Geothermal activity

The Waikato region contains about 70% of New Zealand's geothermal systems. Geothermal areas contain natural hazards such as hot springs, boiling mud pools and unstable ground, and can produce hydrothermal eruptions. Geothermal areas are also valuable as tourist attractions, energy sources and unique habitats.

Geothermal systems are places where the earth is hotter than surrounding areas, due to hot rock or magma near the earth's surface. Most of New Zealand's geothermal systems are hydrothermal systems, which means ground water from the surrounding area is heated by hot rocks and rises to the surface.

For more information about geothermal systems in the Waikato, visit our Geothermal resources page.

Geothermal hazards include:

• Scalding hot water and boiling mud
• Geyser eruptions
• Hydrothermal eruptions
• Acidic water
• Steam, and other gases which can be toxic
• Geothermally altered unstable ground (more prone to landslides, e.g. Hipaua Geothermal Area)
• Subsidence

Natural hydrothermal eruptions nearly always occur without warning. They happen when superheated water trapped below the surface of the earth rapidly converts from liquid to steam (often caused by earthquake or volcanic activity), violently disrupting the confining rock. Boiling water, steam, mud, and rock fragments are ejected into the air, but are generally limited to a few hundred metres from the vent. They are a significant risk to life for anyone in the vicinity.