• Question: why do volcanos erupt ?? I was wondering

    Asked by anon-189942 to Matt, Maia, Lyndsay, Liam, Dionne, Brendan on 8 Nov 2018.
    • Photo: Matt Bower

      Matt Bower answered on 8 Nov 2018:

      Good question! I think molten rock (magma) flowing within the Earth builds up at certain points – once the pressure of magma gets to a certain point, it reaches the surface and erupts through the volcano. Some volcanoes erupt regularly, but others almost never.

    • Photo: Dionne Turnbull

      Dionne Turnbull answered on 8 Nov 2018:

      There is a lot of gas involved! Bubbles form in the molten rock, and this gas exerts a lot of pressure – the bubbles force their way out taking a lot of lava along in the process. Its a bit like shaking a bottle of fizzy juice… when you open it, its not just the bubbles that come out but a lot of the liquid too!

    • Photo: Liam Taylor

      Liam Taylor answered on 9 Nov 2018:

      I love this! To follow on from what Matt and Dionne have said, there are loads of different types of volcanoes too! The stuff that is coming out of the volcano is actually liquid rock (imagine being so hot that even rocks are melting!). Where there isn’t much gas, and the rock is a certain type, the liquid rock (magma) sort of dribbles out and it happens almost every day. Where there is lots of gas, and the rock is a different type….. BOOM! Those are the ones that don’t erupt very often, but when they do…. they’re quite spectacular!

    • Photo: Brendan Marrinan

      Brendan Marrinan answered on 9 Nov 2018:

      Everyone else seems to have pretty much covered this one…..build up of pressure, molten rock (magma) than when it comes out of the ground becomes lava. Well done team.

      I’ll throw some interesting volcano facts at you instead:
      – Most volcanoes happen at the edge of tectonic plate boundaries where the pressure is greatest.
      – Volcanoes have three ages: Active (where they erupt a lot), Dormant (where they only erupt sometimes) and Extinct (where there is no magma chamber under the volcano).
      – Dormant Volcanoes are the ones that are the most catastrophic, between eruptions the hole at the top is sealed so the pressure builds up inside the volcano and when that gets too high the volcano can explode (look up Mt St Helens in America).

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