White Island was always 'too dangerous' for the number of tourists visiting the island, experts have said, as they warned of risks of further blasts and landslides.

Emeritus Professor Ray Cas, from Monash University, branded the island - also known by its Maori name Whakaari - 'a disaster waiting to happen for many years'.

'I have always felt that it was too dangerous to allow the daily tour groups that visit the uninhabited island volcano by boat and helicopter,' he said. 

In 1914, a small mining community on the island was wiped out after falling rocks weakened by the island's volcanic activity swept through the village. 

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The violent volcanic eruption on New Zealand's white Island was caused because ocean crust is being subducted (pictured, the series of events leading to the spontaneous eruption).  This constant movement means sudden explosions can occur at any moment 

Mining activity was subsequently banned and the island has been uninhabited now for more than a century, but is a hotspot for tourists hoping to get close to an active volcano.

Large volcanic events such as the White Island eruption can often cause subsequent disasters.

GeoNet, New Zealand's geological hazard information centre, describes White Island as New Zealand's most active cone volcano. Only the top is visible, with around 80 per cent of it underwater.

Rescuers have been unable to visit the island in the wake of the disaster in order to search for survivors and victims, saying it is still too dangerous.

Explaining the dangers, Chris Elders, professor of Geology at Curtin University's School of Earth and Planetary Sciences, told MailOnline: 'This may be a combination of the ash in the atmosphere that would affect any helicopters.

'Also, when you get an eruption like this, the ash deposits very quickly and creates rocks which are extremely unstable.

'Any rainfall, which can be triggered by the ash sent into the atmosphere, could cause a landslide if the unstable rocks come loose.'

By Karen Ruiz for Daily Mail Australia 

More than 20 Australians including a Sydney family-of-four and a newlywed couple are listed as missing by the New Zealand Red Cross in the wake of the deadly White Island volcano eruption. 

Five people have been confirmed dead and dozens were still unaccounted for as of early Tuesday after the volcano exploded shortly after 2pm local time on Monday. 

An estimated 50 tourists - from New Zealand and overseas - were on or around the crater, located off the coast of the North Island, at the time of the blast. 

Eighteen survivors were evacuated - some suffering severe burns - leaving an estimated 27 people unaccounted for. 

Police say the number of missing is in double figures - and that they do not expect to find any further survivors.

Names of those still unaccounted for have been listed by concerned family members on the Restoring Family Links website. The website is not an official missing persons list.

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Newly-wed couple James, 23, and Madeleine Whitehouse, 24, from Brisbane, were listed as missing as of early Tuesday morning, according to a list compiled by concerned family members on the Red Cross website 

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Amy Miall, 30, from Brisbane, and partner Mathew Thomas (pictured) 31, from Tamsworth, are still unaccounted for 

Among the Australians listed as missing are North Sydney family-of-four, parents Anthony, 51, and Kristine Langford, and their two teenage children Jesse, 19, and Winona, 17. 

Newlywed couple James, 23, and Madeleine Whitehouse, 24, from Brisbane, were also listed as missing as of early Tuesday morning. 

According to social media, the couple had married last September and had been on holiday in New Zealand.

Other Australians on the missing list include Amy Miall, 30, from Brisbane, Mathew Thomas, 31, from Tamsworth, Richard Aaron Elzer, 32, and Jason Griffiths, 33, from Coffs Harbour, and Jane Murray, 56, from Sydney. 

A 12-year-old boy from Western Australia and seven-year-old the youngest still unaccounted for, according to the site.  

Prime Minister Scott Morrison confirmed 24 Australians were visiting the island as part of a cruise ship tour group on Monday.  

AFP are working with New Zealand counterparts to confirm information on the well-being of those involved, Mr Morrison said.

'We have so far been able to identify a number of Australians who have been hospitalised and will we working further on this through the night,' the prime minister said.     

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Among those listed as missing is North Sydney family of four, parents Anthony, 51, and Kristine Langford (pictured) and their two teenage children 

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Siblings Jesse Langford (left) 19, and Winona Langford, 17, were believed to be on holiday with their family

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Jason Griffiths (pictured) 33, from Coffs Harbour, NSW, was listed as missing as of early Tuesday

New Zealand officials said early Tuesday morning that 'no signs of life have been seen at any point', meaning the death toll could be as high as 32. 

Three Britons are believed to be among those still missing.

Speaking earlier on Monday, New Zealand Prime Minister Jacinda Ardern said there were 'a number of tourists' from her country and overseas on the island at the time.  

'I know there will be a huge amount of anxiety for those who have loved ones on or around the island at the time. I can assure them police are doing everything they can,' Ardern said.

Ardern and Civil Defence Minister Peeni Henare travelled to the nearby Whakatane on Monday night. 

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An estimated 50 tourists - from New Zealand and overseas - were on or around the crater, located off the coast of the North Island, at the time of the blast

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Prime Minister Scott Morrison confirmed 24 Australians were visiting the island as part of a cruise ship tour group on Monday

National Operation Commander Deputy Commissioner John Tims on Monday confirmed five people have died and multiple people were taken to hospital with burns, with the death toll expected to rise.   

'I can confirm there are five people now deceased from the eruption on White Island,' Mr Tims told reporters on Monday evening. 

'A number of other people have been taken to a hospital. A number of people have burns as a result of the eruption. It is still too early for police to confirm how many people are involved.'  

