Volcanic eruptions are dangerous and difficult to predict. A team has found that the ratio of atoms in specific gases released from volcanic fumaroles (gaps in the Earth’s surface) can provide an indicator of what is happening to the magma deep below — similar to taking a blood test to check your health. This can indicate when things might be ‘heating up.’ Specifically, changes in the ratio of argon-40 and helium-3 can indicate how frothy the magma is, which signals the risk of different types of eruption. Understanding which ratios of which gases indicate a certain type of magma activity is a big step. Next, the team hopes to develop portable equipment which can provide on-site, real-time measurements for a 24/7 volcanic activity monitoring and early warning system.