Activity: Gelatin Volcanoes

Hawai'i Space Grant College, Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, 1996

Gelatin Volcanoes

Purpose

To understand how and why magma moves inside volcanoes.

Key Words

magma

dike

eruption

volcano

lava

rift zone

Materials

Unflavored gelatin, 28 gm (one-ounce) box containing four packages

Spoon

Bowls or bread pans, either one 2-liter (or 2-quart) capacity, or smaller sizes

Red food coloring, to mix with water in a glass to make "magma"

Syringe for injecting magma, best to use a plastic variety found at pet stores for feeding birds

Peg board, 40 x 60 cm, with 5-mm-diameter holes spaced 2.5 cm apart. Or you can use a large, disposable aluminum pan that you've punched holes into.

Two bricks, 30 cm high

Large knife to cut through the gelatin model

Tray, for collecting drips

Rubber gloves (optional) for protecting hands from food coloring

Procedure

1.: Prepare gelatin for the volcano model by mixing two cups of cool water with four packages of unflavored gelatin in a large bowl. Stir for 30 seconds. Then add six cups of boiling water and stir until gelatin is dissolved. Transfer mixture to a 2-liter bowl, smaller bowls, or bread pans. Refrigerate gelatin at least three hours or until set.
2.: Prepare "magma" by mixing water in a glass with enough red food coloring to make a very dark liquid.
3.: Loosen the gelatin by dipping the bowl briefly in a larger bowl of hot water.
4.: Transfer the gelatin upsidedown to the center of the peg board and lift off the bowl. The gelatin cast will settle somewhat after being removed from the bowl. It should resemble a colorless to milky, shimmering volcano. There should be no cracks in the gelatin, but it's OK to proceed if one develops during unmolding.
5.: Place the peg board on top of the two bricks.
6.: Fill a syringe with red water. Remove air bubbles from the syringe by holding it upright and squirting out a small amount of water. Air tends to fracture the gelatin.
7.: Predict what will happen when red water is injected into the gelatin cast. What direction will it go? What shape will it take? Will it erupt through the surface of the gelatin? If so, where?
8.: Insert the syringe through a hole in the peg board into the center of the gelatin cast. Inject the red water slowly, at a rate of about 20 cc/minute, and watch carefully.
9.: Describe how the experimental results compare with your predictions.
10.: Refill and insert the syringe as many times as possible. Compare magma migration each time. Are there differences in the direction the magma takes when the syringe is inserted in different parts of the gelatin cast? Describe and explain what you see.
11.: Looking directly down on the gelatin cast, sketch the positions and shapes of the magma bodies. Label your drawing "Map View."

12.: Use a sharp knife to cut through the gelatin cast. Separate the pieces and examine the cut surfaces. Note the traces made by the magma bodies; these are similar to what we see in highway road cuts or cliff faces.
13.: Sketch the positions and shapes of the magma bodies on a cut face. Lable your drawing "Cross-sectional View."
14.: Compare what you see in two dimensions on the cut face with what you see in three dimensions looking into the gelatin cast. Which view gives you more information. Why?
15.: How and why does magma move through volcanoes?

Extension

1.: Repeat the experiment with an elongated model such as a bread pan. Before injecting the magma, try to predict what will happen. What effect does gelatin shape have on magma movement?

Experimental Setup

Go to Gelatin Volcanoes Teacher pages.

Return to Volcanology Activity Index.

Return to Hands-On Activities home page.
http://www.spacegrant.hawaii.edu/class_acts/