Travel Reference
In-Depth Information
Environment
Geologically speaking, the Tongariro volcanoes are relatively young. Both Ruapehu and
Tongariro are less than 300,000 years old. They were shaped by a mixture of eruptions and
glacial action, especially in the last ice age. At one time, glaciers extended down Ruapehu to
below 1300m, leaving polished rock far below their present snouts.
Ngauruhoe is even younger. Its first eruptions are thought to have occurred 2500 years
ago. Until 1975 Ngauruhoe had erupted at least every nine years, including a 1954 eruption
that lasted 11 months and disgorged six million cubic metres of lava.
Ruapehu is one of the world's most active volcanoes. One eruption began in March 1945
and continued for almost a year, spreading lava over Crater Lake and sending huge dark
clouds of ash as far away as Wellington. Ruapehu rumbled again in 1969 and 1973, but its
worst disaster was on Christmas Eve 1953, when a crater lake lip collapsed. An enormous
lahar (mudflow) swept down the mountainside, taking everything in its path, including a
railway bridge. Moments later a crowded train plunged into the river, killing 151 people; it
was one of NZ's worst tragedies.
Ruapehu hasn't let up, with significant eruptions occurring with suspicious frequency. In
2007 a primary school teacher had a lucky shave when a rock was propelled through the
roof of Dome Shelter. He survived, but his leg was crushed.
Ongoing rumbles are reminders that these volcanoes are very much in the land of the liv-
ing. The last major event was in 2012 when Mt Tongariro gave a couple of good blasts from
its northern craters, causing a nine-month partial closure of the famous Alpine Crossing
track.
To see video of recent eruptions, visit
www.doc.govt.nz/eruption.
