Daniel J. Johnson
Dan Johnson, a.k.a. “DJ,” died tragically in an auto accident on October 4, 2005 while working in the field – something he truly enjoyed. His excitement and interest in volcanoes was infectious, and his loss leaves a tremendous void in the volcanological community. Admired by his colleagues, Dan made important contributions to volcano science, while brightening the spirits of his companions and never taking himself too seriously.
Dan began his career in volcano geodesy as an undergraduate at the University of Puget Sound in 1979, participating in a deformation and gravity change study at Pacaya volcano in Guatemala. Just a year later, he was an integral part in the response to the reawakening of Mount St. Helens. DJ helped establish a dry-tilt station, locate a critical EDM benchmark, and conduct water-level measurements at Spirit Lake to determine ground tilt prior to the May 18, 1980 eruption. Upon graduation from UPS in 1981, Dan worked for the fledgling Cascades Volcano Observatory as a Physical Science Technician, installing tiltmeters and conducting gravity surveys in the crater of Mount St. Helens and becoming experienced in the monitoring of other Cascade volcanoes. Even as he worked with the U.S. Geological Survey, Dan pursued a doctorate at the University of Hawaii, which be obtained in 1986. His research used gravity and deformation measurements to model the magma plumbing system beneath Kilauea volcano, and set a high standard for subsequent gravity investigations on other active volcanoes. Dan also made pioneering contributions on the feedback between pressure and volume changes in vesiculated magma, and how those effects can be studied with gravity and deformation measurements. DJ was always at the leading edge of technological advancements, becoming an authority on the application of the Global Positioning System (GPS) to Earth science problems and even tackling such complex issues as whole-Earth geodetic reference frames. While working at Central Washington University, Dan was a pivotal member of the team that characterized episodic tremor and slip events in Cascadia. Most recently, DJ was involved in gravity and deformation measurements in the Galapagos archipelago and at South Sister volcano in Oregon.
DJ’s enthusiasm and commitment to science and discovery were unparalleled. He worked tirelessly in the field, driven by his love for volcanoes and the process of discovery, and unencumbered by the need for recognition that drives many scientists. Dan delighted in being unpredictable and his quirky sense of humor made him a popular member of field crews. Around the campfire or on the trail, DJ energized his compatriots with hilarious anecdotes of his own off-beat experiences from work in various parts of the world.
This volume contains a paper coauthored by Dan on geodetic measurements in the Galapagos. That research, which combined daunting field work with quantitative assessments of GPS and gravity data, epitomizes DJ’s scientific skills and contributions to volcanology. Dan will be sorely missed. We hope that the dedication of this issue to DJ will honor his spirit and accomplishments – a fitting tribute to the memory of a wonderful scientist and friend.