Try the BUBBLE ESCAPE AND DRAG RACE experiment for yourself - Visit www.esc.cam.ac.uk/ExplosiveEarth to download the "Experiments on Earthquakes and Volcanoes" instruction booklet!

INTRODUCTION:
There are many different types of volcanoes. Shield volcanoes have a broad rounded shape and gentle splattery eruptions often described as fire fountains. Strato volcanoes are sharp and steep sided in shape and have violent explosive eruptions. But what makes these two types of volcano look and erupt so differently? It is mainly controlled by how thick (viscous) or runny the magma in the volcano is…

In this experiment you can you use 3 fluids of different viscosity (thickness) to see what differences runny or thick magma can cause in volcanoes. This experiment can get a bit messy, so make sure you do it somewhere easy to clean up


WHAT'S HAPPENING?
The thick viscous golden syrup is very hard to blow bubbles in, while the runny water is very easy to blow bubbles in and very splattery. This means that when gases come out of magma they find if much harder to escape from thick viscous magma than runny magma. When the gas can’t easily escape from viscous magma, pressure builds up causing explosive eruptions. Gas easily escapes from runny fluid magma causing splattery non-explosive (effusive) eruptions.

The thick viscous golden syrup runs down the slope very slowly, while the runny fluid water runs down very quickly. If this were lava erupted from a volcano, this means that viscous lava couldn’t travel very far from the vent before cooling and solidifying, whereas runny lava can go long distances before cooling. This means that volcanoes with runny lava can create broad shallow sloping volcanoes, whereas volcanoes with thick lava quickly build up steep sides.


Brought to you by the Explosive Earth exhibit team - Royal Society Summer Science Exhibition 2016. Featuring Jenny Jenkins and Jenny Woods. Filmed, directed and edited by Greg Palmer, Tom Merry and Sarah Humbert - University of Cambridge Earth Sciences.

Music: Guatemala - Panama March by Heftone Banjo Orchestra, used under http://creativecommons.org/licenses/b....