Volcanic activity

Volcanic activity threatens people and property. The Waikato region has multiple volcanic centres that vary in activity and risk.

The central North Island features many landforms that have been created over the last 1.6 million years through volcanic activity. Volcanic soils are important in supporting farming and forestry.

Volcanic activity has been responsible for many fatalities in New Zealand over the last 150 years. Over 100 people died when Mount Tarawera erupted in 1886, and 151 people were killed after a mudflow (‘lahar’) from Mt Ruapehu’s crater lake derailed a passenger train at Tangiwai in 1953. Taupo is a ‘supervolcano’, capable of producing devastating eruptions; however, these are extremely rare, with the most recent occurring 1800 years ago. It is important to monitor volcanic zones, and to prepare for and mitigate effects from future volcanic activity.

Most of New Zealand’s volcanic activity has taken place in the Taupo Volcanic Zone (TVZ), a long rectangular area from White Island to Ruapehu.

Active volcanos in the Waikato region include:

• Taupo Volcano
• Ruapehu
• Ngauruhoe
• Tongariro

Other volcanos such as Whakaari/White Island, Mt Taranaki, Mt Tarawera and Auckland Volcanic Field are close to our region and could also affect people and property in the Waikato.

For more information on these volcanoes, visit the GNS Science website.

Numerous types of hazards may result from a volcanic eruption, often simultaneously. They types of hazards that occur will depend on the volcano that is erupting and the nature of the eruption.

Volcanic hazards include ashfall, ballistics (flying rocks), lava flows, lahars (mudflows), pyroclastic flows (fast moving hot, dense ash clouds) and volcanic gases. Other potential hazards include landslides, tsunami, electrical storms and hydrothermal eruptions. For more information on these hazards, visit the GNS Science website.

As well as potentially threatening lives and property, any of these hazards may also damage our region’s:

• lifeline facilities, such as electricity supplies, rail networks and road access
• economy, affecting agriculture and tourist attractions, such as fishing and skiing
• air carrier network, if ‘no-fly’ zones are put in place.

Many volcanic hazards will only affect an area very close to the volcano. However, volcanic ash fall can be deposited hundreds to thousands of kilometres from its source, making it the product most likely to affect the largest area and the greatest number of people.

GeoNet (a collaboration between GNS Science and EQC) constantly monitors New Zealand’s volcanoes, sets Volcanic Alert Levels for each active volcano and issues Volcano Alert Bulletins when required. 

In New Zealand, a system of Volcanic Alert Levels is used to define the current status of each volcano. The alert levels range from 0 to 5 and are used to guide any appropriate response. For more information on these alert levels, visit the GeoNet website.

When monitoring the volcanoes, scientists look for changes in:

• the composition of the gases produced by the volcano
• the amount of gas being produced by the volcano
• water temperature
• ground water level
• topography (land features).

Changes in the above do not necessarily mean an eruption will happen. However, they are good indicators that something might happen.