Escaping Steam: Fumaroles

Ever wonder why some fumaroles produce large amounts of steam, while others produce very little? Try out this experiment to find out one of the reasons! This experiment requires adult help and supervision.

Materials:

• Medium saucepan
• Water
• Disposable tin pie pan
• Hammer
• Nail
• Oven mitts
• Stove or hot plate

What To Do:

1. Fill the saucepan about half full with water and place it on the stove. Heat it until the water is steaming but not boiling.
2. While waiting for the water to heat, take the pie pan and turn it upside down. Use the hammer and nail to gently put a small hole in the center of the pan.
3. Put the oven mitts on and place the pan right side up over the pot. What does the steam do?
4. Still wearing the oven mitts, take the pie pan off towards you so that it makes a shield between you and the steam. Never lift the pan off away from you, or the escaping steam may burn you!
5. Turn the pan over again and gently hammer another hole into the bottom of the pan, about an inch away from the first hole.
6. Place the pan on the pot again. What do you see happening to the steam?
7. Continue this cycle about 4 or 5 times, adding one more nail hole with each new cycle. What do you notice happening to the steam with each new hole in the pan?

What's Happening?

In this experiment, you were demonstrating how fumaroles work. A fumarole is a vent (hole) that lets out steam from within the Earth. The holes in the tin pan are simulating how steam escapes the Earth. When there is just one hole or fumarole, steam only has one exit, causing it to exit quickly and forcefully. Sometimes, the amount of steam coming out of one fumarole becomes too much for it, and the steam will follow cracks in the Earth to a new place to vent out of the surface. This formation of a new fumarole causes the pressure of the steam to ease up a bit, and the escaping steam comes out less quickly and less forcefully from both fumaroles. The more fumaroles present, the less pressure the steam is under. Later on in the life of these fumaroles, the steam escaping may decrease due to not enough water and/or a decrease in the heat from the underground magma chamber, causing smaller steaming vents.

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