I've been reading your posts from the beginning of the thread -so put on the flame-retardent attire now. ; )
You keep referring to tsunamis as waves when they're actually energy-surges caused by the displacement of the earth's crust. Besides totally different mechanics, the energy transmitted through the ocean by a 9.0 earthquake is several orders of magnatudes greater than the wind-generated waves your basing your advice on.
Would you similarly advise someone to 'duck under' a storm surge? How about a dam burst? A tsunami is much closer to these than a surf wave.
Have you seen any of the videos? Most of the ones I've seen were from Thai resorts, as in these photos. The tsunamis which hit Indonesia, Sri Lanka and India were much larger. I saw one which was supposedly from Sri Lanka. It showed a 10'+ surge going through a city at probably 15 mph. It ran the entire length of the video. No one was going to be holding their breath under that. And if they were unfortunate enough to be out in the water at the time well... where do you think all the water going through the town came from?
As these photos clearly show tsunamis are not waves but entire bodies of water moving ashore. No one's going to be able to duck under or hold their breath through any appreciably-sized tsunami any better than they could a bursting dam.
"You keep referring to tsunamis as waves when they're actually energy-surges caused by the displacement of the earth's crust."
Which are transmitted as waves, albeit waves of longer duration than wind driven waves.
"the energy transmitted through the ocean by a 9.0 earthquake is several orders of magnatudes greater than the wind-generated waves your basing your advice on."
True.
"Would you similarly advise someone to 'duck under' a storm surge? How about a dam burst?"
If there was breaking water on their faces and there was calm water beneath them.
"Have you seen any of the videos?"
Yes. As I have said, diving under the breaking face is impossible if there is no deep calm water beneath it.
"It ran the entire length of the video. No one was going to be holding their breath under that."
No need. All diving under the breaking face does is allow one to skip the spin cycle of the breaking face. As I said in #231 it won't do much good unless far out in deeper water.
If on the beach or in shallow water it is best to run for higher ground. It is impossible to dive under a wave from the beach or from shallow water.
Once you dive under the breaking face you may surface behind and be carried along by calm water, relative to you, on the back of the tsunami.
If it carries you all the way onto land you will have to contend with trees and buildings but at least you won't be battered by the wave face and all the junk caught up in it.
I suppose all the confusion means I have explained it poorly. Sorry.