What was it like deep in the magma chamber when the pumice formed? What was the temperature? What was the pressure?
We experiment with different conditions until we have re-created the same rock. Then, we will know more about what it was like deep inside the magma chamber, before the volcano erupted.
FIRST, we prepare a mini-magma chamber
We combine all of the ingredients needed to make our own rock.
SECOND, we turn it into magma...and make a rock!
We put our capsule, or mini-magma chamber, under some pretty extreme conditions.
If it has the same amount of gas as the original rock, we know we chose the right temperature and pressure. If not, we try again.
It can take many experiments to discover the same conditions as the original magma chamber. But, every time that we do it, we are learning more about what makes volcanoes explode.