Calderas in the sandpit
In this activity, students pop a balloon in a container of sand to model caldera volcanoes and learn how lakes like Taupō and Rotorua were formed.
Modelling a caldera formation
Use a balloon, which represents an exploding magma chamber, to model a caldera formation.
By the end of this activity, students should be able to:
demonstrate how caldera volcanoes are formed
demonstrate how depressions are left after the volcano erupts
identify Lakes Taupō and Rotorua and discuss their formation.
Download the Word file for:
introduction/background notes
what you need
what to do
extension idea.
Related content
Watch this animated video to see how Lake Rotorua could have formed from a caldera eruption.
Researchers discovered that the large underwater Hunga Tonga–Hunga Haʻapa volcano had a hidden caldera 150 m below the waves. Read about the devastating volcanic eruption in January 2022, the tsunami that followed, and what we might expect next. Find out what scientists have discovered a year after this eruption in this article.
Extension ideas
If students enjoyed making models of caldera volcanoes, try the Making a model of a cinder cone activity.
Make the connection between volcanic activity and tsunamis with the activity Tsunamis in the sandpit.
Useful link
For more fun in the sandpit, watch volcano expert Dr Ben Kennedy demonstrate how subsidence craters form. Magma leaks out sideways and the summit of the volcano sinks to form a crater.
Calderas in the soil
Students bury the balloon in the sandpit or in a bucket of sand or soil. Students pop the balloon – this represents the eruption – and then view the caldera or crater that is left behind.
