New Zealand Under Tsunami Threat

[PhantomWolf]

So we have had three massive Earthquakes off of the East Cape and near the Kermadec Islands in the past 7 hours. The first was a 7.1 at 2.27 am local time, followed by a 7.4 at 6:41 am and an 8.0 a little under an hour ago at 8.28 am.

We now have Tsunami Warnings in place for eastern parts of The North Island and they are continuing to assess the dangers to other coastal areas.

Fun times. Hopefully it will all pass without further incident and no losses of property or lives.

 

[William Parcher]

Any updates?

 

[Puppycow]

Kaiju activity?

 

[The Atheist]

Any updates?

Yeah, massive overkill by Civil Defence.

Hundreds of thousands of people have evacuated low-lying towns, when all that was needed was a warning to stay away from the coast.

Waves as high as one foot are expected!

I can understand erring on the side of caution, but we've had tsunami warnings at our place, which wouldn't get hit by a 1000-foot high tsunami.

 

[The Atheist]

Kaiju activity?

Tangaroa.

 

[Skeptic Ginger]

Better overkill than actual kill.

 

[Skeptic Ginger]

Any updates?

From the same link:

The National Advisory issued following the 7.3 earthquake near EAST OF THE NORTH ISLAND NEW ZEALAND at 2021-03-05 2:27 AM New Zealand Daylight Time is cancelled.

Based on GNS Science's modelling and ocean observations on tide gauges and the New Zealand DART Buoys, our science advice is that the threat of strong and unusual currents has now passed for all parts of New Zealand including the Chatham Islands.

 

[PhantomWolf]

Any updates?

We haven't been washed away, yet.

The first waves have hit and so far they have remained small enough to not be damaging, though much of the Eastern Coast has been evacuated and flooding is still expected as more come in. Even here on the West Coast, we are being advised to stay clear of the beaches and to expect surges and wild currents for the next 24 hours.

 

[PhantomWolf]

From the same link:

You have to remember that this was a series of three Earthquakes, the one you refer to happened at 2:27 am local time, the one we are getting waves from happened at 8:28 am local and was about 10x bigger being an 8.1 vs a 7.3.

 

[sackett]

Another bullet dodged.

Yes, I know, it went wide. But NZ means a lot to people all over the world.

 

[PhantomWolf]

Another bullet dodged.

Yes, I know, it went wide. But NZ means a lot to people all over the world.

Thanks, though it's not so much dodged as it just hasn't had the expected impact, yet. Some places are still under warnings of up to a 3m surge, though most of our coast is now at possible 1m ones ongoing. We do seem to have gotten off lightly compared to some of the Tsunami that have occurred in past years elsewhere. Still, if we have a 3m one come in, it could still so significant property damage.

 

[Skeptic Ginger]

You have to remember that this was a series of three Earthquakes, the one you refer to happened at 2:27 am local time, the one we are getting waves from happened at 8:28 am local.

I was just quoting your link. I thought it had been updated since you cited it.

Quake was 8.1 if that holds.

Looks like tsunami warnings are for 0.3 to 1 meter hitting all over the Pacific including the west coast of South America, so that's significant.

Tsunami waves observed is one step up from possible to: we don't know how big yet.

TSUNAMI WAVES REACHING 0.3 TO 1 METERS ABOVE THE TIDE LEVEL
ARE POSSIBLE FOR SOME COASTS OF

ANTARCTICA... AUSTRALIA... CHILE... COLOMBIA... COOK
ISLANDS... COSTA RICA... ECUADOR... FIJI... FRENCH
POLYNESIA... KOSRAE... MEXICO... NAURU... NEW ZEALAND...
NICARAGUA... PANAMA... PERU... PITCAIRN ISLANDS...
POHNPEI... SAMOA... SOLOMON ISLANDS... TONGA... AND WALLIS
AND FUTUNA.

ETA is listed for all those areas in UT.

Even a 1 foot wave can do damage depending on the local geography.


A significantly bigger risk however:

* TSUNAMI WAVES REACHING MORE THAN 3 METERS ABOVE THE TIDE
LEVEL ARE POSSIBLE ALONG SOME COASTS OF

KERMADEC ISLANDS.


* TSUNAMI WAVES REACHING 1 TO 3 METERS ABOVE THE TIDE LEVEL ARE
POSSIBLE ALONG SOME COASTS OF

NEW CALEDONIA... AND VANUATU.

