Sand slugs come slip-sliding from mountain

By VIRGINIA WINDER

OAKURA man Gary Bruckner is standing in a wave-tumbling storm checking out the Kumara Patch.
But the board rider and teacher (right) isn’t sizing up the surf on Taranaki’s wild west coast; he’s sampling the sand.
To put it in literal terms, he was doing research for his Beaches and Littoral Sand Transport of Taranaki study, backed by the Royal Society of New Zealand and administered by the Government.
Put even simpler, he was watching sand movements along the coast between the Hangatahua (Stony) River and Kaihihi Rd (where the Okato pub is).
Or, in other words, he was surveying a sand slug, which is a large amount of sand that gets moved along the coastline.
In Taranaki, along with the weather, how much snow is on the mountain and the surf conditions, the coming and going of our black iron sand is a common topic of small talk.
That’s why Bruckner took last year off to stake out the Kumara Patch, one of Taranaki’s most-famous surf spots at Okato.
The Californian primary school teacher, who with wife Becky became a New Zealand permanent resident in 1990, was fascinated by the region’s ever-changing beaches.
He was used to white sandy beaches that stayed basically the same. In his new land, he noticed how Surf Highway 45’s beaches transformed dramatically from storm to storm, and sometimes for no apparent reason at all.
Bruckner refers to Ahuahu Rd. “I was amazed to see how much sand filled up that bay.”
He became curious: “Where is all the sand coming from and where is going to?”
The first time he walked the Kumara patch beach, it was all just rocks (see picture below, taken in March 2006). “No sand whatsoever.”
Then in 1998, there was a huge slip on Mt Taranaki and the Stony River filled up with sediment, destroying fishing holes, and pouring sand on to the beach, covering the rocks.
“That’s the first time I saw the accretion of it,” he says.
Accretion is the building up of a beach, which is the complete opposite to erosion.
Experts from the Taranaki Regional Council told Bruckner it took five years for the Stony River to flush itself out and all the fishing holes to come back.
A great fishing year was expected in 2003, with the trout back and thriving. But the mountain was having none of that. Another large slip fell into the river, filling it up all over again and sending another sand slug sliding along the coast towards New Plymouth.
The predominant swell direction, which comes out of the south-west, hits beaches like Opunake straight on. But around the bump, it comes at an angle, pushing the sand along.
The bays along the coast fill up with sand, then when they can’t take any more, the excess is washed along to the next bay.
New Plymouth oceanographer Peter McComb describes it like this: “A bay is like a cup. When you keep filling the cup, it will get filled to overflowing. Then the sediment (sand) has to be spread elsewhere.”
Dr McComb, of MetOcean Solutions, is a “big picture” man.
He says if it wasn’t for Mt Taranaki providing the heavy-duty rock armour for the region via eruptions, the bump would have been flattened thousands of years ago.
Even now the mountain continues to protect the coast by sending slips down the rivers to replenish the sand.

“If you turned off the rivers, eventually all the sediment would be stripped off the beaches.”
He describes the mountain as a “sand factory”, with the Stony River the most efficient chute for delivering sand because of its steepness.
The latest sand slug is making a difference to the beaches, but it’s not all good news. While Oakura Beach’s sand erosion problem has gone – for now – so have a number of good paua collecting spots.
Dr McComb says that while the beaches are growing at this point in time, geological time tells a different story. “Five thousand years ago the beach was right out here,” he says using an opaque window like a white board to draw a line out from Taranaki, flattening the bump into a gentle rise.
“Twenty thousand years ago, the Maui platform would have been dry just about.”
Bruckner’s study only encompassed a twitch of the eye, not even a blink in the time scale. He also focused on just a 2.38km stretch of beach, which he marked out with five stakes.
His studies took him there every week and sometimes more, especially in stormy weather when change was often more obvious.
He regularly took GPS readings to see how far the sand stretched into the sea and measured the changing contours of the sand.
During his year of sand watching, he saw the beach grow and go dramatically.
In September last year, the sand just north of the Stony River stretched 85 metres towards the sea. In October, it measured 100m and December it went right out to 150m, covering more and more rocks. “I have the information for January – it went out even further,” he says.
Even a wee lagoon formed high up on the beach, providing a private swimming hole for his family (pictured, right).
Bruckner has graphed and mapped his results, which show the beach is definitely growing.
He’s now passing the baton, or the stake in this case, to a Waikato University masters student, who will be supervised by coastal oceanography Professor Terry Healy.

