And if you think the Alpine Fault is bad....

[kiwithrottlejockey]

New Rangitoto volcano research prompts re-think

By CASSANDRA MASON = The New Zealand Herald | 12:43PM - Thursday, April 11, 2013


An aerial view of Auckland City with Rangitoto in the background.
— Photo: Brett Phibbs.

A NEW DISCOVERY that shows that Rangitoto erupted "semi-continuously" for about 1000 years is prompting scientists to re-think what the volcano could do in the future.

The most recent volcano to erupt in Auckland, Rangitoto was thought to be close to 550-years-old and to have erupted once or twice in its lifetime.

However, new University of Auckland research shows that the volcano actually erupted "intermittently" or "semi-continuously" from about 1500 years to 500 years ago, smashing traditionally-held beliefs about volcanoes here and around the globe.

The findings are also prompting scientists to re-think how Auckland's volcanoes will behave in the future.

"The old paradigm was that these volcanoes erupt suddenly in a new location each time, and only live for months to a year or two," said lead researcher Associate Professor Phil Shane.

"This needs to be revisited in light of the new Rangitoto history of activity."

While the scientists acknowledge that Rangitoto's surroundings are unique, the findings mean that long-lived activity cannot be ruled out, and Auckland needs to prepare for that.

"The Auckland volcanic field could be going into a new mode of operation. If so we need to think about hazard planning and risk in a very different way," said Shane.

He said future planning would have to consider living with active volcanism for a long period of time.

"It's not as bizarre as it sounds, if you think about Iceland and Hawaii — societies have gotten used to living with volcanic activity for generations."

"At the moment, people think that volcanoes in Auckland would probably occur at a location that hasn't had a volcano in the past and that it would be short lived .. and then the activity would be over."

The discovery was made by examining volcanic ash in the build-up of sediment in nearby Lake Pupuke. The sediment, which can be very accurately dated, revealed a "chemical fingerprint" of tiny volcanic glass shards. Studying this material showed researchers when the eruptions happened.

Up until now, scientists have used radiocarbon dating to determine the age of samples taken directly from the volcano. But sediment examination has proved to show much more detailed evidence of volcanic activity that has been buried by further eruptions.

The study is part of an ongoing research project into the history of volcanic eruptions and lakes in the Auckland region. The research has been published in the latest issue of the Journal of Volcanology and Geothermal research.

______________________________________

GETTING THROUGH

What You Need:

All homes should have getaway kits, emergency survival items, a first aid kit and food and water for at least three days. You should also have essential emergency items in your workplace and in your car.

Emergency Survival Items:

• Torch with spare batteries or a self-charging torch.
• Radio with spare batteries.
• Wind and waterproof clothing, sun hats, and strong outdoor shoes.
• First aid kit and essential medicines.
• Blankets or sleeping bags.
• Pet supplies.
• Toilet paper and large rubbish bags for your emergency toilet.
• Face and dust masks.
• Food and water for at least three days.

Source: Civil Defence.

Learn more about natural hazards in your area, what to do in an emergency and how to prepare at GetThru.govt.nz.

www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10876897

[beagle]

And do you think us south islanders are laughing

[ngatimozart]

Apr 11, 2013 16:31:22 GMT 12 beagle said:

And do you think us south islanders are laughing

;D ;D ;D

[beagle]

Looks like Whenuapai will become the international airport again.

[brassnz]

Why on earth would any Kiwi find this scenario funny, particularly at this point in our history?

[Dave Homewood]

Exactly. I agree brassnz. There is nothing funny at all in this scenario. Perhaps sensationalist. But not funny. Such an event wiping out Auckland would basically send NZ back to the stone age.

[kiwithrottlejockey]

Mind you, it is rather silly (or funny in a facical way) building our biggest city on top of one of the world's most active volcanic fields.

Eventually, shit is going to happen, whether we like it or not. All you have to do is to open your eyes and observe all the volcanic cones & craters around Auckland as evidence of what happens at regular intervals of time.

[ngatimozart]

And we built our capital city on a plate boundary. You've got to have a bit of a senses of humour about these things because if you don't you aint a happy chappy.

[beagle]

Just a bit od North and South Island banter.
Dunedin used to be the capital of New Zealand anyway

[flyjoe180]

Dunedin was also built on a former volcanic field.

[kiwithrottlejockey]

Apr 13, 2013 9:08:50 GMT 12 flyjoe180 said:

Dunedin was also built on a former volcanic field.

So was Christchurch (Lyttelton Harbour is a giant volcanic crater); however both the Christchurch and Dunedin volcanic fields are no longer hot-spots due to shifts in the plate boundaries. Whereas the Auckland volcanic field is still very active, and the frequency between eruptions is decreasing while the intensity of eruptions is increasing. Naturally, the timescale is huge compared with human lifespans, but it is a given that eruptions will continue around the Auckland isthmus.

[Dave Homewood]

Aucklanders should tap into the thermal energy and power the city from it, while also reducing the pressure beneath - like Rotorua has done.

[ngatimozart]

The last euption in the Banks Peninsula volcanic field was about 6 million years ago so that kinda makes them extinct. Had to study them in my 1st year geology many jam seasons back. Am not sure about the dates of the Otako (Dunedin) volcanoes as never done any study on them. However would presume they are of similar time period or older.

[kiwithrottlejockey]

Rangitoto's blasts from the past

Study of volcanic field reveals island's long, explosive
history — and may help predict when it will blow next.

