Twenty-two people died but only twenty bodies were recovered. Australian teenager Winona Langford and New Zealand guide
Hayden Marshall-Inman - are still missing despite repeated ground and sea searches. Their bodies are believed to be in the water.
A pyroclastic flow is part of a volcanic eruption. Consisting mainly of small particles and gasses it can reach speeds of 200m/s and temperatures of 1,000 °C.
The volcano has been closed to any visitors since the tragedy.
Historically, the volcano has erupted every 3 years. This means it's due an eruption around late 2022.
The initial Westpac Rescue helicopter responding and backdrop city skyline is of Sydney, Australia instead of Auckland, NZ.