There's a video shot in Onagawa during the tsunami, from the tower atop the building visible at 1:13 - the one with the white car hanging from it. Originally there was a raised walkway connecting this building to the red brick building seen at 1:20, over the road between them. The depth of the water here, and its violence, were almost beyond belief. You see whole wooden buildings being bashed to pieces against the brick building by the water's backwash as it returns to the sea.
you have to differentiate between tsunami inundation height and tsunami run-up... run-up was over 40m in some places, were inundation height was around 17m there... essentially when the tsunami reaches a hill it will start to go up, the highest distance it reaches is called run-up height.... the height of the tsunami at the beach would (on the other hand) be called inundation height. This is a very simple explanation but hope it helps?
The tsunami is not really water though, is it? In most cases, by the time it reaches a built up area it is carrying so much sediment that is in fact more like very thin mud. This has a much greater density than water and so behaves differently. It is more powerful and destructive than clean water and, I imagine, would drive further up a slope. But, I don't know that. My question is, under laboratory conditions does the sediment content of water affect the run-up height, given that all other parameters are identical?
@@lucianisidro Indeed, you are correct. A tsunami has so much sediment in it (when doing fieldwork, our team has often been bogged down in mud left after the water recedes). Also, it carries with it wood and any other floating debris, so it is indeed a very viscous fluid. However, under laboratory conditions we cannot simulate all this, given scale factors. Truthfully, most of the time we also use freshwater (as seawater could corrode much of the equipment, etc). So, these are all known factors. However, compared with other issues related to how the tsunami propagates inland (for example, the quantification of how the forests would reduce velocity -and to what extent the forests survive-, the effect of complicated patterns of buildings -again, and which are destroyed or remain, etc) this issue of the "higher viscosity" of the tsunami is relatively minor (I am sure in 5-10 years time we will be starting to fine tune for such things, but in the meantime we still have many "bigger" problems to solve, if this makes sense?)
@@adrao77 When related to the bigger picture, yes this does make sense. However, when an engineered structure like a bridge is overwhelmed then the density of the fluid can mean the difference between the decks staying in place or being flipped over. The case of the Utatsu Bridge springs to mind, where entrained sediment was seen to be essential to the failure of the decks. When analysing structures like this, I think then the devil is in the details. www.yumpu.com/en/document/read/24265888/cfd-analysis-of-bridge-deck-failure-due-to-tsunami As for forest survival, a very interesting example is that of the Matsubara Forest, planted on Oppa Bay to act as a windbreak for the town of Kamaya. It consisted of 20,000 pine trees, up to 60 feet high and some 100 years old. When the tsunami approached, as a witness attested, "the sea was overwhelming them, swallowing up their pointed green peaks and tearing up the forest in a frothing surge" (Richard Lloyd Parry, Ghosts of the Tsunami, 2017 p. 128). These huge trunks were then carried into the town, smashing everything in their path. If there hadn't been any trees, there would arguably have been less damage, and the New Kitakami Great Bridge would have likely survived intact. In the Kamaya event and many others like it, it was the river that was the gateway through which the tsunami gained access to the land, but the trees did more harm than good in that particular case. Of course every event is different, but I still maintain that turbidity, entrained sediment and debris has an enormous effect on how the currents behave, especially when dealing with specific issues of structural integrity. Many thanks for your informed conversation!
Yes in many instances it seems to do as much damage when it leaves, though each case is different. In Onagawa half of the breakwater at the entrance of the bay failed towards the town (i.e. destroyed by the incoming wave) and the other half was destroyed by the returning wave (so it failed towards the sea). I hope this illustrates a bit the point...
Would you say that the tsunami does just as much damage going back out to sea with all the debris in the water, than it does when it arrives.? Amazing footage.
So did the water rise to 17 meters when it entered the bay/city? Or was this wave already at 17 meters when it struck the city? Can you point me to documentation of what the hightest tsunami that struck Japan? I read on one video that somewhere the tsunami was 40 meters?
If the tsunami manage to reach the hospital then how did the recorder who was on the the brick building manage to capture the water receding. That hospital was higher then that building.
