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tsunami warning


Fogg

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I did hear the GC tell some boaties at Half Moon Bay .."if yer not on yer boat in the next 30 seconds then run for the hills''

 

Some of the more enteraining TR's were from those cheesy pohms...

 

"Mustang Sally heading to sea with 3 BOP and one sleepy cat"

""*** oh yes heeeellloooo CG, I take it you must be very busy tday so will try not to waste any of your time, how are you today"... that one even had my cheesy pohm wife cringing....

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I was in 2 minds over taking the boat out of the marina but as I wanted to suss her and the 60fter I have on a mooring off Bayswater anyway I thought why knot go out in the am 'just in case' rather than the planed pm instead. Also I looked at that geonet, after AC's txt, and Welly did show the start of what could have been a big nasty with almost a 2mt variation at the time so I thought what the hell lets go for a motor.

 

Saw SD come out. Didn't realise the tugs dragged the frigate off. There one mo moving the next so I though she'd done it herself, which was a slight surprise I must say.

 

I have no issue with the wave warnings. As they said 'we didn't know if it was big or knot and wouldn't do so until it would have been too late to move masses of people' so either we all just ignore them and maybe die one day or run the 'better safe than sorry' programme. Personally I don't mind changing plans for a few hours rather than spend the time and dramas of funerals, which take a pile longer.

 

TR's bloody funny to listen too but don't do them myself. I do flying a lot and are make sure they are cancelled. If you don't 5mins after you were due in they start spooling up choppers and SAR teams. They get a bit pissed off if they find you still alive.

 

The days of Radphone calls were so much better. Some of those were fecking brilliant.

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Guest Rocket

First thing they tell you in Hawaii YCs is if those sirens go off get on your boat and get out of the marina. I would do that no matter what size wave was expected.

 

Point of order : from my observation SD did not have to endure a "waste of time" - looked like a bloody good way to spend an afternoon.....

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i survived a direct hit from the tsunami :wink:

i was on big manly beach in about ankle deep water rigging my yacht, about 10 minutes later i went to move the trailer and the water was about 30ft down the beach, then as i was putting the centre board in, in about waist deep water there was a very strong onshore current, which would have been all the water coming back in. no physical wave though.

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Comments like "the time came and went and nothing happened" are quite relative, in my view. From what I have been able to glean, things happened at places like Tutukaka, Lyttelton and the Avon River :wtf: for up to 36 hours after "the time". We returned to Tutukaka from the BOI about 4pm on Sunday and slipped into our berth thinking all the drama was over but 20 minutes after we tied up, it was all on again and even 45-foot twin screw launches were aborting their docking attempts and bailing back to the outer harbour.

 

One day - maybe even soon - they will have the ability to accurately predict exactly where and when but until then, I am comfortable with the general "bad sh*t may happen over the next 24 to 36 hours".

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First thing they tell you in Hawaii YCs is if those sirens go off get on your boat and get out of the marina. I would do that no matter what size wave was expected.

 

They have had several destructive tsunamis in Hawaii in the past and a lot of people have died, particularly in Hilo in 1946 and 1960. Generally places that have experienced fatal natural disasaters are less complacent about them than those that haven't. I'd guess that Sri Lanka and Aceh province in Indonesia would take tsunami warnings pretty seriously these days.

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I'm not sure how to react in future to warnings, like SD the 1.5 metres at the Chathams made me think it was serious. I would probably react the same way I guess as Sunday.

Always err on the side of caution. Being hit by a big wave can really give you a bad hair day. The problem is that a Tsunami is about as easy to predict as the Weather is for next week. How it actualy sets off across the ocean is purely dependant on what occured on the sea floor to start it in the first place. I do believe that in the not too distant future, the science dudes are going to be able to give far greater accuracy to what is coming and where it is headed. But other issues that they can not predict is the local isues of the countries coast line that it is about to hit. Local knowledge helps, but it also depends on the energies direction. The Indonesia Tsunami showed that very clearly. Beaches on one side of a bay were wiped out, beaches on the other side of the same bay unscathed. Also depending on the Ocean floor layout. CHCH is a nightmare. The sea floor is shallow at only 30-60ft and rises slowly from a long way out from extremely deep water. The actual shockwave can be hundreds and I really mean hundreds of feet in depth. Usually the shockwave height that of sea floor to seas surface where is was created. As that shock wave reaches the shallower waters, it rises up. Depending on the direction it was actually travelling, it could rise a little, or it could turn into a monster. Direction is influenced by what actually created the shockwave in the first place. It maybe the earths movement sloshing huge volumes of water or it could be a huge lift or slump in the sea floor or it could be an underwater landslide. So could Wellington be hit by something bad?? yes if it comes in at the right direction and speed and where it may have been created and how it was created. And Geographic history has shown that waves have been through the Wellington area before. A massive earthquake in NZ waters could easily cause a massive landslide under the water and we could easily see waves as high as several hundred feet. There is geographical evedence of a Tsunami having reached 150m up the hills behind Nelson and it is was created the boulder bank in Neslon and Grevell Harbors. The last point, as shalowing sea floor influences the wave height, so can the sides of a harbor or sound. And most of our harbors in NZ are built in area's of natural geographic protection, having very steep sides and thus the waves can grow to huge heights. The Alaskan Earthquake in the 60's had a wave travel down the sound that broke off tree's 200ft up the sides of the surrounding hills.

