hckrnws
Century-old stone “tsunami stones” dot Japan's coastline (2015)
by deegles
Fun facts, Fukushima Daiichi Nuclear Power Plant was built beyond the warning limit of the tsunami stones.
If those people that setup the tsunami stones are still alive during the incident they will have a kahuna of "I told you" moment.
>Onagawa was… 60 kilometers closer than Fukushima Daiichi [to the epicenter] and the difference in seismic intensity at the two plants was negligible. Furthermore, the tsunami was bigger at Onagawa, reaching a height of 14.3 meters, compared with 13.1 meters at Fukushima Daiichi. The difference in outcomes at the two plants reveals the root cause of Fukushima Daiichi’s failures: the utility’s corporate “safety culture.”
>Before beginning construction, Tohoku Electric conducted surveys and simulations aimed at predicting tsunami levels. The initial predictions showed that tsunamis in the region historically had an average height of about 3 meters. Based on that, the company constructed its plant at 14.7 meters above sea level, almost five times that height.
>Tepco, on the other hand, to make it easier to transport equipment and to save construction costs, in 1967 removed 25 meters from the 35-meter natural seawall of the Daiichi plant site and built the reactor buildings at a much lower elevation of 10 meters.
https://thebulletin.org/2014/03/onagawa-the-japanese-nuclear...
The reactors were also largely fine except for grid connections and the hurricane-resistant backup generator in the basement. It was told ad nauseum at the time that there could have been couples of those on the roofs and the reactor could have just survived.
"Beyond" is completely ambiguous in this case. Do you mean above or below?
Well obviously they mean below
Not obvious to me
Unless they mean beyond the reach of the flood waters.
I got very confused too. After reading a few times I interpreted it as a typo.
...beyond the (possible) reach...(of whatever(waves in this case))
Do you have a citation for this? The most Gemini could say is: "While research has not identified a specific tsunami stone located at the Fukushima Daiichi site that was directly violated, the spirit of these ancient warnings was undeniably ignored." (https://aistudio.google.com/app/prompts?state=%7B%22ids%22:%...)
I don't know if there are "Tsunami stones" in the area but the nuclear power plant is built at sea level [1] so would most probably be below them.
The issue is the height of the seawalls that was not sufficient (and perhaps historical warnings, if any, were ignored):
"The subsequent destructive tsunami with waves of up to 14 metres (46 ft) that over-topped the station, which had seawalls" [1]
Edit: Regarding historical warnings:
"The 2011 Tōhoku earthquake occurred in exactly the same area as the 869 earthquake, fulfilling the earlier prediction and causing major flooding in the Sendai area." [2]
[1] https://en.wikipedia.org/wiki/Fukushima_Daiichi_Nuclear_Powe...
IIRC the issue was the emergency diesel generators being flooded, preventing them from powering the emergency cooling pumps, resulting in the meltdowns from residual heat in the reactor cores and spent fuel pools.
Various construction changes could have prevented this from happening:
- the whole power plan being built higher up or further inland
-> this would likely be quite a bit more expensive due to land availability & cooling water management when not on sea level & next to the sea
- the emergency generators being built higher up or protected from a tsunami by other means (watertight bunker ?)
-> of course this requires the plan cooling systems & the necessary wiring itself working after surviving a massive earthquake & being flooded
An inland power plant - while quite wasteful in an island country - would be protected from tsunamis & certainly doable. On the other hand, I do wonder how would high concrete cooling towers handle strong earthquakes ? A lot of small cooling towers might have ti be used, like in Palo Verde nuclear generating station in Arizona.
Otherwise a bizzare case could still happen, with a meltdown possibly happening due to your cooling towers falling over & their cooling capacity being lost.
Another option is designing fail safe reactors. CANDU reactors designs are over 60 years old now and were built fail safe so that if outside power to the core is cut off the system would safe itself by dropping control rods which are held up by electromagnets into the core.
A reactor scram isn't necessarily enough -- you still have decay heat to worry about. In the case of Fukushima, the fission chain reaction was stopped but without cooling pumps the decay heat was still too much.
It seems like you should build a water reservoir at a higher elevation than the core and then apply a similar principle where valves regulate the water stream, but if the valves lose power they fail open. The reservoir can be built so that there is always enough water to cool the core.
For light water reactors this basically just amounts to a large pool up a nearby hill or in a water tower.
That is easier said than done - modern reactors are in the 1000 MW+ electrical power range, which means about 3x as much heat needs to be generated to get this much electricity - say 3000 MW.
Even when you correctly shut down the chain reaction in the reactor (which correctly happened in the affected Fukushima powerplant) a significant amount of heat will still be generated in the reactor core for days or even weeks - even if it was just 1% of the 3 GW thermal load, that is still 30 MW. It will be the most intense immediately after shutdown and will then trail off slowly.
The mechanism for this is inherent to the fission reactors - you split heavier elements into lighter ones, releasing energy. But some of the new lighter elements are unstable and eventually split to something else, before finally splitting into a stable element. These decay chains can take quite some time to reach stable state for a lot of the core & will still release radiation (and a lot of heat) for the time being.
(There are IIRC also some processes where neutrons get captured by elements in the core & those get transmutated to other, possibly unstable elements, that then decay. That could also result add up the the decay heat in the core.)
And if you are not able to remove the heat quickly enough - the fuel elements do not care, they will just continue to heat up until they melt. :P
I am a bit skeptical you could have a big enough reservoir on hand to handle this in a passive manner. What on the other hand I could image could work (and what some more modern designs include IIRC) is a passive system with natural circulation. Eq. you basically have a special dry cooling tower through which you pass water from the core, it heats up air which caries the heat up, sucking in more air (chimney effect). The colder water is more dense, so it sinks down, sucking in more warm water. Old hot water heating worked like this in houses, without pumps.
