[HN Gopher] Century-old stone "tsunami stones" dot Japan's coast...
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       Century-old stone "tsunami stones" dot Japan's coastline (2015)
        
       Author : deegles
       Score  : 123 points
       Date   : 2025-08-04 12:51 UTC (10 hours ago)
        
 (HTM) web link (www.smithsonianmag.com)
 (TXT) w3m dump (www.smithsonianmag.com)
        
       | atopal wrote:
       | Reminds me of the hunger stones in Germany and neighboring
       | countries: https://en.wikipedia.org/wiki/Hunger_stone
        
       | Mistletoe wrote:
       | 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?
        
         | thinkingtoilet wrote:
         | 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.
        
         | NilMostChill wrote:
         | 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.
        
         | 01HNNWZ0MV43FF wrote:
         | https://www.reddit.com/r/georgism/comments/102jg2f/everybody...
        
           | lostlogin wrote:
           | What's the counter argument to that sign?
        
         | imchillyb wrote:
         | 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.
        
       | porphyra wrote:
       | 1896 is pretty recent actually I thought they were like thousands
       | of years old
        
         | muyuu wrote:
         | 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.
        
         | mytailorisrich wrote:
         | 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 Tohoku 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.
         | 
         | [1] https://en.wikipedia.org/wiki/869_J%C5%8Dgan_earthquake
        
       | anonu wrote:
       | 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.
        
       | josefritzishere wrote:
       | 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...
        
         | MarkusQ wrote:
         | 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.
        
           | penneyd wrote:
           | They just do the same thing with regular homes :)
        
             | MarkusQ wrote:
             | 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).
        
               | lostlogin wrote:
               | 'How old are these buildings?' would be wise to consider.
               | 
               | This probably works for a variety of things and in many
               | places.
        
               | hinkley wrote:
               | 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.
        
               | anigbrowl wrote:
               | _1000 year old temples_
               | 
               | Well it depends. Very important shrines are dismantled
               | and rebuilt every 20 years, eg https://japanwoodcraftasso
               | ciation.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.
        
           | hinkley wrote:
           | It has been [?] years since a tsunami washed away this stone.
        
             | dylan604 wrote:
             | 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
        
               | hinkley wrote:
               | I suspect after a tsunami not all of the stones would be
               | found again, so that's probably a good idea.
        
       | willidiots wrote:
       | The Cascadia Subduction Zone earthquake of 1700 was dated using
       | Japanese tsunami records:
       | https://ui.adsabs.harvard.edu/abs/1996Natur.379..246S/abstra...
        
         | tobinc wrote:
         | Can't wait for round 2!
        
       | teleforce wrote:
       | 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.
        
         | bumbledraven wrote:
         | 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%22
         | ids%22:%...)
        
           | mytailorisrich wrote:
           | 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 Tohoku 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_P
           | owe...
           | 
           | [2] https://en.wikipedia.org/wiki/869_J%C5%8Dgan_earthquake
        
             | m4rtink wrote:
             | 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.
        
               | __turbobrew__ wrote:
               | 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.
        
               | cperciva wrote:
               | 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.
        
         | aaronax wrote:
         | "Beyond" is completely ambiguous in this case. Do you mean
         | above or below?
        
           | jonplackett wrote:
           | Well obviously they mean below
        
             | gus_massa wrote:
             | I got very confused too. After reading a few times I
             | interpreted it as a typo.
        
             | aaronax wrote:
             | Unless they mean beyond the reach of the flood waters.
        
             | baobabKoodaa wrote:
             | Not obvious to me
        
           | LargoLasskhyfv wrote:
           | ...beyond the (possible) reach...(of whatever(waves in this
           | case))
        
         | 542354234235 wrote:
         | >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...
        
         | numpad0 wrote:
         | 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.
        
       | xrayarx wrote:
       | FTA cites this article in the NYT, archive link:
       | 
       | https://archive.is/20161221102801/http://www.nytimes.com/201...
        
       | NaOH wrote:
       | 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)
        
       | rembal wrote:
       | 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 :)
        
         | chollida1 wrote:
         | or its just a new round of 10,000 who are learning about this
         | for the first time, just like you once were
         | 
         | https://xkcd.com/1053/
        
       | burnt-resistor wrote:
       | Need those here in hill country in flash flood alley. Perhaps
       | towers with an inscription and a windsock.
        
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       (page generated 2025-08-04 23:00 UTC)