So yep it was annoying to have all the constant warnings, but at the same time, one day a real big one is going to ride in and sadly at the moment, there is really no real way of knowing what event is going to cause that.

We do know two things that will give a close possible. How close and how big the Earthquake was. In fact, CD had dismissed the idea of a wave at first because info had suggested the quake was on land and was only 8.3. But as info came in, they revised that due to the epicentre getting further and further out to sea and the reported strength increasing. They didn't actually know if a wave existed at first, they just knew it was more than likely.

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interesting reading:

 

http://www.teara.govt.nz/en/tsunamis/2

 

During the earthquake, the entire region west of the Wairarapa fault lurched abruptly north-east. Like soup in a bowl that is jostled, the water of Wellington Harbour slopped onto the adjacent land. The next movement of water occurred because the entire Wellington region had tilted – the eastern side of the harbour was now about 80 centimetres higher than the western side. The harbour waters ponderously moved off downhill, towards central Wellington. Houses and shops were flooded along Lambton Quay, which at that time was along the shore.

 

A good reason to avoid Wellington maybe :)

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There's a YouTube vid of the fifth tsunami wave coming into the Heathcote/Avon estuary in Christchurch.

 

OK, so the wave doesn't look that big but by crikey there's some power behind it!

 

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Like this one? - The biggest wave on record occurred in Lituya Bay on the southern coast of Alaska in 1958. Caused by an earthquake measuring 8.3, the wave measured 524 m!!!! :shock:

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Was it 1958. I studied it when in high school and got to see the film of it. A guy was filming on the deck of a ship at the time (no vid back then) and it was in black and white. The earth quake and turmoil of water made him drop the camera on the Deck, but the camera carried on running. It filmed the water rushing out of the harbor and rushing back in and picking up everything, ships and biuldings and everything. But it wasn't as big as the wave that went down the other sound. I maybe wrong, but I am pretty sure it was Anchorage Alsaka that the film was taken in. Apparently a light stood on top of a tower in the middle of one of the sounds. It was broken off and it was 300ft up.

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Half KM? I tell ya, I reckon I'd be climbing on the other guys shoulders on top of cook with that one. Yikes.

Actually, I am confused(Not unusual). But the Alaskan Earthquake I am thinking of was indeed in 1964.

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We are quite likely to get it when a bit of the Kermadec trench drops off the top to the bottom - like an underwater landslide

 

Its happening all the time - just little bits. Problem is...not much warning as its so close relatively speaking. Hopefully not in my lifetime.

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http://www.businessweek.com/news/2010-0 ... -says.html

 

The earthquake that killed more than 700 people in Chile on Feb. 27 probably shifted the Earth’s axis and shortened the day, a National Aeronautics and Space Administration scientist said.

 

Interesting . . . heard something on the news and was unsure that was what I heard - seems the earthquake was so big it probably caused some changes in earths rotation - Maybe we will need extra leap years :roll:

 

I seem to remember a movie about the earth shifting on its axis - The Quite Earth . . .

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The day shortened by 1/1000000 of a second. Darn it, like I don't have enough time in a day as it was :wink:

In the greater scheme of things, the earth is actuay very fluid. The Earths crust is very thin and quite plyable. An earthquake, or any shock for that matter, transfers itself right though the earth. This is how Epicentres of quakes are pinpointed. Just like GPS satellites send a signal with a time stamp that enables the GPS to calculate your position, the ripple of a quake does something very similar. The ripple runs around and through the earth in two very diffeferent ways. One ripple runs around the Earths Crust. The other type of ripple runs through the Earths molten core. The two arrive at a point at different times. A sismic station on the other side of the world can measure the difference and calculate the ruff location. Many stations then eventually pinpoint the epicentre with greater accuracy. That's the reason why it actualy takes some time to get an accurate location and position.

Back to the Earth slowing...so a quake of magnitude causes the Earth to wobble or vibrate or best explanation would be "ring" just like a bell. The Earth is spinning and even though we don't notice it, at 1000Mph, it is spinning quite fast. Just like a gyroscope, the momentum of such mass opposes any other force from changing it's speed and direction. That's a good thing. But also, any force in opposition to that gyroscopic affect results in energy being lost from rotation. It's why in the greater scheme of things, such a small amount of earth movement results in a the greater mass being affected. It is also sean the opposite direction. That Gyroscopic affect is also transposed into the part of the Earth that is moving. If that didn't happen, then we would have a very simple "slide" of earths crust against itself. Well simple in the Big earth picture. But it is that opposing force that causes the huge mass of crust to "vibrate" in a way that we feel as shaking. Tied in with the fact that the Crust is also very "spongy". It's all quite complex along with being all quite simplistic. :wink: So in a simplistic nut shell, the mass of crust moving directly results in energy being robed from Earths rotation.

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If the day was shortened wheels, would that not mean that the earth actually moved forward in its rotation? Surely if the rotation was momentarily slowed, then the day would be micro seconds longer?

 

:think:

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