: The amount of magma in a volcano controls the volume of an eruption, according to a new study
published in Nature Geoscience
. Using computer models and simulations, Luca Caricchi of the University of Geneva and colleagues studied temperature, pressure, and other factors involved when a volcano erupts. They found that big eruptions and smaller eruptions are caused by different processes. Smaller eruptions, which occur more frequently, are triggered by a buildup of pressure as magma fills an underground chamber. Larger eruptions, however, involve magma chambers too large to explode because of magma injections. Rather, the magma, which is less dense and more buoyant than the surrounding rock, accumulates until enough rises to the top of the chamber to burst it open.