Recent major eruptions occurred in 1895, 1945, 1995, 1996 and 2006. The Taumarunui Borough found for a short period after this eruption that the pH of their water supply dropped to 5.6 pH and turbidity was high. Mount Ruapehu is one of the world's most active volcanoes. Mt Ruapehu ash cloud, eruption 1996.

On Christmas eve 1953 a lahar (or mudflow) caused by the eruption of Ruapehu destroyed the Tangiwai railway bridge. ... Output Side of the Mt Ruapehu Eruption . work was the 1953 event which caused the Tangiwai disaster. Estimates of Mt Ruapehu (North Island, New Zealand):increasing crater lake temperature ... An eruption on 24th December 1953 caused a catastrophic lahar that destroyed a rail bridge 42 km from the volcano, just as the Wellington-Auckland passenger train was crossing and fell into the valley, causing 151 fatalities. An eruption of Ruapehu volcano on 22nd June 1969 was the largest at the volcano since 1945. Ruapehu is an active volcano with an extensive history of eruptive activity spanning at least the last 250,000 years. Mt Ruapehu (2797m) is the North Island's highest mountain and one of the world’s most active volcanoes. Ice cave on Ruapehu - Tangiwai disaster A volcanologist’s photograph of the ice cave that melted on Mt Ruapehu, resulting in the lahar that caused the Tangiwai disaster. Earlier, on Christmas Eve 1953, 151 people […] Effects of the 1995-1996 Ruapehu eruptions on communities in central North Island, New Zealand, and people's perceptions of volcanic hazards after the event.
World volcano Profiles > New Zealand>Ruapehu Mt.Ruapehu volcano lies within Tongariro National Park, a world heritage site,along with two other large volcanoes Mount Ngauruhoe and Mount Tongariro. The aim was to prevent a repeat of the 1953 Tangiwai tragedy, where 151 people died after a lahar undermined a railway bridge. Mt. During the 1995-96-eruption sequence of Ruapehu, volcanic ash was dispersed over a wide area of the North Island.

A devastating lahar in 1953 killed more than 150 people, who died when a passenger train plunged into a ravine when a railroad bridge was taken out by the lahar. The need for the monitoring was shown when the anticipated lahar occurred in March of 2007. The most recent eruption began in January 1995 with the first significant eruption occurring on 29 June. 1953 – Ruapehu Alpine Lifts Ltd is established. Scientists estimate that Ruapehu has experienced 60 lahars in the last 150 years. The 25th of September of the same year saw an eruption occur on Mount Ruapehu.