Hydrothermal activity

Thermal activity in close proximity to homes in Rotorua. Photo attribution at bottom of page.

Most of New Zealand’s hydrothermal activity occurs in the Taupo Volcanic Zone, an area that extends from White Island to Mt. Ruapehu.

Here – and in other regions with hydrothermal activity – there is risk to property and people from hazards such as hydrothermal eruptions, ground subsidence and hydrogen sulphide gas emissions.

  • Hydrogen sulphide gas can build up to lethal levels in poorly ventilated spaces such as closed sheds and garages.
  • As well as natural causes of ground instability, there is risk from disused soak holes and geothermal bores that were not made safe before being abandoned and forgotten. 
  • The risk of hydrothermal eruptions increases following an earthquake.

Being prepared for a hydrothermal event

  1. Check with your local council to see whether your home is at risk of hydrothermal activity.
  2. Prepare an emergency plan and kit.
  3. Keep a look out around your property for warning signs of hydrothermal activity, such as:
  • grass dying
  • hard surfaces, such as paths and driveways, becoming unusually warm
  • cracks appearing in hard surfaces
  • holes, steam or hot water appearing. 

During a hydrothermal event

  1. Evacuate your property quickly. 
  2. Grab your emergency kit on your way out the door.
  3. Warn your neighbours.
  4. Notify your local council.

After the event

Only return to your property when the authorities tell you it's safe to do so.


  • Waikato Regional Council: The Waikato region contains almost 80 percent of New Zealand’s geothermal areas. Find out more about natural hazards caused by geothermal activity in the Waikato region, what the council is doing, and what you can do.
  • Te Ara describes New Zealand's hydrothermal areas, tells the stories of people living in hydrothermal areas, and outlines the human impact of these fragile environments. 


  • The Volcanic Activity Centre at Wairakei, near Taupo, provides a visitor experience that includes simulators, interactive displays, scientific instruments and video.  (EQC is a long-term sponsor of the centre.)

  • Te Papa's Awesome Forces exhibition shows how plate tectonics, earthquakes, volcanic eruptions and erosion have shaped our landscape – and the lives of the people who live here. (EQC has sponsored Awesome Forces since 2008.)

Learn more about EQC's public education programme.


The Waimangu geyser appeared suddenly in 1900 (Te Ara website). Water shot up to a height of 150 metres. Three people died in a sudden eruption in 1903, and the geyser stopped the following year.

More recently, a hydrothermal eruption shot steam and ash into the air in Reporoa in 2005 (Te Ara website). It left a 50 metre wide crater.


Photo attribution: 'Thermal activity in close proximity to homes in Rotorua'. Photo by, 'Jinny'. http://www.flickr.com/photos/jinnpod/

This photograph is used under a Creative Commons Attribution-Noncommercial license: http://creativecommons.org/licenses/by-nc/3.0/.

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