Auckland’s volcanoes have released tens of thousands of
kilotonnes of gas in past eruptions – and new research is
helping scientists understand what that could mean for the
city’s future.
The study, funded by the Natural
Hazards Commission Toka Tū Ake (NHC) and Auckland Council,
is the first to estimate volcanic gas emissions from the
Auckland Volcanic Field (AVF), filling a critical gap in
hazard modelling and emergency planning.
Volcanic
gases – particularly sulphur dioxide (SO) and carbon
dioxide (CO) – can pose serious risks to people,
infrastructure and the environment. SO can irritate
airways and corrode materials, while high concentrations of
CO can cause suffocation.
“Gas is a significant
but under-recognised hazard in Auckland,” says lead author
Elaine Smid from the University of Auckland.
“Until
now, we haven’t had local data to understand how much gas
could be released in an eruption, or what that might mean in
practice.”
Because Auckland has not erupted in the
modern monitoring era, researchers turned to the past –
analysing ash and rock fragments from five previous
eruptions, including Rangitoto.
By comparing gas
trapped deep within magma crystals to that in rapidly cooled
volcanic glass, they estimated how much gas was released
during eruptions.
The results show that over the past
200,000 years, the AVF has emitted around 26,000 kilotonnes
of CO and 9,000 kilotonnes of SO.
But this alone
doesn’t tell the full story.
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“The speed of release
is what really drives impact,” says Smid. “The same
amount of gas released over a few hours versus several
months would produce very different
consequences.”
To better understand those impacts,
researchers applied their findings to existing Auckland
eruption scenarios used by scientists and emergency
managers.
“This is the first time we’ve been able
to plug Auckland-specific gas data into these models,”
Smid says. “It gives us a much clearer picture of how gas
hazards could play out across the city under different
conditions.”
While gas monitoring is widely used
overseas as an early warning signal, its role in Auckland is
still emerging.
“We don’t yet know whether gas
would be released before magma, how concentrated it could
be, or how much warning it might provide – but that’s
exactly what ongoing research is working to
answer.”
NHC Chief Resilience Officer Jo Horrocks
says the research marks a step change in
understanding.
“This is about lifting the lid on a
hazard we’re only just beginning to understand. It will
directly improve how we model, plan for and respond to
future eruptions.
“The likelihood of an eruption in
Auckland remains low – about 10% over the next 50 years.
What this research does is help us better understand the
potential impacts, so we can be better
prepared.”
About the Natural Hazards
Commission
The Natural Hazards Commission
Toka Tū Ake exists to help New Zealanders prepare for and
recover from the impact of natural hazards. One of the ways
we do this is by providing natural hazards insurance for
homes and residential land.
Homeowners have access to
our scheme if they have an insurance policy with fire cover.
The premium paid to insurers includes a Natural Hazards
Insurance Levy, which is the amount homeowners pay for this
cover.
You can find out more about Natural
Hazards Cover/NHCover on our website to inform reporting
on the issue –
http://www.naturalhazards.govt.nz/know-your-cover
You
can also read more about our annual investment in research
and resilience through regular updates on our news page –
https://www.naturalhazards.govt.nz/news/