The odds of Lake Taupō erupting and the scale of an eruption: An expert explains

Lake Taupō has been shaken by 40 tremors a week since May, and 700 overall since January.
Lake Taupō has been shaken by 40 tremors a week since May, and 700 overall since January. Photo credit: Getty Images

For the first time ever GNS upgraded Lake Taupō's volcanic alert level from zero to one. So, if it did erupt, what would that look like?

GNS' volcanic alert level ranges from zero to five - zero being no volcanic unrest and five a major volcanic eruption. 

The recent upgrade in alert level from GNS is the lowest level of volcanic unrest in its alert level system. It comes after a raft of quakes around Lake Taupō this year. 

"With the current level of activity that we recorded, the earthquakes and the ground deformation, we feel it is appropriate to set the alert level at one," said GNS Volcanology Team Leader Nico Fournier.

Lake Taupō has been shaken by 40 tremors a week since May, and 700 overall since January. The volcano caused the largest eruption on Earth in the past five millennia when it last exploded about 1800 years ago.

Earthquakes located by GeoNet in the Lake Taupō area from January 1 to September 18.
Earthquakes located by GeoNet in the Lake Taupō area from January 1 to September 18. Photo credit: GeoNet

What's the likelihood of an eruption? 

Newshub spoke with professor of volcanology James White, who said the amount of unrest beneath Lake Taupō is "low-level" and the likelihood of an event eventuating is low too. 

"The interpretation from GNS is that the small earthquakes that are occurring are a result of some movement underground, movement down where the magma is stored," he said.

Victoria University of Wellington volcano seismologist Finn Illsley-Kemp told RNZ Taupō is a Rhyolite volcano - holding a type of magma that is viscous and sticky. 

Dr Illsley-Kemp said the magma sits in a chamber at depth of about 5km.

"The magma is moving around, jostling for space," he told RNZ.

White said the movement underground doesn't necessarily mean it's moving towards the surface, instead "causing a bit of shaking". 

Most likely scenario: 

White told Newshub Lake Taupō has a history of small eruptions and that there have only been a handful of large-scale ones.

If Lake Taupō did erupt, White predicts it would be minor. 

"The smallest you wouldn't see, it would just be beneath the lake, there would be some cloudy water and possibly sulphuric gas that would bubble through the surface."

White said another small-scale eruption, which has been seen before at Lake Taupō, would produce big blocks of pumice that would float to the surface and drift into the shoreline.