A laboratory volcano: a multi-purpose educational tool for children, the public, and graduate students

Eruption experiments by mixing an acid solution and baking soda have been used to display how a volcanic eruption works. We have upgraded such experiments to include many volcanological components, from magma mixing to eruption and geophysical observations.

 

The essential apparatus configuration contains two plastic beverage bottles, plastic tubes, a plug closing the mouth of the tube, and an air compressor. An innovative element of our experiment is the specifically designed connector that allows two insulated vents (IN and OUT) to be hosted on the bottle cap. The plastic tube connected the compressor to the lower bottle IN, its OUT to the upper bottle IN, and its OUT to the vent. Initially, syrups containing acid and sodium bicarbonate (SB) particles are put in the lower and upper bottles, respectively, simulating basaltic magma in a deep reservoir and crystal-baring silicic magma in a shallow reservoir. The vent is sealed by the plug. The acidic syrup is injected into the SB syrup by the compressor. The mixing of the two syrups generates bubbles and increases the system pressure. When the overpressure exceeds the plug strength, an eruption starts. Various styles and sequences of eruptions are generated depending on the viscosities of the two magmas, the positions of the inlet and outlet of the upper reservoir, the plug strength, and so on. We can also install sensors, such as pressure sensors to measure the system pressure, accelerometers to measure the vibration of the bottles, microphones to measure acoustic waves associated with the eruption, and cameras. The audience can monitor these data in real-time.

 

We use this experiment for various educational needs. Children enjoy watching explosions, fountains, and lava flows. To high-school students and the public, we explain the mechanisms controlling the occurrences and styles of eruptions and the meaning and significance of volcano monitoring. In educating graduate students in volcanology, we let them design the monitoring system and try controlling eruption styles by thinking about their mechanisms. This presentation introduces various eruptions designed by graduate student groups and shows how these experiments are used in education onsite and online.