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Bit of weather heading our way?


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There are two forms of Tsunami. One is formed when a large mass of Sea Floor moves due to say an Earthquake or underwater landslide, or an above water landslide that falls down a steep hill side into water etc. These are slower moving "Displacement" waves and tend to be Waves of significant height. Japans big Tsunami was one of these. These type do not tend to have the same energy over distance, so they dissipate the further they travel. They can be seen even in deep Deep water as a wave.
The other form is as a Shockwave which travels through water at fantastic speeds. Usually as fast as 900Km/hr. In deep water, they cannot be seen. I do know of someone that was in their boat when one struck their Hull. The guy said it was like someone had just slammed the Hull. No wave, just a loud bang.

The Tongan Volcano detonating like it did, would most likely have produced a Shockwave. Hence why it had traveled clean acoss the Pacific to hit the west coast of the US, in such a short time.
A shockwave maintians significant energy for a long time. It would likely have lost very little energy by the time it crossed the Pacific. Hence why Japan had so much damage for a Country well prepared for Tsunamis.
As the water depth decreases, the shockwave is forced to slow down, but this results in the Shockwave growing in height. Once the wave has moved into shallow water, slowed and increased in height, it can still be traveling at quite a pace. Faster than the speed of a natural beach wave. Because it can still be moving fast, what could seem like a small wave rushing into a shore, can still have a significant amount of energy causing the wave to push inland much further than one would expect. If anyone saw the video of the Boy wearing blue seemingly defying the wave, even though the wave did not look like much, it hit the shore and washed over those young people sweeping them off their feet and bowling them along for some distance. I don't think they were expecting that. 
 

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10 minutes ago, Black Panther said:

Expecting a warning system for one tiny location is unrealistic.  

Utilizing a system that alerts the entire population because a few boats might get damaged is irresponsible. 

Saying there is no threat when there is a threat is a bit irresponsible also. 

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It wasn't about warning for a tiny little place BP. The System was down yet again.
Civil Defense was working on what was called "an Advisory". I had seen that advisory (if it is the same one) and it warned of potential threats and included a warning that Ash might make it as far as Wellington. The Actual early warning system that the Gvt has spent hundreds of millions on, in relation to Ocean monitoring bouys strung from NZ to the Kermadecs, is not operational, yet again. We have had (I think form memory) 3 significant events since that system was deployed and not once has it worked due to some kind of technical issue. The  difference this time being that no warning was given at all, where as last time the Sirens went off when nothing much affected us.
To me, what I believe is worse, is that the US has hundreds of monitoring bouys all over the Pacific. They are whom published the advisory. Why could Civil Defence not get on the phone to the US and ask questions. Oh wait, I think everyone was on Holiday.
Or even better, why can NZ don't log onto their system and use it. Even if they have to pay to access it while the NZ system is down. That way at least the early heads up part of the system would have paged all the NZ need to be's that they need to get on a phone and call someone. What the heck is the point in spending hundreds of millions for some useless Yellow floaty things out there in the water. Which it seems half forget how to float.
Hmmm, should we be adding Yellow Early warning Bouys to the Drowning Toll.

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A bit of handwringing here, I think every active boat owner would be aware of the Tsunami from the media. If there was a serious risk to population centres then I am sure the CD text service would have been used.

Looking at it another way, what would all these boat owners do in any case, move their boats to where exactly? If a Tsunami was hitting Auckland harbour what would I do? Probably zero, hope for the best and rely on insurance to sort it out.

People can move to higher ground, boats just get what they get unless you decide to head offshore.

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I heard a report that the warning system we have is way better at earthquake generated tsunami than volcano generated. No idea why.

In this case the early reports from Tonga and Fiji should have given them a clue.

I agree with Psyche in this case with a warning the only real option is to put to sea so not realistic for many.

Wheels I'm not sure about the Japanese tsunami being short range. I saw the damage in Crescent City marina after that one.

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The system is far from perfect, a perfect system does not exist, what we have is the best we can do, I'd rate it about 70%. 

It does not have the definition to predict this, hitting the red button would have been highly irresponsible. 

