Old tech gets new look at volcanoes

Technology designed for the military could offer a crucial early look at the same volcanic rumblings that just prompted GNS Science to ramp up Mt Ruapehu’s warning level.

A new study will draw on sophisticated remote-sensing equipment to peer inside volcanoes’ hydrothermal systems, which could change over years — or even days.

As last year’s eruption at Whakaari/White Island tragically illustrated, large blows can happen with few warning signs.

This month at Mt Ruapehu, scientists recorded tremors, the largest amounts of carbon dioxide and sulphur gases measured in two decades, and Crater Lake temperatures as high as 43C.

Temperatures in the mountain-top lake each year typically cycle between 15C and 40C, and while it’s crossed that threshold at times since Ruapehu’s surprise 2007 bang, none of those episodes ended in an eruption.

GNS Science said the flow of these gases and heat through the lake signalled the vent underlying it was open, which triggered a shift to alert level 2 and its official flagging of “moderate to heightened volcanic unrest”.

Massey University scientist Dr Gabor Kereszturi said gaining a clearer picture of hydrothermal systems like Ruapehu’s was important to learn about hidden processes that came before bouts of volcanic unrest.

As was happening now, he said, hot fluids circulated within volcanoes, making rock weaker over time.

Hazards remained notoriously hard to predict — which was where Kereszturi’s new study into hyperspectral technology came in.

Pioneered for military use in the 1970s, hyperspectral imaging involves collecting data from across the electromagnetic spectrum and then piecing it together to create highdefinition, three-dimensional profiles.

“It is an extremely versatile sensing technology that can detect physical and chemical properties of the surface of the Earth or any other objects,” he said. “It can also be used in the lab, or as mounted on low-flying aircraft; or now on satellites.”

When it came to volcanoes, it could be used from safe distances to measure the properties of otherwiseinaccessible volcanic rocks.

Kereszturi’s project, made possible through a just-awarded Rutherford Discovery Fellowship, would develop fresh applications for it to use in labs, or from aircraft and space.

As it happened, the study’s focus would be on Mt Ruapehu, as well as the nearby Tongariro Volcanic Complex to look inside the volcanic features.