 

[PhantomWolf]

I was just quoting your link. I thought it had been updated since you cited it.

Quake was 8.1 if that holds.

Looks like tsunami warnings are for 0.3 to 1 meter hitting all over the Pacific including the west coast of South America, so that's significant.

8.1 is pretty significant.

The first one happened to our east, about 100km offshore from East Cape, the other two further north by the Kermadec Islands. That's about 800km away.

The troubling thing is that this fault line is in the main subduction zone that creates a major fault line that runs right through the middle of New Zealand, passing through the East Cape out into the Pacific to our east, then turning north to the Kermadecs. This is the fault line that created the Southern Alps, runs under Wellington, and caused the 1931 Napier EQ disaster, and the 1968 Inangahua one.

To be having this sort of movement on that fault is a little concerning, though hopefully, these have released stress on the fault and not added to it, especially down here to the south.

 

[PhantomWolf]

Seems that they are happy that the worst has passed now, there are still warning to stay clear of the beaches over the next 24 hours, but people are being allowed to return home.

 

[Skeptic Ginger]

The March 4 2021 M 8.1 earthquake was preceded ~107 minutes by an M 7.4 thrust earthquake located ~50 km west of the M 8.1. The proximity and timing of the two events indicates that the M 7.4 was likely a foreshock of the M 8.1 earthquake. In terms of seismic moment, the M 8.1 was ~11 x larger than the M 7.4 foreshock. Additionally, a M 7.3 oblique reverse faulting earthquake occurred ~6 hours prior to the M 8.1 and ~900 km to the south; however, the spatial and temporal gap between these earthquakes likely indicates that static stress changes induced by the earlier M 7.3 did not directly cause the M 7.4 or M 8.1 earthquakes.

M 8.1 - Kermadec Islands, New Zealand

Yeah, I would want to evacuate uphill if I lived on the North Is near the coast. I don't see any overkill in that warning level.

 

[The Atheist]

Yeah, I would want to evacuate uphill if I lived on the North Is near the coast.

You don't understand NZ's topography. There are only a very few places likely to impacted beyond the shoreline on that side of the island, unless it's a tsunami of significant height, which this one never was.

I don't see any overkill in that warning level.

We received a warning in Auckland, and 99.9% of the population couldn't be hit by a tsunami. You could have a Fukushima 100 km off Auckland we'd hardly notice.

The actual warnings caused hundreds of thousands of people to all travel the same way. I don't know how many crashes and consequent injuries there were, but I'd be surprised if it wasn't a significant number.

Add to that lots of people were standing around for hours on a stinking hot day, most without drinks, and you've got a recipe for heat exhaustion, and I'd bet there were plenty of cases of that, too.

We have a system that impacts far too many people. Central Whangarei was evacuated, and short of a 3-4 metre tsunami, they were never going to be impacted.

It was a big earthquake, but a long way away and even the earliest forecasts were for 0.3 to 1 metre in NZ, and it turned out to be less than that - there are a couple of pictures of very mild surge in a couple of inlets, and there were tens of thousands watching and filming.

Going by the amount of Ministerial input, it looked a lot like a photo-op for politicians rather than an actual emergency.

Yes, there should have been warnings, but only an infinitesimal portion of those who received warnings needed them. Given the current limit of max 100 people at any gathering to stop Covid spread, cramming thousands of people into small spaces isn't all that smart, either. We'll get away with that, but if we were in the midst of a serious outbreak, the evacuations would have caused multiple super-spreading events.

 

[Samson]

Two tragic fizzers today.

The lockdown which may have been unnecessary and the tsunami evacuation that was.

Still on results actually a good day at the office.

 

[Vixen]

Stay safe guys.

When the tide goes out as rapidly as that it can instil a false sense of calm and before you know it, you have another Indonesia or Japan, with waves quickly overtaking fleeing inhabitants and motorists.

 

[Samson]

Stay safe guys.

When the tide goes out as rapidly as that it can instil a false sense of calm and before you know it, you have another Indonesia or Japan, with waves quickly overtaking fleeing inhabitants and motorists.

They were 9s
This was a baby 8 thirty times less.

 

[Puppycow]

Better overkill than actual kill.

Yes, but false alarms are actually harmful. It's the boy who cried wolf principle, and it killed a lot of people in Japan.

Why?

Because lots of the people who died had heard tsunami warnings in the past that didn't amount to anything actually dangerous. They became lulled into complacency from so many false alarms.