By JAMIE MORTON - The New Zealand Herald | 5:30AM - Friday, April 12, 2013


Rangitoto is older than previously believed. — Photo: Brett Phibbs.

RANGITOTO may be much older — and more explosive — than previously believed.

A new study has led scientists to reassess how volcanoes may behave in the future and could be a large step toward unlocking Auckland's mysterious volcanic past.

Contrary to the long-held belief that Rangitoto was formed less than 700 years ago and has erupted only twice, University of Auckland researchers now suspect there may have been intermittent activity from between 1500 years ago to 500 years ago.

Alongside basaltic ash from the island volcano's most recent eruption between 500 and 550 years ago, sediment samples taken from Lake Pupuke have revealed evidence of minor eruptions 922 years ago, 1040 years ago and 1500 years ago.

"That's much longer than we've traditionally believed for basaltic volcanoes of this kind, not only in Auckland but anywhere in the world," said lead researcher, Associate Professor Phil Shane.

The findings, published in the Journal of Volcanology and Geothermal Research, were important for understanding the risk posed by volcanoes in the Auckland region — and perhaps elsewhere, Dr Shane said.

"The old paradigm was that these volcanoes erupt suddenly in a new location each time, and only live for months to a year or two. This needs to be revisited in light of the new Rangitoto history of activity."

Future long-lived activity was a possibility, either at Rangitoto or at other eruption sites across the Auckland Volcanic Field, home to more than 50 volcanoes.

"We cannot rule out long-lived activity in the future, or eruptions at sites that have experienced previous activity," Dr Shane said. "The Auckland volcanic field could be going into a new mode of operation. If so we need to think about hazard planning and risk in a very different way."

The new study is part of an ongoing research project into the history of volcanic eruptions and lakes in the Auckland region involving Dr Shane, Associate Professor Paul Augustinus and PhD student Ola Zawalna-Geer.

The largest and most recently active of Auckland's volcanoes, 260m-high Rangitoto has long proven an enigma for scientists trying to unravel what eruptions have occurred in Auckland. More importantly, it may be the key to understanding where the next blow might take place.



Rangitoto's most recent eruption, between 500 to 550 years ago, happened near the site of the field's oldest eruption, Lake Pupuke, leaving no obvious northward or southward trend to draw a pattern from.

Scientists believe the answer to Rangitoto's riddle is that either its activity was an anomaly and had now ceased, that the field's activity has now moved to Rangitoto, or that future eruptions may occur at Rangitoto and elsewhere in the field for the next 500,000 years.

Unfortunately, the new study did not solve the puzzle, said University of Auckland volcanologist Dr Jan Lindsay.

"Will it continue erupting in 500 years' time, will the activity switch somewhere else, or will it occur in connection to activity somewhere else? We don't know."

When and wherever the next eruption does come, Civil Defence planners believe sufficient warning time would result in no casualties, with even a three-day lead-up providing plenty of time for evacuation.

Research by Market Economics estimated that in a worst-case eruption near the CBD, the Auckland region could suffer a 47 per cent reduction in gross domestic product.

But this could be reduced by 40 per cent if businesses had effective preparedness measures in place.

New Zealand would suffer a 14 per cent decline in GDP. However, relocated business could bring about a 3 per cent rise in GDP in the rest of the country.

www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10877015

[701driver]

Hmmmm - I guess that means south Island farmers and exporters would have to export through south island ports so we could buy our new toyotas and flat screen tv's ! Oh shit arent all the tv studios in auckland, never thought that through. hell where's Marsden point is that close to auckland? cos we will need fuel for those toyotas .... Oh no the stone age here we come, well maybe not. humour always better than crying in your soup, no one likes salty watery soup.

[shamus]

Just imagine, Motat aircraft collection, Subritzky's and Stan Smith's on the North Shore.
Warbirds collection and the restorations of Pioneer and Avspecs at Ardmore all crushed and destroyed under a million tons of molten rock. That would be a loss for the whole of NZ.

[Dave Homewood]

It doesn't bear thinking about. Hopefully it never happens. Don't forget the Zero and Spitfire at AWM too.

[ngatimozart]

Apr 15, 2013 22:12:35 GMT 12 Dave Homewood said:

It doesn't bear thinking about. Hopefully it never happens. Don't forget the Zero and Spitfire at AWM too.

Not a matter of if but when. There's a lot of variables involved and in the case of Rangi2toes a lot of unknowns. If it really spits the dummy and goes bang, it's not going to affect the Marsden Point refinery because that is too far away. 80 odd nautical miles at a guess. Ardmore is a reasonable distance and it's not as though lava flows from Rangitoto will reach Ardmore immediately. The immediate danger to the AWM, MOTAT and possibly Ardmore will be ashfall and possibilty of bombs in case of AWM if it is a really explosive eruption.

To many unknowns at the moment. They will need to do a lot more time consuming and expensive work before they can make any reasonable assumptions of its history and eruptive capabilities.

Just to be on the safe side maybe we should move the Spitfire & Zero from the AWM to Wigram and same with lancaster Sunderland etc., from MOTAT ;D ;D

[suthg]

HAHA! What? To put them outside... But can they stand earthquakes? And the snow, and southerly storms... nah - better leave them up north I think!! More people to respect them too...

[kiwithrottlejockey]

The War Memorial Museum sits on the rim of a volcanic crater, and quite a decent-sized one at that.

And these scientists are now telling us that NONE of the Auckland volcanos are, in reality, extinct.