• Question: Why does the lava goes up when it errupts?

    Asked by to Becky on 24 Jun 2014. This question was also asked by .
    • Photo: Rebecca Williams

      Rebecca Williams answered on 24 Jun 2014:

      Hi Claudia,
      Volcanoes erupt because the magma inside the volcano starts letting its gas out in bubbles. This makes a magma foam. Think about shaking up a fizzy drink and then opening a lid – you can make a foam too. This foam is less dense than the surrounding fizzy drink, so it rises upwards and bursts out of your bottle. The same thing happens in volcanoes – the magma foam is less dense than the surrounding magma to it rises upwards and bursts out the top of the volcano.

      Not all eruptions go upwards though. The Mt ST Helens eruption in 1980 happened when an avalanche took off the side of the volcano. As you can see in these pictures here, this forced the eruption to come out of the volcano sideways

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