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Ever Wondered? Episode 4

The titans of Mother Nature - earthquakes, tsunamis and volcanoes

In Episode 4 of Ever Wondered?, Dr John Watt visits various parts of New Zealand to investigate the way the forces of Mother Nature can affect us and how researchers are working to understand them.


At Te Papa's Awesome Forces exhibition, John meets geologist Dr Hamish Campbell who points out that New Zealand straddles the boundary between 2 tectonic plates (the Pacific and Australian) and that Wellington is subjected to collision, compression and subduction because of this. Scientists know that Wellington generally feels the effects of plate activity about every 200 years or so and that we are about 40 years overdue for more!

John discusses the devastating 1931 Napier earthquake, and Dr Campbell explains that scientists still can't determine where and when a serious earthquake will strike.

At Victoria University, Dr John Townsend is researching slow slips, which are areas of land moving so slowly that the movement doesn't show up on seismometers. The slips are tracked using satellites to pinpoint GPS systems located in areas of interest throughout New Zealand. Slow slips are important as they may provide evidence as to where the next earthquake may occur.


Still in Wellington but now at GNS, John visits Dr Graham Leonard whose research field is tsunamis. He uses a model to demonstrate the effect a possible tsunami could have on the coastline. The largest tsunami in the world could be generated just 100km off the east coast of Wellington. John learns that the reason for this is the subduction zone between the 2 tectonic plates presently 'locked' in position. If there is a sudden release, the massive forces that result could cause a huge tsunami. Computer graphics show that, by the time this wave hits Wellington's east coast, it could reach a height of 35 metres. This is half the height of the Beehive! A tsunami's speed after an earthquake means that there will be little time for warning residents.


Subduction zones are not just associated with tsunamis and earthquakes but create the magma 'feeding' volcanoes. New Zealand has an active volcanic zone running from White Island in the Bay of Plenty to Mt Ruapehu. Below our largest city, geologists have located an 'intra-plate hot spot', which is a very active volcanic area.

Dr Jan Lindsay, a geologist at the University of Auckland, explains to John that there are about 50 volcanoes in the Auckland area making up the Auckland Volcanic Field. These volcanoes differ from those further down the North Island as they are possibly more volatile. John watches computer graphics showing that, in the Auckland field, magma rises straight through the crust, giving little warning of eruption. In the central region, however, magma rises from magma chambers inside the volcanoes. Although not all Auckland volcanoes are active, Dr Lindsay explains that the area under them is seismically active. She shows John the results of the mapping she has done on past eruptions using sediment cores. This knowledge will help scientists understand future eruptions.

Another tool in the quest to understand and monitor seismic activity is the use of seismometers in boreholes. John visits a hallowed shrine of New Zealand rugby - Eden Park - with Dr Liam Wotherspoon to view a particularly deep borehole. The seismometer located in this borehole gives accurate readings of earth movements, possibly leading to an early warning of eruption danger.

In his mission to understand nature's most violent forces, John then visits Dr Tom Wilson in the Engineering Department at the University of Canterbury. Here, he learns first-hand about the hazards of volcanic ash particularly in relation to electricity transmission that is so vital to community life.

Activity idea

In conjunction with this episode of Ever Wondered?, your students may enjoy these activities.

In this activity, students use maps to plot a graph of earthquakes under New Zealand to show the shape of the North Island subduction zone and compare this to the distribution of earthquakes in the South Island.
In this activity, students make and/or observe two 3D moving models of the different tectonic plate boundaries under the North and South Islands representing the North Island subduction zone and the South Island Alpine Fault.
In this activity, students use data on historical earthquakes to identify when and where they occurred and make predictions about future earthquakes. Do their findings back up Dr Hamish Campbell's assertion that scientists still can't determine where and when a serious earthquake will strike?

In this activity, students investigate the causes of slow slips and read and plot data on slow slips.
In this computer-based activity, students work in pairs or threes to find New Zealand volcanoes using a map and Google Earth.

In this activity, students select items to include in a home disaster kit in case of emergency and calculate how much food and water they will need to include in a disaster kit for their family.

Context links

To further investigate earthquakes, tsunamis and volcanoes, check out these Science Learning Hub contexts.

Earthquakes: In this context, you will find research articles, science ideas and concepts and interviews with scientists and engineers about the fault lines, seismic engineering, plate tectonics, seismic waves and slow slips.

Volcanoes: This context provides material on types of volcanoes and volcanic rock, plate tectonics and volcanoes, as well as interviews with geologists and volcanologists.

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