Earthquakes - Local navigation

User tools

Key Terms

This resource provides explanations of the key concepts encountered when exploring Earthquakes – the ‘basics’ that every student should understand.

Page links to Key Term definitions

  1. Australian plate
  2. Building standards
  3. Earth structure
  4. Convection currents
  5. Earthquake
  6. Faults
  7. Fluid
  8. Geophysics
  9. Lithosphere
  10. Locking interface
  11. Pacific plate
  12. Richter scale
  13. Seismic waves
  14. Seismograph
  15. Subduction zone
  16. Tectonic plate

List of Key Term definitions

  1. Australian plate key term.

    1. Australian plate

    The main land masses on this plate are Australia and India, so the plate is also called the Indo-Australian plate. Movement of this plate has caused earthquakes and volcanoes across regions from Indonesia to New Guinea and the Pacific, and it has created the Himalayan Mountains.

  2. Building standards key term.

    2. Building standards

    In New Zealand, buildings have to be constructed to a certain legal standard. Part of the aim is to keep damage low in an earthquake, and to help keep people safe inside affected buildings.

  3. Earth structure key term.

    3. Earth structure

    The Earth has four main layers:
    • Inner core – solid, mostly iron
    • Outer core – liquid, mostly iron
    • Mantle – viscous rock (solid, but can flow)
    • Crust – solid, rigid rock

  4. Convection currents key term.

    4. Convection currents

    These are currents that occur in heated fluids, including the Earth’s mantle. Hot areas of mantle are less dense and rise up. As the hot areas meet the lithosphere, they transfer heat energy to it, cool and sink back down. There is also horizontal movement, which drags tectonic plates with it.

  5. Earthquake key term.

    5. Earthquake

    An earthquake occurs when a fault suddenly gives way and creates a break-point in the rock under the Earth’s surface. This generates seismic waves that, if strong enough, cause damage from shaking when they reach the surface. The closer the break-point is to the surface and the greater the energy, the more destructive the earthquake.

  6. Faults key term.

    6. Faults

    These are areas of crust (much smaller than a tectonic plate) that are moving in relation to each other. Because rock doesn’t move easily, strain can build up in these areas, and in an earthquake, the rock suddenly gives way at weak points. A fault trace is what we see of the surface features of a fault. Often this can be a ridge or a rift (a gap where the ground has pulled apart). 

  7. Fluid key term.

    7. Fluid

    A substance that can flow like a liquid or gas. The fluid part of the earth's mantle is solid but, as it can flow, we call it “plastic”.

  8. Geophysics key term.

    8. Geophysics

    The part of Earth science that deals with the structure and evolution of the Earth. This includes earthquakes, volcanoes and Earth’s gravitational and magnetic fields.

  9. Lithosphere key term.

    9. Lithosphere

    The rigid rocky outer layer of the Earth, composed of the crust and the upper part of the mantle.

  10. Locking interface key term.

    10. Locking interface

    Where one tectonic plate is driven down beneath another one, they are not free to pass each other smoothly. In some places, they grate slowly and steadily past each other, but often they lock together to some extent. The area of the plates that touch and lock is called the locking interface.

  11. Pacific plate key term.

    11. Pacific plate

    The features related to this plate include most of the Pacific Ocean, but no major landmasses. Earthquakes and volcanoes are associated with regions on the edge of the Pacific plate, like Japan, the West Coast of North America and New Zealand.

  12. Richter scale key term.

    12. Richter scale

    This is a scale used to show the strength of the seismic waves in an earthquake. In the Richter scale, an increase of one in earthquake magnitude (e.g. from magnitude 6 to magnitude 7) represents 30 times increase in energy released.

  13. Seismic waves key term.

    13. Seismic waves

    These are vibrations from earthquakes that travel through the Earth. Different types of seismic waves include P-waves and S-waves, which can sometimes be felt before the main earthquake. The waves that cause the damage in earthquakes are called surface waves and have both up and down and side to side movement.

  14. Seismograph key term.

    14. Seismograph

    An instrument that detects and records earthquakes. A seismometer generates an electrical current when the ground shakes. This is digitised by a seismograph and transmitted to a computer. Older types record directly onto paper.

  15. Subduction zone key term.

    15. Subduction zone

    At a plate boundary where one tectonic plate is moving towards another, one plate can sink below the other, where it is eventually recycled into the mantle. This is called subduction. Along the east of the North Island, the Pacific Plate is subducting (sinking under) the Australian Plate, but along the southwest of the South Island the Australian Plate is subducting the Pacific Plate.

  16. Tectonic plate key term.

    16. Tectonic plate

    This is a piece of the Earth’s lithosphere that moves on top of the fluid part of the mantle. There are seven main plates and a number of smaller ones.

Science Learning Hub Survey 2014

Dear Hub visitor,

You're invited to participate in an online survey about the New Zealand Science Learning Hub. This survey was designed to help Hub staff enhance and develop further the site. This is different from our November 2013 survey, so even if you took part in that survey, we would appreciate you taking this survey as well.

Take the survey