Read the paper: Generation of air lubrication within pyroclastic density currents

When a volcano erupts, pyroclastic flows are often the biggest danger to anyone nearby. These fast-flowing currents of rock, ash and hot gas are extremely difficult to study, so researchers in New Zealand created their own. By closely studying pyroclastic flows in their specially-made lab, they identified a very thin layer of gas that helps explain how this volcanic phenomenon moves so fast and can travel so far.