# Tsunami in Hawaii

Discussion in 'All Discussions' started by RIsurfer, Feb 19, 2014.

Yes, longer period waves move faster then slower period waves.
Speed = Distance / Time.

Surfers are used to talking about wave period, because that is what is reported on buoy observations, but it is directly correlated to wavelength. When wave period (time) increases, the wavelength (distance) increases greater at a known rate, because wave motion is always elliptical (the shape of the wave in deep water is always the same).

You only need either wave period or wavelength to determine speed. This is the equation for deep water waves, where the wavelength is > 1/2 of the depth. This is the depth at which the wave does not interact with the ocean bottom, and thus the bottom does not slow down the wave.

L = 1.56T*2
C = 1.56T

C - speed(m/s)
L - wavelength(m)
g - gravity(9.8 m/s*2)
T - wave period(s)

Last edited by a moderator: Feb 21, 2014
2. ### yankeeWell-Known Member

Sep 26, 2008
"What cost \$15,000 in 1970 would cost \$58,788.20 in 1995."

Sep 17, 2013

great post

4. ### tropic surferWell-Known Member

Dec 7, 2011
Question for consideration...if you're surfing, and the ocean begins to recede, you'll surely be drawn out with it, correct?
You realize a tsunami is on it's way, you may have what, 5-8-10 minutes before it arrives? Is your best chance to paddle for the horizon...?
But what if you're on the inside, say 20-30 yeards from shore. Make a run for it on land?
I know bottom geography and ocean depth probably come into play as to where each tsunami will actually break, but hypothetically, "what would you do?"

5. ### DawnPatrol321Well-Known Member

Mar 6, 2012
I'd thank god for an awesome ride, pretty sure either way your F'd, but instinct would probably take over and you'd probably start paddling in to get to land and run, IDK if paddling for the horizon would be a safe bet either, pretty sure it's a no win situation

6. ### Gary WilliamsWell-Known Member

Dec 18, 2013
lol true, I'd be out whipping into it tho, we're talking tow ins baby

7. ### SandblastersWell-Known Member

May 4, 2013
i saw math and failed to read the rest... there for big swell period means more energy behind the waves and that means bigger waves. other then that idk brahz

8. ### goosemagooWell-Known Member

May 20, 2011
I'd ride in and save some unsuspecting boat owners boat or jetski by hotwiring it and heading east all while saving myself in the process. What a nice guy I am, always looking out for others.

9. ### EmassSpicoliWell-Known Member

Apr 16, 2013
I think when it sucks dry you've got about 3 minutes to get outta Dodge. Once 6 minutes comes, you're now in the eager to shore trough that's still moving 30-100mph after the shelf has slowed it down from 100-700mph sustained speed out at deep sea. Screw the jet ski - my toy of choice that day is a non-street legal ATV that's torqued and twin-screwed to the gills to climb me to elevation in the next 180 seconds. And yes, it would have a banner for tsunami survival flying off the rear fender. Boom.

10. ### goosemagooWell-Known Member

May 20, 2011
Until you hit the wall of cars trying to flee along the same routes.

11. ### leetymike808Well-Known Member

Nov 16, 2013
you dont really have to be that high in a tsunami. I live on maui and once you're about 10ft above sea level you're out of the evac areas. Ok maybe its 20ft, i dont really know. I know the last time one was coming i lived 1 block from the beach and just stayed in my apartment.

Anyhow, theres plenty of warning time. And once they know one is coming the sirens (yes tsunami warning sirens, they sound like air-raid sirens) go off every hour till it hits.

12. ### Special Whale GlueWell-Known Member

Oct 8, 2011
CR 250! Ride that b!tch though yards, on sidewalks, what ever. It's easier to maneuver a dirtbike then a quad.
That's what I've always used for my tsunami escapes in NJ.

13. ### EmassSpicoliWell-Known Member

Apr 16, 2013
ATV bro. Off-road capabilities. This is a MacGuyver-approved vehicle, don't you mistake it for anything else.

leetymike, I'm reading that the height of tsunami waves widely from 10ft to 100ft. At Lituya Bay in the 50s, the run-up was 1,720 feet. By your math, you'd be waterborne for the last 1,710 of it. You're the one out there on the island, so I won't go tell you your business, and I've never seen a tsunami or been somewhere that even has felt much effect from them in history. That said, simple math bro. What's the truth I need to go forward with?

When I was talking about the lead time when you saw the water sucked out it was just that and no alarms. I do think there are alarms everywhere except for '04 in Indo.

14. ### leetymike808Well-Known Member

Nov 16, 2013
height of tsunami waves is also measured differently than your standard wind waves. Its more the water behind the initial surge, and the ensuing extreme tidal shifts that cause all the damage. The tides shift from high to low in 5-10 min intervals, for a good day after. its a trip.

I'm no scientist.

And yes i am aware that not all places have a warning system,

15. ### seldom seenWell-Known Member

Aug 21, 2012
Just saw this online and wanted to post here. Peep the reform after hitting the breakwall at appx 1:10, unreal.

[video]http://www.santacruzwaves.com/videos/japan-tsunami-3-11-2011/[/video]

16. ### goosemagooWell-Known Member

May 20, 2011
^^^WOAH! The vid guy obviously doesn't surf. How could you not keep the camera on that giant, perfectly peeling monster. And that reform was crazy. How the hell does the wave come over the breakwall and reform that nicely?

17. ### RIsurferWell-Known Member

Dec 5, 2012
WHERES GMAC AND THE BIG WAVE BOYZZZ!?!?!?! OR NJSHREDMACHINE!??!?! Holy crap dood, that looked like a scene from the 2012 movie. Thanks for sharing!!!!!

Dec 5, 2012
19. ### HARDCORESHARTHUFFER-RIWell-Known Member

Sep 17, 2013
were those people on the promenade at 1:43?

20. ### surfingwastelandWell-Known Member

Jul 24, 2011
That was ridiculous. Wonder what happened to those boats