Harry Glicken was a 33-year old volcanologist who was killed on 3 June 1991 by a pyroclastic flow on Mount Unzen in Japan, along with 42 other scientists and journalists, including well-known vulcanologists Katia and Maurice Krafft.

On 18 May 1980, the day of the eruption of the Mount St. Helens volcano, Harry Glicken was supposed to be observing the volcano from an observation post 10 km (6 miles) away, but he had to take the day off to attend an interview in a College in California. He was replaced by David A. Johnston, who died shortly after reporting the eruption.