Tell-tale hints before volcanic eruptions found

Whakaari Island was among the volcanoes studied Photo: Supplied/ University of Canterbury.

Researchers have pinpointed precursors to volcanic eruptions, in data collected before explosions including the deadly 2019 Whakaari surge that killed 22 people.

Artificial intelligence algorithms were used to scan thousands of seismic recordings taken before 18 eruptions on six active volcanoes around the world, including Mount Ruapehu, Mount Tongariro and Whakaari Island.

The findings have now been published in the Nature Communications journal.

University of Canterbury geophysicist Dr Alberto Ardid used recordings of ground noises and shaking that were taken within three to four weeks of the 18 eruptions.

The key discovery was a common peak in the 'displacement seismic amplitude ratio' in the days leading up to the eruptions.

This signals a blockage occurring in the shallow part of a volcano, which then forms a seal or lid, trapping hot gas, building pressure, and sometimes triggering an explosion.

The DSAR measure is a ratio comparing volcanic 'noise' 100 metres below ground to that at the surface.

University of Canterbury geophysicist Dr Alberto Ardid Photo: Supplied/ University of Canterbury.

Ardid says the method applied well to 'wet volcanoes', which are those with hydrothermal systems beneath the crater, but was not as transferable to those without.

He also says most of the time that these signs are identified by the AI the volcano did not erupt.

"Probably 90 per cent of the time when the seal forms and the pressure increases, probably the volcano just releases the energy passively ...

"But sometimes the volcano is not as good at releasing the pressure in a passive way and there'll be an explosive event."

Dr Alberto Ardid Photo: Supplied/ University of Canterbury.

Ardid hopes the findings will improve volcanic alert level systems that are used to manage human activity on and around volcanoes to save lives.

As did Dr David Dempsey, a senior lecturer in civil and natural resources engineering at the University of Canterbury, who is a co-author on the journal article.

Dr David Dempsey Photo: Supplied.

He says the research was prompted by the 2019 Whakaari eruption, but it's "certainly not suggesting that there was any shortcoming in terms of these methods not being applied prior to the eruption, because they didn't exist".

"We've only developed them subsequently," he says.

-RNZ/Sam Olley.




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2 Comments

nah

Posted on 11-05-2022 01:49 | By hexsayer

i went over in 2012/13 the guide thats still missing was who took the group i was in. i got to asking him a query, i had read somewhere of a Yellowstone geologist/volcanologist who witnessed a Yellowstone creek change colours (to green) before a small eruption due to chemical reactions, and what he thought of that geologists speculation. he didnt have an answer. guess he does now.

Always good...

Posted on 21-04-2022 14:09 | By morepork

...to see Science advancing and some good results coming out of a bad event.

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