How earthquakes affect buildings

The SEP shake table.

The shake table with three different lengths of straw and modelling clay blob

Some buildings may remain intact, while others nearby are severely damaged by the same earthquake. How does the structure of a building affect the way it behaves in an earthquake?

  1. Set up the shake table: the metal plate should be between the guide posts on the acrylic base; there should be apiece of felt between the metal plate and the base.
  2. Set the power supply to 6V DC. Check that when you switch on the power supply and adjust the knob on the control unit, it starts to push the vibration plate back and forth. Switch off.
  3. Press some modelling clay firmly onto the vibrating plate, then stick three straws into it: one should be about 15 cm (or more) long, another about two thirds this length and the last about half the length of the first straw.
  4. Make three small balls of modelling clay and stick them on the top of the straws.
  5. Turn the knob on the control unit down to its lowest value and switch on.
  6. Watch what happens to the straws as you slowly turn the knob to increase the frequency of vibration.
  7. Try this again with slightly larger balls of modelling clay: what difference does it make?
  8. What happens if you change the position of the clay 'blob' on a straw?

Teachers' notes

How earthquakes affect buildingsHow earthquakes affect buildings

Students use a shake table to investigate the effects of earthquakes on structures.