When White Island volcano unexpectedly erupted in New Zealand

A webcam set up on New Zealand's White Island volcano shows at least one group of tourists were inside the crater moments before it erupted and blanketed the area in a massive ash cloud.

A crater rim camera owned and operated by New Zealand geological hazards agency GeoNet shows groups of people walking near the rim inside the crater, where white smoke constantly billows at a low level, in the hour leading up to the eruption at 2:11 pm.

Tourist Michael Schade stood at the crater of New Zealand's White Island volcano minutes before it erupted on Monday and shared his terrifying experience in a series of messages and videos posted on social media. "My God, White Island volcano in New Zealand erupted today for first time since 2001. My family and I had gotten off it 20 minutes before, were waiting at our boat about to leave when we saw it," he tweeted.

The White Island volcano's last fatal eruption was in 1914, when it killed 12 sulphur miners. There was a short-lived eruption in April 2016. White Island became a private scenic reserve in 1953, and daily tours allow more than 10,000 people to visit the volcano every year.

There seemed to be no danger for people in coastal areas farther away, authorities said. The eruption was unexpected, but not unusual, an expert said. "Sudden, unheralded eruptions from volcanoes such as White Island can be expected at any time," Shane Cronin, a volcanologist at University of Auckland, said in comments published by the Australia Science Media Centre.

"We know hydrothermal and so-called 'phreatic' eruptions can occur suddenly and with little or no warning because they are driven by the expansion of super-heated water into steam," he added. Geological hazard tracker GeoNet raised the alert level for the White Island volcano in November due to an increase in volcanic activity.

The White Island volcano is one of New Zealand's most active. 'Whakaari', as it is known in Maori, is New Zealand’s most active cone volcano, built up by continuous volcanic activity over the past 150,000 years, according to geological hazard tracking agency GeoNet.