Explosive eruptions are normally driven by molten rock rising, or steam expanding, however those processes couldn’t explain these particular eruptions.

Josh Crozier and colleagues instead suggest that a mechanism similar to a stomp-rocket toy might be the answer.

The researchers used geophysical data to determine the magma reservoir’s pressure changes and used 3D models to simulate the ascent of the eruptive plume.

Crozier and colleagues suggest that observations of the eruptions are consistent with the collapse of the magma reservoir suddenly increasing the pressure of gas trapped in the chamber and leading to the explosive eruption.