power. (10^1).
The Moment Magnitude Scale (the more modern/replacement of Richter Scale) is based on energy. Geological organisations reporting on an earthquake will usually show this as "M <number>" or "Mw <number>".
Richter works well for small-to-medium earthquakes, and it's not accurate for really large or distant earthquakes.
The energy released in an earthquake increases exponentially, not just linearly.
EDIT: The Moment Magnitude Scale is where the "10^1.5" figure is coming from. https://en.wikipedia.org/wiki/Moment_magnitude_scale
I agree that it is not intuitive.
AFAIK, it was done that way to maintain rough congruence with historical seismic magnitude scales, which were more qualitative in nature. Modern seismic scale systems are significantly more scientific and quantitative but you can kind of retcon the historical systems if you set the exponential strength scale to 10^1.5 in the modern systems.
It's a log10 scale measuring amplitude.
I'm actually not sure the Northridge earthquake was cited in the Richter scale, most references I see have it as about a 6.7, which based on the USGS catalog, was it's moment magnitude 6.7 Mw
https://earthquake.usgs.gov/earthquakes/eventpage/ci3144585/...
And today's earthquake for comparison:
https://earthquake.usgs.gov/earthquakes/eventpage/us6000qw60...
And some information of Magnitude types: https://www.usgs.gov/programs/earthquake-hazards/magnitude-t...
I think it's probably safe to assume, that today's earthquake is much more energetic at least.
yeah i misread the charts, where like 3.5ML (richter) is ~5.0, and i missed that it was mb rather than ML, 8.8 ~= 6.7ish body wave magnitude.
That's the thing with standards, there's so many to choose from.
What? No that was a 6.7 or less than one hundredth an 8.8 on a log10 scale