Ruapehu is the Māori word for ‘pit of noise’ or ‘exploding pit’.
For a one page fact sheet / poster on Ruapehu volcano click VolcanoFactSheets Ruapehu.pdf (547.52 kB)
It is the largest active volcano in New Zealand and is located at the southern end of the Taupo Volcanic Zone. Rising above the surrounding plains to 2797m, Ruapehu is the highest peak in the North Island, with several subsidiary peaks. There are several small glaciers around the summit slopes – the only glaciers at present in the North Island.
Three summit craters have been active in the last 10,000 years. The active vent is now beneath the crater lake of South Crater. The crater lake contains warm, acidic water that is fed by snow melt.
Ruapehu is a stratovolcano (composite cone volcano) made of successive layers of andesite lava and ash deposits. The mountain is surrounded by a ring plain of volcanic material from lahars, landslides and ash falls.
Tephra ranging in size from dust (ash fall) to bombs and blocks are produced in every eruption. Usually the crater lake causes magma to cool and fragment (explode) quickly and violently leading to fine ash eruptions. There are frequent lahars during eruptions or later due to collapse of the crater lake wall. A long predicted dam break lahar on18th March 2007 gave GNS scientists an opportunity to study this phenomenon in close detail.
Ruapehu began erupting at least 250,000 years ago, and there are believed to be a number of small inter-linked magma bodies between 1 and 5 km below the crater.
In recorded history major eruptions have been 50 years apart, in 1895, 1945 and 1995. Minor eruptions are frequent, with about 60 occurring since 1945.
GNS Science is monitoring Ruapehu with 2 web cameras, 10 seismographs, 6 microphones and 9 continuous GPS stations (to record ground deformation). There are regular water and gas monitoring visits to the crater lake as well as airborne gas surveys.
Have a look at our giant Gigapan panorama of Ruapehu’s Crater Lake here.