@@jessejaymes8684 I'm sorry i still don't understand. That red brick building under the hospital not even covered by sea water. n nearest the sea. Logically the area under the hospital it supposed all were sunk.? Since the sea water rose and reached to first floor of the hospital which so much more higher area than that brick building......
Thank you for the correction yoriiso!. And yes, its a pretty dramatic site, as you can see in many of the videos where the actual tsunami was captures. We have visited this are many times actually, and during the last visit there was still no reconstruction, though much had been cleared (as you can see in some other of my videos). It will probably take a long time for the town to recover, though the central government in Japan will be providing a lot of funds for that to happen.
Yes, probably this would be a correct explanation... we are currently trying to do some experiments on this effect, and it seems that indeed it is the case of a lot of the damage that can be observed....
dutch government and engineers are hardly qualified... biggest storm surge over there is hardly even considered dangerous by japanese disaster risk managers...
I HAD A DREAM YESTERDAY 2-5-2012 ..THERE IS A BIG TSUNAMI COMING IT TOOK PLACE HIGH ABOVE THE MOUNTAINS..IN A FOREST SOMEWHERE..IT LOOKED SIMULAR TO NEW ZEALAND FOREST..THATS MY 3RD DREAM OF TSUNAMI..COULD THE 3RD 1 BE THE BEGINING OF THE END?
GOD SO LOVED THE WORLD THAT HE GAVE HIS ONLY BEGOTTEN SON THAT WHOSOEVER BELIEVETH IN HIM SHOULD NOT PERISH BUT HAVE EVERLASTING LIFE THE WAGES OF SIN IS DEATH BUT THE GIFT OF GOD IS ETERNAL LIFE THROUGH MESSIAH GOD ALMIGHTY KING JESUS CHRIST!
There's a video shot in Onagawa during the tsunami, from the tower atop the building visible at 1:13 - the one with the white car hanging from it. Originally there was a raised walkway connecting this building to the red brick building seen at 1:20, over the road between them.
The depth of the water here, and its violence, were almost beyond belief. You see whole wooden buildings being bashed to pieces against the brick building by the water's backwash as it returns to the sea.
you have to differentiate between tsunami inundation height and tsunami run-up... run-up was over 40m in some places, were inundation height was around 17m there... essentially when the tsunami reaches a hill it will start to go up, the highest distance it reaches is called run-up height.... the height of the tsunami at the beach would (on the other hand) be called inundation height. This is a very simple explanation but hope it helps?
The tsunami is not really water though, is it? In most cases, by the time it reaches a built up area it is carrying so much sediment that is in fact more like very thin mud. This has a much greater density than water and so behaves differently. It is more powerful and destructive than clean water and, I imagine, would drive further up a slope. But, I don't know that. My question is, under laboratory conditions does the sediment content of water affect the run-up height, given that all other parameters are identical?
@@lucianisidro Indeed, you are correct. A tsunami has so much sediment in it (when doing fieldwork, our team has often been bogged down in mud left after the water recedes). Also, it carries with it wood and any other floating debris, so it is indeed a very viscous fluid. However, under laboratory conditions we cannot simulate all this, given scale factors. Truthfully, most of the time we also use freshwater (as seawater could corrode much of the equipment, etc). So, these are all known factors. However, compared with other issues related to how the tsunami propagates inland (for example, the quantification of how the forests would reduce velocity -and to what extent the forests survive-, the effect of complicated patterns of buildings -again, and which are destroyed or remain, etc) this issue of the "higher viscosity" of the tsunami is relatively minor (I am sure in 5-10 years time we will be starting to fine tune for such things, but in the meantime we still have many "bigger" problems to solve, if this makes sense?)
@@adrao77 When related to the bigger picture, yes this does make sense. However, when an engineered structure like a bridge is overwhelmed then the density of the fluid can mean the difference between the decks staying in place or being flipped over. The case of the Utatsu Bridge springs to mind, where entrained sediment was seen to be essential to the failure of the decks. When analysing structures like this, I think then the devil is in the details. www.yumpu.com/en/document/read/24265888/cfd-analysis-of-bridge-deck-failure-due-to-tsunami
As for forest survival, a very interesting example is that of the Matsubara Forest, planted on Oppa Bay to act as a windbreak for the town of Kamaya. It consisted of 20,000 pine trees, up to 60 feet high and some 100 years old. When the tsunami approached, as a witness attested, "the sea was overwhelming them, swallowing up their pointed green peaks and tearing up the forest in a frothing surge" (Richard Lloyd Parry, Ghosts of the Tsunami, 2017 p. 128).