Dr McComb welcomes the study, which begins in December.
He’s hoping it reveal new scientific data about the shifting sands of Taranaki.

Keeping eye on southern sky

By VIRGINIA WINDER
A BUNCH of Taranaki amateur astronomers have landed the job of patrolling the southern sky as part of an international collaboration.
The flipside is that astronomers at the Jarnac Observatory in Vail, Arizona, will also be able to check out the sky Down Under. And vice versa.
The night watchers, including comet spotter Rodney Austin, have been donated a $13,000 telescope (pictured) by American astronomer David Levy and his wife Wendee, plus the National Sharing the Sky Foundation.
Levy is a bright star in astronomy, especially because of his comet spotting. He has found 22 of the long-tailed icy gas-and-dust trails.
Together with Eugene and Caroline Shoemaker, he discovered Shoemaker-Levy 9. That’s the comet that collided with Jupiter in 1994, producing the most spectacular explosions ever witnessed in the solar system.
Austin says the brand new 14-inch Ritchey-Chretien reflector telescope touched down about a month ago.
“It came out of the blue,” he says.
Just like the offer of the telescope, made by Meade in the US.
Last year, Levy was a keynote speaker at the Royal Astronomical Society of New Zealand conference in New Plymouth.
“David fell in love with the place,” says Austin (pictured). “There wasn’t a cloud over the province for 10 days. We got talking one day and he said ‘we have this foundation and we would like you to have one of these telescopes’.”
From Vail, Levy tells his version.
“We were very impressed with the enthusiasm of the people there during our visit in June and July of 2006,” he says.
“And then after we returned to the US, we tried letting them have a remote observing session with our telescope here in Arizona. That also was successful. We thought that collaboration would be beneficial.”
Levy explains why. “They get a nice telescope with which they can observe the southern sky and we hopefully get to use it remotely once the details are worked out.”Using an internet programme, the Taranaki team gets the opportunity to look at the flipside of space.
“They should be able to make Northern Hemisphere observations as well,” Levy says.
Austin says the remote observing, including the practice session, is a breakthrough for Kiwi amateur astronomers.
“As a training run, during a massive thunderstorm we had here, a group of us operated David Levy’s telescope in Arizona by remote control. As far as we know that was the first time in New Zealand that a bunch of amateurs operated a telescope overseas remotely.”
The donation is another first. “There have only been four telescopes donated so far, and we are the only ones outside the United States,” Austin says.
The Taranaki telescope is to be housed at a secret location in north Taranaki. Austin says to keep whereabouts of the star-watching instrument safe, its whereabouts cannot be revealed.
But this is not a closed-scope affair.
“It’s not going to be a visual telescope – it’s going to have a camera,” he says. “It will take images. The idea of the project is we will use it to patrol the southern sky looking for new comets and asteroids, which are bits of rock in the orbit around the sun,” he says of the latter.
It was also be able to record novae and supernovae (exploding stars) and minor planets. The stargazers then go over the photographs taken, looking for changes in planets and any foreign bodies.
While it’s not officially a New Plymouth Astronomical Society project, members are involved and those who have expertise will be able to contribute, he says.
Housing for the telescope is still being built, but it’s expected to be up-and-scanning by summer. Then the universe will be at their fingertips.

