Send in the drones: Probing White Island's toxic plume

Scientists are using drones to go where they can't - into the toxic plume billowing from New Zealand's most active volcano. Photo / File

Scientists are using drones to go where they can't - into the toxic plume billowing from New Zealand's most active volcano.

White Island's signature plume can offer an early warning of what is happening inside the fiery bowels of the offshore Bay of Plenty volcano, but scientists attempting to measure its gases have never been able to get closer than several hundred metres from it.

"The gases can tell us a lot about what is happening at depth in the volcano, so we really want to know exactly what gases are there," said Victoria University's Dr Ian Schipper, who is leading a new EQC-funded study.

"We are using specially hardened and built drones to measure right in the densest part of the plume to get the true volcanic signals."

Gases sometimes changed before an eruption because different types of gases were released from different depths.

By sampling the gases in the plume, the researchers could find out if fresh hot magma was entering the volcano from depth.

When volcanoes erupt, it was magma – a mixture of molten and semi molten rock – that was thrown out as lava or explosive fragments of rock.

"We know that carbon dioxide is released from very deep in the system and sulphur dioxide is released at a shallower level," Schipper said.

"So if we see the carbon-sulphur ratios go up, it indicates there is fresh magma entering the system from great depth."

That could be an indication that the volcano could be building up to an eruption.

Drones still didn't allow continuous monitoring, but allow high-quality measurements that would otherwise be impossible to get at all.

"Until now samples have been taken downwind so you don't know how much the gases have been diluted or changed as they travelled through air," he said.

"The toxic gases and difficulty of access make it too dangerous, or impossible, for a human to take a sample right in the plume."

EQC science and education manager Dr Richard Smith said the project will bring a big advance in volcano scientific work.

"Dr Schipper and his team are developing technology that will let us sample all the components of a volcano plume," he said.

White Island's signature plume can offer an early warning of what is happening inside the fiery bowels of the offshore Bay of Plenty volcano. Photo / File

"This will let volcanologists get a much better idea of how plume chemistry works, and what the plume is doing to the local atmosphere."

Using the drones would also make it much easier to keep a regular eye on volcanic activity, giving officials more time to act in the event of an eruption.

Schipper said drones were just starting to be used around the world to get more accurate data from volcanoes that could help forecast eruptions – critical information for New Zealand's emergency management and industries such as tourism.

"I was part of a project in Chile to develop a drone that can handle the heat and acidity in a volcano's plume," he said.

"We have brought the drone back from Chile and are collaborating with TurboAce in the USA to build around four or five drones.

"They will be very light 2kg quadcopters that can be easily carried to a site then launched.

"We will also build special housing for the electronics to protect against the water and acid gases in the plume."

Though there were many different gases and elements in a volcano's plume - even gold - Schipper's team would be focusing on analysing isotopes of carbon and sulphur, and on the toxic trace metals that are transported in the plume and that are very difficult to measure.

White Island is an ideal place to perfect the sampling technology and drone operation for New Zealand conditions.

"Once we know it works there, we can use it anywhere."

Drones and science

• GNS Science technicians have already used a high-end hobby drone to help map and monitor our most active volcano, White Island. It's also been used to survey river terraces and geothermal systems around the North Island.
• EQC also recently funded a study using drones to reveal the threat landslides pose to many parts of Auckland.
• Drones have been used in a Surf Life Saving New Zealand pilot study looking at how rip currents work.
• Otago University scientists deployed drones to capture detailed images of Southern right whales during an expedition to the wild and windy subantarctic islands.
• AUT scientists have flown drones over the freezing landscapes of Antarctica, the hot deserts of Namibia, and the wilderness of New Zealand for conservation surveys.