David Alexander Johnston was an American volcanologist with the United States Geological Survey (USGS) who was killed by the 1980 eruption of Mount St. Helens in Washington. One of the principal scientists on the monitoring team, Johnston died while manning an observation post about 6 miles (10 km) from the volcano on the morning of May 18, 1980. He was the first to report the eruption, transmitting the message "Vancouver! Vancouver! This is it!" before being swept away by the lateral blast created by the collapse of the mountain's north flank. Though Johnston's remains have never been found, remnants of his USGS trailer were found by state highway workers in 1993. Johnston's comprehensive, although truncated, career took him across the United States, where he studied Augustine Volcano in Alaska, the San Juan volcanic field in Colorado, and long-extinct volcanoes in Michigan. Johnston was a meticulous and talented scientist who was known for his analyses of volcanic gases and their relationship to eruptions. This, along with his enthusiasm and positive attitude, made him liked and respected by many of his co-workers. After his death, other scientists lauded his character both verbally and in dedications and letters. Johnston felt that scientists must do what is necessary, including taking risks, to help protect the public from natural disasters. His work and that of his fellow USGS scientists convinced the authorities to close Mount St. Helens to the general public prior to the 1980 eruption, and to maintain the closure in spite of heavy pressure to re-open the area; their work saved thousands of lives. His story has become part of the popular image of volcanic eruptions and their threat to society, and also part of the history of volcanology. To date, Johnston is one of just two American volcanologists known to have been killed in volcanic eruptions. Following his death, Johnston was commemorated in several ways, including a memorial fund set up in his name at the University of Washington to fund graduate-level research. Two volcano observatories were established and named after him: one in Vancouver, Washington, and the other on the ridge where he died. Johnston's life and death have been featured in several documentaries, films, docudramas and books about the eruption. Along with other people killed by the volcano, Johnston's name is inscribed on memorials dedicated to their memory.