Authorities are yet to confirm the nationalities of the victims or if there are still survivors because they had been unable to establish communication with anyone on the island on Monday.

'There are possibilities of further eruptions. The physical environment is unsafe for us to return to the island. It is important that we consider the health and safety of those that are going to rescue those on the island. So we will be taking that advice,' Mr Tims said. 

White Island is New Zealand's most active volcano and had seen its last major eruption in 2001, with smaller events over the years until now.  

The island is frequently visited by tourists as part of organised boat tours from nearby Whakatane.

Geological hazard trackers GeoNet had registered moderate volcanic unrest on the island for weeks.

But the nature of volcano activity is unpredictable, with the eruption unforeseen by authorities.

A camera of the crater's rim, run by monitoring agency GeoNet, set to take pictures every 10 minutes showed a string of people visiting the crater at 2.10pm.

The next shot taken, at 2.20pm, was unreadable as the blast had rendered the camera inoperable.

By Charlie Moore for Daily Mail Australia

Tourists have been travelling to White Island for years despite warnings from scientists that it could erupt at any time.

Between 2011 and 2016 the volcano to the north of New Zealand's north island - which erupted on Monday - had a period of increased activity but still boatloads of tourists arrived.

Volcanologists at the time refused to step foot on the island because it was too dangerous and warned tourists not to go - but still the boats kept landing.

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An aerial view of the volcano, which is currently the most active in New Zealand and erupted in 2016 and 2012 before today

In recent weeks the volcano has been going through another period of activity but tourism was not stopped.

Last month monitoring outfit GNS Science raised the alert level for the volcano to level two because of increase activity.

'Volcanic unrest continues at Whakaari/White Island and some monitored parameters show further increases in activity,' the agency said.

'Hazards on the island are now greater than during the past few weeks.

'The patterns of signals are similar to those through the 2011 - 2016 period and suggest that Whakaari/White Island may be entering a period where eruptive activity is more likely than normal.'

New Zealand, struck by a deadly volcanic eruption Monday, lies in a zone where Earth's tectonic plates collide, making it a hotspot for earthquakes and volcanic activity.

In one of its worst natural disasters, a huge mass of volcanic debris from the eruption of Mount Ruapehu triggered a mudslide in 1953 that washed away a bridge and caused a passenger train to plunge into a river with the loss of 151 lives.

After Monday's eruption on New Zealand's White Island, here is a recap of some of the deadliest volcanic eruptions around the world in the past 25 years.

- 2018: Indonesia -

In December the Anak Krakatoa volcano, a small island in the Sunda Strait between Java and Sumatra, erupts and a section of its crater collapses, sliding into the ocean and generating a tsunami. More than 420 people are killed and 7,200 wounded.

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Anak Krakatoa, meaning 'Child of Krakatoa', erupted off the coast of Indonesia in 2018 - triggering an underwater landslide and 20ft tsunami that killed more than 420 people as it swept ashore

- 2018: Guatemala -

The June eruption of the Fuego volcano, about 35 kilometres (22 miles) from the capital, unleashes a torrent of mud and ash that wipes the village of San Miguel Los Lotes from the map. More than 200 people are killed.

- 2014: Japan -

The sudden eruption in September of Mount Ontake, in the central Nagano region, kills more than 60 people in Japan's worst volcanic disaster in nearly 90 years. The mountain is packed with hikers at the time. In 1991 an eruption of the southwestern Unzen volcano kills 43.

- 2014: Indonesia -

At least 16 people are killed on the island of Sumatra in February by a spectacular eruption of Mount Sinabung, which had lain dormant for 400 years before roaring back to life five months earlier. In 2016 villages are scorched and farmland devastated after another eruption kills seven.

- 2010: Indonesia -

Indonesia's most active volcano, Mount Merapi on Java island, starts a series of explosions in October, eventually killing more than 320 people. An 1930 eruption of the volcano killed 1,300 people and one in 1994 claimed more than 60 lives.

- 2002: DR Congo -

The eruption in July of Mount Nyiragongo in the eastern Democratic Republic of Congo destroys the centre of Goma town, along with several residential areas, and kills more than 100 people.

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The Roman city of Pompeii was wiped off the map when Mount Vesuvius erupted in 79AD, burying it under piles of hot ash

- 1997: Montserrat -

The capital of the small British colony, Plymouth, is wiped off the map and 20 are killed or left missing in avalanches of hot rock and ash clouds when the Montserrat volcano erupts in June.

- 1995: The Philippines -

At least 70 are killed and another 30 missing after the crater of the Parker volcano in the south of the island of Mindanao collapses. Five years earlier the eruption of Mount Pinatubo, 80 kilometres north of the capital Manila, kills more than 800 people.

- Worst ever -

The explosion of Indonesia's Krakatoa volcano in 1883 is considered the worst ever seen. The eruption sent a jet of ash, stones and smoke shooting more than 20 kilometres (12 miles) into the sky, plunging the region into darkness, and sparking a huge tsunami that was felt around the world. The disaster killed more than 36,000 people.

The most famous eruption in history is that of Mount Vesuvius in modern-day Italy in 79 AD, which destroyed the towns of Herculaneum, Stabiae and Pompeii, wiping out an estimated 10 percent of the population of the three cities.