White Island eruption: Magma just tens of metres below surface

Magma is sitting just tens of metres below the surface of White Island – but scientists say it's unlikely to erupt again over the next 24 hours.

GNS Science has also indicated that a wind-shift might mean some people in Eastern Bay of Plenty might notice gas from the offshore volcano.

Since last Monday's blast, which has left 16 people dead and around 30 injured, volcanologists say there has been no further eruptions, and the level of tell-tale tremors around the volcano has remained low.

"The expert judgment made this morning calculated the likelihood of another eruption within the next 24 hours at 30 to 40 per cent," GNS Science duty volcanologist Craig Miller said.

"This decrease in likelihood means another eruption is unlikely over the next 24 hours."

Through aerial flights over the weekend, scientists have also been able to observe more of the volcano's post-eruption environment.

They sighted three main vents within a 100sq m area – one of which was sending out transparent high temperature gas that indicated a shallow magma source within a few tens of metres below the surface.

Miller said this open, hot vent explained a glow that could be seen in night-time images using specialised low light cameras.

While the volcano's alert level was being kept at Level 2 – signaling "moderate to heightened unrest", and the same as it was before the disaster – that didn't mean another blast couldn't happen suddenly.

"An explosive eruption can still occur with no precursory activity from this vent especially if there is a collapse of unstable material around the vent, or if the gas emission decreases allowing groundwater to enter the vent," Miller said.

"The other vents are also producing large amounts of steam and gas, and sudden [steam or gas driven] eruptions from them are still possible."

Some monitoring equipment had been partially buried under ash and the batteries at one site have gone flat, affected one of three cameras keeping watch on the island.

"We still receive data from the remaining equipment, which allows us to continue monitoring the volcano," he said.

"Both seismic stations on the island are fully operational and are providing us with round the clock data."

Miller added that, as the wind shifted to become more northerly today, gas might be noticed in the Ōpōtiki to Whakatāne area, as occurred on many occasions during an eruptive period between 1976 and 2000.

"People may feel this gas as a slight irritant on skin or eyes. Should any explosive activity produce an ash cloud, the anticipated impact on the mainland is very low," Miller said.

"If ash did reach the mainland it would be more of a nuisance or disruption and not life threatening."

Miller also noted that a 133km-deep earthquake that struck last night in the Bay of Plenty didn't cause any change in activity at White Island.