A volcano off the New Zealand coast has erupted with a towering blast of ash and scalding steam as dozens of tourists were exploring the moon-like surface, killing five people and leaving eight missing feared dead, authorities said.

Helicopter crews landed on White Island despite the danger and helped rescue dozens of survivors, some of them critically injured.

Hours after the disaster, the site was still considered too dangerous for rescuers to search for the missing, but aircraft flew over the island and “no signs of life have been seen at any point”, prime minister Jacinda Ardern said.

The missing and injured included New Zealanders and tourists from the US, China, Australia, Britain and Malaysia, she said.

“My god,” Michael Schade tweeted as he posted video of the eruption. “My family and I had gotten off it 20 minutes before, were waiting at our boat about to leave when we saw it. Boat ride home tending to people our boat rescued was indescribable.”

His video showed a wall of ash and steam around White Island and a helicopter badly damaged and covered in ash. He said one woman was badly injured but seemed “strong” by the end.

The disaster raised questions of why people were allowed to visit the island 30 miles off mainland New Zealand after scientists had noted an increase in volcanic activity in recent weeks. White Island is the tip of an undersea volcano.

Authorities said 47 people were on the island at the time. In addition to the dead and missing, 31 survivors were admitted to hospital and three others were released, officials said. Some of the victims were reported severely burned.

The eruption took place about 2pm on Monday local time and consisted of two explosions in quick succession, Ms Ardern said.

It sent a plume of steam and ash an estimated 12,000ft into the air. One of the boats that returned from the island had half a yard of ash on it.

NZEALAND Volcano
(PA Graphics)

Some of the visitors were passengers from the Royal Caribbean cruise ship Ovation of the Seas.

“We will offer all possible assistance to our guests and local authorities. Please keep all those affected in your prayers,” the cruise line said.

The ship had left Sydney last week and had been scheduled to sail to the New Zealand capital of Wellington on Monday night, but Royal Caribbean said it would instead remain in port on neighbouring North Island until more was known about the situation.

The GeoNet agency, which monitors volcanoes and earthquakes in New Zealand, had raised the alert level on White Island on November 18 from 1 to 2 on a scale where 5 represents a major eruption, noting an increase in sulphur dioxide gas, which originates from magma deep in the volcano.

It also said that volcanic tremors had increased from weak to moderate strength.

Ms Ardern said the focus remained on the search-and-rescue mission for now and questions about whether tourists should be visiting would be addressed later.

Brad Scott, a volcanologist with research group GNS Science, said the alert level on White Island was often raised and then later dropped again without any eruption.

He said there had not been any major problems with tourists visiting the island in the past, although there had been some close calls.

White Island is New Zealand’s most active cone volcano. About 70% of the volcano lies under the sea.

Twelve people were killed on the island in 1914 when it was being mined for sulphur. Part of a crater wall collapsed and a landslide destroyed the miners’ village and the mine itself.