Around 25 faults have now been discovered around Hamilton, New Zealand's fourth biggest city. Photo / NZ Herald
Around 25 faults have now been discovered around Hamilton, New Zealand's fourth biggest city. Photo / NZ Herald
Hamilton might better known for foggy mornings than big earthquakes – but freshly unearthed evidence of shakes under the city has prompted a rethink.
In a new investigation, Waikato University's Professor David Lowe and colleagues aim to get a clearer picture of past quakes around New Zealand's fourth biggest city, to better understand what might unfold in the future.
For decades, the basin that Hamilton sits in was thought to be free of faults, save for some older ones around its margins, and the distant Kerepehi Fault near Matamata.
But more recent work has upended that notion: surveys have now revealed at least 25 faults in and near the city.
It's also explained mysterious features preserved in ash layers that Lowe came upon back in the 1980s, while analysing sediment core samples recovered from beneath local lakes.
"In some cores, it was evident that some ash layers had holes in them and what looked like cracks beneath them infilled with volcanic ash projecting downwards into the lake sediment," he explained.
"With the discovery of the multiple faults in Hamilton, I realised that the holes and ash infilled cracks were likely caused by shaking."
After further analysis, his colleague Dr Vicki Moon suggested there was also evidence for liquefaction – the quake-shaken slurry that left whole suburbs in eastern Christchurch covered in stinking mud.
"We knew therefore that there had been at least one violent shaking episode in the Hamilton area in the last 20,000 years, because the lakes I had cored back in the 1980s are about 20,000 years old," Lowe said.
Considering the newly-found faults and the ancient earthquake evidence together, it became obvious that Hamilton wasn't immune to big quakes.
But, with few tell-tale signs of the surface, the scientists needed another way to assess how these faults behaved.
So, they came up with a clever method that drew back on those markers – or "tephra seismites" – that Lowe uncovered in the old lake sediments.
"There are around 30 lakes in the Hamilton lowlands scattered amidst the newly-discovered faults," Lowe said.
"We think the relationships between the faults and lakes provide the key to mapping and dating earthquakes in the lowlands since 20,000 years ago and form part of our plan to develop new earthquake-hazard assessments for the region."
His team now plan to take samples from as many of those 30 lakes as they can, and then use cutting-edge CT imaging technology to characterise them.
"Some lakes are close to faults and others are distant – and so by examining which ash layers, if any, are liquefied in the sediments, we can potentially work out which faults were active and when," he said.
This image shows faults in the Hamilton area that have been mapped and inferred to exist, along with areas of lakes which Waikato University's Professor David Lowe and colleagues believe will yield more evidence of past earthquake behaviour. Image / Supplied
"Our preliminary works shows that the same ash layer is not necessarily liquefied in every lake, suggesting that the effect of an earthquake relies on proximity to a nearby fault."
Lowe noted the Hamilton lowlands were still classified under New Zealand's National Seismic Hazard Model as being of "low-to-moderate seismic risk".
"But this classification is based on the limited historic record of earthquake activity in the record - only about 100 years," he said.
"Our research may or may not change this classification, depending on what we find."
In any case, he expected the new insights would help improve hazard planning in the region – and even offer up new approaches that could be applied to other places in the country.
Hamilton, one of the fastest growing cities in New Zealand, was home to around 170,000 people, as well as crucial infrastructure such as a multi-billion dollar inland port.
An assessment carried out after the Canterbury quakes found there were hundreds of quake-prone buildings that needed strengthening.
Five big questions
Lowe's new three-year study was being supported through grants from the Government's Endeavour and Marsden funds.
A total 125 projects under the Royal Society Te Apārangi-managed Marsden Fund, announced today, have been awarded more than $83m.
The Herald looked at five others.
WHAT MAKES A 'SUCCESSFUL' PYSCHOPATH?
Christian Bale's character Patrick Bateman in the movie American Psycho portrayed a "successful" psychopath living and working in society. Photo / File
We might think of psychopaths as movie characters like Hannibal Lecter, Norman Bates and Patrick Bateman – but the personality disorder is much more common in our society than we think.
