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Make a volcanic crater!

About the demonstration

This hands-on demonstration illustrates how volcanic craters and calderas form and how they can be measured using GPS. You’ll be able to see how fractures and cracks form with an eruption even happening!

As a volcano inflates and deflates, the rocks at the summit weaken and crack forming a crater or a caldera. The difference between a volcanic caldera and a volcanic crater, is that calderas are really wide, often more than a mile in diameter. The Yellowstone caldera is approximately is 50 miles (80 km) long and 40 miles (65 km) wide!

Points to remember:

  • The demonstration illustrates that fractures develop over time and calderas can form without an eruption
  • Flour fractures and collapses in a similar pattern to rock
  • Most volcanoes have one source of magma, similar to this model
  • Flour is not rock. Rock is much stronger.
  • Magma chambers aren’t really like empty balloons. As magma moves through a magma chamber, it melts the rock, pushes rock out of way, and squeezes into rock cracks. Some of the magma might escape as lava.
  • Magma is very hot, hot enough to melt rock. This demonstration is at room temperature.

More ideas!

  • Use flour or spackling compound to illustrate other faults and fractures. The model below illustrates regions undergoing extension, creating basin and rangers, such as Nevada and western Utah.
  • To emphasize overall deformation (instead of fracturing and caldera formation), use sand. This works well in an augmented reality sandbox!

Demonstration Length:

5 – 20 minutes to demonstrate
30 minutes to construct

Major concepts

  • Volcanic craters and calderas can form by the collapse of the rock near the summit without an eruption.
  • Volcanoes inflate (pressurize) and deflate (depressurize) - without necessarily erupting
  • We can understand what’s going on inside a volcano by measuring changes at the surface, even a few millimeters of movement, using GPS.
  • Most craters form slowly over time as the volcano inflates and deflates, deforming and weakening the rocks near the summit.
  • The volcano's magma chamber is made up of sponge-like rock

Supplies

  • A box, approximately 8” x 8” x 6” (shoe boxes work well or small storage box)
  • 5 - 10 lbs Flour (2 bags of flour works well)
  • Red balloon - small
  • Balloon pump (opt, and worth it)
  • 2 feet of flexible tubing (¼-inch diameter)
  • Duct/ clear tape
  • Gum drops and toothpicks (to make GPS models)

Assembly

  1. Tape balloon onto tubing and tape tubing firmly to the bottom of container - off center
  2. Attach the other end of the tubing to balloon pump (cut small hole in tubing at the pump to let out air)
  3. Cover balloon with 3-5 inches of flour
  4. For an added touch, make GPS monuments out of toothpicks and gumdrops and place on either side of balloon to measure the inflation and deflation of the volcano.

Leading the demonstration

  1. Invite visitors to place GPS instruments on flour to measure the inflation and deflation of the volcano
  2. Pump air slowly to inflate the balloon to form radial and ring fractures. Invite visitors to comment on their observations
  3. Let some air after a few pumps out to form a small caldera. Repeat.
  4. While visitors observe; allow the balloon to deflate quickly
  5. Optional: Have visitors measure the distance between the GPS models at various stages while inflating the volcano

Sample questions to consider

  • What is the first sign the volcano is changing?
  • What patterns do you see in the cracks?
  • Did the GPS instruments change their position?
  • How did the GPS instruments move (farther apart, closer together, up, down?)
    • About the demonstration

      This hands-on demonstration illustrates how volcanic craters and calderas form and how they can be measured using GPS. You’ll be able to see how fractures and cracks form with an eruption even happening!

      As a volcano inflates and deflates, the rocks at the summit weaken and crack forming a crater or a caldera. The difference between a volcanic caldera and a volcanic crater, is that calderas are really wide, often more than a mile in diameter. The Yellowstone caldera is approximately is 50 miles (80 km) long and 40 miles (65 km) wide!

      Points to remember:

      • The demonstration illustrates that fractures develop over time and calderas can form without an eruption
      • Flour fractures and collapses in a similar pattern to rock
      • Most volcanoes have one source of magma, similar to this model
      • Flour is not rock. Rock is much stronger.
      • Magma chambers aren’t really like empty balloons. As magma moves through a magma chamber, it melts the rock, pushes rock out of way, and squeezes into rock cracks. Some of the magma might escape as lava.
      • Magma is very hot, hot enough to melt rock. This demonstration is at room temperature.

      More ideas!

      • Use flour or spackling compound to illustrate other faults and fractures. The model below illustrates regions undergoing extension, creating basin and rangers, such as Nevada and western Utah.
      • To emphasize overall deformation (instead of fracturing and caldera formation), use sand. This works well in an augmented reality sandbox!

      Demonstration Length:

      5 – 20 minutes to demonstrate
      30 minutes to construct

      Major concepts

      • Volcanic craters and calderas can form by the collapse of the rock near the summit without an eruption.
      • Volcanoes inflate (pressurize) and deflate (depressurize) - without necessarily erupting
      • We can understand what’s going on inside a volcano by measuring changes at the surface, even a few millimeters of movement, using GPS.
      • Most craters form slowly over time as the volcano inflates and deflates, deforming and weakening the rocks near the summit.
      • The volcano's magma chamber is made up of sponge-like rock

      Supplies

      • A box, approximately 8” x 8” x 6” (shoe boxes work well or small storage box)
      • 5 - 10 lbs Flour (2 bags of flour works well)
      • Red balloon - small
      • Balloon pump (opt, and worth it)
      • 2 feet of flexible tubing (¼-inch diameter)
      • Duct/ clear tape
      • Gum drops and toothpicks (to make GPS models)

      Assembly

      1. Tape balloon onto tubing and tape tubing firmly to the bottom of container - off center
      2. Attach the other end of the tubing to balloon pump (cut small hole in tubing at the pump to let out air)
      3. Cover balloon with 3-5 inches of flour
      4. For an added touch, make GPS monuments out of toothpicks and gumdrops and place on either side of balloon to measure the inflation and deflation of the volcano.

      Leading the demonstration

      1. Invite visitors to place GPS instruments on flour to measure the inflation and deflation of the volcano
      2. Pump air slowly to inflate the balloon to form radial and ring fractures. Invite visitors to comment on their observations
      3. Let some air after a few pumps out to form a small caldera. Repeat.
      4. While visitors observe; allow the balloon to deflate quickly
      5. Optional: Have visitors measure the distance between the GPS models at various stages while inflating the volcano

      Sample questions to consider

      • What is the first sign the volcano is changing?
      • What patterns do you see in the cracks?
      • Did the GPS instruments change their position?
      • How did the GPS instruments move (farther apart, closer together, up, down?)

Last modified: Tuesday, 11-Apr-2017 23:28:56 UTC

 

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