Rockin' down Shake Highway 45

By VIRGINIA WINDER

MT TARANAKI is soundly asleep, but you could still be shaken awake by a quake.
That’s according to seismologist Steve Sherburn, who is an expert on Taranaki’s tremors.
In the past 60 days there have been more than 30 shallow shudders on the coast, with about 25 of those in the Okato area, 26km south-west of New Plymouth, on the west coast of New Zealand's North Island.
Many have been too light to make the GeoNet website “recent quakes” section, but they do appear as splodges on a map that makes coastal Taranaki look like a teenager with severe acne.
New Plymouth looks worse, as if the pimples have become infected. While there has been less activity beneath the city, the quivers have been bigger.
Sherburn, from GNS Science in Taupo, says the cluster of quakes is normal for us. “The pattern that we see is fairly typical of what’s normal for Taranaki.”
That’s because of the Cape Egmont Fault Zone, which is a line of faults that run north-east and south-west off Cape Egmont. They are mostly offshore where there are no recorders, but the faults come onshore at the extreme west of the bump.
The fault belt heads towards Nelson and up towards New Plymouth, so the lines would look like 2o’clock on a watch face.
Our region is shaken between 200 and 300 times a year. “Some years there will be a lot more than that.”
New Zealand’s most active area is Matata in the Bay of Plenty, where there have been more than 700 earthquakes since November last year.
In Taranaki, we are having a normal year, says Sherburn, who has been one of Taranaki’s major fault-finders. A few years back he set up 70 seismic recorders around the region. For six months he monitored the movement of the ground and learnt something that will reassure those who fear our volcano could suddenly erupt.
In the whole time he took those recording, there were only three earthquakes under the mountain and they were “bog standard fault shakes”.
Sherburn is absolutely certain they had nothing to do with moving molten rock or gaseous liquids – nor have any quakes since.
“When volcanoes are waking up they produce a characteristic earthquake.”
These are, rather obviously, called “volcanic earthquakes” and their movement is not like a fault jolt.
“It’s more of a rocking than a sharp shaking,” he says.
It can, therefore, be picked up instantly by a seismologist, which is good news for those living in the shadow of Mt Taranaki.
“There is no evidence that it’s waking up,” he says. “Because we are not getting any now, hopefully when it does start to wake up, we will notice and, hopefully, get quite a long period of warning.”
But don’t start relaxing yet – there’s still the matter of the moving plates and our fault belt. Perhaps our surfing route could be renamed Shake Highway 45?

Bets Mt Taranaki blowing top in 50 years

By VIRGINIA WINDER
IF betting agencies took punts on natural disasters, you’d be wise to put your money on New Zealand's Mt Taranaki blowing its top in the next 50 years.
You might not be around to collect the winnings, but your descendants would be toasting your foresight with an expensive bottle of champers, probably far from the poison ash fallout. Perhaps Paris.
Massey University scientists have fresh evidence the Egmont Volcano, as it’s known in geological terms, may have a history of violence even worse than previously thought.
So bad, that if it continues its destructive track record, there’s 50-50 chance it will act up before 2057.
Associate professor in statistics Mark Bebbington (left) has been calculating the odds based on a five-metre-deep core sample taken from Lake Umutekai, south-east of New Plymouth in New Zealand's North Island.
Imagine the sample as a standing pole with a series of horizontal stripes made up of alternating layers of ash and soil.
The ash tells the scientists when an eruption occurred and the soil in-between shows them how much time passed between volcanic events. The longest lull appears to be 450 years, while the shortest span is placed at 10 years.
Dr Bebbington says the ash at the bottom has been dated at 10,000 years old, while the top layer is just 1500 years old. The sample shows there have been 104 events in those 8500 years. But scientists know the mountain’s last blast was in 1854.
Unlike Split Enz, geologists and statisticians believe history does in fact repeat.
“Basically, volcanoes are recurrent systems,” Dr Bebbington says.
“The wild card is that we are saying that the past is the best model for the future.”
With that in mind, it appears Mt Taranaki could be in another long sleeping spell.
But then again scientists believed Mt St Helens was an extinct volcano. In 1980, the mountain proved, catastrophically, how wrong those experts were.
Not Massey’s mountain specialists. They know the 2518-metre-high cone is just biding its time to vent.
After examining the figures and working out a distribution system on that one core sample, Bebbington says there is a 33-50% chance of Taranaki becoming active in the next half-century. “That’s fairly conservative,” he says of the estimate.
That’s because there’s more. In fact, another core, this sample taken last year from Lake Rotokare, south-east of the mountain near Eltham.
“It appears there were quite a number of events in that sample that don’t correspond with the one from Lake Umutekai,” he says. What this means is that the chance of an eruption just rose – along with the eruption count from days gone by.
“My gut feeling is that there have been somewhere between 150 and 200 (volcanic) events,” Bebbington says of that 10,000-year period.
While the new numbers don’t go back as far as the 450-year slumber period, the ash deposits show that wind direction has a lot to do with reading the life-lines of volcanoes.
In other words, if the wind was blowing a different way during the volcanic explosion, the ash may have landed somewhere else.
The discrepancies between the two core samples show this.
But Bebbington says scientists are still trying to match up the geochemistry of the ash samples, so a final reading on the mountain’s fiery future is yet to be revealed.
Just know, there are sensitive seismic recorders all over the rising landmark, which is being (thankfully) stubbornly still.
There is movement though. “East off the end of Taranaki there’s some activity there,” Bebbington says.
These deep-earth rumbles may be a sign, a hint from down-under, that the sleeper is about to awake.