Mt. Ruapehu is the largest composite stratovolcano in North Island, New Zealand. Currently at Alert level 3, the volcano is active, mainly small strombolian steam eruptions through the crater lake. In the past 50 years the main eruptive styles of the volcano have been Strombolian - spasmodic gas and steam escape with ejection of pyroclastic material, phreatomagmatic - mixing of hot pyroclastic material with external water and vulcanian - violent ejection of pyroclastic material with rising viscous magma. In 1945 occurred the only eruption ever ....