Scientists have found an intriguing new way to peer into the fiery belly of New Zealand's hottest island.

Volcanologists from GNS Science have been using hand-held thermal infrared (TIR) cameras and thermal sensor modules (TSM) to track the heat and energy being generated by White Island, the country's most active volcano.

GNS currently monitors the island, a 2km-wide, 321m-high, circular chunk of rock 48km off the coast of the Bay of Plenty, with an array of web cameras, along with other instruments and regular tests.

GNS volcanologist Brad Scott wrote in a blog post how these cameras work well in daylight when their lenses aren't covered in dusts or material thrown by volcanic plumes.


But there was new promise in TSM technology - recently developed by the security industry and now also incorporated into web cams - to improve night views.

Scott said it didn't take long before GNS technicians saw how this could be used for volcano monitoring - and there was nowhere better to test it out than White Island, which last erupted as recently as September.

"Since we need to understand how volcanoes work, and what they are up to is a big part of our monitoring, it sounds perfect," Scott said.

"A camera that works 24 hours would be a great tool - even better if it can tell us something about the temperatures as well."

TIR cameras, meanwhile, measured the emitted energy from the surface it was pointed at, showing more energy coming from hot surfaces than cold ones.

The camera collected the data, then applied a "false colour" to make an image.

"One of the advantages is images can be collected at night - plus day - while our traditional web cameras see little at night unless the moon is out," Scott said.

"The thermal sensor module will potentially give higher-quality data with spatial coverage of areas around the vents as well and appears to be cost-effective."

His team recently took TSM technology to the island to learn about the data
quality, thermal range, spatial cover and the effect of steam and gas on the path between the sensor and feature they were looking at.

They now plan to make use of it at other New Zealand volcanoes and geothermal systems.

However, Scott noted the technology was constrained by the fact that all web cameras at active volcanoes must have protected lenses.

It was also unclear what impact acid rain created by the volcanoes would have on the equipment.

"If we can make all this work, it will improve our understanding of how volcano systems work and better inform us about the hazards and risks from volcanoes."

While White Island erupted between April and September last year, its Volcanic Alert Level was currently at 1 - reflecting "minor volcanic unrest" - and there are no aviation warnings in place.

Our angriest island

• White Island is just the tip of a submarine mountain that rises a staggering 1.6km from the sea floor, its fiery innards sealed shut from the surrounding Pacific Ocean.

• Over more than 150,000 years, the volcano has been building towards the sky, the magma chamber inside punching up like a fist and shooting off into fingers that form billowing vents at the surface.

• The surface is transformed with every violent episode - what were once multiple large craters, or a huge lake once 90m deep, is now a rock-strewn field that can be traversed in a matter of minutes.