• Question: What are volcanic plugs?

    Asked by megansaurus to Davie, Gemma, James P, James V, Nuala on 28 Jun 2012.
    • Photo: James Verdon

      James Verdon answered on 28 Jun 2012:

      Hi megan,
      Volcanic plugs are bits of left-over magma that block up volcanic vents. They are more common in volcanoes with sticky magma. Not all of the magma is forced through the vent during the eruption, and the bit that is left behind hardens and solidifies in the vent, blocking it. This means that for the next eruption, pressure builds up below the plug until the pressure is sufficient to blow the plug out of the way, leading to an explosive eruption.

    • Photo: James Pope

      James Pope answered on 28 Jun 2012:

      Hi megansaurus,

      I think (maybe James V can confirm) that the volcanic plug is all that remains of the volcano that existed in what is now Edinburgh 300 million years ago, which the people of Edinburgh call Arthurs Seat.

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