Up to 90 schoolchildren were on the mountain and two hours into a tramping trip; they are now safe and well. The group were near the Katetahi hot springs when they saw the eruption begin, about one kilometre away from them. They witnessed many tourists running from the eruption (video here: http://bit.ly/S9Xbt7). 30-50 people were evacuated from the Tongariro Crossing track; no injuries were reported and the crossing has now been closed. Scientists have been collecting ash from the eruption to be analysed at Massey University in order to ascertain potential human and animal health effects; results are expected in the next few days.
The eruption lasted about five minutes although earthquake activity continued locally for about 15 minutes. The alert level on Tongariro has been upgraded to level 2 by GNS (New Zealand’s Geological and Nuclear Sciences). Alert level 2 means there is minor eruptive activity. Geonet's Alert levels for volcanoes range from 0 (typical background surface activity) through to 5 (hazardous large volcanic eruption in progress). The aviation colour code was upgraded to red, meaning there was a significant emission of ash in the atmosphere. As of 5:30pm NZ time 21 November (4:30am UTC/GMT) the aviation colour code has been downgraded to orange, indicating a volcanic eruption is underway but there is little to no ash being produced.
The national airline, Air New Zealand, has cancelled all flights between Taupo and Wellington because of the volcanic activity. The ash is expected to be pushed in an easterly direction and away from the main route that airlines fly across the North Island, as there currently are light south-westerly winds in the region. The ash will most likely be ‘pushed’ towards State Highway 1. NZ’s Civil Defence has issued a national advisory saying regions from Waikato down to Hawke’s Bay could be affected by the ash cloud.
Mt Raupehu has also been active recently but has not yet erupted. GNS reported last week that there was pressure building under the volcano and there was an increased likelihood of a volcanic eruption. Recent temperature readings from the volcano indicate that an eruption may occur in the coming weeks. As a result, hikers have been requested to keep off the summit.
Scientists have been monitoring a snow melt lake in the crater and have discovered that while the lake is only 20°C, the temperature a few hundred meters beneath the lake is 800°C; this may suggest that volcanic vent is partially blocked and pressure may be building up. Ruapehu is New Zealand’s largest active volcano with historic major eruptions occurring every 20 to 50 years. There was a small eruption in 2007 which propelled a large rock onto the leg of a nearby hiker. The last large eruptions were in 1995 and 1996. Tongariro and Ruapehu are relatively close to each other but scientists report no evidence that the activity at both volcanoes was related.
In Maori legend, Ruapehu was a beautiful maid who was married to Taranaki (a volcano near New Plymouth in the North Island of NZ). Ruapehu was wooed away from her husband by Tongariro; Taranaki discovered the affair and fought Tongariro. Taranaki was defeated so retreated towards the west coast, but he now faces towards Ruapehu and Tongariro, watching them silently. Ruapehu still loves her husband and sighs occasionally when she recalls memories of him; Taranaki’s mist which drifts easterly is the visible sign of his lingering love for her. Tongariro is angered by this activity and often smokes and smoulders in a jealous rage.
If the region looks familiar, Ruapehu and nearby Mount Ngauruhoe 'starred' as Mount Doom in “Lord of the Rings”.
View a timelapse of the most recent Tongariro eruption here (there’s a short ad first):http://www.3news.co.nz/
To see a timelapse of Tongariro National Park during a calmer period: http://www.youtube.com/
Te Maari crater camera: http://www.geonet.org.nz/
Photo: LOMI SCHAUMKEL/Tamatea Intermediate School