Plato (428–348 BC) Pliny the Elder (23–79 AD) Pliny the Younger (61 – c. 113 AD) George-Louis Leclerc, Comte de Buffon (1707–1788) James Hutton (1726–1797) Déodat Gratet de Dolomieu (1750–1801) George Julius Poulett Scrope (1797–1876) Giuseppe Mercalli (1850–1914) Alfred Lacroix (1863–1948) Frank A. Perret (1867–1943) Thomas Jaggar (1871–1953), founder of the Hawaiian Volcano Observatory Alfred Rittmann (1893–1980) Sigurður Þórarinsson (1912–1983), Haroun Tazieff (1914–1998), advisor to the French Government and Jacques Cousteau George P. L. Walker (1926–2005), pioneering volcanologist who transformed the subject into a quantitative science Katia and Maurice Krafft (1942–1991 and 1946–1991, respectively), died at Mount Unzen in Japan, 1991 Peter Francis (1944–1999) David A. Johnston (1949–1980), killed during the 1980 eruption of Mount St. Helens Harry Glicken (1958–1991), died at Mount Unzen in Japan by Pyroclastic flow, 1991