VOLCANIC ERUPTION

New Zealand is situated on the Ring of Fire, a geographic belt encircling the Pacific Ocean. This ring contains about 90% of the Earth’s volcanoes.
There are six active volcanic regions in New Zealand. Five are in the North Island and one is in the northern offshore islands.

 

Ngauruhoe eruption.

Volcanoes come in different shapes and sizes. There are three main types found in New Zealand:

  • cone volcanoes, such as Mounts Ruapehu, Taranaki and Ngauruhoe
  • volcanic fields, such as the ones found in the Auckland Volcanic Field which has about 50 volcanoes.
  • calderas, large craters formed by huge explosions. Lakes Taupō and Rotorua are calderas.

Volcanoes erupt when pressure builds up inside the Earth and forces molten rock (magma) towards the surface. New Zealand volcanoes have different levels of activity. White Island is busy all of the time, while some volcanoes can have hundreds, or or even thousands of years between eruptions.

The type of eruption depends on the amount of gases in the magma (which determines the explosiveness) and the silica content (which determines the runniness). Some eruptions are explosive, blowing out great volumes of rocks and molten material. Other volcanoes erupt in flows, pouring out clouds of hot gas mixed with streams of liquid lava.

People living in volcanic regions are at risk from ash, debris and lava flows. For instance, the eruption of Mount Tarawera in 1886 killed around 106 people. When there is a crater lake or torrential rain, water can mix with volcanic debris to form a swiftly-moving avalanche of mud called a lahar. A lahar swept off Mount Ruapehu in 1953 and caused the deaths of 151 people in the Tangiwai railway disaster.

It is important to know what to do before, during and after a volcanic eruption. The most frequent volcanic hazard is ash. It can travel a long way, depending on the wind, and can cause health problems for people and animals and damage buildings and cars. A lot of ash can be very heavy.

What do we do before a volcanic eruption?

  • Know where active volcanoes are and whether they are likely to affect you.

  • Have an evacuation plan – where to go and how to get there.

  • Store water as water supplies may become polluted. Keep your empty water, juice and fizzy drink bottles, give them a good clean and fill them with water – you need three litres of water for each person for at least three days. Don’t forget to store water for babies and pets too.

     

What do we do during a volcanic eruption?

  • Close all doors and windows and stay indoors.

  • If you are outside near an eruption, shelter in a car or building.

  • If you are outside in volcanic ashfall, wear a dust mask or cover your mouth and nose with a cloth.

  • Listen to the radio, follow the instructions of emergency services and keep out of restricted areas.

What do we do after a volcanic eruption?

  • If in a safe place – stay put.

  • Listen to the radio for information.

  • Return home only when told.

Home learning

PaulHave you seen the GeoNet volcano cameras?
Ask an adult to help you to download an image and then share it with your class.

Make a plan with your family to get through an emergency. Think about the things you need every day and work out what you would do if you didn't have them. 

Make your plan  – print it out, stick it on the fridge and make sure everyone knows the plan. 

DIGITAL RESOURCES

Learnz field trips