One billion people currently live within 150 kilometers of active volcanos. Ample warnings are needed when an eruption is imminent to safeguard human lives as well as prevent damage to infrastructure, such as supply chains. To get advance warning of an eruption, we can monitor the flux of volatile species, like He, CO2, CO, SO2, H2S and HCl that are emitted by volcanos, which all send important clues. Besides the amount of those gases, isotope composition is also an important parameter. Learn more.