Tongariro National Park is an active volcanic area. Eruptions from any of the three volcanoes can happen at any time without warning.
If you are hiking or climbing within the active volcanic hazard zones when an eruption happens, you could be in danger from eruption hazards.
In an eruption you could be in danger of:
- Flying rocks
- Fast moving burning clouds
- Lahars (flash floods)
- Falling ash
- Volcanic gases
If you are not comfortable with the risk, turn back before you enter the Volcanic Hazard Zones (the area around the active vents on Mount Tongariro, Ngauruhoe and Ruapehu).
You enter the active zones at your own risk - move quickly through. Are you prepared to take the risk?
What to do if there is an eruption
- Stop, watch for burning ash clouds and flying rocks.
- Run away from the path of fast moving burning clouds.
- Otherwise find shelter behind something - banks, ridges or in hollows.
- Shelter from flying rocks and cover your head with your pack.
- Move out of the bottom of a valley if a lahar is possible.
- Evacuate out of the Hazard Zone and away from the eruption site keeping on ridges if possible.
There are several systems within and around Tongariro National Park that are designed to monitor potential volcanic activity and help provide warnings of volcanic hazards. They help manage and reduce potential volcanic risk, however visitors must not expect that these risk mitigation systems will ensure their personal safety. Some eruptions cannot be predicted and facilities may not be able to be closed in time. Visitor safety cannot be guaranteed.
Volcanic Hazard Zones
Mount Tongariro and Mount Ngauruhoe
Mount Tongariro has two active volcanic vents - Te Maari Crater and Red Crater. Mount Ngauruhoe is an active volcanic vent. There are Volcanic Hazard Zones around all these vents.
Te Maari has an Active Volcanic Hazard Zone within a 3 km radius of the upper craters.
Tongariro Alpine Crossing and Tongariro Northern Circuit
Te Maari Active Volcanic Hazard Zone escape routes and rāhui(PDF, 105K)
Both tracks pass through these Volcanic Hazard Zones. Even when these tracks are open, volcanic risk exists.
Avoiding the Volcanic Hazard Zone
If you wish to walk on Mount Tongariro but avoid the active Volcanic Hazard Zone around Te Maari, these are the points where you should turn back:
- If walking from Mangatepopo, either at the top of Red Crater or at Emerald Lakes
- If walking from Ketetahi, where the track emerges from the forest
Electronic signs on the Tongariro Alpine Crossing
Electronic warning signs will be installed if volcanic risk increases. There are two sets of electronic signs:
- Each side of the Te Maari Active Volcanic Hazard Zone and on the shoulder of the Red Crater. These signs have one red light. If the light is flashing, the track is closed beyond them because of increased volcanic risk. Turn around and go back the way you came.
- Mangatepopo and Ketetahi parking areas. These signs have three lights: red, yellow and green.
- Red flashing means track closed - volcanic risk too high for track to be open
- Yellow means elevated risk - volcanic risk higher than normal but track still open
- Green flashing means track open - volcanic risk normal but not zero
When installed, the Mangatepopo car park light operates between 5 am - 5 pm, while the Ketetahi car park light operates between 6 am - 8 pm. The Active Volcanic Hazard Zone and Red Crater lights operate between 7 am - 6 pm. The lights are changed when seismicity, gas emissions or other monitored parameters indicate volcanic unrest has changed.
The Summit Hazard Zone is the area within a 2 km radius around the Crater Lake, which fills the volcanic vent.
The main volcanic risk on Ruapehu is lahar, or fast volcanic mud flows. In the event of an eruption, the water in Crater Lake is ejected, then mixes with ash/snow/rock and flows very fast down mountain valleys in a flash flood. The Eruption Detection System or EDS provides warning of eruption lahars though Whakapapa ski area and is one of the most important volcanic risk management systems.
If the EDS alarm sounds what should you do?
- Move out of the valleys, especially those that lahars are likely to follow.
- If the sirens sound, climb the valley walls to a ridge top.
- Know where the safe areas are (such as buildings, lift lines and ridge tops).
- Stay in a safe area until advised otherwise by area staff. If in a ski lodge or car park, stay put.
- Ask ski area or DOC staff for more information.
- If you are in the Summit Hazard Zone move down the mountain following ridge lines.
Maps of lahar paths
Video about lahars, volcanic hazards and alarms
Mount Ruapehu last erupted in 2007
Mount Ngauruhoe's last major eruption was in 1975, and there was a small eruption in 1977
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