These huge trunks were then carried into the town, smashing everything in their path. If there hadn't been any trees, there would arguably have been less damage, and the New Kitakami Great Bridge would have likely survived intact. In the Kamaya event and many others like it, it was the river that was the gateway through which the tsunami gained access to the land, but the trees did more harm than good in that particular case. Of course every event is different, but I still maintain that turbidity, entrained sediment and debris has an enormous effect on how the currents behave, especially when dealing with specific issues of structural integrity. Many thanks for your informed conversation!
Thanks
Yes in many instances it seems to do as much damage when it leaves, though each case is different. In Onagawa half of the breakwater at the entrance of the bay failed towards the town (i.e. destroyed by the incoming wave) and the other half was destroyed by the returning wave (so it failed towards the sea). I hope this illustrates a bit the point...
Would you say that the tsunami does just as much damage going back out to sea with all the debris in the water, than it does when it arrives.? Amazing footage.
And even the tower with the white car hanging on it was totally covered with water. Still cannot believe the size of the tsunami. Its really insane.
It is indeed.. I still remember standing there myself, in disbelief (and it was not the first tsunami we had surveyed...)
So did the water rise to 17 meters when it entered the bay/city? Or was this wave already at 17 meters when it struck the city? Can you point me to documentation of what the hightest tsunami that struck Japan? I read on one video that somewhere the tsunami was 40 meters?
If the tsunami manage to reach the hospital then how did the recorder who was on the the brick building manage to capture the water receding. That hospital was higher then that building.
Simply... Run-up vs Innundation
@@jessejaymes8684 Yes, it's called tsunami innundation and it's different from tsunami run-up.
@@jessejaymes8684
I'm sorry i still don't understand. That red brick building under the hospital not even covered by sea water. n nearest the sea. Logically the area under the hospital it supposed all were sunk.? Since the sea water rose and reached to first floor of the hospital which so much more higher area than that brick building......
4rth floor and still not safe? God DAMN !!
Thank you for the correction yoriiso!. And yes, its a pretty dramatic site, as you can see in many of the videos where the actual tsunami was captures. We have visited this are many times actually, and during the last visit there was still no reconstruction, though much had been cleared (as you can see in some other of my videos). It will probably take a long time for the town to recover, though the central government in Japan will be providing a lot of funds for that to happen.
Yes, probably this would be a correct explanation... we are currently trying to do some experiments on this effect, and it seems that indeed it is the case of a lot of the damage that can be observed....
Straight up from sea level to even with the second floor of onagawa hospital is how many feet? Altitude of what?
鉄筋コンクリートの建物が倒れているのは衝撃的すぎる…
今は綺麗な街並みになりましたね。
could you please point out to a book that shows a storm surge event which is 17m high?
How many feet is 17.47 meters?
It's "Oshika" not "Ojika" peninsula.
Can hear nothing but birds noise here, wispering guy &@
sorry, thanks for the correction
dutch government and engineers are hardly qualified... biggest storm surge over there is hardly even considered dangerous by japanese disaster risk managers...
I HAD A DREAM YESTERDAY 2-5-2012 ..THERE IS A BIG TSUNAMI COMING IT TOOK PLACE HIGH ABOVE THE MOUNTAINS..IN A FOREST SOMEWHERE..IT LOOKED SIMULAR TO NEW ZEALAND FOREST..THATS MY 3RD DREAM OF TSUNAMI..COULD THE 3RD 1 BE THE BEGINING OF THE END?
GOD SO LOVED THE WORLD THAT HE GAVE HIS ONLY BEGOTTEN SON THAT WHOSOEVER BELIEVETH IN HIM SHOULD NOT PERISH BUT HAVE EVERLASTING LIFE THE WAGES OF SIN IS DEATH BUT THE GIFT OF GOD IS ETERNAL LIFE THROUGH MESSIAH GOD ALMIGHTY KING JESUS CHRIST!