If you build it just right, it should be able to handle the decay heat load without any moving parts or electricity until the core is safe.
there are reactor designs that work that way, but most civilian power plants are pressurized water reactors. it is important that the water stays pressurized or you get a chernobyl
Fukushima was based on a Westinghouse BWR (Boiling Water Reactor) design, so pressurization was not that much of an issue - if enough of sufficiently cold water was provided, there would be no meltdown.
Reminds me of the hunger stones in Germany and neighboring countries: https://en.wikipedia.org/wiki/Hunger_stone
The Cascadia Subduction Zone earthquake of 1700 was dated using Japanese tsunami records: https://ui.adsabs.harvard.edu/abs/1996Natur.379..246S/abstra...
Can't wait for round 2!
I love how this article, just like a tsunami stone, surfaces on HN every few years. It just shows even shorter cycles of collective memories :)
or its just a new round of 10,000 who are learning about this for the first time, just like you once were
FTA cites this article in the NYT, archive link:
https://archive.is/20161221102801/http://www.nytimes.com/201...
Need those here in hill country in flash flood alley. Perhaps towers with an inscription and a windsock.
Previous and related:
Century-old stone "tsunami stones" dot Japan's coastline (2015) - https://news.ycombinator.com/item?id=39892533 - April 2024 (142 comments)
Tsunami Warnings, Written in Stone (2011) - https://news.ycombinator.com/item?id=10122825 - Aug 2015 (10 comments)
1896 is pretty recent actually I thought they were like thousands of years old
Oldest known stones date back to the early 1400s but there must have been older stones. Already those stones are mostly unreadable because of erosion and they are dated by secondary sources.
You can put warnings everytime there is a tsunami, which is "often" in Japan, but the issue is that a massive one like the 2011 earthquake and tsunami is a once in a millenium event so would indeed need to rely on very old warnings:
"The 2011 Tōhoku earthquake occurred in exactly the same area as the 869 earthquake, fulfilling the earlier prediction and causing major flooding in the Sendai area. [1]
Modern society is not good at this sort of very long term consideration and planning.
This is a deeper dive on the stones and their locations. Please note that 317 stone tablets were built after the 2 tsunamis, 125 (40%) of them were washed away or destroyed by the 2011 tsunami. https://thefunambulist.net/magazine/cartography-power/incomp...
That suggests a possibly better strategy (though very long term): pepper the portion of the landscape believed to be safe with "it is safe to build here" monoliths, each as stable as a typical building, and over time only the ones that speak truly will remain.
Would work for volcanoes and earthquakes as well.
They just do the same thing with regular homes :)
Sadly, that's at least partially true. But rebuilding on a sight where a home was destroyed eliminates the information value (that this site isn't safe from tsunami) and the coverage is far from uniform/regular (so you can't tell if there are no buildings in an area because it was previously undeveloped or is unsafe).
‘How old are these buildings?’ would be wise to consider.
This probably works for a variety of things and in many places.
Japan has a bad habit of considering buildings as disposable. Odd that a land with 1000 year old temples knocks down 40 year old houses with zero remorse, but that seems to be the case.
I'm not sure that judgement of calling it 'bad' is warranted. Certainly it's different that western approaches to housing but I'm not sure whether it's better or worse. My understanding of the 1000 year old temples is that they are periodically replaced and rebuilt, like a Ship of Theseus situation
1000 year old temples
Well it depends. Very important shrines are dismantled and rebuilt every 20 years, eg https://japanwoodcraftassociation.com/2020/02/13/traditions-...
There are lots of old houses in use and for sale in Japan, but many people prefer building a new house to renovating or maintaining an old one - partly for practical reasons, partly because newer structures are more likely to be earthquake-resilient, partly due to haunting.
It has been ∞ years since a tsunami washed away this stone.
It should also include the location of where the stone lived before the tsunami. That would help future archaeologists determine how big the tsunami was
I suspect after a tsunami not all of the stones would be found again, so that's probably a good idea.
Reminds me of the forest inscriptions in the mountains of Lebanon which date from the time of the Roman Emperor Hadrian (~100 AD): Lebanese cedar wood was prized for shipbuilding and forests were decimated due to heavy logging. Nice to see that nature conservancy was alive and well, even 2000 years ago.
I've always been fascinated by these because I love long term thinking. What current "tsunami stone" would you leave to future generations to prevent catastrophe?
Depends on how metaphorical and/or political you want to get.
Arguably books could be considered warning waystones, but that's a stretch in this context.
Physical monuments though, we have loads, lots of war memorials are/were intended as warning about the cost of war.
Auschwitz-Birkenau being left as as it is could be considered another.
If you want to get really close to similar intentions there are the long term nuclear waste warnings:
https://en.wikipedia.org/wiki/Long-term_nuclear_waste_warnin...
A bit more esoteric (and less warningy) and you get the signals we send in to space intentionally as a time-capsule/marker for potential alien contact.
I think the obvious answer in the modern world would not be a phsyical one, but some sort of measure of wealth inequality. At some point, if too few have too much it destroys a country from the inside out over the long run. It does far more damage than any tsunami ever could. I don't have a number or exact measure in mind, but that would be the warning I would leave to future generations.
What’s the counter argument to that sign?
With radiation half lives what they are, our society should be brainstorming how to segregate and mark nuclear waste storage areas. All areas that store radioactive waste.
Without clear warnings and boundaries humanity is just waiting for a catastrophe.
A tiny sign and words don’t count.
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Crafted by Rajat
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