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If you were living aboard in Tut as some do -double up lines and go ashore, I think apart from the Fuel jetty and the big Cats wanderings most was confined to the piles, perhaps the Fuel jetty floated off the piles as A pier Westhaven started to in Jan 97 Cyclone Drena

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2 minutes ago, eruptn said:

Satellite images showing refracting waves about 13hr after the main eruption.

 

image.png

Brad - that's really interesting-can you help with approx scale please?

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4 hours ago, Fish said:

No, the problem is they said there was "No Threat". That was the first statement. I read it at about 7:30 pm, turned the internet off, watch some TV and went to bed. govt warning systems?

I don;t think that's true.

https://www.rnz.co.nz/news/national/459618/tsunami-advisory-for-parts-of-nz-s-north-island-waves-crash-into-tonga-after-volcanic-eruption

The message I got from the announcements was stay away from the beaches and harbours, there'll be crazy s**t happening.

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17 minutes ago, DoT said:

I don;t think that's true.

https://www.rnz.co.nz/news/national/459618/tsunami-advisory-for-parts-of-nz-s-north-island-waves-crash-into-tonga-after-volcanic-eruption

The message I got from the announcements was stay away from the beaches and harbours, there'll be crazy s**t happening.

The initial advisory was issued at 8:14pm.

Not sure why the flounderers in the Hokianga thought this would not apply to them. And anyone with history at Tut's knows it has been punished by tsunami waves in the past.

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Hmm What ,didnt get deployed or just dont work??

https://niwa.co.nz/news/new-tsunami-monitoring-system-for-pacific

 

22 September 2020

A network of 12 tsunami buoys are being deployed off New Zealand and up into the Pacific over the next few months to help ensure New Zealanders near the coast and Pacific Islands get more accurate information in the event of a tsunami.

“The buoys will detect tsunamis but also provide verification one is actually happening which can avoid false evacuation warnings.”

 

The closest buoy to New Zealand is about 150 nautical miles offshore.

Three trips aboard NIWA’s flagship research vessel Tangaroa are needed to deploy the buoys with two already completed taking in Tonga and Niue. The third will head towards New Caledonia.

The buoys are fourth generation technology manufactured in the US and together they will comprise the most advanced monitoring system in the world.

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1 hour ago, DoT said:

I don;t think that's true.

https://www.rnz.co.nz/news/national/459618/tsunami-advisory-for-parts-of-nz-s-north-island-waves-crash-into-tonga-after-volcanic-eruption

The message I got from the announcements was stay away from the beaches and harbours, there'll be crazy s**t happening.

 

1 hour ago, DoT said:

The initial advisory was issued at 8:14pm.

Not sure why the flounderers in the Hokianga thought this would not apply to them. And anyone with history at Tut's knows it has been punished by tsunami waves in the past.

I check online at 7:30 pm. Saw the first reports of tsunami in Tonga. It specifically said "no threat" to NZ.

Had to put the kids to bed after that and didn't see any cause to go re-checking for alerts when they said there was no threat. Noting that my missus heard the sonic booms and our front door and windows were rattling (that have never rattled in 10 years of living in this house). The news of the eruption explained the rattling. 

This issue here is the initial statement saying there was no threat. That was clearly wrong. It is far better to say nothing than to give the wrong answer. If there was no comment on the tsunami threat, I would have checked back latter. Having stated there is no threat, there is no mechanism for many people to then re-check when the govt changes it mind.

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13 minutes ago, Fish said:

I check online at 7:30 pm. Saw the first reports of tsunami in Tonga. It specifically said "no threat" to NZ.

What did you see exactly?  What was the source of the information? 

GNS and NEMA first issued official advice at 8.14pm.  That was the first official notification in NZ.  There is no record of any other notifications prior to this. 1h15m later Tutes was rolled. 

NEMA were very clear from the first announcement that there was no flooding threat to land.   They only send TXT alerts if land evacuations are recommended. 

Quote

 

People in or near the sea should move out of the water, off beaches and shore areas and away from harbours, rivers and estuaries until at least 04:00am NZDT Sunday 16 January 2022.

STAY OFF THE BEACHES AND SHORE AREAS
There is no need to evacuate other areas unless directly advised by local civil defence authorities. Coastal inundation (flooding of land areas near the shore) is not expected as a result of this event.

 

 

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