Ash plumeMany of Europe’s travellers got very angry yesterday (and it looks like are going to be for a while yet) as their flights were grounded due to the enormous ash cloud caused by the eruption of Icelandic volcano Eyjafjallajoekull (extra marks shall be awarded for correct pronunciation).

Volcanologists have had an idea that this could happen for a while now, as this eruption is essentially the same as the one that happened in March.  It’s just that the lava has found a new opening to emerge through.  The bad news is that there may be another, larger eruption after this one as the lava finds yet another fissure.  This is a worst case scenario, so let’s just hope that it doesn’t happen.

All of this talk of volcanoes gives lots of opportunities for use in the classroom. As it’s the ash that is big news, it would be worth looking at why volcanoes release so much.  It’s all to do with pressure and the explanation of why ash is made is a good way of applying the science of gas pressure.

Volcanoes are places on Earth where molten rock called magma escapes.  Magma resides in chambers deep within the Earth’s crust, so it is kept at a high pressure.  Gases in the magma are kept dissolved because of this pressure – like carbon dioxide in a bottle of fizzy drink.

Students could then be asked to predict what will happen to the gas as the magma rises upwards during the eruption.  When the magma rises during an eruption the pressure decreases, which causes the gases to form bubbles and fizz.  This is also seen when the bottle of fizzy drink is opened. This causes a violent spray of magma, which solidifies as it meets the cool air, forming tiny fragments of cooled rock – ash.  The violent explosion also blasts small bits of rock away from the inside of the volcano – more ash.

If you want to demonstrate a volcano in the classroom, shaking up a bottle of fizzy drink and then opening it is a much better model than the traditional baking powder and vinegar one.  In fact, showing both models could lead to a good discussion on the strengths and weaknesses of each.

The video below would be a good starter to any lesson based on this eruption, as it shows the ominous approach of the black ash cloud towards Britain.

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