Now, an Otago University-led study seeks to shed more light on complex neural functions thought to be connected to psychopathy, using electroencephalographic (EEG) measures.
What makes the study yet more interesting is that Professor Martin Sellbom and colleagues won't recruit participants from prisons, where much research has been focused, but directly from the community.
What enabled psychopaths to blend into society wasn't well understood – but they were known to frequently create hostile work environments, along with emotional distress and financial hardship for those left in their wake.
The researchers say their work could lead to a new theory-based understanding of what sets these "successful psychopaths" apart from those who turned to crime.
WILL #METOO REALLY DRIVE A CULTURE SHIFT?
The #MeToo movement has empowered women around the world to hit back against sexual harrassment. Photo / 123RF
The worldwide #MeToo movement has exposed villains like now-disgraced Hollywood producer Harvey Weinstein and given women a powerful new voice.
Now a new study, led by Victoria University's Associate Professor Sue Jackson, will explore how young Kiwis learn about gender and sexual harassment through the platform that has propelled #MeToo – social media.
The team will look at how they feel about debates playing out on sites like Twitter and Facebook – and what that meant for their everyday lives.
Discovering more about how boys, particularly, have been responding was seen as crucial, given that a lack of understanding about gender equality was directly related to supporting violence against women.
While there have been some studies with mostly white, middle class, young feminists about the use of social media to resist sexual harassment, there has been scant research with boys, young men and minority groups.
CAN THIS 'SUPERFOOD' SAVE THE KAKAPO?
Kakapo are close to extinction. Photo / File
With a remaining population of just over 200, kakapo are perched at the brink of extinction.
Now Victoria University's Dr Janet Pitman and Dr Simon Hinkley want to know whether a "superfood" that triggers their breeding could be key to their survival.
While the exact nature of the link between the mass rimu fruiting and kākāpō breeding is far from clear, the researchers have previously suggested that hormone-like compounds in the fruit, which are similar to oestrogen, may play a part.
They hypothesise these compounds trigger breeding by raising circulating oestrogen levels and promoting egg yolk protein and sperm production – something they'll now test through a range of new experiments.
Their project, benefiting from the recent Kākāpō 125 project that sequenced the DNA of every living bird, could ultimately lead to a new natural therapeutic aid to save the species.
WHY DO KIDS EAT WORSE WHEN THEY SLEEP WORSE?
Although sleep loss probably isn't a direct cause of weight gain, it can set up just the right conditions for bad eating. Photo / 123RF
We know that when children lose sleep, they're more likely to eat unhealthy food – but why this happens is still largely unknown.
Researchers say that, although sleep loss probably isn't a direct cause of weight gain, it can set up just the right conditions for bad eating – especially when energy-dense foods like those snacks from the pantry are right there for them.
Studies have even suggested that losing even just a few hours of sleep over one to five nights can increase energy intake by seven to 21 per cent.
Now, Otago University's Associate Professor Barbara Galland and Professor Rachael Taylor will lead a study that will effectively turn children's bedrooms into "sleep labs".
By carefully manipulating their sleep and wake times at night, and observing their eating habits under normal everyday living conditions during day time, they expect to learn how sleep loss can trigger a cascade of effects on food choices, energy intake and weight gain.
WHY DON'T SIBLINGS SHARE DISEASE?
While the inflammatory pathways in gout have been well characterised, less is known about triggers it. Photo / 123RF
Siblings share roughly half of their genes, and are often raised in the same environment – so how was it possible that one brother could develop a disease, while the other didn't?
The answer may lie in how the environment influences gene expression through what's called epigenetics.
Flares of gout are understood to be the result of our innate immune system reacting in the wrong way to non-threatening cues – meaning that this extremely painful form of auto-inflammatory arthritis isn't just influenced by our genes, but our environment, too.
While the inflammatory pathways have been well characterised, less was known about triggered it – and why it only occurred in some people.
Otago University's Dr Tanya Major planned to solve the mystery by comparing epigenetic markers on the genes of pairs of brothers, and then seeing whether these changed in response to environmental factors like diet.
Maori and Pasifika people, who were at heightened risk of gout and suffered more severe symptoms, would make up half the participants of the study, which could ultimately improve longer-term health outcomes.
