We live in a very exciting country. A day’s drive in a car can take us from snowy mountains, past geysers and hot mud pools to white, sandy Pacific beaches. Have you ever wondered why New Zealand has so many different types of landscapes? Our extremes are due to where our country sits. The good news is that we get to enjoy rugged mountains for skiing and tramping and thermal spots for warm swims. The not so good news is that we also get shaky ground in the form of earthquakes and, less often, volcanic eruptions.

New Zealand sits on the edges of two tectonic plates – the Australian and the Pacific plates. The plates slowly move and push against each other. This has created our mountains and our many extinct and active volcanoes. The plates are also responsible for the thousands of earthquakes we have every year.

What is an earthquake?

Very simply, an earthquake is a release of energy. If you brace your shoulder against someone else’s shoulder and push, the energy is stored up until one of you is pushed aside. The same thing happens with the tectonic plates. They push or scrape against each other until something has to give – and boom! The energy is released. The energy spreads outward in waves, which shake the Earth. The ground starts to shake once the waves reach the Earth’s surface. New Zealand records 14,000–15,000 earthquakes every year. Around 100 to 150 are big enough for us to feel.

What is a volcano?

We usually think of volcanoes as cones with smoke coming from the top – and it’s true for some volcanoes like Mt Ruapehu. But scientists say a volcano is an opening in the Earth’s crust in which lava, steam, gases or ash is ejected. Some volcanoes are actually deep craters called calderas. New Zealand has had some amazing volcanic eruptions in its history, but most of our volcanoes are dormant (asleep) or extinct. White Island is our most continually active volcano. It’s been active for 150,000 years! Fortunately, it mostly releases gases and steam.

Are volcanoes and earthquakes related?

Volcanoes and earthquakes are often found in the same place, but are they related? Does one trigger the other? In New Zealand, volcanoes and earthquakes are related in that they are both caused by the tectonic plates our country sits on. Sometimes the pressure of magma forcing its way through to the Earth’s surface will trigger earthquake activity. For example, when Tarawera erupted in 1886, more than 30 earthquakes were felt in the Rotorua region just before the eruption.

Monitoring earthquakes and volcanoes

GNS Science is the Crown research institute responsible for monitoring earthquakes and volcanoes. Their GeoNet Project uses special equipment to observe and monitor the land. GNS scientists gather this information to learn about our shaky country so they can warn us and try and reduce the risk of harm.

Nature of Science

Scientists gather data and try to predict the risk and size of earthquakes or volcanic eruptions, but it is impossible to predict the exact timing of any natural event.

Useful links

GeoNet is New Zealand’s official source of earthquakes and volcanic alerts. It lists recent earthquakes and information about their intensity and location.
geonet.org.nz/quakes/

    Published 18 August 2014