Volcanologists are scientists who study volcanic eruptions. however, most volcanologists rarely get to witness a volcanic eruptions actually occurring. instead, many volcanologists use models to study volcanic eruptions. what is the most likely reason why volcanologists often rely on models to study volcanic eruptions?

The temperature in the interior of earth is very high and this high temperature causes the rocks in the interior to melt. Hot fluids being less dense than cold fluid rise upwards. Thus the molten rock called magma rises up and gets stored in magma chambers.  

During the time of an eruption the pressure of the dissolved gases in the magma causes it flow out through fissures on mountain surfaces. The thickness of the magma decides the intensity of the volcanic eruption. Gases escape easily through thin magma and the eruption will be slow and less dangerous.  

But if the magma is thick the dissolved gases can’t escape easily and they will build pressure on the magma and it will erupt with very high speeds destroying everything on its way. Thus conducting an experimental study on a volcanic spot is practically impossible.