Abstract
Geochemists often describe volcanic gases in the words of Sadao Matsuo, as “telegrams from the Earth’s interior”. Yet after a hundred years of dedicated research, we still have major difficulties reading and understanding these telegrams. In this presentation, I will give an overview of some of the major breakthroughs (including very recent ones) in our quest to understand what the geochemistry of volcanic gases tells us and how they can be used for volcano monitoring.