As New Zealand authorities continue their bid to retrieve the victims of last week's Whakaari/White Island volcano eruption, volcanologists have now released their observations about the volcano's active conditions.

Key points: NZ authorities anticipate further explosive activity, but so far this has not happened

NZ authorities anticipate further explosive activity, but so far this has not happened The volcano is spewing gas at temperatures at a minimum of 200 degrees Celsius

The volcano is spewing gas at temperatures at a minimum of 200 degrees Celsius Divers are continuing to search for two people who were on the island during the eruption

On Sunday, a volcanologist from GeoNet — New Zealand's geological hazard information authority — travelled with specialist teams of four who were continuing efforts to find the remains of two people thought to have been killed by the eruption.

Operations to the heavily toxic island have been short, as teams have been using a breathing apparatus that allowed them to search for only 75 minutes.

Specialist teams of four have been travelling to the island to search for the two bodies. ( Supplied: New Zealand Police )

Findings released by GeoNet on its website said that gas coming out of the volcano's active vent would be at least 200 degrees Celsius.

"To us, it looks like a typical open vent volcanic system with magma not too far below the surface, possibly as shallow as a few 10s of metres beneath the surface," the website read.

The statement added that the gas is "dominated by sulphur dioxide", which comes from shallow magma (or molten rock).

It also noted the change in the volcano's Crater Lake Basin, which previously held a hot, acidic lake.

Recently published photos now show that much of the lake has been filled with "numerous, isolated ponds", which GeoNet believes is due to reactions between eruption deposits and rainfall.

An archival photo of the volcano shows highly acidic gases emanating from its core. ( Supplied: GeoNet )

The volcano is one of many of New Zealand's active volcanos clustered in the centre and north of the country's North Island — an area known as the Taupo Volcanic Zone.

It is one of the most active volcanic regions in the world.

GeoNet said it anticipates more explosive activity from Whakaari/White Island but so far this hasn't happened.

If it did, the authority said there was an "extremely low likelihood of any potential ash affecting the mainland", but it did advise those concerned about their health to contact their local GP.

The latest GeoNet analysis said on Monday that there would be an unlikely chance of an eruption that could impact areas outside of the volcano's vent.

Whakaari/White Island is NZ's most active cone volcano

This image taken last week shows the volcano spewing hot gases from its vent. ( Supplied: NZ Police / GeoNet )

Whakaari/White Island is New Zealand's most active cone volcano — a stereotypical volcano type defined by its triangular shape vent at its top.

These volcano types produce an intermediate composition of magma that trickles down the side of the vents, which over time creates a volcano's cone-like shape.

They are expected to have explosive eruptions every few decades.

Between 1975 to 2000, Whakaari/White Island experienced its longest eruption episode, which resulted in the formation of a new explosion crater measuring 150 metres across.

Since then it erupted in 2012, 2013 and 2016 prior to Monday's blast.

On the GeoNet website, RSAM (Real Time Seismic Amplitude) time series plots visualise how much energy volcanos produce over time, and in the past week, the island volcano's RSAM plot showed a spike around the time of the eruption.

The volcano's energy released between December 10–14 spiked. ( Supplied: GeoNet )

To date, any fallout from the eruption has made the sea near the island toxic and divers have had to be washed clean after every completed dive.

"We have always anticipated recovering all bodies from the island and we remain deeply committed to that goal to allow families some closure," New Zealand Police Deputy Commissioner John Tims told reporters on Sunday.

"Divers have reported seeing a number of dead fish and eels washed ashore and floating in the water."

At the latest count, 16 people have died from the eruption, but police have not included the two missing — believed to be a New Zealander tour guide and a boat captain who had taken tourists to the island — among the dead until their bodies are recovered.

ABC/AP