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
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.
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
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