How to Make a Model of Liquefaction

When liquefaction occurs during an earthquake, the normal solidity of the ground turns brittle and almost liquid-like, losing integrity for anything built on top of it. For example, during the Loma Prieta earthquake in 1989 liquefaction caused a significant number of structure failures in buildings in the San Francisco Marina District due to the landfill area of the ground. Thus, for explaining the effects of earthquakes on structures, models of liquefaction can provide significant benefits and education.

Big rectangular lid from a game box
Sand
Marbles
Cardboard
Building blocks
Butter
Wood blocks
Cookie dough
Candy-coated chocolate pieces

Instructions

- 1
  Take the lid of a game box and turn it upside-down. Fill the lid with sand so that it’s about 1/2-inch thick as a layer.
- 2
  Place box on a number of marbles on the table. Use a piece of cardboard to level the sand out again if it moved around and became uneven.
- 3
  Place building blocks in the sand so that you begin to construct a basic structure. Layer a bit of butter or margarine between the blocks to provide a basic mortar between the blocks – you can wash it off later. Build the structure upward a few layers until it forms a bit of a tower.
- 4
  Gently begin to move the box on the marbles forward and backward. Start slowly at first, barely moving the box. Begin to increase the effect. Takes notes with pen and paper on how much effort is taken before the structure begins to collapse. Note how the sand shifts due to the movement of the box.
- 5
  Repeat the exercise using different materials than sand as the base of the structure. Try the exercise with wood blocks, cookie dough that is flattened out, and candy-coated chocolate pieces. Each time, note the effect of the material and how fast the building block structure collapses based on how hard you shake the box on the marbles.

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