A volcanologist is a geologist who studies the processes involved in the formation and eruptive activity of volcanoes and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra (such as ash or pumice), rock and lava samples. One major focus of enquiry is the prediction of eruptions; there is currently no accurate way to do this, but predicting eruptions could alleviate the impact on surrounding populations.
- David A. Johnston, killed during the 1980 eruption of Mount St. Helens (1949–1980)
- Déodat Gratet de Dolomieu (1750–1801)
- Georges-Louis Leclerc, Comte de Buffon (1707–1788)
- George Patrick Leonard Walker (1926–2005)
- Katia and Maurice Krafft (1942–1991 and 1946–1991, respectively)