Scientists use Auckland’s fibre network to better understand region's volcanoes

Tuesday, 18 January 2022

Scientists are predicting that Tonga's main island, Tongatapu, could be blanketed in ash on Sunday. Auckland University volcanologist Professor Shane Cronin says the magma type erupted is what's called an intermediate composition.

Auckland’s fibre network will be used to provide an insight into volcanic activity under the region.

Researchers from Victoria University of Wellington and the University of Auckland will use fibre-optic technology, known as Distributed Acoustic Sensing (DAS), to find earthquakes of less than magnitude 1.

Earth scientist Calum Chamberlain said an eruption on the Auckland Volcanic Field (AVF) was likely to happen sometime in the future, and earthquakes might provide some insight into the volcanic unrest in the area.

Tāmaki Makaurau is built on a volcanic field containing 53 recognised volcanoes, which could pose a “substantial natural hazard” to the nation’s largest city.

Tāmaki Makaurau is built on 53 recognised volcanoes, including Rangitoto Island, pictured.

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Previous eruptions have happened at different times and locations, making it hard to predict future events.

Earth scientist Calum Chamberlain and his team will use Auckland's fibre network to study the city's volcanoes.

“Being able to accurately monitor seismic signals is essential to forecast the location and timing of an eruption,” Chamberlain said.

Chamberlain is one of 13 researchers who received funding through the Earthquake Commission’s (EQC) Biennial Grants programme which awards a total of $1m for research into natural hazards and their impacts from the Government.

The 11 GeoNet seismometers around Auckland provided good recordings of seismic activity, but the nationwide focus applied to them didn’t capture low-magnitude earthquakes, he said.

Chamberlain said DAS used “dark strands” of fibre networks – the sections not used by telecommunications - to monitor the seismic activity.

Researchers would use laser pulses to repeatedly measure the length of the cables, allowing them to record stretching due to passing seismic waves.

“Background knowledge of smaller earthquakes will allow us to better understand active faults beneath the AVF and what level of activity is normal, and also possibly identify and map new faults not yet discovered.”

EQC research manager Natalie Balfour said the team was developing and testing new tools to measure earthquake activity that many others would use in future.

“With many cities having fibre networks and undersea fibre cables running offshore, the techniques and technology the team is developing will be hugely useful for getting a better picture of seismic hazard in and around Aotearoa New Zealand,” Balfour said.

The project starts in April, with Chamberlain and his team providing the findings to Auckland Council, Tūpuna Maunga Authority and other key stakeholders.

CORRECTION: An earlier version of this story was entitled 'Scientists use Auckland's fibre network to predict city's volcanic activity', but has since been changed to 'Scientists use Auckland’s fibre network to better understand region's volcanoes'. The research could provide forecasts, but not predictions of volcanic activity. Updated 4.22pm, January 18, 2022.